A cosmetic composition comprising thiopyridinone compounds and reducing agent

Abstract

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

Description

A COSMETIC COMPOSITION COMPRISING THIOP YRIDINONE COMPOUNDS AND REDUCING AGENTFIELD OF INVENTION

[0001] The present invention relates to stabilization of thiopyridinone compound. The present invention in particular relates to a composition comprising thiopyridinone compound and a reducing agent stabilizing the compound and the composition thereof.BACKGROUND OF INVENTION

[0002] Cosmetic products that provide an unblemished skin by means of cleansing, hydration, moisturization, anti-aging, anti -wrinkling, brightening are much sought- after products in everyday life.

[0003] At various periods of their lives, some people have dark appearance on their skin, and more in particular on their faces and hands, of darker and / or more colored spots, which give the skin heterogeneity. These spots are due to a high concentration of melanin in the keratinocytes located at the surface of the skin.

[0004] The use of harmless topical depigmenting substances with good efficacy in treating pigmentation spots are most particularly desired. For example, arbutin, niacinamide and kojic acid are known as skin depigmenting agent.

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

[0006] The thiopyridinone compound can show strong depigmenting or whitening effects by reducing the production of melanin.

[0007] There is a nevertheless a need to develop a cosmetic composition comprising thiopyridinone compound with increased stability, to impart skin brightening and whitening effects.SUMMARY OF THE INVENTION

[0008] According to one aspect of the present disclosure, there is provided a composition, preferably a cosmetic composition, comprising thiopyridinone compound(s) of formula (I) or (I’), and reducing agent(s), wherein the stability, preferably the thermal stability and / or the photostability, of the thiopyridinone compound(s) is increased. The inventors surprisingly discovered that the use of reducing agent(s) improves the stability, preferably the thermal stability and / or the photostability, of the compound of formula (I) or (I’) in the composition.

[0009] The present invention provides a composition, preferably a cosmetic composition comprising: i) at least one compound selected from a compound of Formula (I) below, its tautomer of formula (I’) below; salts, solvates, hydrates, optical isomers, racemates, or mixtures thereof:Formula (I) Formula (F) wherein,- Ri denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear Ci-Cio or branched C3-C10 alkyl group optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; ii) -S-R3;- R2 denotes a radical chosen from: a) a hydrogen atom;b) a saturated linear C1-C12 or branched C3-C12 or cyclic C3-C8 hydrocarbonated group, optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; ii) -S-R3; iii) -C(O)-O-R3; iv) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals, and c) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals;- R3 denotes a radical chosen from: a) a hydrogen atom, and b) a saturated linear C1-C10 or branched C3-C10 alkyl group; and ii) at least one inorganic reducing agent of formula (II), wherein the compound of formula (II) is selected from: a) an inorganic reducing agent of formula (IIA) its mesomeric forms, and its solvates such as hydrateswherein,X represents a heteroatom selected from oxygen or sulfur, preferably oxygen;m is 0 or 1;M+is a cation, preferably selected from alkali metal, alkaline earth metal or ammonium, more preferably selected from an alkali metal such as sodium or potassium;R represents a group selected from: i) -OH, ii) -O-M’+with M’+as previously defined for M+,iii) wherein,• p is an integer inclusively selected between 0 and 4, preferably 0, 1, 2, and more preferably 0 or 2;• m’ is 0 or 1, preferably 1;• X’ is as defined for X, preferably X’ represents an oxygen atom; andM”+is as previously defined for M+, and M+, M’+, M”+are identical or different, preferably identical or, b) a thiolated amino compound of formula (IIB), its optical, geometric isomers, solvates, hydrates, salts of bases, or of acids thereof,Ra-N(Rb)-CH(Rc)-(CH2)n-S-Rd(HB) wherein, n is an integer selected from 0 to 3;- Rarepresents a hydrogen atom or -C(Xa)-Ra' with Xarepresenting an oxygen or sulfur atom, preferably oxygen, and Ra' representing a linear or branched hydrocarbon chain, saturated or unsaturated, comprising from 1 to 8 carbon atoms, preferably saturated hydrocarbon such as (Ci-Ce)alkyl, said chain being: i) optionally substituted by one or more groups chosen from (di)(Ci- C4)(alkyl)amino, and -C(O)OM, with M representing a hydrogen atom, or a cationic counterion preferably chosen from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+ and K+; and / or ii) optionally interrupted by one or more heteroatoms or groups chosen from O, S, N(Re), -C(O)-, -C(O)-N(Re)- or -N(Re)-C(O)-, with Rerepresenting a hydrogen atom or a (Ci-C4)alkyl group such as methyl, preferably Rerepresents a hydrogen atom;- Rb represents a hydrogen atom or a (Ci-C4)alkyl group such as methyl, preferably Rb represents a hydrogen atom;- Rc represents one of the following selected from: a) a hydrogen atom, b) -C(O)OM’ with M’ as defined previously for M; or c) -C(O)-N(Re')-Ra" with Ra" being as defined previously for Ra', preferably Ra" is different from Ra', more preferably Ra" represents (Ci-C4)alkyl optionally substituted with one or more -C(O)OM groups with M as defined above, preferably -C(O)OH;- Rd represents a hydrogen atom or -S-CH2-CH(Rf)-N(Rg)-Rh with Rf being as defined previously for Rc, Rgbeing as defined previously for Rb, and Rh being as defined previously for Ra, preferably Rd represents a hydrogen atom; it is understood that:- Rf is identical or different to Rc, preferably identical;- Rgis identical or different to Rb, preferably identical;- Rh is identical or different to Ra, preferably identical; and- M and M’ are identical or different, preferably identical.

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

[0011] According to one another aspect of the present disclosure, there is provided a use of the composition as disclosed herein for whitening or depigmenting a keratin material, preferably skin.

