Cosmetic composition comprising a thiopyridinone compound and a reducing agent

Abstract

The present invention relates to a composition, preferably a cosmetic composition, comprising at least one thiopyridinone compound of formula (I) or (I') and at least one reducing agent of formula (II). The present invention also provides a composition comprising a thiopyridinone compound with improved stability of the thiopyridinone compound over time.

Description

Technical Field

[0001] This invention relates to the stabilization of thiopyridone compounds. In particular, this invention relates to a composition comprising a thiopyridone compound and a reducing agent for stabilizing the compound and the composition thereof. Background Technology

[0002] Cosmetics that provide flawless skin through cleansing, hydration, moisturizing, anti-aging, anti-wrinkle, and brightening are extremely popular products in daily life.

[0003] At various stages of their lives, some people develop a dark appearance of dark spots and / or freckles on their skin, particularly on their face and hands, resulting in uneven skin tone. These spots are due to a high concentration of melanin in the keratinocytes located on the skin's surface.

[0004] The most desired treatment is a harmless, topical depigmenting substance that is effective in treating pigmentation spots. For example, arbutin, niacinamide, and kojic acid are known as skin depigmenting agents.

[0005] It is known, as disclosed in WO2017 / 102349, that certain thiopyridone compounds exhibit good depigmenting activity even at low concentrations.

[0006] Thiopyridone compounds can exhibit strong depigmentation or whitening effects by reducing melanin production.

[0007] Nevertheless, there is still a need to develop cosmetic compositions containing thiopyridone compounds with improved stability to impart skin-brightening and whitening effects. Summary of the Invention

[0008] According to one aspect of the invention, a composition, preferably a cosmetic composition, is provided comprising a thiopyridone compound of formula (I) or (I') and a reducing agent, wherein the stability, preferably thermal stability and / or photostability, of the thiopyridone compound is improved. The inventors have unexpectedly discovered that the use of a reducing agent improves the stability, preferably thermal stability and / or photostability, of the compound of formula (I) or (I') in the composition.

[0009] This invention provides a composition, preferably a cosmetic composition, comprising: i) At least one compound selected from compounds of formula (I), tautomers of formula (I'), salts, solvates, hydrates, optical isomers, racemates, or mixtures thereof: in, - R1 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 10 Or branched C3-C 10 Alkyl groups, optionally substituted with one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -S-R3; - R2 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 12 Or branched C3-C 12 Or a cyclic C3-C8 hydrocarbon group, optionally substituted by one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -S-R3; iii) -C(O)-O-R3; iv) C5-C 12 aryl groups, optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups, and c) C5-C 12 Aryl group, which is optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups; - R3 refers to a group selected from the following: a) Hydrogen atom, and b) Saturated straight-chain C1-C 10 Or branched C3-C 10 alkyl; and ii) At least one inorganic reducing agent of formula (II), wherein the compound of formula (II) is selected from: a) Inorganic reducing agents of formula (IIA), their racemic forms, and their solvates, such as hydrates. (IIA) in, X represents a heteroatom selected from oxygen or sulfur, preferably oxygen; m is 0 or 1; M + It is a cation, preferably selected from alkali metals, alkaline earth metals or ammonium, more preferably selected from alkali metals such as sodium or potassium; R represents a group selected from the following: i) -OH, ii) -O-M' + , where M' + As previously stated regarding M + Limited, iii) in, • p is an integer chosen between 0 and 4 (inclusive), preferably 0, 1, or 2, more preferably 0 or 2; • m' is 0 or 1, preferably 1; • X', as defined for X, preferably represents an oxygen atom; and M'' + As previously stated regarding M + Limited by, and M + M' + M'' + Same or different, same is preferred or, b) Thiolized amino compounds of formula (IIB), their optical isomers, geometric isomers, solvates, hydrates, salts of bases or salts of acids, R a -N(R b )-CH(R c )-(CH2) n -SR d (IIB) in n is an integer selected from 0 to 3; - R a Represents a hydrogen atom or -C(X) a )-R a ', where X a Represents an oxygen or sulfur atom, preferably oxygen, and R a 'Represents a saturated or unsaturated straight-chain or branched hydrocarbon chain containing 1 to 8 carbon atoms, preferably a saturated hydrocarbon such as (C1-C6) alkyl, wherein the chain: i) Optionally substituted with one or more groups selected from (di)(C1-C4)(alkyl)amino and -C(O)OM, wherein M represents a hydrogen atom or is preferably selected from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+ and K. + Cation counterions; and / or ii) Optionally selected from O, S, N(R) e -C(O)-, -C(O)-N(R) e - or -N(R) e One or more heteroatoms or groups of )-C(O)- are interrupted, where R e Representing a hydrogen atom or a (C1-C4) alkyl group such as methyl, preferably R e Represents a hydrogen atom; - R b Representing a hydrogen atom or a (C1-C4) alkyl group such as methyl, preferably Rb Represents a hydrogen atom; - R c Representatives are selected from one of the following: a) Hydrogen atom, b) -C(O)OM', where M' is as previously defined for M; or c) -C(O)-N(R e ')-R a '', where R a As previously stated regarding R a 'As defined, preferably R' a Unlike R a ', more preferably R a '' represents an (C1-C4) alkyl group optionally substituted with one or more -C(O)OM groups as defined above, preferably -C(O)OH; - R d Represents a hydrogen atom or -S-CH2-CH(R) f )-N(R g )-R h , where R f As previously stated regarding R c As specified, R g As previously stated regarding R b Limited by, and R h As previously stated regarding R a As defined, preferably R d Represents a hydrogen atom; What needs to be understood is: - R f With R c Whether they are the same or different, the same is preferred; - R g With R b Whether they are the same or different, the same is preferred; - R h With R a Same or different, same is preferred; and - M and M' may be the same or different, preferably the same.

[0010] According to another aspect of this disclosure, a cosmetic method for treating keratin materials is provided, the method comprising applying a composition as disclosed herein to the keratin material, preferably to the skin.

[0011] According to another aspect of this disclosure, the use of the compositions disclosed herein for use in keratin materials, preferably for whitening or depigmenting skin, is provided.

[0012] According to another aspect of this disclosure, the use of at least one reducing agent of formula (II) in a composition comprising at least one compound selected from formula (I), its tautomers, salts, optical isomers, racemic derivatives, solvates, hydrates, or mixtures thereof for stabilizing the compound of formula (I), its tautomers, salts, optical isomers, racemic derivatives, solvates, hydrates, or mixtures thereof in the composition is provided. The compounds of formula (II) are selected from: a. Inorganic reducing agents of formula (IIA), their racemic forms, and their solvates, such as hydrates. (II) in, X represents a heteroatom selected from oxygen or sulfur, preferably oxygen; m is 0 or 1; M + It is a cation, preferably selected from alkali metals, alkaline earth metals or ammonium, more preferably selected from alkali metals such as sodium or potassium; R represents a group selected from the following: i) -OH, ii) -O-M' + , where M' + As previously stated regarding M + Limited, iii) in, • p is an integer chosen between 0 and 4 (inclusive), preferably 0, 1, or 2, more preferably 0 or 2; • m' is 0 or 1, preferably 1; • X', as defined for X, preferably represents an oxygen atom; and • M'' + As previously stated regarding M + Limited by, and M + M' + M'' + Same or different, same is preferred. or b) Thiolized amino compounds of formula (IIB), their optical isomers, geometric isomers, solvates, hydrates, salts of bases or salts of acids, R a -N(R b )-CH(R c )-(CH2) n -SR d (IIB) in, n is an integer selected from 0 to 3; - R a Represents a hydrogen atom or -C(X) a )-R a ', where X a Represents an oxygen or sulfur atom, preferably oxygen, and R a 'Represents a saturated or unsaturated straight-chain or branched hydrocarbon chain containing 1 to 8 carbon atoms, preferably a saturated hydrocarbon such as (C1-C6) alkyl, wherein the chain: i) Optionally substituted with one or more groups selected from (di)(C1-C4)(alkyl)amino and -C(O)OM, wherein M represents a hydrogen atom or is preferably selected from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+ and K. + Cation counterions; and / or ii) Optionally selected from O, S, N(R) e -C(O)-, -C(O)-N(R) e - or -N(R) e One or more heteroatoms or groups of )-C(O)- are interrupted, where R e Representing a hydrogen atom or a (C1-C4) alkyl group such as methyl, preferably R e Represents a hydrogen atom; - R b Representing a hydrogen atom or a (C1-C4) alkyl group such as methyl, preferably R b Represents a hydrogen atom; - R c Representatives are selected from one of the following: a) Hydrogen atom, b) -C(O)OM', where M' is as previously defined for M; or c) -C(O)-N(R e ')-R a '', where R a As previously stated regarding R a 'As defined, preferably R' a Unlike R a ', more preferably R a '' represents an (C1-C4) alkyl group optionally substituted with one or more -C(O)OM groups as defined above, preferably -C(O)OH; - R d Represents a hydrogen atom or -S-CH2-CH(R) f )-N(R g )-R h , where R f As previously stated regarding R c As specified, R gAs previously stated regarding R b Limited by, and R h As previously stated regarding R a As defined, preferably R d Represents a hydrogen atom; What needs to be understood is: - R f With R c Whether they are the same or different, the same is preferred; - R g With R b Whether they are the same or different, the same is preferred; - R h With R a Same or different, same is preferred; and - M and M' may be the same or different, preferably the same. In equations (I) and (I'): - R1 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 10 Or branched C3-C 10 Alkyl groups, optionally substituted with one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -S-R3; - R2 refers to a group selected from the following: a) Hydrogen atom; b) Saturated hydrocarbon groups, straight-chain C1-C 12 Or branched C3-C 12 Or cyclic C3-C8, optionally substituted with one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -S-R3; iii) -C(O)-O-R3; iv) C5-C 12 Aryl group, which is optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups; c) C5-C 12 aryl groups, optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups; and - R3 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 10 Or branched C3-C 10 alkyl.

[0013] These and other features, aspects, and advantages of this subject matter will be better understood by referring to the following description and the appended claims. This overview is provided to introduce a range of concepts in a simplified form. This overview is not intended to specify key or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter. Detailed Implementation

[0014] Those skilled in the art will recognize that variations and modifications can be made to this disclosure in addition to those specifically described. It is to be understood that this disclosure includes all such variations and modifications. This disclosure also includes all such steps, features, compositions, and compounds individually or collectively mentioned or indicated in this specification, as well as any and all combinations of any or more of these steps or features.

[0015] limited For convenience, certain terms used in the specification and embodiments are described herein before further description of this disclosure. These limitations should be interpreted in light of the remainder of this disclosure and as understood by those skilled in the art. The terms used herein have meanings recognized and known to those skilled in the art; however, for convenience and completeness, specific terms and their meanings are set forth below.

[0016] The articles “a,” “a,” and “the” are used to refer to one or more (i.e., at least one) grammatical objects of the article.

[0017] The terms “comprise” and “comprising” are used in an inclusive, open sense, meaning that additional elements may be included. They are not intended to be interpreted as “consisting only of…”.

[0018] The term "at least one" is used to indicate one or more components, and therefore includes both single components and mixtures / combinations.

[0019] Throughout this specification, unless the context otherwise requires, the word “comprise” and its variations such as “comprises” and “comprising” shall be understood to mean that the specified element or step or group of elements or steps is included, but does not exclude any other element or step or group of elements or steps.

