Lightening compositions and use of compounds as depigmenting agents

Abstract

The present invention relates to a lightening composition comprising a lightening effective amount of a compound of formula (I), or a tautomer, a stereoisomer, a hydrate, a solvate, a salt, or a polymorph thereof, wherein R1, R2, R3, R4, R5, R6, R7, m and n are as defined in the description and claims. The present invention also relates to a compound of formula (I2) or a tautomer, a stereoisomer, a hydrate, a solvate, a salt, or a polymorph thereof, wherein R1, R2, R3, R4, R5, R6, and R7 are as defined in the description and claims. The present invention also relates to the use of at least one compound of formula (I) or any subgroup thereof, or mixtures thereof, as depigmenting agent. The present invention also relates to the use of at least one compound of formula (I) or any subgroup thereof, or the use of the lightening composition, for preventing and / or reducing pigmentation of normal skin. The present invention also relates to the use of at least one compound, or the use of the lightening composition according to the first aspect, for decreasing the amount of melanin in melanocytes, for decreasing melanin synthesis, for impairing melanin transport and / or for impairing the distribution of melanin in suprabasal layers.

Description

[0001]LIGHTENING COMPOSITIONS AND USE OF COMPOUNDS AS DEPIGMENTING AGENTS FIELD OF INVENTION The present invention relates to compositions and compounds able to modulate skin pigmentation as well as the use thereof to induce a decrease of melanin content in skin and thus induce a depigmenting or a lightening effect of the skin. BACKGROUND OF THE INVENTION Melanins are predominantly indolic polymers that serve as the major pigment present in vertebrate skin, hair, fur and feathers. Melanin has many interesting properties, among which its ability to absorb ultraviolet light (sunlight or other light sources) and prevent DNA damages. Two types of melanin co-exist: eumelanin- brown-black insoluble polymer- and pheomelanin - red-yellow soluble polymer. Eumelanin is the major type in individuals with dark skin / hair and is more efficient in photoprotection. Skin has epidermal components that are responsible for melanin synthesis (melanocytes) and distribution (keratinocytes). Melanin biogenesis, called melanogenesis, occurs in melanosomes, a specialized lysosome-related organelle, present in melanocytes. This complex process includes different stages and starts from an oxidation of amino acid L- Tyrosine. Once synthesized, the melanin is transferred via cellular extensions (dendrites) of the melanocytes to the neighboring keratinocytes, the major cell type present in the epidermis (30-40 keratinocytes for 1 melanocyte). Many factors are known as regulators of melanin synthesis but the most common is ultraviolet light exposure or Ultraviolet Radiation (UVR) that leads to sun-tanning, using either natural sunlight or ultraviolet light sources such as tanning lamps. Nowadays, skin whitening is a popular trend in many parts of the world because it is often associated with notions of beauty, youth, and success. In some cultures, fair skin is viewed as a symbol of higher social status and is often seen as more desirable than darker skin tones. Moreover, some non-pathologic melanin spots on the skin, such as freckles or melasma can be viewed as unaesthetic and their attenuation or suppression can be desired by concerned persons. Additionally, media and advertising play a significant role in promoting the idea that lighter skin is more beautiful and desirable. Many beauty products, such as skin lightening creams, are heavily marketed to consumers, particularly in Asia and Africa. However, it's worth noting that skin whitening products can be dangerous and have been linked to various health issues, such as skin cancer, liver damage, and mercury poisoning. Among the skin-lightening and depigmenting agents, magnesium-l-ascorbyl-2-phosphate (MAP), hydroxyanisole, N-acetyl-4-S-cysteaminylphenol, arbutin (hydroquinone-beta-d- glucopyranoside, kojic acid, arbutin, catechins and azelaic acid (Maeda and Fukuda, 1996; Katagiri et al., 1998) are the most widely used worldwide. Different reports show their potential as mutagenicity agents and, it’s now clear that their uses are associated to epidemics of ochronosis in African nations for examples. For the above reasons, it clearly appears that finding alternative new efficient and non-cytotoxic depigmenting agents is a public health priority. The present invention addresses these needs and prioritize efficient, healthy, and safe practices when it comes to skin care and beauty. SUMMARY OF THE INVENTION The present invention provides lightening compositions comprising lightening compounds that can induce depigmentation / lightening of the skin. In particular, in a first aspect, the present invention provides a lightening composition comprising a lightening effective amount of a compound of formula (I), or a tautomer, a stereoisomer, a hydrate, a solvate, a salt, or a polymorph thereof, wherein n is an integer selected from 0, 1, or 2, m is an integer selected from 1, 2, or 3; R1is selected from the group comprising alkynyl, alkyl, hydrogen, and alkenyl; wherein each of said alkynyl, alkyl, and alkenyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R2is selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy, or R1and R2together with the carbon atoms to which they are attached can form a cycloalkyl, a cycloalkenyl or a cycloalkynyl, wherein each of said cycloalkyl, cycloalkenyl and cycloalkynyl can be unsubstituted or substituted with one or more substituents R8, wherein each R8is independently selected from the group comprising alkyl, alkenyl, alkynyl, hydroxyl, halo, haloalkyl, and haloalkoxy; each R3is independently selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl, and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; each R4is independently selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R5is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R6is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R7is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy. Preferably, the present invention provides a lightening composition comprising a lightening effective amount of a compound of formula (I), or a tautomer, a stereoisomer, a hydrate, a solvate, a salt, or a polymorph thereof, wherein n is an integer selected from 0, 1, or 2, m is an integer selected from 1, 2, or 3; R1is selected from the group comprising alkynyl, alkyl, hydrogen, and alkenyl; wherein each of said alkynyl, alkyl, and alkenyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R2is selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy, or R1and R2together with the carbon atoms to which they are attached can form a cycloalkyl, a cycloalkenyl or a cycloalkynyl, wherein each of said cycloalkyl, cycloalkenyl and cycloalkynyl can be unsubstituted or substituted with one or more substituents R8, wherein each R8is independently selected from the group comprising alkyl, alkenyl, alkynyl, hydroxyl, halo, haloalkyl, and haloalkoxy; each R3is independently selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl, and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; each R4is independently selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R5is hydrogen; R6is hydrogen; and R7is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy. The present invention also provides, in a second aspect a compound of formula (I2) or a tautomer, a stereoisomer, a hydrate, a solvate, a salt, or a polymorph thereof, wherein R1is alkynyl; wherein said alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R2is selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R3is independently selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl, and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R4is independently selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R5is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R6is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; and R7is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy. Preferably, the present invention provides a compound of formula (I2) or a tautomer, a stereoisomer, a hydrate, a solvate, a salt, or a polymorph thereof, wherein R1is alkynyl; wherein said alkynyl is substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R2is selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R3is independently selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl, and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R4is independently selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R5is hydrogen; R6is hydrogen; R7is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy. The present invention also provides the use of at least one compound as defined in the first or second aspects, or a stereoisomer, tautomer, salt, and / or solvate thereof, including mixtures thereof, as depigmenting agent. The present invention also provides the use of at least one compound as defined in the first or second aspects, or the use of the lightening composition according to the first aspect, for preventing and / or reducing pigmentation of normal skin. The present invention also provides the use of at least one compound as defined in the first or second aspects, or the use of the lightening composition according to the first aspect, for decreasing the amount of melanin in melanocytes, for decreasing melanin synthesis, for impairing melanin transport and / or for impairing the distribution of melanin in suprabasal layers. The present invention also encompasses a method for decreasing the amount of melanin in melanocytes, for decreasing melanin synthesis, for impairing melanin transport and / or for impairing the distribution of melanin in suprabasal layers comprising applying at least one compound as defined in the first or second aspects, or the lightening composition according to the first aspect. The compounds and compositions as defined herein can therefore be used to decrease melanin synthesis in melanocytes thereby decreasing the melanin content, and thus decreasing subject pigmentation such as skin pigmentation. The melanocytes that are in contact with the compounds of invention may be present in vertebrate skin. The present compounds and compositions thereof can induce depigmentation of the skin in a safe manner. A decrease of melanin in the skin can therefore be induced, thereby preventing skin hyperpigmentation, formation of age spots, freckles and melasma for example, preferably in a non-therapeutic manner. Given the importance of the use of depigmenting agents in Africa and Asia and their actual consequences (ochronosis, cancer, liver damages for examples), the present invention would allow a safer way of depigmenting skin and avoid actual deleterious side-effects observed with the known depigmenting agents. The above and other characteristics, features, and advantages of the present invention will become apparent from the following detailed description, which illustrate, by way of example, the principles of the invention. BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a schematic representation of the ex vivo treatment schedule of skin explants with the tested compounds . Black-filled cells in the table represent the action performed according to the first column indication during the time course of the experiment (from day 0 to day 6). Figure 2A represents a graph plotting the effects of tested compounds on the survival of skin explants obtained from donor 1 (MTT assay, see Protocols section). Results are expressed as average of the absorbance / weight values + / - SEM of 6 measurements: n=6 on 2 biopsies. DMSO (vehicle) and Kojic acid 0.5% correspond to controls. Untreated skin explants are the reference and represent 100% viability. Figure 2B represents a graph illustrating the effects of 2-ethyl fenchol, Terranol, 2-ethynyl- 5-isopropyl-1,3-dimethylbicyclo[3.2.1]octan-2-ol (CC001) and 2-(3-hydroxyprop-1-yn-1-yl)- 1,3,3-trimethylbicyclo[2.2.1]heptan-2-ol (CC002) on the survival of skin explants obtained from donor 2 (MTT assay, see Protocols section). DMSO (vehicle) and Kojic acid 0.5% correspond to controls. Results are expressed as average of the absorbance / weight values + / - SEM of 6 measurements: n=6 on 2 biopsies. Untreated skin explants are the reference and represent 100% viability. Figure 3A shows representative pictures of explants, stained with the Trichrome Masson, Goldner variant method, showing the effect of the tested compounds on the pigmentation of human skin living explants. Biopsies were treated topically for 6 days with 300µM, 1mM and 3mM of 2-ethyl fenchol. Untreated, DMSO, and Kojic acid 0.5% correspond to controls. The * corresponds to the basal layers where melanocytes are located. Figure 3B represents a graph illustrating the effects of different concentrations of 2-ethyl fenchol on the intracellular content of melanin in melanocytes present in the basal layer of the skin living explants from different donors. DMSO and Kojic acid 0.5% correspond to controls. Results are represented as average of relative values of the melanin content in the untreated condition + / - SEM of 10 measurements: n=10. Figure 3C shows representative pictures of explants, stained with the Trichrome Masson, Goldner variant method, showing the effect of the tested compounds on the pigmentation of human skin living explants. Biopsies were treated topically for 6 days with Terranol 1mM and 2-ethynyl-5-isopropyl-1,3-dimethylbicyclo[3.2.1]octan-2-ol (CC001) 1 mM. Untreated, DMSO (vehicle), and Kojic acid 0.5% correspond to controls. The * corresponds to the basal layers where melanocytes are located. Figure 3D represents a graph illustrating the effects of Terranol, and 2-ethynyl-5-isopropyl- 1,3-dimethylbicyclo [3.2.1]octan-2-ol (CC001) on the intracellular content of melanin in melanocytes located in the basal layer of the skin explants from donor 2. DMSO (vehicle) and Kojic acid 0.5% correspond to controls. Results are represented as average of pigmentation scores + / - SEM of 10 measurements: n=10. The melanin content in the untreated condition was considered as 100%; * p<0.05 and **p<0.01. Figure 3E represents a graph illustrating the effects of Terranol, 2-ethynyl-5-isopropyl-1,3- dimethylbicyclo[3.2.1]octan-2-ol (CC001) and 2-(3-hydroxyprop-1-yn-1-yl)-1,3,3- trimethylbicyclo[2.2.1]heptan-2-ol (CC002) on the intracellular content of melanin in melanocytes located in the basal layer of the skin explants from donor 3. DMSO (vehicle) and Kojic acid 0.5% correspond to controls. Results are represented as average of pigmentation scores + / - SEM of 10 measurements: n=10. The melanin content in the untreated condition was considered as 100%, **p<0.01. Figure 3F shows representative pictures of explants stained with the Trichrome Masson, Goldner variant method, showing the effect of 2-(3-hydroxyprop-1-yn-1-yl)-1,3,3- trimethylbicyclo[2.2.1]heptan-2-ol (CC002) at 1 mM on the pigmentation of human skin living explants of donor 3. Biopsies were treated topically for 6 days with CC002 at 1 mM. Untreated, vehicle (DMSO) and Kojic Acid 0.5% correspond to controls. The * corresponds to the basal layers where melanocytes are located. DETAILED DESCRIPTION OF THE INVENTION When describing the invention, the terms used are to be construed in accordance with the following definitions, unless a context dictates otherwise. Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention. When describing the compounds, compositions, methods and uses of the invention, the terms used are to be construed in accordance with the following definitions, unless the context dictates otherwise. Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some, but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. As used herein, the singular forms "a", "an", and "the" include both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a compound" means one compound or more than one compound. The terms "comprising", "comprises" and "comprised of" as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. It will be appreciated that the terms "comprising", "comprises" and "comprised of" as used herein comprise the terms "consisting of", "consists" and "consists of". The recitation of numerical ranges by endpoints includes all integer numbers and, where appropriate, fractions subsumed within that range (e.g. 1 to 5 can include 1, 2, 3, 4 when referring to, for example, a number of elements, and can also include 1.5, 2, 2.75 and 3.80, when referring to, for example, measurements). The recitation of end points also includes the end point values themselves (e.g. from 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all sub-ranges subsumed therein. The term "and / or" where used herein is to be taken as specific disclosure of each of the two specified features or components with or without the other. Thus, the term "and / or" as used in a phrase such as "A and / or B" herein is intended to include "A and B," "A or B," "A" (alone), and "B" (alone). Likewise, the term "and / or" as used in a phrase such as "A, B, and / or C" is intended to encompass each of the following aspects: A, B, and C; A, B, or C; A or C; A or B; B or C; A and C; A and B; B and C; A (alone); B (alone); and C (alone). Whenever the term “substituted” is used in the present invention, it is meant to indicate that one or more hydrogens on the atom indicated in the expression using “substituted” is replaced with a selection from the indicated group, provided that the indicated atom’s normal valency is not exceeded, and that the substitution results in a chemically stable compound. Where groups can be substituted, such groups may be substituted with one or more, and preferably one, two or three substituents. The term “halo” or “halogen” as a group or part of a group is generic for fluoro, chloro, bromo, iodo. The term “hydroxyl” or “hydroxy” as used herein refers to the group -OH. The term "alkyl" as a group or part of a group, refers to a hydrocarbyl group of formula CnH2n+1wherein n is a number greater than or equal to 1, with no site of unsaturation. Alkyl groups may be linear or branched and may be substituted as indicated herein. Generally, alkyl groups can comprise from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, more preferably from 1 to 6 carbon atoms, more preferably from 1 to 4 carbon atoms. When a subscript is used herein following a carbon atom, the subscript refers to the number of carbon atoms that the named group may contain. For example, the term "C1-6alkyl", as a group or part of a group, refers to a hydrocarbyl group of formula CnH2n+1 wherein n is a number ranging from 1 to 6. Thus, for example, “C1-6alkyl” includes all linear or branched alkyl groups with between 1 and 6 carbon atoms, and thus includes methyl, ethyl, n-propyl, i-propyl, butyl, and its isomers (e.g., n-butyl, i-butyl, and t-butyl); pentyl and its isomers, hexyl, and its isomers, etc. For example, C1-4alkyl includes all linear or branched alkyl groups having 1 to 4 carbon atoms, and thus includes for example methyl, ethyl, n-propyl, i-propyl, 2-methyl-ethyl, butyl, and its isomers (e.g., n-butyl, i-butyl, and t-butyl), and the like. In particular embodiments, the term alkyl refers to C1-12alkyl (C1-12 hydrocarbons), yet more in particular to C1-10alkyl (C1-10 hydrocarbons), yet more in particular to C1-9alkyl (C1-9 hydrocarbons), yet more in particular to C1-6alkyl (C1-6 hydrocarbons) as further defined herein above. Non-limiting examples of alkyl include methyl, ethyl, 1-propyl (n-propyl), 2-propyl (iPr), 1-butyl, 2-methyl-1-propyl(i-Bu), 2- butyl (s-Bu), 2-dimethyl-2-propyl (t-Bu), 1-pentyl (n-pentyl), 2-pentyl, 3-pentyl, 2-methyl-2- butyl, 3-methyl-2-butyl, 3-methyl-1-butyl, 2-methyl-1-butyl, 1-hexyl, 2-hexyl, 3-hexyl, 2-methyl- 2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl, 3-methyl-3-pentyl, 2-methyl-3-pentyl, 2,3- dimethyl-2-butyl, 3,3-dimethyl-2-butyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, and n-icosyl. The term “alkenyl” as a group or part of a group, refers to an unsaturated hydrocarbyl group which may be linear, or branched, comprising one or more with at least one site (usually 1 to 3, preferably 1) of unsaturation, namely at least one sp2carbon-sp2carbon double bond. Generally, alkenyl groups can comprise from 2 to 12 carbon atoms, preferably from 2 to 10 carbon atoms, preferably from 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms. When a subscript is used herein following a carbon atom, the subscript refers to the number of carbon atoms that the named group may contain. Examples of C2-6alkenyl groups are ethenyl, 2-propenyl, 2-butenyl, 3-butenyl, 2-pentenyl and its isomers, 2-hexenyl and its isomers, 2,4-pentadienyl, and the like. The double bond may be in the cis or trans configuration. The term “alkynyl” as a group or part of a group, refers to a branched or straight chain hydrocarbon comprising at least one site (usually 1 to 3, preferably 1) of unsaturation, namely a sp1carbon-sp1carbon triple bond. In particular embodiments, the term alkynyl refers to C2-12alkynyl (C2-12hydrocarbons), preferably to C2-9alkynyl (C2-9hydrocarbons) yet more preferably to C2-6alkynyl (C2-6hydrocarbons) as further defined herein above with at least one site (usually 1 to 3, preferably 1) of unsaturation, namely at least one sp1carbon-sp1carbon triple bond. Examples of alkynyl include but are not limited to: ethynyl (-C ^CH), 3-ethyl-cyclohept-1- ynylene, and 1-propynyl (propargyl, -CH2C ^CH). The term “cycloalkyl”, as a group or part of a group, refers to a cyclic alkyl group, that is a monovalent, saturated, hydrocarbyl group having 1 or more cyclic structure, and comprising from 3 to 20 carbon atoms, more preferably from 3 to 10 carbon atoms, more preferably from 3 to 8 carbon atoms; more preferably from 3 to 6 carbon atoms. Cycloalkyl includes all saturated hydrocarbon groups containing one or more rings, including monocyclic, bicyclic groups or tricyclic. For example, cycloalkyl comprises a C3-10monocyclic or C7-18polycyclic saturated hydrocarbon, such as for instance cyclopropyl, cyclobutyl, cyclopentyl, cyclopropylethylene, methylcyclopropylene, cyclohexyl, cycloheptyl, cyclooctyl, cyclooctylmethylene, norbornyl, fenchyl, trimethyltricycloheptyl, decalinyl, adamantyl and the like. The further rings of multi-ring cycloalkyls may be either fused, bridged and / or joined through one or more spiro atoms. When a subscript is used herein following a carbon atom, the subscript refers to the number of carbon atoms that the named group may contain. For example, the term “C3-10cycloalkyl”, refers to a cyclic alkyl group comprising from 3 to 10 carbon atoms. For example, the term “C3-8cycloalkyl”, refers to a cyclic alkyl group comprising from 3 to 8 carbon atoms. For example, the term “C3-6cycloalkyl”, refers to a cyclic alkyl group comprising from 3 to 6 carbon atoms. For the avoidance of doubt, fused systems of a cycloalkyl ring with a heterocyclic ring are considered as heterocycle irrespective of the ring that is bound to the core structure. Fused systems of a cycloalkyl ring with an aryl ring are considered as aryl irrespective of the ring that is bound to the core structure. Fused systems of a cycloalkyl ring with a heteroaryl ring are considered as heteroaryl irrespective of the ring that is bound to the core structure. The term “cycloalkenyl” as a group or part of a group, refers to a non-aromatic cyclic alkenyl group, with at least one site (usually 1 to 3, preferably 1) of unsaturation, namely a sp2carbon- sp2carbon double bond; preferably from 5 to 18 carbon atoms, more preferably from 5 to 10 carbon atoms, more preferably from 5 to 6 carbon atoms. Cycloalkenyl includes all unsaturated hydrocarbon groups containing one or more rings, including monocyclic, bicyclic, or tricyclic groups. For example, cycloalkenyl can comprise C5-10monocyclic or C7-18polycyclic hydrocarbon. The further rings may be either fused, bridged and / or joined through one or more spiro atoms. When a subscript is used herein following a carbon atom, the subscript refers to the number of carbon atoms that the named group may contain. For example, the term “C5-10cycloalkenyl”, refers to a cyclic alkenyl group comprising from 5 to 10 carbon atoms. For example, the term “C5-8cycloalkenyl”, refers to a cyclic alkenyl group comprising from 5 to 8 carbon atoms. For example, the term “C5-6cycloalkyl”, refers to a cyclic alkenyl group comprising from 5 to 6 carbon atoms. Examples include but are not limited to: cyclobutenyl, cyclopentenyl (-C5H7), cyclopentenylpropylene, methylcyclohexenylene, and cyclohexenyl (- C6H9). The double bond may be in the cis or trans configuration. For the avoidance of doubt, fused systems of a cycloalkenyl ring with a heterocyclic ring are considered as heterocycle irrespective of the ring that is bound to the core structure. Fused systems of a cycloalkenyl ring with an aryl ring are considered as aryl irrespective of the ring that is bound to the core structure. Fused systems of a cycloalkenyl ring with a heteroaryl ring are considered as heteroaryl irrespective of the ring that is bound to the core structure. The term “cycloalkynyl” as a group or part of a group, to a non-aromatic hydrocarbon group preferably having from 8 to 18 carbon atoms with at least one site (usually 1 to 3, preferably 1) of unsaturation, namely a sp1carbon-sp1carbon triple bond and consisting of or comprising a C8-10 monocyclic or C10-18 polycyclic hydrocarbon. Examples include but are not limited to: cyclooctynyl, cyclononynyl, and the like. In particular embodiments, the term cycloalkynyl refers to C8-12 cycloalkynyl, preferably to C8-10 cycloalkynyl, yet more preferably to C8-9 cycloalkynyl as further defined herein above with at least one site (preferably 1) of unsaturation, namely a sp1carbon-sp1carbon triple bond. For the avoidance of doubt, fused systems of a cycloalkynyl ring with a heterocyclic ring are considered as heterocycle irrespective of the ring that is bound to the core structure. Fused systems of a cycloalkynyl ring with an aryl ring are considered as aryl irrespective of the ring that is bound to the core structure. Fused systems of a cycloalkynyl ring with a heteroaryl ring are considered as heteroaryl irrespective of the ring that is bound to the core structure. The term “alkoxy" or “alkyloxy”, as a group or part of a group, refers to a group of formula – ORbwherein Rbis alkyl as defined herein. Non-limiting examples of suitable C1-6alkoxy include methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentyloxy, and hexyloxy. The term "haloalkyl", as a group or part of a group, refers to an alkyl group having the meaning as defined herein, wherein one or more hydrogen atoms are each replaced with a halogen as defined herein. Non-limiting examples of such haloalkyl groups include chloromethyl, 1-bromoethyl, fluoromethyl, difluoromethyl, trifluoromethyl, 1,1,1-trifluoroethyl and the like. The term “haloalkoxy”, as a group or part of a group, refers to a group of formula -O-Re, wherein Reis haloalkyl as defined herein. Non-limiting examples of suitable haloalkoxy include fluoromethoxy, difluoromethoxy, trifluoromethoxy, 2,2,2-trifluoroethoxy, 1,1,2,2- tetrafluoroethoxy, 2-fluoroethoxy, 2-chloroethoxy, 2,2-difluoroethoxy, 2,2,2-trichloroethoxy, trichloromethoxy, 2-bromoethoxy, pentafluoroethyl, 3,3,3-trichloropropoxy, 4,4,4- trichlorobutoxy. Any substituent designation that is found in more than one site in a compound described herein shall be independently selected. Substituents optionally are designated with or without bonds. Regardless of bond indications, if a substituent is polyvalent (based on its position in the structure referred to), then any and all possible orientations of the substituent are intended. Any reference to a "compound according to the invention", or "compound of formula (I)" also includes isomers such as stereoisomers and tautomers, salts such as pharmaceutically and / or cosmetically and / or physiologically acceptable salts, hydrates, solvates, polymorphs of such compounds unless expressly indicated otherwise. The term "isomers" as used herein means all possible isomeric forms, including tautomeric and stereochemical forms, which the compounds of formulae herein may possess, but not including position isomers. Typically, the structures shown herein exemplify one tautomeric or resonance form of the compounds, but the corresponding alternative configurations are contemplated as well. Depending on its substitution pattern, the compounds described herein may or may not have one or more optical stereocenters and may or may not exist as different enantiomers or diastereomers. Any such enantiomers, diastereomers or other optical isomers are encompassed by the scope of the invention. Unless otherwise stated, the chemical designation of compounds denotes the mixture of all possible stereochemically isomeric forms, said mixtures containing all diastereomers and enantiomers (since the compounds of formulae herein may have at least one chiral center) of the basic molecular structure, as well as the stereochemically pure or enriched compounds. More particularly, stereogenic centers may have either the R- or S-configuration, and multiple bonds may have either cis- or trans- configuration. The terms R- or S-configuration are used herein in accordance with Chemical Abstracts nomenclature. The terms cis and trans are used herein in accordance with Chemical Abstracts nomenclature and include reference to the position of the substituents on a ring moiety. The absolute stereochemical configuration of the compounds of the formulae described herein may easily be determined by those skilled in the art while using well-known methods such as, for example, X-ray diffraction. Separation of stereoisomers is accomplished by standard methods known to those in the art. One enantiomer of a compound can be separated substantially free of its opposing enantiomer by a method such as formation of diastereomers using optically active resolving agents ("Stereochemistry of Carbon Compounds," (1962) by E. L. Eliel, McGraw Hill; Lochmuller, C. H., (1975) J. Chromatogr., 113:(3) 283-302). Separation of isomers in a mixture can be accomplished by any suitable method, including: (1) formation of ionic, diastereomeric salts with chiral compounds and separation by fractional crystallization or other methods, (2) formation of diastereomeric compounds with chiral derivatizing reagents, separation of the diastereomers, and conversion to the pure enantiomers, or (3) enantiomers can be separated directly under chiral conditions. Under method (1), diastereomeric salts can be formed by reaction of enantiomerically pure chiral bases such as brucine, quinine, ephedrine, strychnine, a-methyl-b-phenylethylamine (amphetamine), and the like with asymmetric compounds bearing acidic functionality, such as carboxylic acid and sulfonic acid. The diastereomeric salts may be induced to separate by fractional crystallization or ionic chromatography. For separation of the optical isomers of amino compounds, addition of chiral carboxylic or sulfonic acids, such as camphorsulfonic acid, tartaric acid, mandelic acid, or lactic acid can result in formation of the diastereomeric salts. Alternatively, by method (2), the substrate to be resolved may be reacted with one enantiomer of a chiral compound to form a diastereomeric pair (Eliel, E. and Wilen, S. (1994) Stereochemistry of Organic Compounds, John Wiley & Sons, Inc., p. 322). Diastereomeric compounds can be formed by reacting asymmetric compounds with enantiomerically pure chiral derivatizing reagents, such as menthyl derivatives, followed by separation of the diastereomers and hydrolysis to yield the free, enantiomerically enriched compound. A method of determining optical purity involves making chiral esters, such as a menthyl ester or Mosher ester, a-methoxy-a-(trifluoromethyl)phenyl acetate (Jacob III. (1982) J. Org. Chem. 47:4165), of the racemic mixture, and analyzing the NMR spectrum for the presence of the two atropisomeric diastereomers. Stable diastereomers can be separated and isolated by normal- and reverse-phase chromatography following methods for separation of atropisomeric naphthyl-isoquinolines (Hoye, T., WO 96 / 15111). Under method (3), a racemic mixture of two asymmetric enantiomers is separated by chromatography using a chiral stationary phase. Suitable chiral stationary phases are, for example, polysaccharides, in particular cellulose or amylose derivatives. Commercially available polysaccharide based chiral stationary phases are ChiralCeITMCA, OA, OB5, OC5, OD, OF, OG, OJ and OK, and ChiralpakTMAD, AS, OP(+) and OT(+). Appropriate eluents or mobile phases for use in combination with said polysaccharide chiral stationary phases are hexane and the like, modified with an alcohol such as ethanol, isopropanol, and the like. ("Chiral Liquid Chromatography" (1989) W. J. Lough, Ed. Chapman and Hall, New York; Okamoto, (1990) "Optical resolution of dihydropyridine enantiomers by High-performance liquid chromatography using phenylcarbamates of polysaccharides as a chiral stationary phase", J. of Chromatogr. 