[0012] According to more aspect of the present disclosure, there is provided a use of at least one reducing agent of formula (II), wherein the compound of formula (II) is selected from: a. a) an inorganic reducing agent of formula (IIA), its mesomeric forms, and its solvates such as hydrates ft,wherein,X represents a heteroatom selected from oxygen or sulfur, preferably oxygen; m is 0 or 1 ;M+is a cation, preferably selected from alkali metal, alkaline earth metal or ammonium, more preferably selected from an alkali metal such as sodium or potassium;R represents a group selected from: i) -OH, ii) -O-M’+with M’+as previously defined for M+,iii) wherein,• p is an integer inclusively selected between 0 and 4, preferably 0, 1, 2, and more preferably 0 or 2;• m’ is 0 or 1, preferably 1;• X’ is as defined for X, preferably X’ represents an oxygen atom; and• M”+is as previously defined for M+, and M+, M’+, M”+are identical or different, preferably identical, or, b) a thiolated amino compound of formula (IIB), its optical, geometric isomers, solvates, hydrates, salts of bases, or of acids thereof,Ra-N(Rb)-CH(Rc)-(CH2)n-S-Rd(HB) wherein, n is an integer selected from 0 to 3;- Rarepresents a hydrogen atom or -C(Xa)-Ra' with Xarepresenting an oxygen or sulfur atom, preferably oxygen, and Ra' representing a linear or branched hydrocarbon chain, saturated or unsaturated, comprising from 1 to 8 carbon atoms, preferably saturated hydrocarbon such as (Ci-Ce)alkyl, said chain being: i) optionally substituted by one or more groups chosen from (di)(Ci- C4)(alkyl)amino, and -C(0)0M, with M representing a hydrogen atom, or a cationic counterion preferably chosen from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+ and K+; and / orii) optionally interrupted by one or more heteroatoms or groups chosen from O, S, N(Re), -C(O)-, -C(O)-N(Re)- or -N(Re)-C(O)-, with Rerepresenting a hydrogen atom or a (Ci-C4)alkyl group such as methyl, preferably Rerepresents a hydrogen atom;- Rb represents a hydrogen atom or a (Ci-C4)alkyl group such as methyl, preferably Rb represents a hydrogen atom;- Rc represents one of the following selected from: a) a hydrogen atom, b) -C(O)OM’ with M’ as defined previously for M; or c) -C(O)-N(Re')-Ra" with Ra" being as defined previously for Ra', preferably Ra" is different from Ra', more preferably Ra" represents (Ci-C4)alkyl optionally substituted with one or more -C(O)OM groups with M as defined above, preferably -C(O)OH;- Rd represents a hydrogen atom or -S-CH2-CH(Rf)-N(Rg)-Rh with Rf being as defined previously for Rc, Rgbeing as defined previously for Rb, and Rh being as defined previously for Ra, preferably Rd represents a hydrogen atom; it is understood that:- Rf is identical or different to Rc, preferably identical;- Rgis identical or different to Rb, preferably identical;- Rh is identical or different to Ra, preferably identical; and- M and M’ are identical or different, preferably identical, in a composition comprising at least one compound selected from compounds of formula (I), its tautomer of formula (I’), salts, optical isomers, racemates, solvates, hydrates, or mixtures thereof :wherein formulae (I) and (I’):- Ri denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C10 or branched C3-C10 alkyl group optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; ii) -S-R3;- R2 denotes a radical chosen from: a) a hydrogen atom; b) a saturated hydrocarbonated group linear C1-C12 or branched C3-C12 or cyclic C3-C8 , optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; ii) -S-R3; iii) -C(O)-O-R3; iv) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals;c) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals; and- R3 denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C10 or branched C3-C10 alkyl group, to stabilize the compound of formula (I), its tautomer of formula (I’), salts, optical isomers, racemates, solvates, hydrates, or mixtures thereof, in the composition.

[0013] These and other features, aspects, and advantages of the present subject matter will be better understood with reference to the following description and appended claims. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.DESCRIPTION OF THE INVENTION

[0014] Those skilled in the art will be aware that the present disclosure is subject to variations and modifications other than those specifically described. It is to be understood that the present disclosure includes all such variations and modifications. The disclosure also includes all such steps, features, compositions, and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any or more of such steps or features. Definitions

[0015] For convenience, before further description of the present disclosure, certain terms employed in the specification, and examples are delineated here. These definitions should be read in the light of the remainder of the disclosure and understood as by a person of skill in the art. The terms used herein have the meanings recognized and known to those of skill in the art, however, forconvenience and completeness, particular terms and their meanings are set forth below.

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

[0017] The terms “comprise” and “comprising” are used in the inclusive, open sense, meaning that additional elements may be included. It is not intended to be construed as “consists of only.”

[0018] The term “at least one” is used to mean one or more and thus includes individual components as well as mixtures / combinations.

[0019] Throughout this specification, unless the context requires otherwise the word “comprise,” and variations such as, “comprises” and “comprising,” will be understood to imply the inclusion of a stated element or step or group of element or steps but not the exclusion of any other element or step or group of element 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 of International Nomenclature of Cosmetic Ingredients, which is a system of names provided by the International Nomenclature Committee of the Personal Care Products Council to describe personal care ingredients.

[0022] All percentages, parts and ratios are based upon the total weight of the compositions of the present disclosure unless otherwise indicated. Ratios, concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a weight percentage range of about 0.01 % to 10 %, should be interpreted to include not only the explicitly recited limits of about 0.01% to about 10%, but also to include subranges, such as 0.02% to 0.05%, 1% to 10% and so forth, as well as individualamounts, including fractional amounts, within the specified ranges, such as 1.5 %, 5.3% and 9.25 %, for example.

[0023] For the purpose of the present disclosure, unless otherwise indicated: a) a “saturated linear C1-C12 or branched C3-C12” hydrocarbonated group is equivalent to a “linear (Ci-Ci2)alkyl or branched (C3-Ci2)alkyl group” which correspond to a saturated linear C1-C12 or branched C3- C12 hydrocarbon based group, and preferably a linear C1-C10 or branched C3-C10 hydrocarbon based group, and more preferably a linear Ci-Ce or branched C3-C6 hydrocarbon-based group; Preferentially, the linear or branched groups may be chosen from methyl, ethyl, propyl, isopropyl, butyl, isobutyl and tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl. More preferentially, the saturated linear or branched alkyl groups may be chosen 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) a saturated “cyclic Cs-Cs” hydrocarbonated group is a mono or bicyclic cycloalkyl group containing 3 to 8 carbon atoms especially is a monocyclic cycloalkyl group having C5 to C7 atoms, such as cyclohexyl group; c) an "alkoxy radical" is an alkyl-oxy radical for which the alkyl radical is a linear or branched C1-C16 and preferentially a Ci-Cs hydrocarbonbased radical; when the alkoxy group is optionally substituted, this implies that the alkyl group is optionally substituted as defined herein; d) an "aryl" group represents a fused or non-fused monocyclic or bicyclic carbon-based group comprising from 5 to 12 carbon atoms, preferably from 6 to 10 carbon atoms, and in which at least one ring is aromatic; preferentially, the aryl radical is a phenyl, biphenyl, naphthyl, more preferably a phenyl group; e) the term "at least one” is equivalent to the term "one or more"; and f) the term "inclusive" for a range of concentrations means that the limits of that range are included in the defined range.