[0020] The term "including" is used to mean "including but not limited to". "Including" and "including but not limited to" are used interchangeably.

[0021] The term "INCI" is an abbreviation for International Nomenclature of Cosmetic Ingredients, which is a naming system for describing personal care ingredients provided by the International Nomenclature Committee of the Personal Care Products Council.

[0022] Unless otherwise stated, all percentages, parts, and ratios are based on the total weight of the compositions disclosed herein. Ratios, concentrations, amounts, and other numerical data may be presented herein in range format. It is to be understood that such range format is used for convenience and brevity only and should be flexibly interpreted to include not only the values ​​explicitly listed as limits of the range, but also all individual values ​​or subranges contained within the range, as if the individual values ​​and subranges were explicitly listed. For example, a weight percentage range of approximately 0.01% to 10% should be interpreted to include not only the explicitly listed limits of approximately 0.01% to approximately 10%, but also subranges such as 0.02% to 0.05%, 1% to 10%, etc., and individual amounts within the specified range, including fractions such as 1.5%, 5.3%, and 9.25%.

[0023] For the purposes of this disclosure, unless otherwise stated: a) “Saturated linear C1-C 12 Or branched C3-C 12 "Hydrocarbon groups are equivalent to "straight-chain (C1-C) " 12 )alkyl or branched (C3-C 12 "alkyl", which corresponds to a saturated straight-chain C1-C1 group. 12 Or branched C3-C 12 Hydrocarbon-type groups, preferably straight-chain C1-C 10 Or branched C3-C 10 The hydrocarbon group is preferably a straight-chain C1-C6 or branched C3-C6 hydrocarbon group; preferably, the straight-chain or branched group can be selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl and tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl. More preferably, the saturated straight-chain or branched alkyl group can be selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl and tert-butyl, pentyl, hexyl, heptyl and octyl, such as methyl, ethyl, n-pentyl, n-nonyl, isobutyl; b) Saturated “cyclic C3-C8” alkyl groups are monocyclic or bicyclic cycloalkyl groups containing 3 to 8 carbon atoms, especially monocyclic cycloalkyl groups with C5 to C7 atoms, such as cyclohexyl; c) “Alkoxy” is an alkyloxy group, where the alkyl group is a straight-chain or branched C1-C group.16 Preferably, C1-C8 hydrocarbon groups are used; when the alkoxy group is optionally substituted, this means that the alkyl group is optionally substituted as defined above. d) “Aryl” represents a fused or non-fused monocyclic or bicyclic carbonyl group containing 5 to 12 carbon atoms, preferably 6 to 10 carbon atoms, and wherein at least one ring is aromatic; preferably, the aryl group is phenyl, biphenyl, naphthyl, more preferably phenyl; e) The term "at least one" is equivalent to the term "one or more"; and f) For concentration ranges, the term "inclusive" means that the limits of the range are included within the defined range.

[0024] Salts of compounds of formula (I), (I'), (Ia) or (Ia') comprise conventional non-toxic salts of the compounds, such as salts formed from organic or inorganic acids or organic or inorganic bases.

[0025] As a salt of a compound of formula (I), (I'), (Ia) or (Ia'), it can be mentioned that this is achieved by adding a compound of formula (I) to the following substances: i) Inorganic bases, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonium hydroxide, magnesium hydroxide, lithium hydroxide, and carbonates or bicarbonates of sodium, potassium, or calcium; or ii) Organic bases, such as primary, secondary, or tertiary alkylamines, for example, triethylamine or butylamine. Such primary, secondary, or tertiary alkylamines may contain one or more nitrogen and / or oxygen atoms, and therefore may contain, for example, one or more alcohol functionalities; 2-amino-2-methylpropanol, ethanolamine, triethanolamine, 2-dimethylaminopropanol, 2-amino-2-(hydroxymethyl)-1,3-propanediol, and 3-(dimethylamino)propylamine may be specifically mentioned.

[0026] Salts of amino acids, such as lysine, arginine, guanidine, glutamic acid, and aspartic acid, may also be mentioned. Advantageously, the salts of compounds of formula (I) (when they contain a carboxyl group) may be selected from alkali metal or alkaline earth metal salts, such as sodium, potassium, calcium, or magnesium salts and ammonium salts.

[0027] "Organic or inorganic acid salts" are more specifically selected from salts derived from: i) hydrochloric acid HCl, ii) hydrobromic acid HBr, iii) sulfuric acid H2SO4, iv) alkyl sulfonic acids: Alk-S(O)2OH, such as methanesulfonic acid and ethanesulfonic acid; v) aryl sulfonic acids: Ar-S(O)2OH, such as benzenesulfonic acid and toluenesulfonic acid; vi) citric acid; vii) succinic acid; viii) tartaric acid; ix) lactic acid; x) alkoxysulfinic acids: Alk-OS(O)OH, such as methoxysulfinic acid and ethoxysulfinic acid; xi) aryloxysulfinic acids, such as toluoxysulfinic acid and phenoxysulfinic acid; xii) phosphoric acid H3PO4; xiii) acetic acid CH3C(O)OH; xiv) trifluoromethanesulfonic acid CF3SO3H; and xv) tetrafluoroborate HBF4; Acceptable solvates of the compounds described in this invention include conventional solvates, such as those formed during the preparation of the compounds due to the presence of a solvent. As examples, solvates obtained due to the presence of water or straight-chain or branched alcohols, such as ethanol or isopropanol, may be mentioned.

[0028] Optical isomers of formula (I) or (I'), especially enantiomers and diastereomers.

[0029] The meso form of formula (II) represents an isomer of the compound of formula (II) resulting from the delocalization of electrons around heteroatoms such as oxygen and / or sulfur.

[0030] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Although any methods and materials similar to or equivalent to those described herein may be used in the practice or testing of this disclosure, preferred methods and materials are described hereafter. All publications mentioned herein are incorporated herein by reference.

[0031] The scope of this disclosure is not limited to the specific embodiments described herein, which are for illustrative purposes only. As stated herein, functionally equivalent products, compositions, and methods are clearly within the scope of this disclosure.

[0032] Compositions stabilizing thiopyridone compounds In one embodiment, the present invention provides a composition, preferably a cosmetic composition, comprising: i) At least one compound selected from compounds of formula (I), tautomers of formula (I'), salts, solvates, hydrates, optical isomers, racemates, or mixtures thereof: in, - R1 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 10 Or branched C3-C 10 Alkyl groups, optionally substituted with one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -S-R3; - R2 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 12 Or branched C3-C 12 Or a cyclic C3-C8 hydrocarbon group, optionally substituted by one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -S-R3; iii) -C(O)-O-R3; iv) C5-C 12 aryl groups, optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups, and c) C5-C 12 Aryl group, which is optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups; - R3 refers to a group selected from the following: a) Hydrogen atom, and b) Saturated straight-chain C1-C 10 Or branched C3-C 10 Alkyl groups; and ii) at least one reducing agent of formula (II), wherein the compound of formula (II) is selected from: a) Inorganic reducing agents of formula (IIA), their racemic forms, and their solvates, such as hydrates. (II) in X represents a heteroatom selected from oxygen or sulfur, preferably oxygen; m is 0 or 1; M + It is a cation, preferably selected from alkali metals, alkaline earth metals or ammonium, more preferably selected from alkali metals such as sodium or potassium; R represents a group selected from the following: i) -OH, ii) -O-M' + , where M' + As previously stated regarding M + Limited, iii) in, • p is an integer chosen between 0 and 4 (inclusive), preferably 0, 1, or 2, more preferably 0 or 2; • m' is 0 or 1, preferably 1; • X', as defined for X, preferably represents an oxygen atom; and • M'' + As previously stated regarding M + Limited by, and M + M' + M'' + Whether they are the same or different, the same is preferred; or, b) Thiolized amino compounds of formula (IIB), their optical isomers, geometric isomers, solvates, hydrates, salts of bases or salts of acids, R a -N(R b )-CH(R c )-(CH2) n -SR d (IIB) in n is an integer selected from 0 to 3; - R a Represents a hydrogen atom or -C(X) a )-R a ', where X a Represents an oxygen or sulfur atom, preferably oxygen, and R a 'Represents a saturated or unsaturated straight-chain or branched hydrocarbon chain containing 1 to 8 carbon atoms, preferably a saturated hydrocarbon such as (C1-C6) alkyl, wherein the chain: i) Optionally substituted with one or more groups selected from (di)(C1-C4)(alkyl)amino and -C(O)OM, wherein M represents a hydrogen atom or is preferably selected from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+ and K. + Cation counterions; and / or ii) Optionally selected from O, S, N(R) e -C(O)-, -C(O)-N(R) e - or -N(R) e One or more heteroatoms or groups of )-C(O)- are interrupted, where R e Representing a hydrogen atom or a (C1-C4) alkyl group such as methyl, preferably R e Represents a hydrogen atom; - R b Representing a hydrogen atom or a (C1-C4) alkyl group such as methyl, preferably R b Represents a hydrogen atom; - R c Representatives are selected from one of the following: a) Hydrogen atom, b) -C(O)OM', where M' is as previously defined for M; or c) -C(O)-N(R e ')-R a '', where R a As previously stated regarding R a 'As defined, preferably R' a Unlike R a ', more preferably R a '' represents an (C1-C4) alkyl group optionally substituted with one or more -C(O)OM groups as defined above, preferably -C(O)OH; - R d Represents a hydrogen atom or -S-CH2-CH(R) f )-N(R g )-R h , where R f As previously stated regarding R c As specified, R g As previously stated regarding R b Limited by, and R h As previously stated regarding R a As defined, preferably R d Represents a hydrogen atom; What needs to be understood is: - R f With R c Whether they are the same or different, the same is preferred; - R g With R b Whether they are the same or different, the same is preferred; - R h With R a Same or different, same is preferred; and - M and M' may be the same or different, preferably the same.

[0033] A composition according to one embodiment of the invention, preferably a cosmetic composition, comprises at least one compound of formula (I) or (I'), referred to as a "thiopyridone type compound" or "thiopyridone compound". It is possibly preferred that the invention provides a cosmetic composition comprising a combination of a thiopyridone type compound (I) or (I') with at least one reducing agent of formula (II), said reducing agent improving the stabilization, preferably thermal stabilization, of the thiopyridone compound and the cosmetic composition comprising it.

[0034] The term "stability" for thiopyridone compounds can be determined by the change in the amount of the thiopyridone compound in the composition according to the invention over a certain period of time. The term "thermal stability" for thiopyridone compounds can be determined by the change in the amount of the thiopyridone compound in the composition according to the invention over a certain period of time, particularly when the composition is maintained at room temperature or even at elevated temperatures such as above 40°C for a relatively long time, such as two weeks. The term "light stability" for thiopyridone compounds can be determined by the change in the amount of the thiopyridone compound in the composition according to the invention after exposure to light. Improved "stability," "thermal stability," or "light stability" means that the change in the amount of the thiopyridone compound over time is more limited.