513:375-378). The term “salts” relates to any salts that the compounds may form. They can be cosmetically or pharmaceutically acceptable. Therefore, the compounds optionally comprise salts of the compounds herein, especially cosmetically or pharmaceutically acceptable non-toxic salts containing, for example, Na+, Li+, K+, Ca2+and Mg2+. Such salts may include those derived by combination of appropriate cations such as alkali and alkaline earth metal ions or ammonium and quaternary amino ions with an acid anion moiety, typically a carboxylic acid. The compounds may bear multiple positive or negative charges. The net charge of the compounds may be either positive or negative. Any associated counter ions are typically dictated by the synthesis and / or isolation methods by which the compounds are obtained. Typical counter ions include, but are not limited to ammonium, sodium, potassium, lithium, halides, acetate, trifluoroacetate, etc., and mixtures thereof. Organic bases from which salts can be derived include, for example, primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines, basic ion exchange resins, and the like, specifically such as isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, ethanolamine, and the like. It will be understood that the identity of any associated counter ion is not a critical feature of the invention, and that the invention encompasses the compounds in association with any type of counter ion. Moreover, as the compounds can exist in a variety of different forms, the invention is intended to encompass not only forms of the compounds that are in association with counter ions (e.g., dry salts), but also forms that are not in association with counter ions (e.g., aqueous or organic solutions). Metal salts typically are prepared by reacting the metal hydroxide with a compound as defined herein. Examples of metal salts which are prepared in this way are salts containing Li+, Na+, and K+. A less soluble metal salt can be precipitated from the solution of a more soluble salt by addition of the suitable metal compound. In addition, salts may be formed from acid addition of certain organic and inorganic acids to basic centers, typically amines, or to acidic groups. Examples of such appropriate acids include, for instance, inorganic acids such as hydrohalogen acids, e.g., hydrochloric or hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid and the like; or organic acids such as, for example, acetic, propanoic, hydroxyacetic, 2-hydroxypropanoic, 2-oxopropanoic, lactic, pyruvic, oxalic (i.e., ethanedioic), malonic, succinic (i.e., butanedioic acid), maleic, fumaric, malic, tartaric, citric, methanesulfonic, ethanesulfonic, benzenesulfonic, p-toluenesulfonic, cyclohexanesulfamic, salicylic (i.e., 2-hydroxybenzoic), p-aminosalicylic and the like. Furthermore, this term also includes the solvates which the compounds of formulae herein as well as their salts are able to form, such as for example hydrates, alcoholates and the like. Finally, it is to be understood that the compositions herein can comprise compounds as defined herein in their unionized, as well as zwitterionic form, and combinations with stoichiometric amounts of water as in hydrates. Also included within the scope of this invention are the salts of the compounds with one or more amino acids, especially the naturally-occurring amino acids found as protein components. The amino acid typically is one bearing a side chain with a basic or acidic group, e.g., lysine, arginine or glutamic acid, or a neutral group such as glycine, serine, threonine, alanine, isoleucine, or leucine. The compounds as defined herein also include physiologically acceptable salts thereof. Examples of physiologically acceptable salts of the compounds as defined herein include salts derived from an appropriate base, such as an alkali metal (for example, sodium), an alkaline earth (for example, magnesium), ammonium and NX4+(wherein X is C1-C4 alkyl). Physiologically acceptable salts of a hydrogen atom or an amino group include salts of organic carboxylic acids such as acetic, benzoic, lactic, fumaric, tartaric, maleic, malonic, malic, isethionic, lactobionic, and succinic acids; organic sulfonic acids, such as methanesulfonic, ethanesulfonic, benzenesulfonic and p-toluenesulfonic acids; and inorganic acids, such as hydrochloric, sulfuric, phosphoric and sulfamic acids. Physiologically acceptable salts of a compound containing a hydroxy group include the anion of said compound in combination with a suitable cation such as Na+and NX4+(wherein X typically is independently selected from H or a C1-C4 alkyl group). However, salts of acids or bases which are not physiologically acceptable may also find use, for example, in the preparation or purification of a physiologically acceptable compound. All salts, whether or not derived from a physiologically acceptable acid or base, are within the scope of the present invention. Non-limiting examples of suitable such salts include but are not limited to acid addition salts, formed either with inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and the like, or formed with organic acids such as acetic acid, propionic acid, hexanoic acid, cyclopentanepropionic acid, glycolic acid, pyruvic acid, lactic acid, malonic acid, succinic acid, malic acid, maleic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, 3-(4-hydroxybenzoyl) benzoic acid, cinnamic acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid, 1,2-ethane-disulfonic acid, 2- hydroxyethanesulfonic acid, benzenesulfonic acid, 4-chlorobenzenesulfonic acid, 2- naphthalenesulfonic acid, 4-toluenesulfonic acid, camphorsulfonic acid, 4- methylbicyclo[2.2.2]oct-2-ene-1-carboxylic acid, glucoheptonic acid, 3-phenylpropionic acid, trimethylacetic acid, tertiary butylacetic acid, lauryl sulfuric acid, gluconic acid, glutamic acid, hydroxynaphthoic acid, salicylic acid, stearic acid, and muconic acid. Other salts include 2,2- dichloroacetate, adipate, alginate, ascorbate, aspartate, 2-acetamidobenzoate, caproate, caprate, camphorate, cyclamate, laurylsulfate, edisilate, esylate, isethionate, formate, galactarate, gentisate, gluceptate, glucuronate, oxoglutarate, hippurate, lactobionate, napadisilate, xinafoate, nicotinate, oleate, orotate, oxalate, palmitate, embonate, pidolate, p- aminosalicylate, sebacate, tannate, rhodanide, undecylenate, and the like; or salts formed when an acidic proton present in the parent compound is replaced, such as with ammonia, arginine, benethamine, benzathine, calcium, choline, deanol, diethanolamine, diethylamine, ethanolamine, ethylendiamine, meglumine, glycine, hydrabamine, imidazole, lysine, magnesium, hydroxyethylmorpholine, piperazine, potassium, epolamine, sodium, trolamine, tromethamine, or zinc. The present invention includes within its scope solvates of the compounds as defined herein. The term “solvates” refers to crystals formed by an active compound and a second component (solvent) which, in isolated form, is liquid at room temperature. Such solvates may be formed with common organic solvents, e.g., hydrocarbon solvents such as benzene or toluene; chlorinated solvents such as chloroform or dichloromethane; alcoholic solvents such as methanol, ethanol, or isopropanol; ethereal solvents such as diethyl ether or tetrahydrofuran; or ester solvents such as ethyl acetate. Alternatively, the solvates of the compounds herein may be formed with water, in which case they will be hydrates. The compounds of formula (I) or any subgroups thereof as defined herein (including all embodiments thereof as described herein), may be amorphous or may exist in one or more different crystalline states (polymorphs) which may have different macroscopic properties such as stability or show different biological properties such as activities. The present invention also encompasses amorphous and crystalline form of the compounds of formula (I), mixtures of different crystalline states of the respective compound of formula (I) or any subgroups thereof as defined herein (including all embodiments thereof as described herein). The term “polymorph” refers to a particular crystalline form of a chemical compound that can crystallize in different crystalline forms, these forms having different arrangements and / or conformations of the molecules in the crystal lattice. Different crystalline forms usually have different X-ray diffraction patterns, infrared spectra, melting points, density, hardness, crystal shape, optical and electrical properties, stability, and solubility. Although polymorphs can have the same chemical composition, they can also differ in composition due to the presence or absence of co-crystallized water or other molecules, which can be weakly or strongly bound in the lattice. Polymorphs can differ in such chemical, physical and biological properties as crystal shape, density, hardness, colour, chemical stability, melting point, hygroscopicity, suspensibility, dissolution rate and biological availability. One skilled in the art will appreciate that a polymorph of a compound described herein can exhibit beneficial effects (e.g., suitability for preparation of useful formulations, improved biological performance) relative to another polymorph or a mixture of polymorphs of the same compound. Preparation and isolation of a particular polymorph of a compound can be achieved by methods known to those skilled in the art including, for example, crystallization using selected solvents and temperatures. Recrystallization solvent, rate of crystallization, storage temperature, and other factors may cause one crystal form to dominate. Various polymorphs of a compound can be prepared by crystallization under different conditions. For a comprehensive discussion of polymorphism see Rolf Hilfiker, Ed., Polymorphism in the Pharmaceutical Industry, Wiley-VCH, Weinheim, 2006. When referring to compositions and products and the weight percent of the therein comprised ingredients, it is to be understood that according to the present invention the overall amount of ingredients does not exceed 100 % (± 1 % due to rounding). As used herein the terms “lightening”, “depigmenting”, “bleaching”, “whitening” and “brightening” are synonymous and are used interchangeably. Said terms refers to the lightening of the skin (or providing an even skin color), or loss of pigment. The skin lightening / depigmenting agents or compositions are also referred as "skin lightener", "skin whitener", "skin even-toner" and "skin brightener". Whatever terminology is employed, the general premise is that they all relate to a reduction in the melanization or rate of melanization of the skin which results in loss of pigment. As used herein, the term "lightening the skin" refers generally to lightening, brightening, whitening, and / or evening of the skin tone, skin color, and / or shade of skin, and / or to the reduction in sallowness, and / or to the lightening and / or fading of hyperpigmented marks and / or lesions including, but not limited to, pigmented spots, melanin spots, age spots, sun spots, senile lentigos, freckles, lentigos simplex, pigmented solar keratosis, seborrhoeic keratosis, melasma, acne marks, postinflammatory hyperpigmentation, lentigines, ephelides, combinations of two or more thereof and the like. In certain embodiments, "lightening the skin" also refers to increased skin radiance, glow, translucency and / or luminescence and / or obtaining a more radiant, glowing, translucent or luminous skin tone appearance or a less yellow or sallow skin tone. In certain preferred embodiments, "lightening the skin" refers to lightening and evening the skin tone, increasing skin radiance and / or lightening age spots. As used herein, a "lightening effective amount" or "skin-lightening effective amount" of a compound means an amount of the compound that detectably lightens skin after an effective period of time. One skilled in the art is able to determine an "effective period time" based on the skin-lightening effect desired. Such compounds reduce skin melanin levels by inhibiting the production of melanin, whether the latter is produced constitutively or in response to UV irradiation (such as sun exposure). Thus, the active compounds used in this invention can be used to reduce skin melanin content in non-pathological states so as to induce a lighter skin tone, as desired by the user, or to prevent melanin accumulation in skin that has been exposed to UV irradiation. They can also be used in combination with skin peeling agents (including glycolic acid or trichloroacetic acid face peels) to lighten skin tone and prevent repigmentation. As used herein, "improving the skin tone" means the lightening of the appearance of the skin (e.g., lightening pigmented marks or lesions, reducing skin sallowness, and / or evening the color of the skin). As used herein, "cosmetically / dermatologically acceptable" means suitable for use in contact with tissues (e.g., the skin) without undue toxicity, incompatibility, instability, irritation, allergic response, and the like. The term "topical” or "topically*refers to the application of compound and / or the composition containing the same onto the surface of the skin or a portion thereof. The terms “increase” and “decrease” refer to a change in amount of melanin content present in the melanocytes. An “increase” or “decrease” in melanin production in melanocytes is preferably measured in response to contacting the compounds of formula (I) or any subgroups thereof as defined herein (including all embodiments thereof as described herein) to skin explants, wherein the change in melanin content is relative to the level content of melanin present in the melanocytes in absence of a compound of formula (I) or in presence of Kojic Acid 0.5% or Azelaic Acid 12%. In the present specification, the term “non-therapeutic” refers to the concept which excludes medical practice, that is, treatments to human body by a medical therapy. The terms described herein and others used in the specification are well understood to those in the art. Preferred statements (features) and embodiments of the compositions, compounds, methods, products, and uses of this invention are set herein below. Each statement and embodiment of the invention so defined may be combined with any other statement and / or embodiment, unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other features or statements indicated as being preferred or advantageous. Hereto, the present invention is in particular captured by any one or any combination of one or more of the below numbered statements and embodiments, with any other aspect and / or embodiment. 1. A lightening composition comprising a lightening effective amount of a compound of formula (I), or a tautomer, a stereoisomer, a hydrate, a solvate, a salt, or a polymorph thereof, wherein n is an integer selected from 0, 1, or 2, m is an integer selected from 1, 2, or 3; R1is selected from the group comprising alkynyl, alkyl, hydrogen, and alkenyl; wherein each of said alkynyl, alkyl, and alkenyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R2is selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy, or R1and R2together with the carbon atoms to which they are attached can form a cycloalkyl, a cycloalkenyl or a cycloalkynyl, wherein each of said cycloalkyl, cycloalkenyl and cycloalkynyl can be unsubstituted or substituted with one or more substituents R8, wherein each R8is independently selected from the group comprising alkyl, alkenyl, alkynyl, hydroxyl, halo, haloalkyl, and haloalkoxy; each R3is independently selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl, and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; each R4is independently selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R5is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R6is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; and R7is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy. 2. A lightening composition comprising a lightening effective amount of a compound of formula (I), or a tautomer, a stereoisomer, a hydrate, a solvate, a salt, or a polymorph thereof, wherein n is an integer selected from 0, 1, or 2, m is an integer selected from 1, 2, or 3; R1is selected from the group comprising alkynyl, alkyl, hydrogen, and alkenyl; wherein each of said alkynyl, alkyl, and alkenyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R2is selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy, or R1and R2together with the carbon atoms to which they are attached can form a cycloalkyl, a cycloalkenyl or a cycloalkynyl, wherein each of said cycloalkyl, cycloalkenyl and cycloalkynyl can be unsubstituted or substituted with one or more substituents R8, wherein each R8is independently selected from the group comprising alkyl, alkenyl, alkynyl, hydroxyl, halo, haloalkyl, and haloalkoxy; each R3is independently selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl, and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; each R4is independently selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R5is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R6is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; and R7is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; with the proviso that said compound of formula (I) is not , 3. A lightening composition comprising a lightening effective amount of a compound of formula (I), or a tautomer, a stereoisomer, a hydrate, a solvate, a salt, or a polymorph thereof, wherein n is an integer selected from 0, 1, or 2, m is an integer selected from 1, 2, or 3; R1is selected from the group comprising alkynyl, alkyl, hydrogen, and alkenyl; wherein each of said alkynyl, alkyl, and alkenyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R2is selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy, or R1and R2together with the carbon atoms to which they are attached can form a cycloalkyl, a cycloalkenyl or a cycloalkynyl, wherein each of said cycloalkyl, cycloalkenyl and cycloalkynyl can be unsubstituted or substituted with one or more substituents R8, wherein each R8is independently selected from the group comprising alkyl, alkenyl, alkynyl, hydroxyl, halo, haloalkyl, and haloalkoxy; each R3is independently selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl, and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; each R4is independently selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R5is hydrogen; R6is hydrogen; R7is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy. 4. A lightening composition comprising (a) a cosmetically acceptable carrier, diluent and / or excipient and (b) at least one lightening compound of formula (I) or a tautomer, a stereoisomer, a hydrate, a solvate, a salt, or a polymorph thereof, wherein n is an integer selected from 0, 1, or 2, m is an integer selected from 1, 2, or 3; R1is selected from the group comprising alkynyl, alkyl, hydrogen, and alkenyl; wherein each of said alkynyl, alkyl, and alkenyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R2is selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy, or R1and R2together with the carbon atoms to which they are attached can form a cycloalkyl, a cycloalkenyl or a cycloalkynyl, wherein each of said cycloalkyl, cycloalkenyl and cycloalkynyl can be unsubstituted or substituted with one or more substituents R8, wherein each R8is independently selected from the group comprising alkyl, alkenyl, alkynyl, hydroxyl, halo, haloalkyl, and haloalkoxy; each R3is independently selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl, and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; each R4is independently selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R5is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R6is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; and R7is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy. 5. A lightening composition comprising (a) a cosmetically acceptable carrier, diluent and / or excipient and (b) at least one lightening compound of formula (I) or a tautomer, a stereoisomer, a hydrate, a solvate, a salt, or a polymorph thereof, wherein n is an integer selected from 0, 1, or 2, m is an integer selected from 1, 2, or 3; R1is selected from the group comprising alkynyl, alkyl, hydrogen, and alkenyl; wherein each of said alkynyl, alkyl, and alkenyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R2is selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy, or R1and R2together with the carbon atoms to which they are attached can form a cycloalkyl, a cycloalkenyl or a cycloalkynyl, wherein each of said cycloalkyl, cycloalkenyl and cycloalkynyl can be unsubstituted or substituted with one or more substituents R8, wherein each R8is independently selected from the group comprising alkyl, alkenyl, alkynyl, hydroxyl, halo, haloalkyl, and haloalkoxy; each R3is independently selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl, and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; each R4is independently selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R5is hydrogen; R6is hydrogen; R7is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy. 6. The lightening composition according to any one of statements 1 to 5, wherein said compound has structural formula (I1), 7. The lightening composition according to any one of statements 1-6, wherein n is 1. 