[0024] The salts of the compounds of formula (I), (I’), (la) or (la’) comprises the conventional non-toxic salts of said compounds, such as those formed from organic or inorganic acid or from organic or inorganic base.

[0025] As salts of the compounds of formula (I), (I’), (la) or (la’) mention may be made of by addition of the compound of formula (I) to i) a mineral base, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonium hydroxide, magnesium hydroxide, lithium hydroxide, and sodium, potassium or calcium carbonate or hydrogen carbonate for example; or ii) an organic base such as a primary, secondary, or tertiary alkylamine, for example triethylamine or butylamine. This primary, secondary or tertiary alkylamine may comprise one or more nitrogen and / or oxygen atoms and may thus comprise, for example, one or more alcohol functions; mention may be made in particular of 2-amino-2- methylpropanol, ethanolamine, triethanolamine, 2- dimethylaminopropanol, 2-amino-2-(hydroxymethyl)- 1 ,3 -propanediol and 3- (dimethylamino)propylamine.

[0026] Mention may also be made of the salts of amino acids, for instance lysine, arginine, guanidine, glutamic acid and aspartic acid. Advantageously, the salts of the compounds of formula (I) (when it comprises a carboxy group) may be chosen from alkali metal or alkaline-earth metal salts such as sodium, potassium, calcium or magnesium salts and ammonium salts.

[0027] As "organic or inorganic acid salt" is more particularly chosen from salts chosen from a salt derived from i) hydrochloric acid HC1, ii) hydrobromic acid HBr, iii) sulfuric acid H2SO4, iv) alkylsulfonic acids: Alk-S(O)2OH such as methanesulfonic acid and ethanesulfonic acid; v) arylsulfonic 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) alkoxy sulfinic acids: Alk-O-S(O)OH such as methoxysulfinic acid and ethoxysulfinic acid; xi) aryloxysulfinic acids such as tolueneoxysulfinic acid and phenoxy sulfinic acid; xii) phosphoric acid H3PO4; xiii)acetic acid CH3C(0)0H; xiv) triflic acid CF3SO3H; and xv) tetrafluoroboric acidHBF4.

[0028] The acceptable solvates of the compounds described in the specification comprise conventional solvates such as those formed during the preparation of said compounds owing to the presence of solvents. Mention may be made, by way of example, of the solvates due to the presence of water or of linear or branched alcohols, such as ethanol or isopropanol.

[0029] The optical isomers of formula (I) or (F) are in particular, the enantiomers and the diastereoisomers.

[0030] The mesomeric forms of formula (II) represents isomers of compounds of formula (II) resulting due to electron delocalization around the hetero atoms such as oxygen and / or sulphur.

[0031] Unless defined otherwise, 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 belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the preferred methods and materials are now described. All publications mentioned herein are incorporated herein by reference.

[0032] The present disclosure is not to be limited in scope by the specific embodiments described herein, which are intended for the purposes of exemplification only. Functionally equivalent products, compositions, and methods are clearly within the scope of the disclosure, as described herein.Composition stabilizing thiopyridinone compound

[0033] In an embodiment, the present invention provides a composition, preferably a cosmetic composition comprising: i) at least one compound selected from a compound of Formula (I) below, its tautomer of formula (I’) below; salts, solvates, hydrates, optical isomers, racemates, or mixtures thereof:wherein,- Ri denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear Ci-Cio or branched C3-C10 alkyl group optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; ii) -S-R3;- R2 denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C12 or branched C3-C12 or cyclic C3-C8 hydrocarbonated group, optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; ii) -S-R3; iii) -C(O)-O-R3; iv) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals, and c) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals;- R3 denotes a radical chosen from:a) a hydrogen atom, and b) a saturated linear C1-C10 or branched C3-C10 alkyl group; and ii) at least one reducing agent of formula (II), wherein the compound of formula (II) is selected from: a) an inorganic reducing agent of formula (IIA) its mesomeric forms, and its solvates such as hydrateswherein,X represents a heteroatom selected from oxygen or sulfur, preferably oxygen; m is 0 or 1;M+is a cation, preferably selected from alkali metal, alkaline earth metal or ammonium, more preferably selected from an alkali metal such as sodium or potassium;R represents a group selected from: i) -OH, ii) -O-M’+with M’+as previously defined for M+,wherein,• p is an integer inclusively selected between 0 and 4, preferably 0, 1, 2, and more preferably 0 or 2;• m’ is 0 or 1, preferably 1;• X’ is as defined for X, preferably X’ represents an oxygen atom; and• M”+is as previously defined for M+, and M+, M’+, M”+are identical or different, preferably identical; or, b) a thiolated amino compound of formula (IIB), its optical, geometric isomers, solvates, hydrates, salts of bases, or of acids thereof,Ra-N(Rb)-CH(Rc)-(CH2)n-S-Rd(HB) wherein, n is an integer selected from 0 to 3;- Rarepresents a hydrogen atom or -C(Xa)-Ra' with Xarepresenting an oxygen or sulfur atom, preferably oxygen, and Ra' representing a linear or branched hydrocarbon chain, saturated or unsaturated, comprising from 1 to 8 carbon atoms, preferably saturated hydrocarbon such as (Ci-Ce)alkyl, said chain being: i) optionally substituted by one or more groups chosen from (di)(Ci- C4)(alkyl)amino, and -C(0)0M, with M representing a hydrogen atom, or a cationic counterion preferably chosen from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+ and K+; and / or ii) optionally interrupted by one or more heteroatoms or groups chosen from O, S, N(Re), -C(O)-, -C(O)-N(Re)- or -N(Re)-C(O)-, with Rerepresenting a hydrogen atom or a (Ci-C4)alkyl group such as methyl, preferably Rerepresents a hydrogen atom;- Rb represents a hydrogen atom or a (Ci-C4)alkyl group such as methyl, preferably Rb represents a hydrogen atom;- Rc represents one of the following selected from: a) a hydrogen atom, b) -C(O)OM’ with M’ as defined previously for M; or c) -C(O)-N(Re')-Ra" with Ra" being as defined previously for Ra', preferably Ra" is different from Ra', more preferably Ra" represents (Ci-C4)alkyl optionally substituted with one or more -C(O)OM groups with M as defined above, preferably -C(O)OH;- Rd represents a hydrogen atom or -S-CH2-CH(Rf)-N(Rg)-Rh with Rf being as defined previously for Rc, Rgbeing as defined previously for Rb, and Rh being as defined previously for Ra, preferably Rd represents a hydrogen atom; it is understood that:- Rf is identical or different to Rc, preferably identical;- Rgis identical or different to Rb, preferably identical;- Rh is identical or different to Ra, preferably identical; and- M and M’ are identical or different, preferably identical.