[0035] In some embodiments, the stabilization of compounds of formula (I) or (I') in the composition is improved by a reducing agent of at least one formula (II) as described herein, preferably by thermal stabilization and / or photostability. In other embodiments, the compositions according to the invention exhibit enhanced stability of the thiopyridone compounds of formula (I) and (I'), preferably by thermal and / or photostability. In some embodiments, the compositions according to the invention exhibit enhanced stability of compounds of formula (I) or (I') when stored at room temperature for extended periods. In some embodiments, the compositions according to the invention exhibit enhanced stability of compounds of formula (I) or (I') even when the composition is held and stored at elevated temperatures such as 40 to 60°C for extended periods, such as 2 to 3 weeks. In yet another embodiment, the enhanced stability of compounds of formula (I) or (I') in the composition provides improved bioavailability to result in a prolonged brightening or depigmenting effect on keratin materials.

[0036] According to one embodiment, the present invention provides a method for improving the stability of thiopyridone-type compounds (I) or (I') in cosmetic compositions that can be used to treat keratin materials, such as human facial and neck skin. In some embodiments, the present invention provides a cosmetic method for treating skin, comprising applying the cosmetic composition of the present invention to the skin to achieve a brightening or whitening effect. This cosmetic composition can be used as a non-therapeutic treatment for dark spots and uneven skin texture.

[0037] Thiopyridone compounds of formula (I) or (I') In one embodiment, the composition, preferably a cosmetic composition, comprises: i) At least one compound selected from compounds of formula (I), tautomers of formula (I'), salts, solvates, hydrates, optical isomers, racemates, or mixtures thereof: in, - R1 refers to a group selected from the following: a) Hydrogen atom; and b) Saturated straight-chain C1-C 10 Or branched C3-C 10 Alkyl groups, optionally substituted with one or more groups, which may be the same or different, selected from: i) -O-R3; and ii) -S-R3; - R2 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 12 Or branched C3-C 12 Or a cyclic C3-C8 hydrocarbon group, optionally substituted by one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -S-R3; iii) -C(O)-O-R3; iv) C5-C 12 aryl groups, optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups, and c) C5-C 12 Aryl group, which is optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups; - R3 refers to a group selected from the following: a) Hydrogen atom, and b) Saturated straight-chain C1-C 10 Or branched C3-C 10 alkyl; Therefore, the compounds used according to the present invention correspond to the following formula (I) alone or as a mixture, or to tautomers (I') or their salts, optical isomers, racemates and / or solvates such as hydrates and the thereof.

[0038] In equations (I) and (I'): R1 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 10 Or branched C3-C 10 Alkyl groups, optionally substituted with one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -S-R3; R2 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 12 Or branched C3-C 12 Or a cyclic C3-C8 hydrocarbon group, optionally substituted by one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -S-R3; iii) -C(O)-O-R3; iv) C5-C 12 aryl groups, optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups; and c) C5-C 12 Aryl group, which is optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups; in R3 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 10 Or branched C3-C 10 alkyl; When a tautomeristic equilibrium exists according to the following diagram, compound (I') is the tautomer form of compound (I):

[0039] In some implementations, R1 represents a hydrogen atom.

[0040] In some implementations, R1 represents a straight chain (C1-C). 10 )alkyl or branched (C3-C 10 The alkyl group is particularly straight-chain (C1-C6) alkyl or branched-chain (C3-C6) alkyl, such as methyl, ethyl, n-pentyl, n-nonyl, isobutyl, and more preferably ethyl. In particular, the alkyl group of R1 is not substituted.

[0041] In some implementations, R2 represents a hydrogen atom.

[0042] In some implementations, R2 represents a straight chain (C1-C). 10 )alkyl or branched (C3-C 10 The alkyl group, especially straight-chain (C1-C6) alkyl or branched-chain (C3-C6) alkyl, such as methyl, ethyl, n-pentyl, n-nonyl, isobutyl, more preferably methyl or ethyl; the alkyl group of R2 is not substituted.

[0043] In some implementations, R2 represents a straight chain (C1-C). 10)alkyl or branched (C3-C 10 The alkyl group, particularly straight-chain (C1-C6) alkyl or branched-chain (C3-C6) alkyl, such as methyl, ethyl, n-pentyl, n-nonyl, isobutyl, more preferably methyl or ethyl; said alkyl group is substituted with one or more groups selected from i), ii), iii) and iv) as defined above. Preferably, said alkyl group is substituted with one or two groups selected from i), ii) and iii), more preferably with one or two groups selected from i) and iii), and even more preferably with a group iii) as a carboxyl group.

[0044] In some embodiments, another variation of group R2 is that the alkyl group is replaced by a group (iv), particularly by a phenyl group.

[0045] In some embodiments, R2 represents (C3-C8) cycloalkyl, preferably (C5-C7) cycloalkyl, such as cyclohexyl.

[0046] In some implementations, R2 represents C5-C 12 Aryl group, optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups, preferably particularly unsubstituted phenyl groups.

[0047] In some implementations, R3 represents a hydrogen atom.

[0048] In some implementations, R3 represents saturated linear C1-C 10 Or branched C3-C 10 Alkyl groups; particularly straight-chain (C1-C6) alkyl or branched (C3-C6) alkyl, preferably (C1-C4) alkyl, such as methyl.

[0049] In some embodiments, it may be preferred that the compound of formula (I) alone or as a mixture and its tautomer (I') or salts thereof, their optical isomers, racemates and / or solvates such as hydrates and the thereof; having the following meanings: R1 refers to a group selected from the following: a) Hydrogen atom; b) A saturated straight-chain C1-C6 or branched C3-C6 alkyl group, optionally substituted with one or more groups, which may be the same or different, and are selected from: i) -O-R3 ii) -S-R3; Preferably, it is optionally substituted by one or more groups i); R2 refers to a group selected from the following: a) Hydrogen atom; b) Saturated hydrocarbon groups, straight-chain C1-C 10Or branched C3-C 10 Or cyclic C3-C8, such as C5-C6, optionally substituted with one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -SR3; iii) -C(O)-O-R3; iv) Phenyl, which may optionally be substituted with one or more hydroxyl groups and / or with one or more C1-C4 alkoxy groups, such as methoxy groups; Preferably, it is substituted with one or more groups selected from i) and iii), preferably iii), such as a carboxyl group; R3 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C6 or branched C3-C6 alkyl groups.

[0050] In some embodiments, it may be preferred that the compound of formula (I) alone or as a mixture and its tautomer (I') or salts thereof, their optical isomers, racemates and / or solvates such as hydrates and the thereof have the following meanings: R1 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C4 or branched C3-C4 alkyl groups, optionally substituted with one or more identical or different groups selected from i) -OR3, more preferably unsubstituted; R2 refers to a group selected from the following: a) Hydrogen atom; b) Straight chain C1-C 10 Or branched C3-C 10 Or cyclic C3-C8, such as C5-C6 saturated hydrocarbon groups, optionally substituted by one or more groups, which may be the same or different, selected from: i. -O-R3; ii. -C(O)-O-R3; iv. C5-C 12 Aryl group, which may optionally be substituted with one or more hydroxyl groups and / or one or more C1-C4 alkoxy groups; R3 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C4 or branched C3-C4 alkyl groups, such as methyl or ethyl.

[0051] In some embodiments, it may be preferred that the compound of formula (I) alone or as a mixture and its tautomer (I') or salts thereof, their optical isomers, racemates and / or solvates such as hydrates and the thereof; having the following meanings: R1 is a hydrogen atom; and R2 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C5 or branched C3-C5 or cyclic C3-C8, such as C5-C6 alkylation groups, which are substituted by one or more groups selected from ii) -C(O)-O-R3, which may be the same or different, preferably substituted by one group ii) -C(O)-O-R3; R2 is more preferably a saturated straight-chain C1-C4 or branched C3-C4 alkylating group substituted with a group iii)-C(O)-OR3, and R3 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C4 or branched C3-C4 alkyl groups, such as methyl or ethyl.

[0052] In a preferred embodiment, the compound of formula (I) and the tautomer (I') are selected from the compound of formula (Ia) and its tautomers of formula (Ia'), its salts, its solvates and its optical isomers and racemates, alone or as a mixture:

[0053] In formulas (Ia) and (Ia'), R1 and R3 have the same meaning as in the compounds of formulas (I) and (I'), and X refers to alkylene-(CH2). n - where n is 1 to 10 (inclusive), preferably 1 to 6, more preferably an integer from 1 to 4, such as 1, and preferably R3 represents a hydrogen atom.

[0054] In a preferred embodiment, in the compound of formula (I), the following compounds, either alone or as a mixture, and their tautomers or salts thereof, their optical isomers, racemic derivatives, and / or solvates such as hydrates and the thereof are used:

[0055] In a preferred embodiment, the compound is specifically selected from:

[0056] In a more preferred embodiment, the following compounds are particularly preferred among these compounds:

[0057] In a more preferred embodiment, the following compounds are used more specifically:

[0058] In a preferred embodiment, the compound according to the invention is as follows:

[0059] All of the above compounds can be obtained from commercially available reagents using chemical methods known to those skilled in the art.

[0060] In one embodiment, the thiopyridone compound of formula (I) or (I') can be prepared according to the methods described, for example, in EP-A-3390 363 or WO 2017 / 102349.

[0061] (1) Thiopyridone compounds can be active ingredients or active compounds in cosmetic or dermatological products. The term "active" as used herein refers to an ingredient or compound that has cosmetic or dermatological active properties, such as antioxidant, whitening, UV filtering, and antibacterial effects. The (1) thiopyridone compounds used in this invention can act as depigmenting, brightening, bleaching, or whitening agents; therefore, compositions according to this invention can be used as skin brightening products or cosmetic compositions for brightening keratin materials.

[0062] (1) Thiopyridone compounds can be used as agents for skin, body hair, eyelashes or hair, and lips and / or nails, preferably for skin depigmentation, brightening, bleaching or whitening, especially for eliminating pigmentation spots or age spots, and / or as sunscreens.

[0063] In some embodiments, the amount of (1) thiopyridone compound in the composition may be 0.01% by weight or more, preferably 0.05% by weight or more, and more preferably 0.1% by weight or more, relative to the total weight of the composition.

[0064] In some embodiments, the amount of (1) thiopyridone compound in the composition may be 10% by weight or less, preferably 5% by weight or less, more preferably 3% by weight or less, relative to the total weight of the composition.

[0065] In some embodiments, the amount of (1) thiopyridone compound in the composition according to the invention may be from 0.01% to 10% by weight, preferably from 0.05% to 5% by weight, and more preferably from 0.1% to 3% by weight, relative to the total weight of the composition.

[0066] In some embodiments, the amount of (1) thiopyridone compound in the composition may be from 0.01% to 10% by weight, preferably from 0.1% to 5% by weight, and more preferably from 0.5% to 3% by weight, relative to the total weight of the composition.

[0067] It is likely preferred that the composition according to the invention comprises (1) at least one thiopyridone compound. Two or more (1) thiopyridone compounds may be used in combination. Thus, a single type of (1) thiopyridone compound or a combination of different types of (1) thiopyridone compounds may be used.

[0068] (1) Thiopyridone compounds are selected from compounds of formula (I), tautomers of formula (I'), their salts, their solvates such as hydrates, their optical isomers, their racemates, and mixtures thereof: In equations (I) and (I'): R1 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 10 Or branched C3-C 10 Alkyl groups, optionally substituted with one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -S-R3; R2 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 12 Or branched C3-C 12 Or a cyclic C3-C8 hydrocarbon group, optionally substituted by one or more groups, which may be the same or different, selected from: i. -O-R3; ii. -S-R3; iii. -C(O)-O-R3; iv. C5-C 12 aryl groups, optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups; and c) C5-C 12aryl groups, optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups. in R3 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 10 Or branched C3-C 10 alkyl.