8. The lightening composition according to any one of statements 1-7, wherein n is 2. 9. The lightening composition according to any one of statements 1-8, wherein R1is selected from the group comprising C2-6alkynyl, C1-6alkyl, hydrogen, and C2-6alkenyl; wherein each of said C2-6alkynyl, C1-6alkyl, and C2-6alkenyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. 10. The lightening composition according to any one of statements 1-9, wherein R1is selected from the group comprising C2-6alkynyl, C1-6alkyl, and C2-6alkenyl; wherein each of said C2- 6alkynyl, C1-6alkyl, and C2-6alkenyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. 11. The lightening composition according to any one of statements 1-10, wherein R2is selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. 12. The lightening composition according to any one of statements 1-11, wherein R2is selected from the group comprising C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1- 6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. 13. The lightening composition according to any one of statements 1-12, wherein R1and R2together with the carbon atoms to which they are attached can form a C5-6cycloalkyl, C5-6cycloalkenyl or a C8-10cycloalkynyl, wherein each of said C5-6cycloalkyl, C5-6cycloalkenyl and C8-10cycloalkynyl, can be unsubstituted or substituted with one or more substituents R8, wherein each R8is independently selected from the group comprising C1-6alkyl, C2-6alkenyl, C2-6alkynyl, hydroxyl, halo, and haloC1-6alkyl. The lightening composition according to any one of statements 1-13, wherein each R3is independently selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. The lightening composition according to any one of statements 1-14, wherein each R4is independently selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. The lightening composition according to any one of statements 1-15, with the proviso that at least one of R3and R4is not hydrogen. The lightening composition according to any one of statements 1-16, wherein each R3is independently selected from the group comprising C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. The lightening composition according to any one of statements 1-17, wherein each R4is independently selected from the group comprising C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. The lightening composition according to any one of statements 1-18, wherein R5is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl; preferably R5is hydrogen. The lightening composition according to any one of statements 1-19, wherein R6is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; preferably R6is hydrogen. The lightening composition according to any one of statements 1-20, wherein R7is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. 22. The lightening composition according to any one of statements 1-21, wherein said compound have structural formula (I2) or (I3) 23. The lightening composition according to any one of statements 1-22, wherein said compound have structural formula (I4), (I5) or (I6) wherein s is an integer selected from 0, 1, 2, 3, 4, or 5. 24. The lightening composition according to any one of statements 1-23, wherein said compound have structural formula (I7), (I8) or (I9) wherein s is an integer selected from 0, 1, 2, 3, 4, or 5. 25. The lightening composition according to any one of statements 1-24, wherein R2is C1- 6alkyl; preferably R2is C1-4alkyl; preferably R2is C1-2alkyl; preferably R2is methyl. 26. The lightening composition according to any one of statements 1-25, wherein said compound have structural formula (I10), (I11) or (I12) wherein s is an integer selected from 0, 1, 2, 3, 4, or 5. 27. The lightening composition according to any one of statements 1-26, wherein R3is C1-6alkyl; preferably R3is C1-4alkyl; preferably R3is C1-2alkyl; preferably R3is methyl. 28. The lightening composition according to any one of statements 1-27, wherein R4is C1-6alkyl; preferably R4is C1-4alkyl; preferably R4is C1-2alkyl; preferably R4is methyl. 29. The lightening composition according to any one of statements 1-28, wherein said compound have structural formula (I13), (I14) or (I15) wherein s is an integer selected from 0, 1, 2, 3, 4, or 5. 30. The lightening composition according to any one of statements 1-29, wherein said compound is selected from the group comprising: 31. The lightening composition of any one of statements 1-30, wherein said composition is a skin lightening composition. 32. The lightening composition of any one of statements 1-31, wherein said skin is mammal skin, preferably human skin. 33. The lightening composition according to any one of statements 1-32, wherein said composition is a moisturizing composition or a sunscreen composition. 34. The lightening composition of any one of statements 1-33, wherein said lightening composition is in a suitable form for topical application, preferably a form selected from the group comprising a lotion, a cream, a gel, a serum, a solution, a lotion, a spray, a patch, a cleanser, a powder, a mousse, an ointment, a wax, a lipstick, microencapsulation, an aerosol, a foam, a soap, a shampoo, a bath gel, a bath oil, a bath bubble, a hydroalcoholic solution, a suspension, a scrub, a saturated pad or wipe, and a skin conditioning agent. 35. The lightening composition of any one of statements 1-34, wherein said composition further comprises at least one skin benefit agent, preferably selected from the group comprising alpha-hydroxy acids, beta-hydroxy acids, polyhydroxy acids, nicotinamide, kojic acid, arbutin, deoxyarbutin, depigmenting oligopeptides, soybean extract, licorice extract, phyllanthus emblica extract, Bellis perennis extract, glabridin, polyphenol antioxidants, thiolic antioxidants, cysteamine hydrochloride, hydroquinone, methimazole, pyridines, t- butyl hydroquinone, Vitamin C derivatives, Vitamin E derivatives, Vitamin B derivatives, dioic acids, retinoids, 4-substituted resorcinol derivatives, tranexamic acid or its derivatives, corticosteroids and mixtures thereof. 36. The lightening composition according to any one of statements 1-35, further comprising a sunscreen agent, a skin conditioning agent, a whitening agent, a skin lightening agent, a skin protectant, an emollient, a thickening agent, a humectant, or any combination thereof. 37. The lightening composition according to any one of statements 1-36, wherein at least one further lightening substance is present. 38. A compound of formula (I2) or a tautomer, a stereoisomer, a hydrate, a solvate, a salt, or a polymorph thereof, wherein R1is alkynyl; wherein said alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R2is selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R3is independently selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl, and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R4is independently selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R5is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R6is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; and R7is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy. 39. A compound of formula (I2) or a tautomer, a stereoisomer, a hydrate, a solvate, a salt, or a polymorph thereof, wherein R1is alkynyl; wherein said alkynyl is substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R2is selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R3is independently selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl, and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R4is independently selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R5is hydrogen; R6is hydrogen; and R7is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy. 40. The compound according to statement 38 or 39, wherein R1is C2-6alkynyl; wherein said C2-6alkynyl, can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; preferably said C2-6alkynyl is substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. 41. The compound according to any one of statements 38-40, wherein R2is selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1- 6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. 42. The compound according to any one of statements 38-41, wherein R2is selected from the group comprising C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2- 6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. 43. The compound according to any one of statements 38-42, wherein R3is independently selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. 44. The compound according to any one of statements 38-43 wherein R4is independently selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. 45. The compound according to any one of statements 38-44, with the proviso that at least one of R3and R4is not hydrogen. 46. The compound according to any one of statements 38-45, wherein R3is independently selected from the group comprising C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. The compound according to any one of statements 38-46, wherein R4is independently selected from the group comprising C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. The compound according to any one of statements 38-47, wherein R5is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl; preferably R5is hydrogen. The compound according to any one of statements 38-48, wherein R6is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1- 6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; preferably R6is hydrogen. The compound according to any one of statements 38-49, wherein R7is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1- 6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. The compound according to any one of statements 38-50, wherein said compound has structural formula (I4), The compound according to any one of statements 38-51, wherein said compound has structural formula (I7) The compound according to any one of statements 38-52, wherein R1is C2-6alkynyl; wherein said C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; preferably R1is C2-6alkynyl; wherein said C2-6alkynyl can be unsubstituted or substituted with one or more hydroxyl; preferably R1is C2-6alkynyl; wherein said C2-6alkynyl is substituted with one or more hydroxyl. 54. The compound according to any one of statements 38-53, wherein R2is C1-6alkyl; preferably R2is C1-4alkyl; preferably R2is C1-2alkyl; preferably R2is methyl. 55. The compound according to any one of statements 38-54, wherein said compound has structural formula (I10) 56. The compound according to any one of statements 38-55, wherein R3is C1-6alkyl; preferably R3is C1-4alkyl; preferably R3is C1-2alkyl; preferably R3is methyl. 57. The compound according to any one of statements 38-56, wherein R4is C1-6alkyl; preferably R4is C1-4alkyl; preferably R4is C1-2alkyl; preferably R4is methyl. 58. The compound according to any one of statements 38-57, wherein said compound has structural formula (I13) 59. The compound according to any one of statements 38-58, wherein said compound is 60. Use of at least one compound as defined in any one of statements 1-59 as lightening / depigmenting agent. 61. Use of at least one compound as defined in any one of statements 1 to 59, or use of the lightening composition of any one of statements 1 to 37, for preventing and / or reducing pigmentation of normal skin. 62. Use of at least one compound as defined in any one of statements 1 to 59, or use of the lightening composition of any one of statements 1 to 37, for decreasing the amount of melanin in melanocytes, for decreasing melanin synthesis, for impairing melanin transport and / or for impairing the distribution of melanin in suprabasal layers. 63. Use of at least one compound as defined in any one of statements 1 to 59, or use of the lightening composition of any one of statements 1 to 37, for the manufacture of a composition for decreasing the amount of melanin in melanocytes, for decreasing melanin synthesis, for impairing melanin transport and / or for impairing the distribution of melanin in suprabasal layers. 64. The use according to any one of statements 60-63, wherein said use is in a cosmetic composition. 65. The use according to any one of statements 60-64, wherein said use is for non-therapeutic purpose. 66. The use according to any one of statements 60-65, wherein said composition is a sun protective lightening composition, or a moisturizing composition. 67. The use according to any one of statements 60-66, wherein said composition can be formulated in a suitable form for topical application, preferably a form selected from the group comprising a lotion, a cream, a gel, a serum, a solution, a lotion, a spray, a patch, a cleanser, a powder, a mousse, an ointment, a wax, a lipstick, microencapsulation, an aerosol, a foam, a soap, a shampoo, a bath gel, a bath oil, a bath bubble, a hydroalcoholic solution, a suspension, a scrub, a saturated pad or wipe, and a skin conditioning agent. 68. The use according to any one of statements 60-67, wherein said composition is incorporated in a device adapted for application under the skin tissue, to mucosal tissue, to the surface of skin or to the scalp. 69. The use according to any one of statements 60-68, for lightening skin. 70. A compound as defined in any one of statements 1 to 59 or a lightening composition of any one of statements 1 to 37 for use in a method for preventing and / or reducing skin pigmentation disorders related to an abnormal excessive production of melanin and / or abnormal increased number of melanocytes. 71. A compound as defined in any one of statements 1 to 59 or a lightening composition of any one of statements 1 to 37 for use in decreasing the amount of melanin in melanocytes, for decreasing melanin synthesis, for impairing melanin transport and / or for impairing the distribution of melanin in suprabasal layers. 72. The compound for use or the lightening composition for use according to statement 71, wherein said pigmentation disorders are selected from the group comprising hyperpigmentation, melasma, postinflammatory hyperpigmentation, solar or senile lentigo, freckles due to an abnormal excessive production of melanin, drug induced hyperpigmentation, light induced hyperpigmentation and chemical induced hyperpigmentation. 73. A method for preventing and / or reducing pigmentation of normal skin and / or hair, comprising topically applying at least one compound as defined in any one of statements 1 to 59, or a lightening composition according to any one of statements 1 to 37 to the skin of the subject in need thereof. 74. A method for preventing and / or reducing skin pigmentation disorders, comprising topically applying at least one compound as defined in any one of statements 1 to 59 or the lightening composition of any one of statements 1 to 37 to the skin of the subject in need thereof. 75. The method of statement 74, wherein said pigmentation disorders are selected from the group comprising hyperpigmentation, melasma, postinflammatory hyperpigmentation, solar or senile lentigo, freckles, drug induced hyperpigmentation, light induced hyperpigmentation, and a chemical induced hyperpigmentation. 