[0034] The composition, preferably a cosmetic composition according to an embodiment of the present invention, include at least one compound of formula (I) or (T), referred to as “compound of thiopyridinone type” or “thiopyridinone compound”. It may be preferable that the present invention provides cosmetic compositions which include a combination of compound of thiopyridinone type (I) or (T) with at least one reducing agent of formula (II), that improves the stabilization, preferably the thermal stabilization, of the thiopyridinone compounds and the cosmetic composition comprising the same.

[0035] The term “stability” of the thiopyridinone compound can be determined by the change in the amount of the thiopyridinone compound in the compositionaccording to the present invention, during a certain period of time. The term “thermal stability” of the thiopyridinone compound can be determined by the change in the amount of the thiopyridinone compound in the composition according to the present invention during a certain period of time, in particular when the composition is maintained for a relatively long period, such as two weeks, under room temperature or even under elevated temperature such as above 40°C. The term “photostability” of the thiopyridinone compound can be determined by the change in the amount of the thiopyridinone compound in the composition according to the present invention after exposure to light. An increased “stability”, “thermal stability” or “photostability”, means that the change in the amount of the thiopyridinone compound over time is more limited.

[0036] In some embodiments, the at least one reducing agent of formula (II) as described herein, improves the stabilization, preferably the thermal stabilization and / or photo stabilization, the compound of formula (I) or (T) in the composition. In other embodiments, the composition according to the present invention shows increased stability, preferably thermal stability and / or photostability, of the thiopyridinone compound of formula(I) and (T) therein. In some embodiments, the composition according to the present invention show increased stability of the compound of formula (I) or (T), when stored for a longer period of time at room temperature. In some embodiments, the composition according to the present invention show increased stability of the compound of formula (I) or (T), even when the composition is maintained and stored for a longer period of time such as two to three weeks under elevated temperature such as 40 to 60°C. In yet another embodiment, the increased stability of the compound of formula (I) or (T) in the composition provide improved bioavailability to cause prolonged brightening or depigmenting effects on the keratin material.

[0037] The present invention according to an embodiment, provides methods for improving the stability of compound of thiopyridinone type (I) or (T) in the cosmetic compositions that are useful for treating a keratin material, for example, the skin of the face and neck of a human. In some embodiments, the present invention provides cosmetic methods of treating the skin comprising application ofthe cosmetic composition of the present invention on the skin to cause brightening or whitening effect. The cosmetic compositions are useful in non-therapeutic methods for treating dark spots, and uneven skin texture.

[0038] In an embodiment, the composition, preferably a cosmetic composition includes: i) at least one compound selected from a compound of Formula (I) below, its tautomer of formula (I’) below; salts, solvates, hydrates, optical isomers, racemates, or mixtures thereof:wherein,- Ri denotes a radical chosen from: a) a hydrogen atom; and b) a saturated linear C1-C10 or branched C3-C10 alkyl group optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; and ii) -S-R3;- R2 denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C12 or branched C3-C12 or cyclic C3-C8 hydrocarbonated group, optionally substituted with one or more groups, which may be identical or different, chosen from:i) -O-R3; ii) -S-R3; iii) -C(O)-O-R3; iv) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals, and c) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals;- R3 denotes a radical chosen from: a) a hydrogen atom, and b) a saturated linear C1-C10 or branched C3-C10 alkyl group;

[0039] The compounds used according to the invention therefore correspond to formula (I) or tautomer (F) below or their salts, their optical isomers, racemates, and / or solvates such as hydrates and the thereof, alone or as a mixture.in which Formulas (I) and (I’) :Ri denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C10 or branched C3-C10 alkyl group optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3;ii) -S-R3;R2 denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C12 or branched C3-C12 or cyclic C3- Cs hydrocarbonated group, optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; ii) -S-R3; iii) -C(O)-O-R3; iv) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals; and c) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals whereinRs denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C10 or branched C3-C10 alkyl group;

[0040] Compound (I’) is the tautomer form of compound (I) when a tautomeric equilibrium exists according to the following scheme:

[0041] In some embodiments, Ri represents one hydrogen atom.

[0042] In some embodiments, Ri represents a linear (Ci-Cio)alkyl group or branched (C3-Cio)alkyl group, especially a linear (Ci-C6)alkyl group or branched (C3-C6)alkyl group, such as methyl, ethyl, n-pentyl, n-nonyl, isobutyl, more preferably ethyl. Particularly the said alkyl group of Ri is not substituted.

[0043] In some embodiments, R2 represents one hydrogen atom.

[0044] In some embodiments, R2 represents a linear (Ci-Cio)alkyl group or branched (C3-Cio)alkyl group, especially a linear (Ci-C6)alkyl group or branched (C3-C6)alkyl group, such as methyl, ethyl, n-pentyl, n-nonyl, isobutyl, more preferably methyl or ethyl group; the said alkyl group of R2 being not substituted.

[0045] In some embodiments, R2 represents a linear (Ci-Cio)alkyl group or branched (C3-Cio)alkyl group, especially a linear (Ci-C6)alkyl group or branched (C3-C6)alkyl group, such as methyl, ethyl, n-pentyl, n-nonyl, isobutyl, more preferably methyl or ethyl; the said alkyl group being substituted by one or more groups selected from i), ii), iii) and iv) as defined above. Preferably the said alkyl group being substituted by one or two groups selected from i), ii) and iii), more preferably by one or two groups selected from i) and iii), better substituted by one group iii) as carboxy.

[0046] In some embodiments, another variant for radical R2 is that the said alkyl group being substituted by one group iv) especially substituted by one phenyl group.

[0047] In some embodiments, R2 represents a (C3-Cs)cycloalkyl group, preferably a (Cs-C7)cycloalkyl group such cyclohexyl.

[0048] In some embodiments, R2 represents C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals, preferably a phenyl group particularly not substituted.

[0049] In some embodiments, R3 represents a hydrogen atom.

[0050] In some embodiments, R3 represents a saturated linear C1-C10 or branched C3-C10 alkyl group; particularly a linear (Ci-C6)alkyl group or a branched (C3- Ce)alkyl group, preferably (Ci-C4)alkyl group such as methyl group.