[0069] Reducing agent of formula (II) In one embodiment, the composition of the present invention comprises at least one reducing agent of formula (II), wherein the compound of formula (II) is selected from... a) Inorganic reducing agents of formula (IIA), their racemic forms, and their solvates, such as hydrates. (IIA) in, X represents a heteroatom selected from oxygen or sulfur, preferably oxygen; m is 0 or 1; M + It is a cation, preferably selected from alkali metals, alkaline earth metals or ammonium, more preferably selected from alkali metals such as sodium or potassium; R represents a group selected from the following: i) -OH, ii) -O-M' + , where M' + As previously stated regarding M + Limited, iii) in, • p is an integer chosen between 0 and 4 (inclusive), preferably 0, 1, or 2, more preferably 0 or 2; • m' is 0 or 1, preferably 1; • X', as defined for X, preferably represents an oxygen atom; and • M'' + As previously stated regarding M + Limited by, and M + M' + M'' + Whether they are the same or different, the same is preferred; or b) Thiolized amino compounds of formula (IIB), their optical isomers, geometric isomers, solvates, hydrates, salts of bases or salts of acids, R a -N(R b )-CH(R c )-(CH2)n -SR d (IIB) in, n is an integer selected from 0 to 3; - R a Represents a hydrogen atom or -C(X) a )-R a ', where X a Represents an oxygen or sulfur atom, preferably oxygen, and R a 'Represents a saturated or unsaturated straight-chain or branched hydrocarbon chain containing 1 to 8 carbon atoms, preferably a saturated hydrocarbon such as (C1-C6) alkyl, wherein the chain: i) Optionally substituted with one or more groups selected from (di)(C1-C4)(alkyl)amino and -C(O)OM, wherein M represents a hydrogen atom or is preferably selected from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+ and K. + Cation counterions; and / or ii) Optionally selected from O, S, N(R) e -C(O)-, -C(O)-N(R) e - or -N(R) e One or more heteroatoms or groups of )-C(O)- are interrupted, where R e Representing a hydrogen atom or a (C1-C4) alkyl group such as methyl, preferably R e Represents a hydrogen atom; - R b Representing a hydrogen atom or a (C1-C4) alkyl group such as methyl, preferably R b Represents a hydrogen atom; - R c Representatives are selected from one of the following: a) Hydrogen atom, b) -C(O)OM', where M' is as previously defined for M; or c) -C(O)-N(R e ')-R a '', where R a As previously stated regarding R a 'As defined, preferably R' a Unlike R a ', more preferably R a '' represents an (C1-C4) alkyl group optionally substituted with one or more -C(O)OM groups as defined above, preferably -C(O)OH; - R d Represents a hydrogen atom or -S-CH2-CH(R) f )-N(R g )-Rh , where R f As previously stated regarding R c As specified, R g As previously stated regarding R b Limited by, and R h As previously stated regarding R a As defined, preferably R d Represents a hydrogen atom; What needs to be understood is: - R f With R c Whether they are the same or different, the same is preferred; - R g With R b Whether they are the same or different, the same is preferred; - R h With R a Same or different, same is preferred; and - M and M' may be the same or different, preferably the same.

[0070] In one embodiment, the composition of the present invention contains 0.01% by weight or more, preferably 0.02% by weight or more, more preferably 0.03% by weight or more of a reducing agent of formula (II) relative to the total weight of the composition.

[0071] In some embodiments, the composition of the present invention contains, according to one embodiment, 2.0% by weight or less, preferably 1.0% by weight or less, more preferably 0.05% by weight or less of a reducing agent of formula (II) relative to the total weight of the composition.

[0072] In some embodiments, (2) the amount of reducing agent in the composition according to the invention may be from 0.01% to 2% by weight, preferably from 0.02% to 1.0% by weight, and more preferably from 0.03% to 0.5% by weight, relative to the total weight of the composition.

[0073] Inorganic reducing agent of formula (IIA) In one embodiment, the composition of the present invention comprises at least one reducing agent of formula (II), wherein the compound of formula (II) is an inorganic reducing agent of formula (IIA), its racemic form, or its solvate, such as a hydrate. (IIA) in, X represents a heteroatom selected from oxygen or sulfur, preferably oxygen; m is 0 or 1; M + It is a cation, preferably selected from alkali metals, alkaline earth metals or ammonium, more preferably selected from alkali metals such as sodium or potassium; R represents a group selected from the following: i) -OH, ii) -O-M' + , where M' + As previously stated regarding M + Limited, iii) in, • p is an integer chosen between 0 and 4 (inclusive), preferably 0, 1, or 2, more preferably 0 or 2; • m' is 0 or 1, preferably 1; • X', as defined for X, preferably represents an oxygen atom; and • M'' + As previously stated regarding M + Limited by, and M + M' + M'' + If they are the same or different, the same is preferred.

[0074] In some embodiments, the composition comprises at least one reducing agent of formula (IIA), wherein, In formula (IIA), X represents a heteroatom selected from oxygen or sulfur, preferably oxygen; In equation (IIA), m is 0 or 1; M of formula (IIA) + It is a cation, preferably sodium or potassium; In formula (IIA), R represents a group selected from the following groups. i) -OH, ii) -O-M' + , where M' + As previously stated regarding M + Limited, iii) in, • p is 0 or 2; • m' is 0 or 1; • X', as defined for X, preferably represents an oxygen atom; and M + M' + M'' + same.

[0075] In some embodiments, the reducing agent of formula (IIA) in (2) R represents a group selected from the following: i) -OH, ii) -O-M' + , where M' + iii) in, • p is 0 or 2; • m' is 0 or 1; • X' represents an oxygen atom; and M + M' + and M'' + Same, selected from sodium or potassium.

[0076] In some embodiments, the reducing agent of formula (IIA) in (2) In formula (IIA), X represents sulfur; In equation (IIA), m is 1; M of formula (IIA) + It is sodium or potassium; In formula (IIA), R represents a group selected from the following groups. i) -OH, and ii) -O-M' + , where M' + M + and M' + same.

[0077] In some embodiments, the inorganic reducing agent compound of formula (IIA) may exist in its boundary or delocalized racemic-limited form. When m = 0, R–S(O - M + )=O R–S(=O)–O - M + ,and When m = 1, the mesotropic restricted form is: R–S(O - M + (=X) m =O R–S(=O)(=X) m –O - M + R–S(=O)(X - M + ) m =O Among them, M+, M'+, and M''+ are present to ensure the electroneutrality of the molecule of formula (IIA).

[0078] In a preferred embodiment, the inorganic reducing agent of formula (IIA) (2) can be selected from sodium bisulfite, sodium metabisulfite, sodium sulfite, sodium thiosulfate, sodium sulfate, potassium metabisulfite, potassium sulfite, potassium thiosulfate, potassium sulfate or potassium tetrathionate.

[0079] In a preferred embodiment, the inorganic reducing agent of formula (IIA) (2) can be selected from sodium bisulfite, sodium metabisulfite, sodium sulfite, sodium thiosulfate or sodium sulfate.

[0080] In one embodiment, the composition of the present invention contains 0.01% by weight or more, preferably 0.02% by weight or more, more preferably 0.03% by weight or more of a reducing agent of formula (II) relative to the total weight of the composition.

[0081] In some embodiments, the composition of the present invention contains, according to one embodiment, 2.0% by weight or less, preferably 1.0% by weight or less, more preferably 0.05% by weight or less of a reducing agent of formula (II) relative to the total weight of the composition.

[0082] In some embodiments, (2) the amount of reducing agent in the composition according to the invention may be from 0.01% to 2% by weight, preferably from 0.02% to 1.0% by weight, and more preferably from 0.03% to 0.5% by weight, relative to the total weight of the composition.

[0083] Thiolized amino compounds of formula (IIB) In one embodiment, the composition of the present invention comprises at least one reducing agent of formula (IIB), wherein the compound of formula (IIB) is a thiolized amino compound of formula (IIB), its optical isomer, geometric isomer, solvate, hydrate, salt of a base, or salt of an acid. R a -N(R b )-CH(R c )-(CH2) n -SR d (IIB) in, - n is an integer selected from 0 to 3; - R a Represents a hydrogen atom or -C(Xa)-R a ', where X a Represents an oxygen or sulfur atom, preferably oxygen, and R a 'Represents a saturated or unsaturated straight-chain or branched hydrocarbon chain containing 1 to 8 carbon atoms, preferably a saturated hydrocarbon such as (C1-C6) alkyl, wherein the chain: i) Optionally substituted with one or more groups selected from (di)(C1-C4)(alkyl)amino and -C(O)OM, wherein M represents a hydrogen atom or is preferably selected from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+ and K. + Cation counterions; and / or ii) Optionally selected from O, S, N(R) e -C(O)-, -C(O)-N(R) e - or -N(R) e One or more heteroatoms or groups of )-C(O)- are interrupted, where R e Representing a hydrogen atom or a (C1-C4) alkyl group such as methyl, preferably R e Represents a hydrogen atom; - R b Representing a hydrogen atom or a (C1-C4) alkyl group such as methyl, preferably R b Represents a hydrogen atom; - R c Representatives are selected from one of the following: a) Hydrogen atom, b) -C(O)OM', where M' is as previously defined for M; or c) -C(O)-N(R e ')-R a '', where R a As previously stated regarding R a 'As defined, preferably R' a Unlike R a ', more preferably R a '' represents an (C1-C4) alkyl group optionally substituted with one or more -C(O)OM groups as defined above, preferably -C(O)OH; - R d Represents a hydrogen atom or -S-CH2-CH(R) f )-N(R g )-R h , where R f As previously stated regarding R c As specified, R g As previously stated regarding R b Limited by, and R h As previously stated regarding R a As defined, preferably R d Represents a hydrogen atom; What needs to be understood is: - R f With R c Whether they are the same or different, the same is preferred; - R g With R bWhether they are the same or different, the same is preferred; - R h With R a Same or different, same is preferred; and - M and M' may be the same or different, preferably the same.

[0084] In some embodiments, the composition comprises a thiolized amino compound of formula (IIB), wherein n is 1 or 2; - R in equation (IIB) a Represents a hydrogen atom or -C(Xa)-R a ', where Xa represents an oxygen atom, and R a 'Represents a saturated or unsaturated straight-chain or branched hydrocarbon chain containing 1 to 8 carbon atoms, preferably a saturated hydrocarbon such as (C1-C6) alkyl, wherein the chain: i) Optionally substituted with one or more groups selected from (di)(C1-C4)(alkyl)amino and -C(O)OM, wherein M represents a hydrogen atom or a cationic counterion such as Na+ and K+. + ; and / or ii) Optionally selected from O, S, N(R) e -C(O)-, -C(O)-N(R) e - or -N(R) e One or more heteroatoms or groups of )-C(O)- are interrupted, where R e Representing a hydrogen atom or a (C1-C4) alkyl group such as methyl, preferably R e Represents a hydrogen atom; - R in equation (IIB) b Represents a hydrogen atom; - R in equation (IIB) c Representatives are selected from one of the following: a) Hydrogen atom, b) -C(O)OM', where M' is as previously defined for M; or c) -C(O)-N(R e ')-R a '', where R a As previously stated regarding R a 'As defined, preferably R' a Unlike R a ', more preferably R a '' represents an (C1-C4) alkyl group optionally substituted with one or more -C(O)OM groups as defined above, preferably -C(O)OH; - R in equation (IIB) d Represents a hydrogen atom or -S-CH2-CH(R)f )-N(R g )-R h , where R f As previously stated regarding R c As specified, R g As previously stated regarding R b Limited by, and R h As previously stated regarding R a As defined, preferably R d It represents a hydrogen atom.