76. A method for decreasing the amount of melanin in melanocytes, for decreasing melanin synthesis, for impairing melanin transport and / or for impairing the distribution of melanin in suprabasal layers comprising topically applying at least one compound as defined in any one of statements 1 to 59 or the lightening composition of any one of statements 1 to 37. 77. A lightening method comprising using at least one compound as defined in any one of statements 1 to 59 or the lightening composition of any one of statements 1 to 37, as a lightening substance. 78. A method of lightening skin comprising the step of applying at least one compound as defined in any one of statements 1 to 59 or the lightening composition of any one of statements 1 to 37 onto a desired skin surface. The present inventions relates to a lightening composition comprising at least one compound of formula (I) or a tautomer, a stereoisomer, a hydrate, a solvate, a salt, or a polymorph thereof, or any subgroups thereof as defined herein (including all embodiments thereof as described herein), and further encompasses said at least one compound of formula (I) and any subgroups thereof as defined herein (including all embodiments thereof as described herein), as lightening substance, preferably wherein n is an integer selected from 0, 1, or 2, m is an integer selected from 1, 2, or 3; R1is selected from the group comprising C2-6alkynyl, C1-6alkyl, hydrogen, and C2-6alkenyl; wherein each of said C2-6alkynyl, C1-6alkyl, and C2-6alkenyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; R2is selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy, or R1and R2together with the carbon atoms to which they are attached can form a C5-6cycloalkyl, a C5-6cycloalkenyl or a C8-10cycloalkynyl, wherein each of said C5-6cycloalkyl, C5-6cycloalkenyl and C8-10cycloalkynyl can be unsubstituted or substituted with one or more substituents R8, wherein each R8is independently selected from the group comprising C1- 6alkyl, C2-6alkenyl, C2-6alkynyl, hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; each R3is independently selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; each R4is independently selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; R5is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; R6is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; and R7is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy. In some embodiments, the present invention relates to a lightening compound of formula (I) and any subgroups thereof as defined herein (including all embodiments thereof as described herein), wherein n is an integer selected from 0, 1, or 2, m is an integer selected from 1, 2, or 3; R1is selected from the group comprising C2-6alkynyl, C1-6alkyl, hydrogen, and C2-6alkenyl; wherein each of said C2-6alkynyl, C1-6alkyl, and C2-6alkenyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; R2is selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy, or R1and R2together with the carbon atoms to which they are attached can form a C5- 6cycloalkyl, a C5-6cycloalkenyl or a C8-10cycloalkynyl, wherein each of said C5-6cycloalkyl, C5- 6cycloalkenyl and C8-10cycloalkynyl can be unsubstituted or substituted with one or more substituents R8, wherein each R8is independently selected from the group comprising C1- 6alkyl, C2-6alkenyl, C2-6alkynyl, hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; each R3is independently selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; each R4is independently selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; R5is hydrogen; R6is hydrogen; and R7is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy. In some embodiments, the present invention relates to a lightening compound of formula (I) and any subgroups thereof as defined herein (including all embodiments thereof as described herein), wherein n is 1 or 2, m is 1; R1is selected from the group comprising C2-6alkynyl, C1-6alkyl, hydrogen, and C2-6alkenyl; wherein each of said C2-6alkynyl, C1-6alkyl, and C2-6alkenyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; preferably R1is selected from C2-6alkynyl, or C1-6alkyl, wherein each of said C2-6alkynyl, C1-6alkyl, can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; R2is selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; preferably R2is C1-6alkyl; preferably R2is C1-4alkyl; preferably R2is C1-2alkyl; preferably R2is methyl; or R1and R2together with the carbon atoms to which they are attached can form a C5- 6cycloalkyl, a C5-6cycloalkenyl or a C8-10cycloalkynyl, wherein each of said C5-6cycloalkyl, C5- 6cycloalkenyl and C8-10cycloalkynyl can be unsubstituted or substituted with one or more substituents R8, wherein each R8is independently selected from the group comprising C1- 6alkyl, C2-6alkenyl, C2-6alkynyl, hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; preferably or R1and R2together with the carbon atoms to which they are attached can form a C5-6cycloalkyl, wherein said C5-6cycloalkyl, can be unsubstituted or substituted with one or more substituents R8, wherein each R8is independently selected from the group comprising C1-6alkyl, C2-6alkenyl, C2-6alkynyl, hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; each R3is independently selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; preferably R3is C1- 6alkyl; preferably R3is C1-4alkyl; preferably R3is C1-2alkyl; preferably R3is methyl; each R4is independently selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; preferably R4is C1-6alkyl; preferably R4is C1-4alkyl; preferably R4is C1-2alkyl; preferably R4is methyl. R5is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; R6is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; and R7is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy. In some embodiments, the present invention relates to a lightening compound of formula (I) and any subgroups thereof as defined herein (including all embodiments thereof as described herein), wherein n is 1 or 2, m is 1; R1is selected from the group comprising C2-6alkynyl, C1-6alkyl, hydrogen, and C2-6alkenyl; wherein each of said C2-6alkynyl, C1-6alkyl, and C2-6alkenyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; preferably R1is selected from C2-6alkynyl, or C1-6alkyl, wherein each of said C2-6alkynyl, C1-6alkyl, can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; R2is selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; preferably R2is C1-6alkyl; preferably R2is C1-4alkyl; preferably R2is C1-2alkyl; preferably R2is methyl; or R1and R2together with the carbon atoms to which they are attached can form a C5- 6cycloalkyl, a C5-6cycloalkenyl or a C8-10cycloalkynyl, wherein each of said C5-6cycloalkyl, C5- 6cycloalkenyl and C8-10cycloalkynyl can be unsubstituted or substituted with one or more substituents R8, wherein each R8is independently selected from the group comprising C1- 6alkyl, C2-6alkenyl, C2-6alkynyl, hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; preferably or R1and R2together with the carbon atoms to which they are attached can form a C5-6cycloalkyl, wherein said C5-6cycloalkyl, can be unsubstituted or substituted with one or more substituents R8, wherein each R8is independently selected from the group comprising C1-6alkyl, C2-6alkenyl, C2-6alkynyl, hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; each R3is independently selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; preferably R3is C1-6alkyl; preferably R3is C1-4alkyl; preferably R3is C1-2alkyl; preferably R3is methyl; each R4is independently selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; preferably R4is C1-6alkyl; preferably R4is C1-4alkyl; preferably R4is C1-2alkyl; preferably R4is methyl. R5is hydrogen; R6is hydrogen; and R7is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy. In some embodiments, the present invention relates to a lightening compound of formula (I1) and any subgroups thereof as defined herein (including all embodiments thereof as described herein), wherein n is 1 or 2; m is 1; R1is selected from the group comprising C2-6alkynyl, C1-6alkyl, and C2-6alkenyl; wherein each of said C2-6alkynyl, C1-6alkyl, and C2-6alkenyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; preferably R1is selected from C2-6alkynyl, or C1-6alkyl, wherein each of said C2- 6alkynyl, C1-6alkyl, can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; R2is C1-6alkyl, or C2-6alkynyl; wherein each of said C1-6alkyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC al22 1-6 kyl; preferably R is C1-6alkyl; preferably R is C1-4alkyl; preferably R2is C1-2alkyl; preferably R2is methyl; or R1and R2together with the carbon atoms to which they are attached can form a C5- 6cycloalkyl, wherein said C5-6cycloalkyl, can be unsubstituted or substituted with one or more substituents R8, wherein each R8is independently selected from the group comprising C1- 6alkyl, hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; R3is independently selected from the group comprising C1-6alkyl, hydrogen, and C2-6alkynyl; wherein each of said C1-6alkyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; preferably R3is C1-6alkyl; preferably R3is C1-4alkyl; preferably R3is C1-2alkyl; preferably R3is methyl; R4is independently selected from the group comprising hydrogen, C1-6alkyl, and C2-6alkynyl; wherein each of said C1-6alkyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; preferably R4is C1-6alkyl; preferably R4is C1-4alkyl; preferably R4is C1-2alkyl; preferably R4is methyl; R5is hydrogen or C1-6alkyl; wherein said C1-6alkyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; R6is hydrogen or C1-6alkyl, wherein said C1-6alkyl, can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; and R7is hydrogen or C1-6alkyl, wherein each of said C1-6alkyl, can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy. In some embodiments, the present invention relates to a lightening compound of formula (I1) and any subgroups thereof as defined herein (including all embodiments thereof as described herein), wherein n is 1 or 2; m is 1; R1is selected from the group comprising C2-6alkynyl, C1-6alkyl, and C2-6alkenyl; wherein each of said C2-6alkynyl, C1-6alkyl, and C2-6alkenyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; preferably R1is selected from C2-6alkynyl, or C1-6alkyl, wherein each of said C2- 6alkynyl, C1-6alkyl, can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; R2is C1-6alkyl, or C2-6alkynyl; wherein each of said C1-6alkyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; preferably R2is C1-6alkyl; preferably R2is C1-4alkyl; preferably R2is C1-2alkyl; preferably R2is methyl; or R1and R2together with the carbon atoms to which they are attached can form a C5- 6cycloalkyl, wherein said C5-6cycloalkyl, can be unsubstituted or substituted with one or more substituents R8, wherein each R8is independently selected from the group comprising C1- 6alkyl, hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; R3is independently selected from the group comprising C1-6alkyl, hydrogen, and C2-6alkynyl; wherein each of said C1-6alkyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; preferably R3is C1-6alkyl; preferably R3is C1-4alkyl; preferably R3is C1-2alkyl; preferably R3is methyl; R4is independently selected from the group comprising hydrogen, C1-6alkyl, and C2-6alkynyl; wherein each of said C1-6alkyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; preferably R4is C1-6alkyl; preferably R4is C1-4alkyl; preferably R4is C1-2alkyl; preferably R4is methyl; R5is hydrogen; R6is hydrogen; and R7is hydrogen or C1-6alkyl, wherein each of said C1-6alkyl, can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy. The present invention also encompasses compound of formula (I2) and any subgroups thereof as defined herein (including all embodiments thereof as described herein), wherein R1is C2-6alkynyl; wherein said C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; R2is selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; R3is independently selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; R4is independently selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; R5is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; R6is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; and R7is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy. In some embodiments, the present invention relates to compounds of formula (I2) and any subgroups thereof as defined herein (including all embodiments thereof as described herein), wherein R1is C2-6alkynyl; wherein said C2-6alkynyl is substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1- 6alkoxy; R2is selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; R3is independently selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; R4is independently selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy; R5is hydrogen; R6is hydrogen; and R7is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl, and haloC1-6alkoxy. In some embodiments, the present invention relates to compounds of formula (I2) and any subgroups thereof as defined herein (including all embodiments thereof as described herein), wherein R1is C2-6alkynyl; wherein said C2-6alkynyl, can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; R2is selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; R3is independently selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; R4is independently selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; R5is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloC1-6alkyl; R6is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; R7is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. In some embodiments, the present invention relates to compounds of formula (I2) and any subgroups thereof as defined herein (including all embodiments thereof as described herein), wherein R1is C2-6alkynyl; wherein said C2-6alkynyl is substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; R2is selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; R3is independently selected from the group comprising C1-6alkyl, hydrogen, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl, and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; R4is independently selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl; R5is hydrogen; R6is hydrogen; R7is selected from the group comprising hydrogen, C1-6alkyl, C2-6alkenyl, and C2-6alkynyl; wherein each of said C1-6alkyl, C2-6alkenyl and C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, and haloC1-6alkyl. In some embodiments, the present invention relates to compounds of formula (I2) and any subgroups thereof as defined herein (including all embodiments thereof as described herein), wherein R1is C2-6alkynyl; wherein said C2-6alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; preferably R1is C2-6alkynyl; wherein said C2-6alkynyl can be unsubstituted or substituted with one or more hydroxyl; preferably R1is C2-6alkynyl; wherein said C2-6alkynyl is substituted with one or more hydroxyl; R2is C1-6alkyl; preferably R2is C1-4alkyl; preferably R2is C1-2alkyl; preferably R2is methyl; R3is C1-6alkyl; preferably R3is C1-4alkyl; preferably R3is C1-2alkyl; preferably R3is methyl. R4is C1-6alkyl; preferably R4is C1-4alkyl; preferably R4is C1-2alkyl; preferably R4is methyl. R5is hydrogen or C1-6alkyl; R6is hydrogen or C1-6alkyl; and R7is hydrogen or C1-6alkyl. In some embodiments, the present invention relates to compounds of formula (I2) and any subgroups thereof as defined herein (including all embodiments thereof as described herein), wherein R1is C2-6alkynyl; wherein said C2-6alkynyl is substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; preferably R1is C2-6alkynyl; wherein said C2-6alkynyl is substituted with one or more hydroxyl; R2is C1-6alkyl; preferably R2is C1-4alkyl; preferably R2is C1-2alkyl; preferably R2is methyl; R3is C1-6alkyl; preferably R3is C1-4alkyl; preferably R3is C1-2alkyl; preferably R3is methyl. R4is C1-6alkyl; preferably R4is C1-4alkyl; preferably R4is C1-2alkyl; preferably R4is methyl. R5is hydrogen; R6is hydrogen; and R7is hydrogen or C1-6alkyl. Preferably, the present invention further relates to cosmetic or pharmaceutical composition, comprising at least one compound of formula (I) or any subgroups thereof as defined herein (including all embodiments thereof as described herein) and optionally at least one dermatologically or pharmaceutically acceptable carrier. In the preparation of such composition, at least one compound of formula (I) or any subgroups thereof as defined herein (including all embodiments thereof as described herein) may be combined with other ingredients typically employed. In addition, the composition may contain one or more carriers, excipients or adjuvants, which are typically included in such composition or products in order to aid in their manufacture, storage, application or performance. The compounds of formula (I) or any subgroups thereof as defined herein (including all embodiments thereof as described herein) can be added as a material to compositions, preparations for application to a subject’s tissue, for example topical application, cosmetic products which can be used for decreasing the pigmentation of a subject’s tissue such decreasing skin pigmentation by decreasing the melanin production or preventing, ameliorating, or treating symptoms such as hyperpigmentation, formation of age spots, freckles and melasma.; or can be used for producing these products. These compositions, preparations for example for topical application, cosmetic products, and the like, are also encompassed within the