[0051] In some embodiments, it may be preferable that, the compounds of formula (I) and tautomer (I’) or their salts, their optical isomers, racemates, and / or solvates such as hydrates and the thereof, alone or as a mixture; have the following meanings:Ri denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear Ci-Ce or branched C3-C6 alkyl group optionally substituted with one or more groups, which may be identical or different, chosen from: i. -O-R3; ii. -S-R3; preferably optionally substituted with one or more groups i);R2 denotes a radical chosen from: a) a hydrogen atom; b) a saturated hydrocarbonated group linear C1-C10 or branched C3-C10 or cyclic C3-C8 such as C5-C6, optionally substituted with one or more groups, which may be identical or different, chosen from: i. -O-R3; ii. -SR3; iii. -C(O)-O-R3;iv. a phenyl group optionally substituted with one or more hydroxyls and / or with one or more C1-C4 alkoxy radicals such as methoxy; preferably substituted with one or more groups selected from i) and iii), preferably iii) such as carboxy;R3 denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear Ci-Ce or branched C3-C6 alkyl group.

[0052] In some embodiments, it may be preferable that, the compounds of formula (I) and tautomer (I’) or their salts, their optical isomers, racemates, and / or solvates such as hydrates and the thereof, alone or as a mixture, have the following meanings:Ri denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C4 or branched C3-C4 alkyl group optionally substituted with one or more groups, which may be identical or different, chosen from i) -OR3 , more preferably not substituted;R2 denotes a radical chosen from: a) a hydrogen atom; b) a linear C1-C10 or branched C3-C10 or cyclic C3-C8 as C5-C6 saturated hydrocarbonated group, optionally substituted with one or more groups, which may be identical or different, chosen from: i. -O-R3; ii. -C(O)-O-R3; iv. a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci- C4 alkoxy radicals;Rs denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C4 or branched C3-C4 alkyl group such as methyl or ethyl .

[0053] In some embodiments, it may be preferable that, the compounds of formula (I) and tautomer (I’) or their salts, their optical isomers, racemates, and / or solvates such as hydrates and the thereof, alone or as a mixture; have the following meanings:Ri is a hydrogen atom; andR2 denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C5 or branched C3-C5 or cyclic C3-C8 as C5-C6 hydrocarbonated group , substituted with one or more groups, which may be identical or different, chosen from ii) -C(O)-O-R3, preferably substituted with one group ii) -C(O)-O-R3; andR2 is even more preferably a saturated linear C1-C4 or branched C3-C4 hydrocarbonated group substituted with one group iii) -C(O)-OR3 , andR3 denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C4 or branched C3-C4 alkyl group such as methyl or ethyl.

[0054] In a preferred embodiment, the compounds of formula (I) and tautomer (I’) are selected among compounds of formula (la) and also the tautomers thereof of formula (la’) below, the salts thereof, the solvates thereof and the optical isomers thereof, and the racemates thereof, alone or as a mixture :

[0055] In formula (la) and (la’), Ri and R3 have the same meaning than for compounds of formula (I) and (I’) and X denotes an alkylene radical -(CH2)n- with n being an integer ranging inclusively from 1 to 10, preferably ranging from 1 to 6, more preferably ranging from 1 to 4, such as 1, preferably R3 represents a hydrogen atom.

[0056] In a preferred embodiment, among the compounds of formula (I), the following compounds are used and their tautomer or their salts, their optical isomers, racemates, and / or solvates such as hydrates and the thereof, alone or as a mixture:

[0057] In a preferred embodiment, the compounds are particularly selected from:

[0058] In a much preferred embodiment, among these compounds, the following compounds are more particularly preferred:

[0059] In a much more preferred embodiment, the following compounds are more particularly used:

[0060] In a most preferred embodiment, the compound according to the present invention is the following:

[0061] All the compounds above can be obtained by a chemical method known by man skilled in the art, from commercially available reagents.

[0062] In an embodiment, the (1) thiopyridinone compound of formula (I) or (I’) can be prepared in accordance with the process described in, for example, EP-A- 3 390363 or WO 2017 / 102349.

[0063] The (1) thiopyridinone compound may be an active ingredient or active compound in cosmetics or dermatological products. The term “active” ingredient or compound used herein means an ingredient or compound which has a cosmeticor dermatological active property, such as anti-oxidant, whitening, UV-filtering effects, and anti-bacterial effects. The (1) thiopyridinone compound used in the present invention can function as a depigmenting, brightening, bleaching, or whitening agent, and thus the composition according to the present invention may be used as a skin brightening product or as a cosmetic composition for a brightening keratin material.

[0064] The (1) thiopyridinone compound may be used as an agent for depigmenting, brightening, bleaching, or whitening the skin, body hairs, the eyelashes, or head hair, and also the lips and / or the nails, and preferably the skin, in particular for eliminating pigmentation spots or senescence spots and / or as an anti-tanning agent.

[0065] In some embodiments, the amount of the (1) thiopyridinone compound(s) 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.

[0066] In some embodiments, the amount of the (1) thiopyridinone compound(s) in the composition may be 10% by weight or less, preferably 5% by weight or less, and more preferably 3% by weight or less, relative to the total weight of the composition.

[0067] In some embodiments, the amount of the (1) thiopyridinone compound(s) in the composition according to the present invention may range 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.

[0068] In some embodiments, the amount of the (1) thiopyridinone compound(s) in the composition may range 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.

[0069] It may be preferable that the composition according to the present invention comprises (1) at least one thiopyridinone compound. Two or more (1) thiopyridinone compounds may be used in combination. Thus, a single type of (1)thiopyridinone compound or a combination of different types of (1) thiopyridinone compounds may be used.

[0070] The (1) thiopyridinone compound is selected from compounds of formula (I) below, tautomers of formula (I’) below, salts thereof, solvates, such as hydrates, thereof, optical isomers thereof, racemates thereof, and mixtures thereof:wherein in formulas (I) and (I’) :Ri denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear Ci-Cio or branched C3-C10 alkyl group optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; ii) -S-R3;R2 denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C12 or branched C3-C12 or cyclic C3-C8 hydrocarbonated group, optionally substituted with one or more groups, which may be identical or different, chosen from: i. -O-R3;ii. -S-R3; iii. -C(O)-O-R3; iv. a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals; and c) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals whereinR3 denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C10 or branched C3-C10 alkyl group.Reducing asent of Formula (II)