[0085] In some implementations, R of formula (IIB) d It represents a hydrogen atom.

[0086] In some implementations, R of formula (IIB) a R b and R c It represents a hydrogen atom.

[0087] In some implementation schemes, where n is 1 or 2; - R in equation (IIB) a Represents a hydrogen atom or -C(Xa)-R a ', where X a Represents an oxygen or sulfur atom, preferably oxygen, and R a 'Represents a saturated or unsaturated straight-chain or branched hydrocarbon chain containing 1 to 8 carbon atoms, preferably a saturated hydrocarbon such as (C1-C6) alkyl, more preferably a (C1-C4) alkyl such as methyl; - R in equation (IIB) b and R d Represents a hydrogen atom; and - R in equation (IIB) c The symbol is -C(O)OM', where M' represents a hydrogen atom or is preferably selected from alkali metals, alkaline earth metals, and ammonium, more preferably alkali metals such as Na+ and K. + The cation counterion.

[0088] In some implementation schemes, where n is 1 or 2; R in equation (IIB) d Representative -S-CH2-CH(R) f )-N(R g )-R h ; R in equation (II) a R b R g and R h Independently representing a hydrogen atom; and R in equation (II) cand R f The symbol is -C(O)OM', where M' represents a hydrogen atom or is preferably selected from alkali metals, alkaline earth metals, and ammonium, more preferably alkali metals such as Na+ and K. + The cation counterion.

[0089] In some implementation schemes, where n is 1; - R in equation (IIB) a Representative -C(Xa)-R a ', where X a Represents an oxygen or sulfur atom, preferably oxygen, and R a 'Represents a saturated or unsaturated straight-chain or branched hydrocarbon chain containing 1 to 8 carbon atoms, preferably a saturated hydrocarbon such as (C1-C6) alkyl, more preferably a (C1-C4) alkyl such as methyl; - R in equation (IIB) b and R d Represents a hydrogen atom; and - R in equation (IIB) c The symbol is -C(O)OM', where M' represents a hydrogen atom or is preferably selected from alkali metals, alkaline earth metals, and ammonium, more preferably alkali metals such as Na+ and K. + The cation counterion.

[0090] In some embodiments, the thiolized amino compound of formula (IIB), its optical isomer, and its geometric isomer are in the form of a salt of an inorganic acid such as HHal, where Hal represents a halogen such as chlorine.

[0091] In a preferred embodiment, the thiolated amino compound is selected from N-acetylcysteine, cysteine, homocysteine, cystine, cysteine ​​hydrochloride, cystamine hydrochloride, glutathione, or butyryl glutathione.

[0092] In a most preferred embodiment, the thiolated amino compound is selected from N-acetylcysteine, cysteine, homocysteine, cystine, or cysteine ​​hydrochloride, preferably N-acetylcysteine.

[0093] In one embodiment, the composition of the present invention contains 0.01% by weight or more, preferably 0.02% by weight or more, more preferably 0.03% by weight or more, of a thiolized amino compound of formula (IIB) relative to the total weight of the composition.

[0094] In some embodiments, the composition of the present invention contains, according to one embodiment, 2.0% by weight or less, preferably 1.0% by weight or less, more preferably 0.5% by weight or less of a thiolized amino compound of formula (IIB) relative to the total weight of the composition.

[0095] In some embodiments, the amount of the thiolized amino compound of formula (IIB) in the composition according to the invention may be from 0.01% to 2% by weight, preferably from 0.02% to 1.0% by weight, and more preferably from 0.03% to 0.5% by weight, relative to the total weight of the composition.

[0096] pH adjuster In one embodiment, the composition of the present invention may comprise at least one pH adjuster. Two or more pH adjusters may be used in combination. Therefore, a single type of pH adjuster or a combination of different types of pH adjusters may be used.

[0097] As a pH adjuster, at least one acidifier and / or at least one alkalizing agent (alkali) may be used.

[0098] The acidifier can be a monovalent or polyvalent acid, such as a divalent acid.

[0099] Acidifying agents can be, for example, mineral (inorganic) acids such as hydrochloric acid, sulfuric acid, and phosphoric acid, or organic acids such as carboxylic acids such as tartaric acid, citric acid, and lactic acid, as well as sulfonic acids.

[0100] The alkalizing agent can be a monovalent or polyvalent base, such as a divalent base. The alkalizing agent can be mineral (inorganic), organic, or a mixture of both.

[0101] Inorganic alkalizing agents may be selected from ammonia; alkali metal carbonates or bicarbonates, such as sodium carbonate or potassium carbonate and sodium bicarbonate or potassium bicarbonate; alkali metal hydroxides, such as sodium hydroxide and potassium hydroxide; and mixtures thereof.

[0102] The organic alkalizing agent may be selected from organic amines with a pKb of less than 12, preferably less than 10, and more advantageously less than 6 at 25°C. It should be noted that this refers to the pKb corresponding to the highest basicity of the function. Furthermore, the organic amine does not contain any alkyl or alkenyl aliphatic chains containing more than 10 carbon atoms.

[0103] Organic alkalizing agents can be selected from, for example, alkanolamines, oxyethyleneated and / or oxypropyleneated ethylenediamines, amino acids, and amine compounds of formula (III): (III) in W represents a C1-C6 dialkylene group optionally substituted with one or more hydroxyl groups or C1-C6 alkyl groups and optionally interrupted by one or more heteroatoms such as O and N. R x R y R z and R tThey can be the same or different, representing hydrogen atoms or C1-C6 alkyl, C1-C6 hydroxyalkyl or C1-C6 aminoalkyl.

[0104] Examples of amine compounds of formula (III) that may be mentioned include 1,3-diaminopropane, 1,3-diamino-2-propanol, spermine, and spermidine.

[0105] The term "alkanolamine" refers to an organic amine that contains primary, secondary, or tertiary amine functions and one or more straight-chain or branched C1-C8 alkyl groups with one or more hydroxyl groups.

[0106] Alkanolamines, such as mono-, di-, or tri-alkylolamines comprising one to three identical or different C1-C4 hydroxyalkyl groups, are applicable to this invention. In compounds of this type, references may be made to monoethanolamine (MEA), diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, N-dimethylaminoethanolamine, 2-amino-2-methyl-1-propanol, triisopropanolamine, 2-amino-2-methyl-1,3-propanediol, 3-amino-1,2-propanediol, 3-dimethylamino-1,2-propanediol, and tris(hydroxymethylamino)methane.

[0107] The amino acids that can be used are of natural or synthetic origin, in their L, D, or racemic forms, and contain at least one acidic function more particularly selected from carboxylic acids, sulfonic acids, phosphonic acids, or phosphoric acids. The amino acid can be in neutral or ionic form.

[0108] Among the amino acids that may be used in this invention, aspartic acid, glutamic acid, alanine, arginine, ornithine, citrulline, asparagine, carnitine, cysteine, glutamine, glycine, histidine, lysine, isoleucine, leucine, methionine, N-phenylalanine, proline, serine, taurine, threonine, tryptophan, tyrosine, and valine are particularly mentioned.

[0109] Preferably, the amino acid is a basic amino acid that includes an additional amine function optionally included in a cyclic or urea group.

[0110] Such basic amino acids can preferably be selected from those corresponding to the following formula (IV): (IV) in In formula (IV), R represents a group selected from the following: , -(CH2)3-NH2, -(CH2)2-NH2, -(CH2)2-NH-CO-NH2, and .

[0111] The compounds corresponding to formula (IV) include histidine, lysine, arginine, ornithine, and citrulline.

[0112] Organic alkalizing agents can be selected from heterocyclic organic amines. In addition to histidine, which has already been mentioned in the section on amino acids, pyridine, piperidine, imidazole, triazole, tetraazole, and benzimidazole can be specifically mentioned.

[0113] The organic alkalizing agent may also be selected from amino acid dipeptides. Among the amino acid dipeptides that can be used in this invention, carnosine, anserine, and baleine are particularly noteworthy.

[0114] The organic alkalizing agent may also be selected from compounds containing guanidine functional groups. In addition to arginine, which has already been mentioned as an amino acid, creatine, creatine anhydride, 1,1-dimethylguanidine, 1,1-diethylguanidine, guanidinoacetic acid, metformin, guanidinebutyramine, N-amidinylalanine, 3-guanidinopropionic acid, 4-guanidinobutyric acid, and 2-([amino(imino)methyl]amino)ethane-1-sulfonic acid may also be mentioned.

[0115] In a preferred embodiment of the invention, the organic alkalizing agent may be selected from amino acids, preferably basic amino acids, and more preferably arginine, lysine, histidine, or mixtures thereof. Even more preferably, the organic alkalizing agent may be arginine.

[0116] Hybrid compounds that may be mentioned include salts of the aforementioned amines and acids such as carbonic acid or hydrochloric acid. Guanidine carbonate or monoethanolamine hydrochloride may be used in particular.

[0117] In some embodiments, the amount of pH adjuster in the composition may be equal to or greater than 0.01% by weight, preferably 0.05% by weight or more, and more preferably 0.1% by weight or more, relative to the total weight of the composition.

[0118] In some embodiments, the amount of pH adjuster in the composition may be equal to or less than 15% by weight or less, preferably 10% by weight or less, and more preferably 5% by weight or less, relative to the total weight of the composition.

[0119] In a preferred embodiment, the pH adjuster may be present in an amount of 0.01% to 15% by weight, preferably 0.05% to 10% by weight, more preferably 0.1% to 5% by weight or less, relative to the total weight of the composition.

[0120] Preferably, the composition according to the invention has a pH of 4.5 or greater, more preferably 5 or greater.

[0121] Preferably, the composition according to the invention has a pH of 6.5 or less, more preferably 6 or less.

[0122] Preferably, the composition according to the invention has a pH of 4.5 to 6.5, more preferably 5 to 6.

[0123] The pH of this composition refers to the pH of the aqueous phase of the composition according to the present invention.

[0124] It may be preferred that at least one buffer or buffering agent be used in combination with an acidifier and / or an alkalizer as a pH adjuster to stabilize the pH of the composition according to the invention.

[0125] As a buffer, any known buffer can be used. For example, salts of acids or bases can be used, preferably salts of weak acids or weak bases. For example, if citric acid or lactic acid is used as the acidifying agent, sodium citrate or sodium lactate can be used as the buffer.

[0126] medium / solvent In one embodiment, the composition of the present invention may advantageously comprise at least one medium / solvent, including water and / or an organic medium / solvent.