scope of the present invention. The compounds, compositions, preparations, cosmetic products, can be produced or used for human or non-human animal. The compound for use herein can be the active ingredient decreasing the melanin production, whitening skin, and / or preventing, ameliorating, and / or treating symptoms such as hyperpigmentation, formation of age spots, freckles and melasma. The compounds, compositions, preparations, cosmetic products can be administered by different administration forms. The administration may be oral or parenteral. Examples of the dosage form for oral administration include solid administration forms such as tablets, coated tablets, granules, powders, and capsules, and liquid administration forms such as elixirs, syrups and suspensions; examples of the dosage form for parenteral administration include injections, infusions, topicals, preparations for topical application, subcutaneous, transmucosal, transnasal, enteric, inhalation, suppositories, bolus, and patches. The composition can be preferably in the form of preparations for topical application to the skin. The cosmetic composition comprises the compounds as the active ingredient. Examples of the cosmetic form include any form which can be used for a cosmetic product such as creams, emulsions, lotions, suspensions, gels, powders, packs, sheets, patches, sticks, and cake. The cosmetic compositions are preferably a skin whitening cosmetic product, and also preferably a cosmetic product for topical application to the skin. The cosmetic products are more preferably a cosmetic product for topical application for skin lightening. The packaging could be a patch, bottle, tube, roll-ball applicator, propellant driven aerosol device, squeeze container or lidded jar. The cosmetic compositions or cosmetic products may comprise the above defined compounds in combination with a pharmaceutically or cosmetically acceptable carrier, diluent and / or excipient. The carrier can act as diluent or dispersant for the ingredients of the composition. The carrier may be aqueous-based, anhydrous or an emulsion, such as water-in-oil or oil-in-water emulsion. In addition to water, organic solvents can be used as carrier or diluent in the compositions of the present invention. Non-limiting examples include alkanols like ethyl and isopropyl alcohol, and propane diol. Other suitable organic solvents include ester oils like isopropyl myristate, cetyl myristate, 2- octyldodecyl myristate, avocado oil, almond oil, olive oil and neopentylglycol dicaprate. Typically, such ester oils assist in emulsifying the compositions. Emollients may also be used, if desired, as a carrier. Alcohols like 1 -hexadecanol (i.e. cetyl alcohol) are preferred. Other emollients include silicone oils and synthetic esters. Silicone oils suitable for use include cyclic or linear polydimethylsiloxanes containing from 3 to 9, preferably from 4 to 5 silicon atoms. Non-volatile silicone oils useful as emollients include polyalkyl siloxanes, polyalkylaryl siloxanes and polyether siloxane copolymers. Silicone elastomers may also be used. The ester emollients that may optionally be used are: (i) alkenyl or alkyl esters of fatty acids having 10 to 20 carbon atoms. Examples thereof include isoarachidyl neopentanoate, isononyl isonanonoate, oleyl myristate, oleyl stearate, and oleyl oleate; (ii) ether-esters such as fatty acid esters of ethoxylated fatty alcohols; (iii) polyhydric alcohol esters. Ethylene glycol mono and di-fatty acid esters, diethylene glycol mono- and di-fatty acid esters, polyethylene glycol (200- 6000) mono- and di-fatty acid esters, propylene glycol mono- and di-fatty acid esters, polypropylene glycol 2000 monooleate, polypropylene glycol 2000 monostearate, ethoxylated propylene glycol monostearate, glyceryl mono- and di-fatty acid esters, polyglycerol poly-fatty esters, ethoxylated glyceryl mono- stearate, 1 ,3- butylene glycol monostearate, 1 ,3-butylene glycol distearate, polyoxyethylene polyol fatty acid ester, sorbitan fatty acid esters, and polyoxyethylene sorbitan fatty acid esters are satisfactory polyhydric alcohol esters; (iv) wax esters such as beeswax, spermaceti, stearyl stearate and arachidyl behenate; and, (v) sterols esters, of which cholesterol fatty acid esters are examples. Fatty acids having from 10 to 30 carbon atoms may also be included as carriers. Examples of such fatty acids include pelargonic, lauric, myristic, palmitic, stearic, isostearic, oleic, linoleic, arachidic, behenic or erucic acid and mixtures thereof. Humectants of the polyhydric alcohol type may also be employed in the compositions. The humectant often aids in increasing the effectiveness of the emollient, reduces scaling at the skin surface, stimulates removal of built-up scale and improves skin feel. Typical polyhydric alcohols include glycerol, polyalkylene glycols and more preferably alkylene polyols and their derivatives, including propylene glycol, dipropylene glycol, polypropylene glycol, polyethylene glycol and derivatives thereof, sorbitol, hydroxypropyl sorbitol, hexylene glycol, 1 ,3-butylene glycol, 1 ,2,6-hexanetriol, ethoxylated glycerol, propoxylated glycerol and mixtures thereof. For best results, the humectant is preferably propylene glycol or sodium hyaluronate. Other humectants which may be used include hydroxyethyl urea. Moisturization may be improved through the use of petrolatum or paraffin. Thickeners may also be utilized as a portion of the carrier in the compositions. Typical thickeners include cross- linked acrylates (e.g. Carbopol®982), hydrophobically-modified acrylates (e.g. Carbopol®1382), cellulosic derivatives and natural gums. Among useful cellulosic derivatives are sodium carboxymethylcellulose, hydroxypropyl methylcellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, ethyl cellulose and hydroxymethyl cellulose. Natural gums suitable for the present invention include guar, xanthan, sclerotium, carrageenan, pectin and combinations of these gums. Surfactants may also be present. The surfactant is selected from the group consisting of anionic, nonionic, cationic and amphoteric actives. Particularly preferred nonionic surfactants are those with a C10-20 fatty alcohol or acid hydrophobe condensed with from 2 to 100 moles of ethylene oxide or propylene oxide per mole of hydrophobe; mono- and di- fatty acid esters of ethylene glycol; fatty acid monoglyceride; sorbitan, mono- and di-C8-C20 fatty acids; block copolymers (ethylene oxide / propylene oxide); and polyoxyethylene sorbitan as well as combinations thereof. Alkyl polyglycosides and saccharide fatty amides (e.g. methyl gluconamides) are also suitable nonionic surfactants. Preferred anionic surfactants include soap, alkyl ether sulfate and sulfonates, alkyl sulfates and sulfonates, alkylbenzene sulfonates, alkyl and dialkyl sulfosuccinates, C8 to 20 acyl isethionates, acyl glutamates, C8 to 20 alkyl ether phosphates and combinations thereof. Various other ingredients may also be used in the compositions. Non-limiting examples of additional ingredients can be coating agent, binder, extender, disintegrator, lubricant, diluent, osmotic pressure regulator, pH regulator, dispersant, emulsifier, preservative, stabilizer, antioxidant, colorant, ultraviolet absorber, moisturizer, thickener, activity enhancer, anti- inflammatory agent, disinfecting agent, perfume, flavor, odor improver and the like. The compositions or cosmetic products may also comprise other active ingredients and cosmetic ingredients such as a moisturizer, skin whitening agent, UV protector, cell activator, cleaner, keratolytic agent, and make-up components (e.g., a makeup base, foundation, face finishing powder, powder, cheek color, rouge, eye makeup, eyebrow pencil, mascara, etc.) insofar the effects of the compound are not affected. The above compositions or cosmetic products can be produced by a routine method combining the compounds as necessary with the carrier, diluent, and / or excipient, and / or other active ingredients, cosmetic ingredients, or pharmacological ingredients. For example, the composition for topical application to the skin can be prepared using ingredients typically added to preparations for topical application, pharmaceutical products for topical application or cosmetic products for the skin such as oils or oily substances (e.g., fats or oils, waxes, higher fatty acids, essential oils, silicone oils, or the like), moisturizers (e.g., glycerol, sorbitol, gelatin, polyethylene glycol, or the like), powders (e.g., chalks, talcs, Fuller's earth, kaolin, starch, rubber, or the like), dye, emulsifier, solubilizer, cleaner, ultraviolet absorber, thickener, medicinal component, perfume, resin, antibacterial and antifungal agent, other plant extracts (e.g., crude drugs, Kampo products, herbs), alcohols, polyvalent alcohols, inorganic acids (e.g., bicarbonate, carbonate, sodium chloride, potassium chloride, sodium sulfate, or the like), organic acids (e.g., succinic acid, glutaric acid, fumaric acid, glutamic acid, malic acid, citric acid, ascorbic acid, or the like), vitamins (e.g., vitamin As, vitamin Es, vitamin Bs, vitamin C, folic acid, or the like), water-soluble polymers, anionic surfactants (e.g., alkylbenzene sulfonate, alkylsulfate, or the like), cationic surfactants (e.g., alkyl quaternary ammonium salt, alkyl dimethyl benzyl ammonium salt, or the like), nonionic surfactants (e.g., polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, or the like), and amphoteric surfactants (e.g., imidazoline or carbobetaine containing an alkyl group, or the like). In the case of compositions for topical application, the content of the compound for use in the invention is, on a dry weight basis, preferably from 0.00001 to 20% by weight, more preferably from 0.0001 to 10% by weight. It will be appreciated by those of skill in the art that dark or very dark skin are the most difficult to depigment and may require higher doses than would be necessary for less fair skin and / or hair. For example, subjects that are a Fitzpatrick scale Type IV, V or Type VI may require higher doses to decrease pigmentation than subjects that are a Type II or III. The Fitzpatrick scale is shown in the following table. Fitzpatrick Scale of Skin Color Fitzpatrick Type Scores Characteristics I 0-6 Pale white; blond or red hair; blue eyes; freckles—Always burns, never tans II 7-13 White; fair; blond or red hair; blue, green, or hazel eyes — Usually burns, tans minimally III 14-20 Cream white; fair with any hair or eye color; quite common - Sometimes mild burn, tans uniformly IV 21-27 Moderate brown; typical Mediterranean skin tone—Rarely burns, always tans well V 28-34 Dark brown; Middle Eastern skin types— Very rarely burns, tans very easily VI 35-36 Deeply pigmented dark brown to black— Never burns, tans very easily The present invention is particularly suitable for subjects that are a Fitzpatrick scale Type III, IV, Type V and Type VI. The invention encompasses a method of whitening skin comprising the step of applying at least one compound of formula (I) or any subgroups thereof as defined herein (including all embodiments thereof as described herein), or a composition as hereinbefore disclosed onto the desired skin surface. The method is preferably non-therapeutic in nature. The suitable skin surface includes facial skin, hands, arms, feet, legs, neck, chest, back including the lower back, and scalp. Of interest is facial skin including the forehead, perioral, chin, periorbital, nose, and / or cheeks. The composition may be applied and left on the desired surface for a sufficient time or may be applied repeatedly a sufficient number of times. In certain embodiments, the contact time is greater than 1 hour, greater than 2 hours, greater than 6 hours, greater than 8 hours, greater than 12 hours, or greater than 24 hours. The contact time is the time from application of the composition until the composition is removed. In certain embodiments, the composition may be removed by rinsing or washing the substrate. The composition may be removed by washing or rinsing the skin. The composition may be applied at least once daily. In other embodiments, the composition is applied at least twice daily. Multiple applications may occur over the course of at least about one week. Alternately, the application period may last more than about 3 weeks or more than about 9 weeks. The composition may be applied daily for prolonged period. According to yet another aspect the invention provides for use of at least one compound of formula (I) or any subgroups thereof as defined herein (including all embodiments thereof as described herein) or of the composition as hereinbefore disclosed for whitening skin. The use is preferably cosmetic. The invention also provides for use of at least one compound of formula (I) or any subgroups thereof as defined herein (including all embodiments thereof as described herein) a subgroup thereof, in the manufacture of a composition to provide skin whitening. The present invention provides a method for decreasing the melanin in cells. The method comprises a step of adding at least one compound of formula (I) or any subgroups thereof as defined herein (including all embodiments thereof as described herein), or a composition, as described herein to a tyrosinase-expressing cell in which the tyrosinase production needs to be blocked. The present invention provides a method for decreasing the melanin production in cells. The method comprises a step of adding at least one compound of formula (I) or any subgroups thereof as defined herein (including all embodiments thereof as described herein), or a racemate, stereoisomer, tautomer, salt, and / or solvate thereof, including mixtures thereof, or a composition, as described herein to a melanin-producing cell in which the melanin production needs to be impaired. In the present invention, the “cell” in which the melanin production is to be activated is not particularly limited, insofar as it is a tyrosinase-expressing or melanin-producing cell that is native or modified by a genetic engineering technique. The cell is preferably pigmented cells (melanocyte, retinal pigment epithelial cell, or the like), with melanocytes being more preferable. Alternatively, the “cell” may be a cell debris or cell fraction of the cells mentioned above, tissues containing the cells mentioned above or cultured product derived from the cells mentioned above. When the cell is a cell cultured product, the cell is preferably cultured in the presence of the above composition or compound of the invention. The concentration of the compound to be added is, when the cell is a cell cultured product, as the final concentration in the cultured product range between 0.01 µM to 2 mM, preferably from 50 µM to 1.5 mM, most preferably from 100 µM to 1 mM. In the present invention, the compound or composition, as described herein, can be administered or ingested in an effective amount to or by a subject for decreasing the melanin synthesis, whitening skin, or preventing, ameliorating, or treating symptoms such as skin hyperpigmentation, formation of age spots, freckles and melasma. The administration or ingestion may be carried out non-therapeutically for health promotion or aesthetic purpose. Examples of the subject in the administration or ingestion include animals which need to impair the melanin synthesis. Alternatively, examples of the subject in the administration or ingestion include animals who desire the decrease of melanin production or skin whitening., or animals who desire the prevention, amelioration, or treatment of the symptoms such as skin hyperpigmentation, formation of age spots, freckles and melasma. The animal is preferably a human or non-human mammal, with a human being preferable. The effective amount of administration or ingestion may be an amount which can impair the melanin production in cells of the subject. The preferable amount of administration or ingestion is variable depending on species, body weight, sex, age, conditions of the subject, or other factors. The dose, route, interval of administration or injection, and the amount of ingestion and interval, can be suitably determined by those skilled in the art. For example, when topically administered to the human skin, the amount of administration per adult (60 kg) is from 0.01 µM to 2 mM, preferably from 50 µM to 1.5 mM, most preferably from 100 µM to 1 mM. The following examples are provided for the purpose of illustrating the present invention and by no means should be interpreted to limit the scope of the present invention. EXAMPLES 1 - Protocols: Evaluation of the whitening effect of the compounds a. Explant preparation and culture: Human skin explants of an average diameter of 8x3 mm (diameter x thickness) were prepared on an abdominoplasty coming from Caucasian woman born in 1982 (phototype III, intermediate, donor 1), a Caucasian woman born in 1970 (phototype III, intermediate, donor 2) and Caucasian woman born in 1964 (phototype III, intermediate, donor 3). In all cases, an informed consent was obtained. Skin samples were cultured in an air-liquid interface in a perforated ring of stainless steel in contact with culture medium (modified Williams’ E medium at 37°C, 5% CO2atmosphere) up to planned endpoints. Eight skin biopsies were used for each treatment, two for the viability test and six for the evaluation of skin pigmentation. b. Product preparation and used concentrations: The tested compounds were diluted in DMSO (100%) at the following concentrations: 30µM, 100 µM, 300 µM,1mM and 3mM. DMSO 100% (vehicle) was used as negative control and a solution containing 0.5% (w / v) of Kojic acid or 12% (w / v) azelaic acid were used as positive control. The diluted solutions were stored at 4°C during the study. c. Study schedule: The explants were treated each day for 5 days with the different compounds at different concentrations (see products application below) or with the vehicle or with Kojic acid 0.5% or with Azelaic Acid 12%. On day 3 (D3) a change culture medium was performed. The explants were harvested on day 6. Experimental scheme is shown in Figure 1. d. Products application: Each day of the experiment, the tested products (compounds according to embodiments of the invention or the controls) were applied topically as follows: skin biopsies were gently cleaned with a cotton pad and 4μl of treatment for each tested sample were applied on top of each piece and covered with a 6 mm diameter delivery membrane. The control explants (untreated, DMSO 100%, Kojic Acid 0.5% and Azelaic Acid 12%) were treated using the same method. e. Sampling Eight skin biopsies were used for each treatment, two were used for the viability test and six for the evaluation of skin pigmentation. 