[0071] In an embodiment, the composition of the present invention, comprises at least one (2) reducing agent of formula (II), wherein the compound of formula (II) is selected from a) an inorganic reducing agent of formula (IIA), its mesomeric forms, and its solvates such as hydrateswherein,X represents a heteroatom selected from oxygen or sulfur, preferably oxygen; m is 0 or 1;M+is a cation, preferably selected from alkali metal, alkaline earth metal or ammonium, more preferably selected from an alkali metal such as sodium or potassium;R represents a group selected from: i) -OH, ii) -O-M’+with M’+as previously defined for M+,in) wherein,• p is an integer inclusively selected between 0 and 4, preferably 0, 1, 2, and more preferably 0 or 2;• m’ is 0 or 1, preferably 1;• X’ is as defined for X, preferably X’ represents an oxygen atom; and• M”+is as previously defined for M+, and M+, M’+, M”+are identical or different, preferably identical; or, b) a thiolated amino compound of formula (IIB), its optical, geometric isomers, solvates, hydrates, salts of bases, or of acids thereof,Ra-N(Rb)-CH(Rc)-(CH2)n-S-Rd(HB) wherein, n is an integer selected from 0 to 3;- Rarepresents a hydrogen atom or -C(Xa)-Ra' with Xarepresenting an oxygen or sulfur atom, preferably oxygen, and Ra' representing a linear or branched hydrocarbon chain, saturated or unsaturated, comprising from 1 to 8 carbon atoms, preferably saturated hydrocarbon such as (Ci-Ce)alkyl, said chain being: i) optionally substituted by one or more groups chosen from (di)(Ci- C4)(alkyl)amino, and -C(O)OM, with M representing a hydrogen atom, or a cationic counterion preferably chosen from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+ and K+; and / or ii) optionally interrupted by one or more heteroatoms or groups chosen from O, S, N(Re), -C(O)-, -C(O)-N(Re)- or -N(Re)-C(O)-, with Rerepresenting a hydrogen atom or a (Ci-C4)alkyl group such as methyl, preferably Rerepresents a hydrogen atom;- Rb represents a hydrogen atom or a (Ci-C4)alkyl group such as methyl, preferably Rb represents a hydrogen atom;- Rc represents one of the following selected from: a) a hydrogen atom, b) -C(O)OM’ with M’ as defined previously for M; or c) -C(O)-N(Re')-Ra" with Ra" being as defined previously for Ra', preferably Ra" is different from Ra', more preferably Ra" represents (Ci-C4)alkyl optionally substituted with one or more -C(O)OM groups with M as defined above, preferably -C(O)OH;- Rd represents a hydrogen atom or -S-CH2-CH(Rf)-N(Rg)-Rh with Rf being as defined previously for Rc, Rgbeing as defined previously for Rb, and Rh being as defined previously for Ra, preferably Rd represents a hydrogen atom; it is understood that:- Rf is identical or different to Rc, preferably identical;- Rgis identical or different to Rb, preferably identical;- Rh is identical or different to Ra, preferably identical; and- M and M’ are identical or different, preferably identical.

[0072] In an embodiment, the composition of the present invention comprises a reducing agent of formula (II) may be in an amount of 0.01% by weight or more, preferably 0.02% by weight or more, and more preferably 0.03% by weight or more, relative to the total weight of the composition.

[0073] In some embodiments, the composition of the present invention according to an embodiment, comprises a reducing agent of formula (II) may be in an amount of 2.0% by weight or less, preferably 1.0% by weight or less, and more preferably 0.05% by weight or less, relative to the total weight of the composition.

[0074] In some embodiments, the amount of the (2) reducing agent in the composition according to the present 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.Inorganic Reducing agent of Formula (II A)

[0075] In an embodiment, the composition of the present invention, comprises at least one (2) reducing agent of formula (II), wherein the compound of formula (II) is an inorganic reducing agent of formula (IIA), its mesomeric forms, and its solvates such as hydratesO - S - O~M+[X]ra(IIA) wherein,X represents a heteroatom selected from oxygen or sulfur, preferably oxygen; m is 0 or 1;M+is a cation, preferably selected from alkali metal, alkaline earth metal or ammonium, more preferably selected from an alkali metal such as sodium or potassium;R represents a group selected from: i) -OH, ii) -O-M’+with M’+as previously defined for M+,iii) wherein,• p is an integer inclusively selected between 0 and 4, preferably 0, 1, 2, and more preferably 0 or 2;• m’ is 0 or 1, preferably 1;• X’ is as defined for X, preferably X’ represents an oxygen atom; and• M’,+is as previously defined for M+, and M+, M’+, M”+are identical or different, preferably identical.

[0076] In some embodiments, the composition comprises at least one (2) reducing agent of formula (II A) wherein,X of formula (IIA) represents a heteroatom selected from oxygen or sulfur, preferably oxygen; m of formula (IIA) is 0 or 1 ;M+of formula (IIA) is a cation, preferably is sodium or potassium;R of formula (IIA) represents a group selected from i) -OH, ii) -O-M’+with M’+as previously defined for M+,iii) wherein,• p is 0 or 2;• m’ is 0 or 1;• X’ is as defined for X, preferably X’ represents an oxygen atom; andM+, M’+, M”+are identical.

[0077] In some embodiments, wherein in the (2) reducing agent of formula (IIA)R represents a group selected from i) -OH, ii) -O-M’+with M’+,iii) wherein,• p is 0 or 2;• m’ is 0 or 1;• X’ is represents an oxygen atom; andM+, M’+, and M”+are identical selected from sodium or potassium.

[0078] In some embodiments, wherein in the (2) reducing agent of formula (IIA)X of formula (IIA) represents sulphur; m of formula (IIA) is 1 ;M+of formula (IIA) is sodium or potassium;R of formula (IIA) represents a group selected fromi) -OH, and ii) -O-M’+with M’+, M+, and M’+are identical.

[0079] In some embodiments, the inorganic reducing agent compounds of formula (IIA) can be found in their borderline or delocalized mesomeric limit forms, when m = 0 thuswhen m = 1 thus the mesomeric limit forms arewherein, M+, M’+, M”+ are present to ensure the electroneutrality of the molecule of formula (IIA).

[0080] In a preferred embodiment, the (2) inorganic reducing agent of formula (IIA) may be selected from sodium bisulfite, sodium metabisulfite, sodium sulfite, sodium thiosulfate, sodium sulfate, potassium metabisulfite, potassium sulfite, potassium thiosulfate, potassium sulfate, or potassium tetra thionate.

[0081] In a preferred embodiment, the (2) inorganic reducing agent of Formula (IIA) may be selected from sodium bisulfite, sodium metabisulfite, sodium sulfite, sodium thiosulfate, or sodium sulfate.