[0127] In some embodiments, the composition may contain varying amounts of water. For low-viscosity applications of the composition, such as in the form of leave-on lotion, a relatively large amount of water can be used. For example, water is used at a content greater than or equal to 20% by weight relative to the total weight of the composition. The water content in the low-viscosity composition according to the invention is preferably 20% to 99% by weight, or more preferably 30% to 95% by weight, or 40% to 90% by weight relative to the total weight of the composition. For high-viscosity applications of the composition, such as in the form of leave-on cream, a relatively small amount of water can be used. The high-viscosity composition according to the invention advantageously contains water at a content less than or equal to 40% by weight relative to the total weight of the composition.

[0128] In some embodiments, the amount of water in the composition may be 20% by weight or more, preferably 30% by weight or more, and more preferably 40% by weight or more, relative to the total weight of the composition.

[0129] In some embodiments, the amount of water in the composition may be 99% by weight or less, preferably 95% by weight or less, more preferably 90% by weight or less, relative to the total weight of the composition.

[0130] In a preferred embodiment, the amount of water in the composition may be from 20% to 99% by weight, preferably from 30% to 95% by weight, and more preferably from 40% to 90% by weight, relative to the total weight of the composition.

[0131] In some embodiments, the composition may further comprise one or more organic media / solvents, preferably water-soluble organic media / solvents (with a solubility in water greater than or equal to 5% at 25°C and atmospheric pressure).

[0132] Examples of organic media / solvents that may be mentioned include alcohols: particularly monohydric alcohols such as ethanol, isopropanol, benzyl alcohol, and phenethyl alcohol; diols such as ethylene glycol, propylene glycol, and butanediol; other polyhydric alcohols such as glycerol, sugars, and sugar alcohols; and ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol monobutyl ether, as well as butanediol monomethyl ether, butanediol monoethyl ether, and butanediol monobutyl ether.

[0133] When present, the amount of organic medium / solvent is from 0.1% to 40% by weight, preferably from 1% to 30% by weight, or from 5% to 20% by weight, relative to the total weight of the composition according to the invention.

[0134] In some embodiments, the composition may also contain other additives, surfactants, carriers, and adjuvants known in the art as being compatible with keratin materials and cosmetically acceptable.

[0135] In some embodiments, the compositions of the present invention incorporate keratin materials, preferably for skin brightening or depigmentation.

[0136] In other embodiments, the compositions of the present invention can be used to treat keratin materials, preferably skin, to impart a whitening or depigmenting effect.

[0137] Preparation of the composition In one embodiment, the present invention provides a method for preparing the composition. The composition according to the invention can be manufactured using known methods commonly used in the fields of cosmetics or dermatology.

[0138] The method involves mixing the aforementioned basic components and optional components by any known method. In one embodiment, the compositions of the present invention can be prepared by a method comprising the following steps: mixing at least one compound of formula (I) or (I') with at least one reducing agent of formula (II), with water or any suitable solvent. Mixing includes the addition of other additives as needed. The method involves mixing the components at any temperature, preferably at room temperature, more preferably at 30°C or higher, 40°C or higher, and even more preferably at 50°C or higher.

[0139] The compositions according to the invention may be in various forms, but are not limited to emulsions, solutions, gels or creams.

[0140] Use of the method / composition In one embodiment, the present invention provides a cosmetic method for treating keratin materials, the method comprising: applying the composition of the present invention to the keratin material, preferably to the skin.

[0141] In some embodiments, the present invention provides a non-therapeutic cosmetic method for treating keratin materials, the method comprising: applying the composition of the present invention to the keratin material, preferably to the skin.

[0142] In other embodiments, the invention provides the use of the composition for keratin materials, preferably for brightening or depigmenting the skin. In some embodiments, the composition is suitable for treating dark spots and / or pigmentation on the skin. In some embodiments, the composition can be used to provide necessary care for the skin, preferably brightening the skin, and / or reducing or lightening dark spots and / or pigmentation on the skin.

[0143] In some embodiments, the present invention provides a cosmetic composition that can be applied once daily, twice daily, or more than once or twice daily. In some cases, the composition is applied before bedtime. In other cases, the composition is applied in the morning. In still other cases, the composition can be applied immediately after washing the skin. The composition can be used once, or for several days, weeks, or months. For example, the composition can be used daily for 1, 2, 3, 4, 5, 6, 7, 8 weeks or longer, or for several months.

[0144] In one embodiment, the present invention provides the use of at least one reducing agent of formula (II) in a composition comprising at least one compound selected from formula (I), its tautomers, salts, optical isomers, racemic derivatives, solvates, hydrates, or mixtures thereof for stabilizing the compound of formula (I), its tautomers, salts, solvates, hydrates, optical isomers, racemic derivatives, or mixtures thereof in the composition. The compounds of formula (II) are selected from: a) Inorganic reducing agents of formula (IIA), their racemic forms, and their solvates, such as hydrates. (IIA) in, X represents a heteroatom selected from oxygen or sulfur, preferably oxygen; m is 0 or 1; M + It is a cation, preferably selected from alkali metals, alkaline earth metals or ammonium, more preferably selected from alkali metals such as sodium or potassium; R represents a group selected from the following: i) -OH, ii) -O-M'+ , where M' + As previously stated regarding M + Limited, iii) in, • p is an integer chosen between 0 and 4 (inclusive), preferably 0, 1, or 2, more preferably 0 or 2; • m' is 0 or 1, preferably 1; • X', as defined for X, preferably represents an oxygen atom; and • M'' + As previously stated regarding M + Limited by, and M + M' + M'' + Same or different, same is preferred. or, b) Thiolized amino compounds of formula (IIB) R a -N(R b )-CH(R c )-(CH2) n -SR d (IIB) in, - n is an integer selected from 0 to 3; - R a Represents a hydrogen atom or -C(Xa)-R a ', where X a Represents an oxygen or sulfur atom, preferably oxygen, and R a 'Represents a saturated or unsaturated straight-chain or branched hydrocarbon chain containing 1 to 8 carbon atoms, preferably a saturated hydrocarbon such as (C1-C6) alkyl, wherein the chain: i) Optionally substituted with one or more groups selected from (di)(C1-C4)(alkyl)amino and -C(O)OM, wherein M represents a hydrogen atom or is preferably selected from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+ and K. + Cation counterions; and / or ii) Optionally selected from O, S, N(R) e -C(O)-, -C(O)-N(R) e - or -N(R) e One or more heteroatoms or groups of )-C(O)- are interrupted, where R e Representing a hydrogen atom or a (C1-C4) alkyl group such as methyl, preferably R e Represents a hydrogen atom; - R b Representing a hydrogen atom or an α (C1-C4) alkyl group such as methyl, preferably Rb Represents a hydrogen atom; - R c Representatives are selected from one of the following: a) Hydrogen atom, b) -C(O)OM', where M' is as previously defined for M; or c) -C(O)-N(R e ')-R a '', where R a As previously stated regarding R a 'As defined, preferably R' a Unlike R a ', more preferably R a '' represents an (C1-C4) alkyl group optionally substituted with one or more -C(O)OM groups as defined above, preferably -C(O)OH; - R d Represents a hydrogen atom or -S-CH2-CH(R) f )-N(R g )-R h , where R f As previously stated regarding R c As specified, R g As previously stated regarding R b Limited by, and R h As previously stated regarding R a As defined, preferably R d Represents a hydrogen atom; What needs to be understood is: - R f With R c Whether they are the same or different, the same is preferred; - R g With R b Whether they are the same or different, the same is preferred; - R h With R a Same or different, same is preferred; and - M and M' may be the same or different, preferably the same. In equations (I) and (I'): - R1 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 10 Or branched C3-C 10 Alkyl groups, optionally substituted with one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -S-R3; - R2 refers to a group selected from the following: a) Hydrogen atom; b) Saturated hydrocarbon groups, straight-chain C1-C 12 Or branched C3-C 12 Or cyclic C3-C8, optionally substituted with one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -S-R3; iii) -C(O)-O-R3; iv) C5-C 12 Aryl group, which is optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups; c) C5-C 12 aryl groups, optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups; and - R3 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 10 Or branched C3-C 10 alkyl.

[0145] The term "stability" has the same meaning as enhancing stability.

[0146] According to one embodiment of the invention, the composition comprises an aqueous phase. The composition is particularly formulated as a water-in-oil or oil-in-water emulsion or a multiple emulsion (oil-in-water-in-oil or water-in-oil-in-water triple emulsion (such emulsions are known and described, for example, by C. Fox in “Cosmetics and Toiletries” - November 1986 - Vol. 101 - pp. 101-112)).

[0147] According to a particular embodiment of the invention, the composition is a direct emulsion, i.e., an oil-in-water or O / W type emulsion. Example

[0148] This disclosure is now illustrated by way of operational examples, which are intended to illustrate the operation of this disclosure and are not intended to imply any limitation on the scope of this disclosure. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Although similar or equivalent methods and materials to those described herein may be used in the practice of the disclosed methods and compositions, exemplary methods, apparatus, and materials are described herein. It is to be understood that this disclosure is not limited to the specific compositions, methods, and experimental conditions described, as such methods and conditions may be applicable. The invention is described in more detail by way of examples. However, these examples should not be construed as limiting the scope of the invention.

[0149] Example 1: Synthesis of Compound 20 Compound 20 is synthesized as disclosed in Example 2 of Patent EP3 390 363.

[0150] Example 2 Cosmetic Composition Cosmetic compositions comprising compound 20 of formula (I) and at least one reducing agent of formula (II) as described herein, as well as other additional ingredients, are prepared by measuring each of the ingredients mentioned in Table 1 below. For example, cosmetic composition EX1 is prepared using 0.50 wt% 2-mercaptonicotinylglycine, 0.2 wt% reducing agent (i.e., sodium thiosulfate), a total of 6.00 wt% glyceryl stearate, PEG-100 stearate and PEG-40 stearate, 2.40 wt% fatty alcohol, 6.00 wt% hydrogenated polyisobutylene, 1.20 wt% preservative, 0.20 wt% chelating agent, 18.00 wt% isohexadecane, 0.36 wt% thickener and 0.36 wt% triethanolamine, and sufficient water. Similarly, compositions EX2, EX3 and EX4 (according to the invention) are prepared using 0.2 wt% each of sodium metabisulfite, sodium sulfite and N-acetylcysteine. The comparative composition CEX1 was also prepared in a similar manner, comprising the components without any reducing agent mentioned in Table 1 below.

[0151] Table 1

[0152] Example 3 Stability of the composition Thermal stability study The composition prepared as in Example 1 was analyzed to determine its stability when stored at different temperatures.

[0153] Approximately 1.0 g of each composition was independently mixed with 50 mL of water to prepare an aqueous solution of the composition. Methanol was added to the aqueous solution of the composition, and the mixture was sonicated and then stirred for approximately 1.5 hours. The resulting solution was filtered. A portion of the filtered solution was analyzed by HPLC-UPLC to determine the amount of compound 20 (2-mercaptonicotinylglycine) at time T0. Another portion of the filtered solution was placed in an oven at 45°C for 2 months, and the presence of compound 20 under accelerated aging was determined at T2M@45°C. Another portion of the filtered solution was stored at room temperature for 2 months, and the presence of compound 20 in the solution was determined at T2M@RT.

[0154] The details of the HPLC-UV determination method are as follows.

[0155] Apparatus / Reagent

[0156] HPLC conditions

[0157] The amount of compound 20 of formula (I) in each solution was determined, and the percentage values ​​of compound 20 of formula (I) were listed in Table 2.