2. Histological processing After fixation for 24 hours in buffered formalin solution, the samples were dehydrated and impregnated in paraffin using a Leica PEARL dehydration automat. The samples were then paraffin-embedded using a Leica EG 1160 embedding station.5-µm-thick sections of paraffin- embedded formol fixed sections were realized using a Leica RM 2125 Minot-type microtome, and the sections were then mounted on Superfrost® Plus glass slides. g.1. Melanin visualization and semi-quantitative analysis Twelve skin sections for each treatment were stained by performing a modified Fontana Masson stain, melanin argentaffin granules are stained in black / dark grey / brown. The amount of melanin present in each slide was evaluated by estimating the intensity and the distribution of grey tone. Briefly, 8-bit grey-scale images for each treatment were captured at the microscope. Then the color space of the images were transformed from RGB into L*a*b* images and each pixel of the picture were evaluated according to its L* values. The obtained results were transformed in ranks of L* and then normalized on the ratio between the selected area and the area of the slide. Pigmentation score: The pigmentation score was based on the following step process: 1) Analysis of the image based on pixel grey intensities. 2) Selection of an informative area excluding the pixel area not covered from tissue. 3) Transformation of pixel grey intensities in degrees of L*. 4) Normalization of the obtained values on the ratio between the selected area and the area of the slide. The standardization of the method involved that the extreme values (min, max) within each treatment were excluded from subsequent analysis. This correction allowed reducing the influence of potential “unusual values” and properly evaluating the “genuine data” resulting from subject-treatment interactions. For each test condition six skin samples were cultured. For each skin sample two sections and two images were acquired and analyzed (N=12, ns= non-significant, *** p value < 0.001). g.2. Cellular viability of the explants At the planned endpoint, two skin biopsies were weighed and, in some cases, reduced in the dermal portion, in order to have approximately the same weight for all of them. Samples were then washed and processed with Methylthiazolyldiphenyl-tetrazolium bromide (MTT). MTT was converted to water-insoluble dark blue colored MTT-formazan by mitochondrial dehydrogenases. Subsequently the blue crystals were solubilized and the color intensity, which is directly proportional to skin vitality, was measured with a plate reader at a wavelength of 570 nm. For each analyzed skin sample, the obtained absorbance value was normalized upon the weight in grams. Effect on viability was considered relevant only when the decrease was more than 30% in comparison to untreated. For each tested condition three readings / skin biopsy were performed (i.e. two skin samples x three readings = six data). f. Statistical analysis: All quantitative data were summarized in terms of the mean score for each treatment. The measures of variation as standard deviation and standard error of mean (SEM) were applied to the original scores. Differences between groups were evaluated by One-way Anova with permutation test followed by Tukey’s and t test with permutation when allowed. 2-Structures of the tested compounds and their respective codes Table 1 Compound Name Struc Provider or N° ture CAS ref for synthesis CC001 2-ethynyl-5-isopropyl-1,3- / Synthesis given dimethylbicyclo[3.2.1]octan-2-ol in Synthesis 1 CC002 2-(3-hydroxyprop-1-yn-1-yl)-1,3,3- Synthesis given trimethylbicyclo[2.2.1]heptan-2-ol / in Synthesis 2 CC003 2-ethyl fenchol 18368-91-7 Sigma Aldrich CC004 Terranol 88644-30-8 BLH ingredient service CC005 Azelaic Acid 123-99-9 Sigma Aldrich CC006 Kojic Acid 501-30-4 Sigma Aldrich Part A represents the preparation of compounds CC001 and CC002 whereas Part B represents the results obtained when testing compounds CC001 to CC006. Part A All starting materials which are not explicitly described were either commercially available (the details of suppliers such as for example Aldrich, Combi-Blocks, Enamine, FluoroChem, MatrixScientific, Merck, TCI, Chempure, Angene, BLDpharm, Apollo Scientific, Nanjing, Avra, etc. can be found in the SciFinder® Database for example) or the synthesis thereof has already been described precisely in the specialist literature (experimental guidelines can be found in the Reaxys® Database or the SciFinder® Database respectively, for example) or can be prepared using the conventional methods known to the person skilled in the art. The reactions were, if necessary, carried out under an inert atmosphere (mostly argon and N2). The number of equivalents of reagents and the amounts of solvents employed as well as the reaction temperatures and times can vary slightly between different reactions carried out by analogous methods. Reaction progression was followed by common analytical techniques, such as TLC or LC-MS by adapting eluent solvents and conditions to the analytes under analysis. The work-up and purification methods were adapted according to the characteristic properties of each compound and can vary slightly for analogous methods. Flash chromatography (FC) purification was performed by means of solid supported silica gel or automated flash chromatography systems. The yields of the compounds prepared were not optimized. Abbreviations used in the description, particularly in the Schemes and Examples, are as follows: ACN: Acetonitrile; Dess-Martin periodinane: DMP; DMSO: Dimethylsulfoxide; eq.; equivalent; EtOAc: Ethyl acetate; FC: Flash chromatography in column or automated system; h: Hour(s); HPLC: High performance liquid chromatography; NaH: Sodium hydride; LC-MS: Liquid chromatography–mass spectrometry; MeOH: Methanol; min: Minute; Methylthiazolyldiphenyl-tetrazolium bromide: MTT; NMR: Nuclear Magnetic Resonance; Pd / C: Palladium on carbon; RT: Room temperature; THF: Tetrahydrofuran; TLC: Thin Layer Chromatography; UV: Ultraviolet. Synthesis 1: Synthesis of 2-ethynyl-5-isopropyl-1,3-dimethylbicyclo[3.2.1]octan-2-ol (CC001) Compound CC001 is prepared according to the general procedure outlined in Scheme 1: Scheme 1 Step 1 can be performed as described in Tetrahedron: Asymmetry (2006), 17(11), 1693- 1699 or in WO2004000776 A1. In short, sodium hydride is added to a solution of 2,6- dimethylphenol 1 in THF at 5-10°C. The resulting suspension is stirred. The mixture is cooled, and prenyl chloride 2 is added stepwise keeping the temperature at 5-10°C. The mixture is then stirred at 5-10°C. Methanol and palladium (10% on charcoal) is added and the suspension is hydrogenated. The suspension is then filtered. The filtrate is washed with water, aqueous sodium hydroxide and brine, dried (MgSO4) and concentrated in vacuo. The residue is distilled to yield 2,6-dimethyl-6-(3-methyl-but-2-enyl)-cyclohex-2-enone 3. Step 2 can be performed as described in Angewandte Chemie, International Edition (2005), 44(1), 99-101, or in WO2004000776 A1. In short, to a solution of 2,6-dimethyl-6-(3-methyl-but- 2-enyl)-cyclohex-2-enone 3 in toluene is added dropwise neat EtAlCl2(1.5 eq.). During the addition, the temperature is kept below 10°C. The mixture is kept at room temperature overnight and is then poured on ice cold saturated NH4Cl. The mixture is extracted with MTBE, washed with brine, dried (MgSO4) and concentrated in vacuo. The residue is distilled to yield. 5-lsopropyl-1 ,3-dimethyl-bicvclof3.2.1loctan-2-one 5 can be obtained as described in WO2004000776 A1, by hydrogenation in methanol and palladium (10% on charcoal) of 5- isopropyl-1,3-dimethyl-bicyclo[3.2.1]oct-3-en-2-one 4. To a solution of compound 4 in THF is added ethynyl magnesium bromide (about 2.5 eq at 0°C, and the mixture is stirred at the same temperature. The reaction is quenched, and the resultant mixture is extracted with a suitable solvent. The combined extracts are washed, dried and concentrated in vacuo. The residue is purified by flash chromatography to give 2-ethynyl- 5-isopropyl-1,3-dimethylbicyclo[3.2.1]octan-2-ol (CC001) (Chemical Communications 2020, 56, 531-534). Synthesis 2: 2-(3-hydroxyprop-1-yn-1-yl)-1,3,3-trimethylbicyclo[2.2.1]heptan-2-ol (CC002) Compound CC002 is prepared according to the general procedure outlined in Scheme 2: Scheme 2 To a stirred solution of 1, 3, 3-trimethylbicyclo [2.2.1] heptan-2-ol 1 (5 g, 32.47 mmol) in CH2Cl2(50 mL) under argon atmosphere was added Dess-Martin periodinane (DMP) (20.06 g, 48.70 mmol) at 0oC. The reaction mixture was stirred at RT for 2 h. The reaction was monitored by TLC; after consumption of the starting material, the reaction mixture was diluted with saturated sodium bicarbonate solution (20 mL) and extracted with CH2Cl2(2 x 20 mL). The combined organic extracts were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by combi flash chromatography eluting with 2% EtOAc / Hexane to afford compound 2 (4.5 g, 91%) as colorless oil. To a stirred solution of prop-2-yn-1-ol (2.21 g, 39.47 mmol) in ether (30 mL) was added n- butyl lithium (5.05 g, 78.94 mmol) under argon atmosphere at -78oC and stirred at RT for 1 h. Then compound 2 (3 g, 19.73 mmol) was added to the reaction mixture at -78oC and stirred at RT for 1 h. The reaction was monitored by TLC; after consumption of the starting material, the reaction mixture was diluted with saturated ammonium chloride solution (50 mL) and extracted with EtOAc (2 x 50 mL). The combined organic extracts were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by combi flash chromatography eluting with 12% EtOAc / Hexane to afford CC002 (800 mg, 19%) as an off-white solid. 1H NMR (400 MHz, DMSO-d6): δ5.03 (t, J = 5.9 Hz, 1H), 4.90 (s, 1H), 4.11 (d, J = 5.9 Hz, 2H), 1.94-1.78 (m, 1H), 1.68-1.52 (m, 3H), 1.39-1.23 (m, 1H), 1.12 (s, 3H), 1.05 (s, 3H), 1.03- 0.93 (m, 2H), 0.85 (s, 3H) LC-MS (ESI): 96.25%; m / z 225.9 [M+H2O]+; (column: X-select C-18 (3.0 × 50 mm, 2.5 µm); RT 3.14 min; 2.5mM Ammonium formate: ACN; 0.8 mL / min); Gradient program: T / B% 0.01 / 5, 3 / 95, 5 / 95, 5.7 / 5. Part B Example 1: Dose-response analyses of organic compounds -OR interactions The determination of the toxicity of the compounds on skin explants and the definition of the maximal concentrations that can be used on skin explants without affecting the viability, was determined using the MTT assay. The MTT assay was performed as described herein above under the Protocols section using the different compounds listed in Table 1, including Azelaic Acid 12% (benchmark reference) and Kojic Acid 0.5%. The viability experiments were performed on donors 1 and 2 with concentrations ranging from 300 µM to 3 mM (Figures 2A and 2B) and were performed in triplicate (n=3) on two different biopsies from the two donors. Results for donor 1 are presented in Figure 2A and results for donor 2 are represented in Figure 2B. Cell viability was analyzed, and toxicity / viability was expressed in percentage relative to the untreated condition which was fixed at 100%. The cytotoxicity threshold was set by convention at 70% of viability. As shown in Figures 2A and 2B, none of the compounds of interest had a significant cell toxicity independently of the tested concentration (One-way ANOVA with permutation test followed by Tukey’s and t-test; ns= non-significant, ***p- value<0.001). After 6 days of treatment, the decrease of viability was significant only for Azelaic Acid, a compound used in several creams at 12% in the cosmetic market (*** p<0.001). From the results shown in Figures 2A and 2B, it can be observed that the tested compounds according to embodiments of the invention did not affect cells viability of skin living explants and were not toxic at the tested concentration in contrast with Azelaic Acid 12%. Example 2: Macroscopic effects of formulation on human skin explants melanogenesis The ex vivo effects on skin pigmentation was evaluated on human biopsies of skin (skin living explants) obtained from 3 different donors as described herein above. The experiment was performed using a topical application of compounds according to embodiments of the invention for 6 days (D6). As controls, untreated explants, and explants treated with DMSO, Azelaic Acid 12% or Kojic Acid 0.5% were used. The effect of compounds according to embodiments of the invention on melanogenesis was measured using Masson’s Fontana staining on paraffin skin sections at D6 as described herein above in the Protocols section. After 6 days of topical application of 300 µM, 1 mM and 3 mM of 2-ethyl fenchol, the macroscopic evaluation showed a normal and typical organization of the papillary dermal and epidermal structures in both conditions confirming no effect on skin explants viability (see Figure 3A). As observed in representative pictures and after semi-quantitative analysis (see Protocols section hereinabove), the results indicated that 2-ethyl fenchol had significantly inhibited the skin pigmentation in a dose-dependent manner (Donor 1: -13% of pigmentation using 1 mM of 2-ethyl fenchol and -22% of pigmentation using 3 mM 2-ethyl fenchol in comparison to DMSO; Donor 3: -4% of pigmentation at 1 mM and -14% of pigmentation at 3 mM vs DMSO; ((*): p < 0.05 and (**): p < 0.01). These semi-quantitative evaluations confirmed that the content of melanin, present in the basal layer of the skin in different donors, was significantly lower after treatment in comparison to untreated or vehicle (DMSO) conditions (see basal layer of melanocytes, Figures 3A, 3B). Moreover, the level of skin pigmentation was equivalent or even lower than the one observed with Kojic Acid 0.5% (positive depigmenting agent; Donor 1 and Donor 3: -14% and -18% vs DMSO respectively). The results obtained with Azelaic Acid 12% were invalidated since this compound showed a high toxicity during the experiment. A “compound-independent” effect on skin pigmentation probably related to the - 59% of viability was reported in Example 1. As shown in Figures 3 C-F, Terranol (CC004), 2-ethynyl-5-isopropyl-1,3-dimethylbicyclo [3.2.1]octan-2-ol (CC001) and compound 2-(3-hydroxyprop-1-yn-1-yl)-1,3,3- trimethylbicyclo[2.2.1]heptan-2-ol (CC002) were also tested as depigmenting agents. MTT assay for these compounds showed no toxicity (Figures 2A and 2B). The results indicated that the topical use of Terranol, CC001 and CC002 had strong macroscopic effects on the content of melanin present in the basal layer of the skin. Representative pictures of the results obtained from living explants of donor 2 (treatment 1 mM of Terranol and 1 mM of CC001) are shown in Figure 3C. Semi-quantitative quantifications using 10 slides of different biopsies confirmed the significant decrease of 20% and 30% of the content of melanin respectively after treatment with 1 mM Terranol and 1 mM CC001 ( **p<0.01 vs DMSO, Figure 3D). In donor 3, a strong effect of the compounds according to embodiments of the invention was also observed. Increasing concentration of Terranol (100 µM, 300 µM and 1 mM) or CC001 (100 µM, 300 µM and 1 mM) were tested and it could be seen that these compounds were already efficient at the lowest tested concentrations (-14% of the pigmentation with 100 µM Terranol and -17% of the pigmentation with 100 µM CC001 in comparison to the untreated condition, **p<0.01; n=10, Figure 3E). The treatment with Terranol at 1mM, CC001 at 300 µM and C002 at 1 mM (Figure 3E) decreased the pigmentation score to a level similar or lower than the one observed with benchmark product Kojic Acid 0.5% (-18%, -27%, -21% respectively versus -19% using Kojic Acid 0.5%; ** p<0.01, n=10 for each condition). Representative pictures showing the effect of CC003 at 1 mM on the content of melanin in the basal layer are represented in Figure 3F. The experiments on human living skin explants and with different concentrations of the compounds (from 100 µM to 3 mM) according to embodiments of the invention, showed that the compounds were well tolerated and that they can be used to decrease pigmentation of the skin. They can constitute a new and safe generation of depigmenting agents that respond to the customers’ needs worldwide.