[0082] In an embodiment, the composition of the present invention comprises a reducing agent of formula (II) may be in an amount of 0.01% by weight or more, preferably 0.02% by weight or more, and more preferably 0.03% by weight or more, relative to the total weight of the composition.

[0083] In some embodiments, the composition of the present invention according to an embodiment, comprises a reducing agent of formula (II) may be in an amount of 2.0% by weight or less, preferably 1.0% by weight or less, and more preferably 0.05% by weight or less, relative to the total weight of the composition.

[0084] In some embodiments, the amount of the (2) reducing agent in the composition according to the present 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.Thiolated Amino compound of Formula (IIB)

[0085] In an embodiment, the composition of the present invention, comprises at least one (2) reducing agent of formula (IIB), wherein the compound of formula (IIB) is a thiolated amino compound of formula (IIB), its optical, geometric isomers, solvates, hydrates, salts of bases, or of acids thereofRa-N(Rb)-CH(Rc)-(CH2)n-S-Rd (IIB) wherein,- n is an integer selected from 0 to 3;- Rarepresents a hydrogen atom or -C(Xa)-Ra' with Xa representing an oxygen or sulfur atom, preferably oxygen, and Ra' representing a linear or branched hydrocarbon chain, saturated or unsaturated, comprising from 1 to 8 carbon atoms, preferably saturated hydrocarbon such as (Ci-Ce) alkyl, said chain being: i) optionally substituted by one or more groups chosen from (di)(Ci-C4)(alkyl)amino, and -C(0)0M, with M representing a hydrogen atom, or a cationic counterion preferably chosen from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+ and K+; and / or ii) optionally interrupted by one or more heteroatoms or groups chosen from O, S, N(Re), -C(O)-, -C(O)-N(Re)- or - N(Re)-C(O)-, with Rerepresenting a hydrogen atom or a (Ci- C4)alkyl group such as methyl, preferably Rerepresents a hydrogen atom;- Rb represents a hydrogen atom or a (Ci-C4)alkyl group such as methyl, preferably Rb represents a hydrogen atom;- Rcrepresents one of the following selected from: a) a hydrogen atom,b) -C(O)OM’ with M’ as defined previously for M; or c) -C(O)-N(Re')-Ra" with Ra" being as defined previously for Ra', preferably Ra" is different from Ra', more preferably Ra" represents (Ci-C4)alkyl optionally substituted with one or more -C(O)OM groups with M as defined above, preferably -C(O)OH;- Ra represents a hydrogen atom or -S-CH2-CH(Rf)-N(Rg)-Rh with Rf being as defined previously forRc, Rgbeing as defined previously for Rb, and Rh being as defined previously for Ra, preferably Rd represents a hydrogen atom; it is understood that:- Rf is identical or different to Rc, preferably identical;- Rgis identical or different to Rb, preferably identical;- Rh is identical or different to Ra, preferably identical; and- M and M’ are identical or different, preferably identical.

[0086] In some embodiments, the composition comprises a (2) thiolated amino compound of formula (IIB) wherein n is 1 or 2;- Raof formula (IIB) represents a hydrogen atom or -C(Xa)-Ra' with Xa representing an oxygen atom, and Ra' representing a linear or branched hydrocarbon chain, saturated or unsaturated, comprising from 1 to 8 carbon atoms, preferably saturated hydrocarbon such as (Ci-C6)alkyl, said chain being: i) optionally substituted by one or more groups chosen from (di)(Ci- C4)(alkyl)amino, and -C(0)0M, with M representing a hydrogen atom, or a cationic counterion such as Na+ and K+; and / or ii) optionally interrupted by one or more heteroatoms or groups chosen from O, S, N(Re), -C(O)-, -C(O)-N(Re)- or -N(Re)-C(O)-, with Rerepresenting a hydrogen atom or a (Ci-C4)alkyl group such as methyl, preferably Rerepresents a hydrogen atom;- Rb of formula (IIB) represents a hydrogen atom;- Rcof formula (IIB) represents one of the following selected from: a) a hydrogen atom, b) -C(O)OM’ with M’ as defined previously for M; or c) -C(O)-N(Re')-Ra" with Ra" being as defined previously for Ra', preferably Ra" is different from Ra', more preferably Ra" represents (Ci- C4)alkyl optionally substituted with one or more -C(O)OM groups with M as defined above, preferably -C(O)OH;- Rd of formula (IIB) represents a hydrogen atom or -S-CH2-CH(Rf)-N(Rg)- Rh with Rf being as defined previously for Rc, Rgbeing as defined previously for Rb, and Rh being as defined previously for Ra, preferably Rd represents a hydrogen atom.

[0087] In some embodiments, wherein Rd of formula (IIB) represents hydrogen atom.

[0088] In some embodiments, wherein Ra, Rb, and Rcof formula (IIB) represents hydrogen atom.

[0089] In some embodiments, wherein n is 1 or 2;- Raof formula (IIB) represents hydrogen atom or -C(Xa)-Ra' with Xa representing an oxygen or sulfur atom, preferably oxygen, and Ra' representing a linear or branched hydrocarbon chain, saturated or unsaturated, comprising from 1 to 8 carbon atoms, preferably saturated hydrocarbon such as (Ci-Ce)alkyl, more preferably (Ci-C4)alkyl such as methyl;-Rb, and Rd of formula (IIB) represents hydrogen atom; and-Rcof formula (IIB) represents -C(0)0M’ with M’ representing a hydrogen atom, or a cationic counterion preferably chosen from alkali metals, alkalineearth metals and ammonium, more preferably alkali metals such as Na+and K+.

[0090] In some embodiments, wherein n is 1 or 2;Rd of formula (IIB) represents -S-CH2-CH(Rf)-N(Rg)-Rh;Ra, Rb, Rg and Rh of formula (II) independently represents hydrogen atom; andRcand Rf of formula (II) represents -C(O)OM’ with M’ representing a hydrogen atom, or a cationic counterion preferably chosen from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+and K+.

[0091] In some embodiments, wherein n is 1;-Raof formula (IIB) represents -C(Xa)-Ra' with Xa representing an oxygen or sulfur atom, preferably oxygen, and Ra' representing a linear or branched hydrocarbon chain, saturated or unsaturated, comprising from 1 to 8 carbon atoms, preferably saturated hydrocarbon such as (Ci-C6)alkyl, more preferably (Ci-C4)alkyl such as methyl;-Rb, and Rd of formula (IIB) represents hydrogen atom; and-Rcof formula (IIB) represents -C(0)0M’ with M’ representing a hydrogen atom, or a cationic counterion preferably chosen from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+and K+.