[0158] Table 2

[0159] As can be observed from Table 2 above, compositions EX1 to EX4 of the present invention are more stable at room temperature and at elevated temperatures, while the comparative composition CEX1 is found to be less stable. This is because the stability of the compound of formula (I) is improved in the presence of a reducing agent (an inorganic reducing agent of formula (IIA) or a thiolated amino compound of formula (IIB), resulting in an increasingly stable cosmetic composition compared to the comparative composition CEX1. In particular, it can be noted that composition EX11 of the present invention, containing sodium thiosulfate, improves the stabilization of the thiopyridone compound at all temperatures (RT and higher) over extended periods. Furthermore, composition EX4 of the present invention, containing N-acetylcysteine ​​of formula (IIB), improves the stabilization of the thiopyridone compound of formula (I), and therefore exhibits much higher thermal stability compared to the comparative composition CEX1, which does not contain N-acetylcysteine.

[0160] Therefore, the compositions according to the invention containing a reducing agent exhibit enhanced stability of thiopyridone compounds, providing stable compositions with extended shelf life at room temperature and under accelerated conditions.

[0161] Light stability study The composition prepared as in Example 1 was analyzed to determine its photostability when exposed to UV radiation.

[0162] Composition EX1 (of the present invention) and comparative composition CEX1 were each independently coated onto an inert carrier. The coated carrier was then exposed to 5 J / cm². 2 The sample was exposed to UV radiation for approximately one hour. The exposed composition was then dissolved in an organic solvent, and the solution was analyzed by HPLC or UPLC.

[0163] The amount of compound 20 of formula (I) in each composition was measured by HPLC-UV assay at two time points mentioned below. Timing (1): immediately after the composition is prepared Timing (2): Solution of the composition after UV exposure The details of the HPLC-UV determination method are as follows.

[0164] Apparatus / Reagent

[0165] HPLC conditions

[0166] The amount of compound 20 of formula (I) remaining in each composition before (time 1) and after (time 2) UV exposure was determined by HPLC-UV assay, and the difference in the amount of compound (I) was calculated.

[0167] The percentage values ​​of the remaining compound 20 of formula (I) in the UV-exposed compositions EX1 and CEX1 are shown in Table 3 below.

[0168] Table 3

[0169] Composition EX1, containing sodium thiosulfate (an inorganic reducing agent of formula (IIA), was found to be more effective and stable than the comparative composition CEX1. The compositions of the present invention, containing an inorganic reducing agent of formula (II) as described herein, provide enhanced thermal and light stability to thiopyridone compounds, thereby resulting in cosmetic compositions with extended shelf life even when stored at different temperatures.

Claims

1. A composition, preferably a cosmetic composition, comprising: i) At least one compound selected from compounds of formula (I), tautomers of formula (I'), salts, solvates, hydrates, optical isomers, racemates, or mixtures thereof: in, - R1 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 10 Or branched C3-C 10 Alkyl groups, optionally substituted with one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -S-R3; - R2 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 12 Or branched C3-C 12 Or a cyclic C3-C8 hydrocarbon group, optionally substituted by one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -S-R3; iii) -C(O)-O-R3; iv) C5-C 12 aryl groups, optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups, and c) C5-C 12 Aryl group, which is optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups; - R3 refers to a group selected from the following: a) Hydrogen atom, and b) Saturated straight-chain C1-C 10 Or branched C3-C 10 alkyl; and ii) At least one inorganic reducing agent of formula (II), wherein the compound of formula (II) is selected from: a) Inorganic reducing agents of formula (IIA), their racemic forms, and their solvates, such as hydrates. (IIA) in, X represents a heteroatom selected from oxygen or sulfur, preferably oxygen; m is 0 or 1; M + It is a cation, preferably selected from alkali metals, alkaline earth metals or ammonium, more preferably selected from alkali metals such as sodium or potassium; R represents a group selected from the following: i) -OH, ii) -O-M' + , where M' + As previously stated regarding M + Limited, iii) in, • p is an integer chosen between 0 and 4 (inclusive), preferably 0, 1, or 2, more preferably 0 or 2; • m' is 0 or 1, preferably 1; • X', as defined for X, preferably represents an oxygen atom; and • M'' + As previously stated regarding M + Limited by, and M + M' + M'' + Same or different, same is preferred or, b) Thiolized amino compounds of formula (IIB), their optical isomers, geometric isomers, solvates, hydrates, salts of bases or salts of acids, R a -N(R b )-CH(R c )-(CH2) n -S-R d (IIB) in, n is an integer selected from 0 to 3; - R a Represents a hydrogen atom or -C(X) a )-R a ', where X a Represents an oxygen or sulfur atom, preferably oxygen, and R a 'Represents a saturated or unsaturated straight-chain or branched hydrocarbon chain containing 1 to 8 carbon atoms, preferably a saturated hydrocarbon such as (C1-C6) alkyl, wherein the chain: i) Optionally substituted with one or more groups selected from (di)(C1-C4)(alkyl)amino and -C(O)OM, wherein M represents a hydrogen atom or is preferably selected from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+ and K. + Cation counterions; and / or ii) Optionally selected from O, S, N(R) e -C(O)-, -C(O)-N(R) e - or -N(R) e One or more heteroatoms or groups of )-C(O)- are interrupted, wherein R e Representing a hydrogen atom or a (C1-C4) alkyl group such as methyl, preferably R e Represents a hydrogen atom; - R b Representing a hydrogen atom or a (C1-C4) alkyl group such as methyl, preferably R b Represents a hydrogen atom; - R c Representatives are selected from one of the following: a) Hydrogen atom, b) -C(O)OM', where M' is as previously defined for M; or c) -C(O)-N(R e ')-R a '', where R a As previously stated regarding R a 'As defined, preferably R' a Unlike R a ', more preferably R a '' represents an (C1-C4) alkyl group optionally substituted with one or more -C(O)OM groups as defined above, preferably -C(O)OH; - R d Represents a hydrogen atom or -S-CH2-CH(R) f )-N(R g )-R h , where R f As previously stated regarding R c As specified, R g As previously stated regarding R b Limited by, and R h As previously stated regarding R a As defined, preferably R d Represents a hydrogen atom; What needs to be understood is: - R f With R c Whether they are the same or different, the same is preferred; - R g With R b Whether they are the same or different, the same is preferred; - R h With R a Same or different, same is preferred; and - M and M' may be the same or different, preferably the same.

2. The composition according to claim 1, wherein... - In formulas (I) and (I'), R1 represents a hydrogen atom. or - R1 in equations (I) and (I') represents the linear chain (C1-C 10 )alkyl or branched (C3-C 10 The alkyl group, especially straight-chain (C1-C6) alkyl or branched-chain (C3-C6) alkyl, is preferably selected from methyl, ethyl, n-pentyl, n-nonyl or isobutyl, more preferably ethyl, and in particular, the alkyl group of R1 is not substituted.

3. The composition according to any one of the preceding claims, wherein - R2 in formulas (I) and (I') represents a hydrogen atom; or - R2 in equations (I) and (I') represents the linear chain (C1-C 10 )alkyl or branched (C3-C 10 The alkyl group, especially straight-chain (C1-C6) alkyl or branched-chain (C3-C6) alkyl, is preferably selected from methyl, ethyl, n-pentyl, n-nonyl or isobutyl, more preferably methyl or ethyl; the alkyl group of R2 is not substituted.

4. The composition according to any one of the preceding claims, wherein - R2 in equations (I) and (I') represents the linear chain (C1-C 10 )alkyl or branched (C3-C 10 The alkyl group, especially a straight-chain (C1-C6) alkyl or a branched-chain (C3-C6) alkyl group, preferably selected from methyl, ethyl, n-pentyl, n-nonyl or isobutyl, more preferably methyl or ethyl; the alkyl group is substituted with one or more groups selected from i), ii), iii) and iv) as defined in claim 1, preferably the alkyl group is substituted with one or two groups selected from i), ii) and iii), more preferably one or two groups selected from i) and iii), and even more preferably substituted with a group iii) as a carboxyl group.

5. The composition according to any one of the preceding claims, wherein - R2 in formula (I) and formula (I') represents (C3-C8) cycloalkyl, preferably (C5-C7) cycloalkyl, such as cyclohexyl; or - R2 in equations (I) and (I') represents C5-C 12 Aryl group, optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups, preferably particularly unsubstituted phenyl groups.

6. The composition according to any one of the preceding claims, wherein - R3 in formulas (I) and (I') represents a hydrogen atom; or - R3 in equations (I) and (I') represents saturated linear C1-C 10 Or branched C3-C 10 Alkyl groups; particularly straight-chain (C1-C6) alkyl or branched (C3-C6) alkyl, preferably (C1-C4) alkyl, such as methyl.

7. The composition according to any one of the preceding claims, wherein - In formulas (I) and (I'), R1 represents a group selected from the following: a) Hydrogen atom; b) A saturated straight-chain C1-C6 or branched C3-C6 alkyl group, optionally substituted with one or more groups, which may be the same or different, and are selected from: i) -O-R3; ii) -S-R3; Preferably, it is optionally substituted by one or more groups i); - In formulas (I) and (I'), R2 represents a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 10 Or branched C3-C 10 Or cyclic C3-C8, such as C5-C6 alkylating groups, optionally substituted by one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -SR3; iii) -C(O)-O-R3; iv) Phenyl, which may optionally be substituted with one or more hydroxyl groups and / or with one or more C1-C4 alkoxy groups, such as methoxy groups; Preferably, it is substituted with one or more groups selected from i) and iii), preferably iii), such as a carboxyl group; - In formulas (I) and (I'), R3 represents a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C6 or branched C3-C6 alkyl groups; Preferably, the compounds of formula (I) and the tautomers, salts, solvates, hydrates, optical isomers, racemates, or mixtures thereof have the following meanings: In formulas (I) and (I'), R1 represents a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C4 or branched C3-C4 alkyl groups, optionally substituted with one or more identical or different groups selected from i) -OR3, more preferably unsubstituted; In formulas (I) and (I'), R2 represents a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 10 Or branched C3-C 10 Or cyclic C3-C8, such as C5-C6 alkylating groups, optionally substituted by one or more groups, which may be the same or different, selected from: i) -O-R3; iii) -C(O)-O-R3; iv) C5-C 12 aryl groups, optionally substituted with one or more hydroxyl groups and / or one or more C1-C4 alkoxy groups; and In formulas (I) and (I'), R3 represents a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C4 or branched C3-C4 alkyl groups, such as methyl or ethyl.

8. The composition according to any one of the preceding claims, wherein, The compound (1) is selected from compounds 1 to 24, their tautomers, their salts, solvates, hydrates, optical isomers, racemates, or mixtures thereof, particularly compounds 1, 2, 4, 6, 7, 9, 11, 12, 14, 15, 16, 17, 18, 19, 20, or 21, more particularly 1, 9, 16, 18, 19, 20, or 21, preferably 18, 19, 20, or 21, more preferably 20: 。 9. The composition according to any one of the preceding claims, wherein the amount of the compound of formula (I) or its tautomer, salt, solvate, hydrate, optical isomer, racemate or mixture of formula (I') is from 0.01% to 10% by weight, preferably from 0.05% to 5% by weight, more preferably from 0.1% to 3% by weight, relative to the total weight of the composition.