Claims

Claims 1. A lightening composition comprising a lightening effective amount of a compound of formula (I),or a tautomer, a stereoisomer, a hydrate, a solvate, a salt, or a polymorph thereof, wherein n is an integer selected from 0, 1, or 2, m is an integer selected from 1, 2, or 3; R1is selected from the group comprising alkynyl, alkyl, hydrogen, and alkenyl; wherein each of said alkynyl, alkyl, and alkenyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R2is selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy, or R1and R2together with the carbon atoms to which they are attached can form a cycloalkyl, a cycloalkenyl or a cycloalkynyl, wherein each of said cycloalkyl, cycloalkenyl and cycloalkynyl can be unsubstituted or substituted with one or more substituents R8, wherein each R8is independently selected from the group comprising alkyl, alkenyl, alkynyl, hydroxyl, halo, haloalkyl, and haloalkoxy; each R3is independently selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl, and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; each R4is independently selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R5is hydrogen; R6is hydrogen; R7is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; whereineach of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy.

2. The lightening composition according to claim 1, wherein said compound has structural formula (I1),3. The lightening composition according to any one of claims 1 or 2, wherein n is 1.

4. The lightening composition according to any one of claims 1 or 2, wherein n is 2.

5. The lightening composition according to any one of claims 1 to 4, wherein said compound have structural formula (I2) or (I3)6. The lightening composition according to any one of claims 1 to 5, wherein said compound have structural formula (I4), (I5) or (I6)wherein s is an integer selected from 0, 1, 2, 3, 4, or 5.

7. The lightening composition according to any one of claims 1 to 6, wherein said compound is selected from the group comprising:

8. The lightening composition of any one of claims 1 to 7, wherein said composition is a skinlightening composition.

9. A compound of formula (I2) or a tautomer, a stereoisomer, a hydrate, a solvate, a salt, or a polymorph thereof, whereinR1is alkynyl; wherein said alkynyl is substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R2is selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R3is independently selected from the group comprising alkyl, hydrogen, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl, and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R4is independently selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy; R5is hydrogen; R6is hydrogen; R7is selected from the group comprising hydrogen, alkyl, alkenyl, and alkynyl; wherein each of said alkyl, alkenyl and alkynyl can be unsubstituted or substituted with one or more substituents each independently selected from the group comprising hydroxyl, halo, haloalkyl, and haloalkoxy.

10. Use of at least one compound as defined in any one of claims 1 to 9 as depigmenting agent.

11. Use of at least one compound as defined in any one of claims 1 to 9, or use of the lightening composition of any one of claims 1 to 8, for preventing and / or reducing pigmentation of normal skin.

12. Use of at least one compound as defined in any one of claims 1 to 9, or use of the lightening composition of any one of claims 1 to 8, for decreasing the amount of melanin in melanocytes, for decreasing melanin synthesis, for impairing melanin transport and / or for impairing the distribution of melanin in suprabasal layers.

13. A compound as defined in any one of claims 1 to 9 or a lightening composition of any one of claims 1 to 8 for use in a method for preventing and / or reducing skin pigmentation disorders related to an abnormal excessive production of melanin and / or abnormal increased number of melanocytes.

14. The compound or lightening composition for use according to claim 13, wherein said pigmentation disorders are selected from the group comprising hyperpigmentation, melasma, postinflammatory hyperpigmentation, solar or senile lentigo, freckles due to an abnormal excessive production of melanin, drug induced hyperpigmentation, light induced hyperpigmentation and chemical induced hyperpigmentation.

15. A method for preventing and / or reducing pigmentation of normal skin, comprising topically applying at least one compound as defined in any one of claims 1 to 9, or a lightening composition according to any one of claims 1 to 8 to the skin of the subject in need thereof.

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