10. The composition according to claim 1, wherein In formula (IIA), X represents a heteroatom selected from oxygen or sulfur, preferably oxygen; In equation (IIA), m is 0 or 1; M of formula (IIA) + It is a cation, preferably sodium or potassium; In formula (IIA), R represents a group selected from the following groups. i) -OH, ii) -O-M' + , where M' + As previously stated regarding M + Limited, iii) in, • p is 0 or 2; • m' is 0 or 1; • X', as defined for X, preferably represents an oxygen atom; and M + M' + M'' + same.

11. The composition according to any one of the preceding claims, wherein In formula (IIA), R represents a group selected from the following groups. i) -OH, ii) -O-M' + , where M' + iii) in, • p is 0 or 2; • m' is 0 or 1; • X' represents an oxygen atom; and M + M' + and M'' + Same, selected from sodium or potassium.

12. The composition according to any one of the preceding claims, wherein In formula (IIA), X represents sulfur; In equation (IIA), m is 1; M of formula (IIA) + It is sodium or potassium; In formula (IIA), R represents a group selected from the following groups. i) -OH, and ii) -O-M' + , where M' + M + and M' + same.

13. The composition according to any one of the preceding claims, wherein the inorganic reducing agent of formula (IIA) is selected from sodium bisulfite, sodium metabisulfite, sodium sulfite, sodium thiosulfate, sodium sulfate, potassium metabisulfite, potassium sulfite, potassium thiosulfate, potassium sulfate, or potassium tetrathionate.

14. The composition according to any one of the preceding claims, wherein the inorganic reducing agent of formula (IIA) is selected from sodium bisulfite, sodium metabisulfite, sodium sulfite, sodium thiosulfate, or sodium sulfate.

15. The composition according to claim 1, wherein - In equation (IIB), n is 1 or 2; - R in equation (IIB) a Represents a hydrogen atom or -C(Xa)-R a ', where Xa represents an oxygen atom, and R a 'Represents a saturated or unsaturated straight-chain or branched hydrocarbon chain containing 1 to 8 carbon atoms, preferably a saturated hydrocarbon such as (C1-C6) alkyl, wherein the chain: i) Optionally substituted with one or more groups selected from (di)(C1-C4)(alkyl)amino and -C(O)OM, wherein M represents a hydrogen atom or a cationic counterion such as Na+ and K+. + ; and / or ii) Optionally selected from O, S, N(R) e -C(O)-, -C(O)-N(R) e - or -N(R) e One or more heteroatoms or groups of )-C(O)- are interrupted, wherein R e Representing a hydrogen atom or a (C1-C4) alkyl group such as methyl, preferably R e Represents a hydrogen atom; - R in equation (IIB) b Represents a hydrogen atom; - R in equation (IIB) c Representatives are selected from one of the following: a) Hydrogen atom, b) -C(O)OM', where M' is as previously defined for M; or c) -C(O)-N(R e ')-R a '', where R a As previously stated regarding R a 'As defined, preferably R' a Unlike R a ', more preferably R a '' represents an (C1-C4) alkyl group optionally substituted with one or more -C(O)OM groups as defined above, preferably -C(O)OH; - R in equation (IIB) d Represents a hydrogen atom or -S-CH2-CH(R) f )-N(R g )-R h , where R f As previously stated regarding R c As specified, R g As previously stated regarding R b Limited by, and R h As previously stated regarding R a As defined, preferably R d It represents a hydrogen atom.

16. The composition according to any one of the preceding claims, wherein R of formula (IIB) d It represents a hydrogen atom.

17. The composition according to any one of the preceding claims, wherein R of formula (IIB) a R b and R c It represents a hydrogen atom.

18. The composition according to any one of the preceding claims, wherein, - In equation (IIB), n is 1 or 2; - R in equation (IIB) a Represents a hydrogen atom or -C(Xa)-R a ', where X a Represents an oxygen or sulfur atom, preferably oxygen, and R a 'Represents a saturated or unsaturated straight-chain or branched hydrocarbon chain containing 1 to 8 carbon atoms, preferably a saturated hydrocarbon such as (C1-C6) alkyl, more preferably a (C1-C4) alkyl, such as methyl; - R in equation (IIB) b and R d Represents a hydrogen atom; and - R in equation (IIB) c The symbol is -C(O)OM', where M' represents a hydrogen atom or is preferably selected from alkali metals, alkaline earth metals, and ammonium, more preferably alkali metals such as Na+ and K. + The cation counterion.

19. The composition according to any one of the preceding claims, wherein In equation (IIB), n is 1 or 2; R in equation (IIB) d Representative -S-CH2-CH(R) f )-N(R g )-R h ; R in equation (IIB) a R b R g and R h Independently representing a hydrogen atom; and R in equation (IIB) c and R f The symbol is -C(O)OM', where M' represents a hydrogen atom or is preferably selected from alkali metals, alkaline earth metals, and ammonium, more preferably alkali metals such as Na+ and K. + The cation counterion.

20. The composition according to any one of the preceding claims, wherein, - In equation (IIB), n is 1; - R in equation (IIB) a Representative -C(Xa)-R a ', where X a Represents an oxygen or sulfur atom, preferably oxygen, and R a 'Represents a saturated or unsaturated straight-chain or branched hydrocarbon chain containing 1 to 8 carbon atoms, preferably a saturated hydrocarbon such as (C1-C6) alkyl, more preferably a (C1-C4) alkyl, such as methyl; - R in equation (IIB) b and R d Represents a hydrogen atom; and - R in equation (IIB) c The symbol is -C(O)OM', where M' represents a hydrogen atom or is preferably selected from alkali metals, alkaline earth metals, and ammonium, more preferably alkali metals such as Na+ and K. + The cation counterion.

21. The composition according to any one of the preceding claims, wherein the thiolized amino compound of formula (IIB), its optical isomer, and its geometric isomer are in the form of a salt of an inorganic acid such as HHal, wherein Hal represents a halogen such as chlorine.

22. The composition according to any one of the preceding claims, wherein the thiolated amino compound of formula (IIB) is selected from N-acetylcysteine, cysteine, homocysteine, cystine, cysteine ​​hydrochloride, cystamine hydrochloride, 20-glutathione or butyryl glutathione.

23. The composition according to any one of the preceding claims, wherein the thiolated amino compound of formula (IIB) is selected from N-acetylcysteine, cysteine, homocysteine, cystine or cysteine ​​hydrochloride, preferably N-acetylcysteine.

24. The composition according to any one of the preceding claims, wherein the amount of the reducing agent is 0.01% to 2% by weight, preferably 0.02% to 1.0% by weight, and more preferably 0.03% to 0.5% by weight, relative to the total weight of the composition.

25. The composition according to any one of the preceding claims, wherein the composition comprises, by weight of the total weight of the composition, 20% to 99% by weight, preferably 30% to 95% by weight, more preferably 40% to 90% by weight of water.

26. The composition according to any one of the preceding claims, wherein the composition comprises a keratin material, preferably a skin whitening or depigmenting agent.

27. A cosmetic method for treating keratin materials, the method comprising: The composition according to any one of the preceding claims is applied to the skin, preferably to a keratin material.

28. The use of the composition according to any one of the preceding claims for the application of keratin materials, preferably for skin whitening or depigmentation.

29. Use of at least one reducing agent of formula (II) in a composition comprising at least one compound selected from formula (I), its tautomers, salts, optical isomers, racemic derivatives, solvates, hydrates, or mixtures thereof for stabilizing the compound of formula (I), its tautomers, salts, optical isomers, racemic derivatives, solvates, hydrates, or mixtures thereof in the composition. The compounds of formula (II) are selected from: a) Inorganic reducing agents of formula (IIA), their racemic forms, and their solvates, such as hydrates. (IIA) in, X represents a heteroatom selected from oxygen or sulfur, preferably oxygen; m is 0 or 1; M + It is a cation, preferably selected from alkali metals, alkaline earth metals or ammonium, more preferably selected from alkali metals such as sodium or potassium; R represents a group selected from the following: i) -OH, ii) -O-M' + , where M' + As previously stated regarding M + Limited, iii) in, • p is an integer chosen between 0 and 4 (inclusive), preferably 0, 1, or 2, more preferably 0 or 2; • m' is 0 or 1, preferably 1; • X', as defined for X, preferably represents an oxygen atom; and • M'' + As previously stated regarding M + Limited by, and M + M' + M'' + Whether they are the same or different, the same is preferred. or b) Thiolized amino compounds of formula (IIB) R a -N(R b )-CH(R c )-(CH2) n -S-R d (IIB) in, - n is an integer selected from 0 to 3; - R a Represents a hydrogen atom or -C(Xa)-R a ', where X a Represents an oxygen or sulfur atom, preferably oxygen, and R a 'Represents a saturated or unsaturated straight-chain or branched hydrocarbon chain containing 1 to 8 carbon atoms, preferably a saturated hydrocarbon such as (C1-C6) alkyl, wherein the chain: i) Optionally substituted with one or more groups selected from (di)(C1-C4)(alkyl)amino and -C(O)OM, wherein M represents a hydrogen atom or is preferably selected from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+ and K. + Cation counterions; and / or ii) Optionally selected from O, S, N(R) e -C(O)-, -C(O)-N(R) e - or -N(R) e One or more heteroatoms or groups of )-C(O)- are interrupted, wherein R e Representing a hydrogen atom or a (C1-C4) alkyl group such as methyl, preferably R e Represents a hydrogen atom; - R b Representing a hydrogen atom or a (C1-C4) alkyl group such as methyl, preferably R b Represents a hydrogen atom; - R c Representatives are selected from one of the following: a) Hydrogen atom, b) -C(O)OM', where M' is as previously defined for M; or c) -C(O)-N(R e ')-R a '', where R a As previously stated regarding R a 'As defined, preferably R' a Unlike R a ', more preferably R a '' represents an (C1-C4) alkyl group optionally substituted with one or more -C(O)OM groups as defined above, preferably -C(O)OH; - R d Represents a hydrogen atom or -S-CH2-CH(R) f )-N(R g )-R h , where R f As previously stated regarding R c As specified, R g As previously stated regarding R b Limited by, and R h As previously stated regarding R a As defined, preferably R d Represents a hydrogen atom; What needs to be understood is: - R f With R c Whether they are the same or different, the same is preferred; - R g With R b Whether they are the same or different, the same is preferred; - R h With R a Same or different, same is preferred; and - M and M' may be the same or different, preferably the same. In equations (I) and (I'): - R1 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 10 Or branched C3-C 10 Alkyl groups, optionally substituted with one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -S-R3; - R2 refers to a group selected from the following: a) Hydrogen atom; b) Saturated hydrocarbon groups, straight-chain C1-C 12 Or branched C3-C 12 Or cyclic C3-C8, optionally substituted with one or more groups, which may be the same or different, selected from: i) -O-R3; ii) -S-R3; iii) -C(O)-O-R3; iv) C5-C 12 Aryl group, which is optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups; c) C5-C 12 aryl groups, optionally substituted with one or more hydroxyl groups and / or one or more C1-C8 alkoxy groups; and - R3 refers to a group selected from the following: a) Hydrogen atom; b) Saturated straight-chain C1-C 10 Or branched C3-C 10 alkyl.

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