[0092] In some embodiments, wherein the thiolated amino compound of formula (IIB) its optical, geometric isomers thereof, is in form of a salt with a mineral acid such as HHal with Hal representing a halogen such as chlorine.

[0093] In a preferred embodiment, the thiolated amino compound is selected from N-acetyl cysteine, cysteine, homocysteine, cystine, cysteine hydrochloride, cysteamine hydrochloride, glutathione, or butyroyl glutathione.

[0094] In a most preferred embodiment, the thiolated amino compound is selected from N-acetyl cysteine, cysteine, homocysteine, cystine, or cysteine hydrochloride, preferably is N-acetyl cysteine.

[0095] In an embodiment, the composition of the present invention comprises a thiolated amino compound of formula (IIB) may be in an amount of 0.01% by weight or more, preferably 0.02% by weight or more, and more preferably 0.03% by weight or more, relative to the total weight of the composition.

[0096] In some embodiments, the composition of the present invention according to an embodiment, comprises a thiolated amino compound of formula (IIB) may be in an amount of 2.0% by weight or less, preferably 1.0% by weight or less, and more preferably 0.5% by weight or less, relative to the total weight of the composition.

[0097] In some embodiments, the amount of the (2) thiolated amino compound of formula (IIB) in the composition according to the present 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. pH adjustins asent

[0098] In an embodiment, the composition of the present invention, may comprise at least one pH adjusting agent (pH adjuster). Two or more pH adjusting agent may be used in combination. Thus, a single type of pH adjusting agent or a combination of different types of pH adjusting agents may be used.

[0099] As the pH adjusting agent, at least one acidifying agent and / or at least one basifying agent (alkaline agent) may be used.

[0100] The acidifying agent may be a monovalent or polyvalent, such as divalent acid.

[0101] The acidifying agents can be, for example, mineral (inorganic) acids such as hydrochloric acid, sulfuric acid, phosphoric acid, or organic acids such as carboxylic acids, for instance tartaric acid, citric acid, and lactic acid, as well as sulphonic acids.

[0102] The basifying agent may be a monovalent or polyvalent, such as divalent, base. The basifying agents may be mineral (inorganic) or organic, or hybrid.

[0103] The mineral basifying agents may be chosen from aqueous ammonia; alkali metal carbonates or bicarbonates such as sodium or potassium carbonates and sodium or potassium bicarbonates; alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; and mixtures thereof.

[0104] The organic basifying agents may be chosen from organic amines with a pKb at 25°C of less than 12, preferably less than 10, and even more advantageously less than 6. It should be noted that it is the pKb corresponding to the function of highest basicity. In addition, the organic amines do not comprise any alkyl or alkenyl fatty chains comprising more than ten carbon atoms.

[0105] The organic basifying agent may be chosen, for example, from alkanolamines, oxyethylenated and / or oxypropylenated ethylenediamines, amino acids and amine compounds of formula (III) below:in whichW represents a Ci-Ce divalent alkylene radical optionally substituted with one or more hydroxyl groups or a Ci-Ce alkyl radical, and optionally interrupted with one or more heteroatoms such as O and N, andRx, Ry, Rz, and Rt, which may be identical or different, represent a hydrogen atom or a Ci-C6alkyl, Ci-Ce hydroxyalkyl, or Ci-Ce aminoalkyl radical.

[0106] Examples of the amine compounds of formula (III) that may be mentioned include 1,3-diaminopropane, l,3-diamino-2-propanol, spermine and spermidine.

[0107] The term “alkanolamine” means an organic amine comprising a primary, secondary, or tertiary amine function, and one or more linear or branched Ci-Cs alkyl groups bearing one or more hydroxyl radicals.

[0108] Alkanolamines such as monoalkanolamines, dialkanolamines or trialkanolamines comprising one to three identical or different C1-C4 hydroxy alkyl radicals may be suitable for the present invention. Among the compounds of this type, mention may be made of 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.

[0109] Amino acids that may be used are of natural or synthetic origin, in their L, D or racemic form, and comprise at least one acid function chosen more particularly from carboxylic acid, sulfonic acid, phosphonic acid or phosphoric acid functions. The amino acids may be in neutral or ionic form.

[0110] As amino acids that may be used in the present invention, mention may be made especially of 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.

[0111] It may be preferable that the amino acids are basic amino acids comprising an additional amine function optionally included in a ring or in an ureido function.

[0112] Such basic amino acids may preferably be chosen from those corresponding to formula (IV) below:in whichR of formula (IV) represents a group chosen from:-(CH2)3-NH2,-(CH2)2-NH2,-(CH2)2-NH-CO-NH2, and

[0113] The compounds corresponding to formula (IV) include histidine, lysine, arginine, ornithine and citrulline.

[0114] The organic basifying agent may be chosen from organic amines of heterocyclic type. Besides histidine that has already been mentioned in the amino acids, mention may in particular be made of pyridine, piperidine, imidazole, triazole, tetrazole and benzimidazole.

[0115] The organic basifying agent may also be chosen from amino acid dipeptides. As amino acid dipeptides that may be used in the present invention, mention may be made especially of carnosine, anserine and baleine.

[0116] The organic basifying agent may also be chosen from compounds comprising a guanidine function. As amines of this type that may be used in the present invention, besides arginine, which has already been mentioned as an amino acid, mention may be made especially of creatine, creatinine, 1,1- dimethylguanidine, 1,1-diethyl-guanidine, glycocyamine, metformin, agmatine, N- amidinoalanine, 3-guanidino-propionic acid, 4-guanidinobutyric acid and 2- ( [amino(imino)methyl] amino)ethane- 1 - sulfonic acid.

[0117] In a preferred embodiment of the present invention, the organic basifying agent may be selected from amino acids, preferably basic amino acids, and morepreferably arginine, lysine, histidine or mixtures thereof. Even more preferentially, the organic basifying agent may be arginine.

[0118] Hybrid compounds that may be mentioned include the salts of the amines mentioned previously with acids such as carbonic acid or hydrochloric acid. Guanidine carbonate or monoethanolamine hydrochloride may be used in particular.

[0119] In some embodiments, the amount of the pH adjusting agent in the composition may be equal to or more 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.

[0120] In some embodiments, the amount of the pH adjusting agent in the composition may be in an amount 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.

[0121] In a preferred embodiment, the pH adjusting agent may be present in an amount ranging from 0.01% to 15% by weight, preferably from 0.05% to 10% by weight, and more preferably from 0.1% to 5% by weight or less, relative to the total weight of the composition.

[0122] It is preferable that the composition according to the present invention have a pH of 4.5 or more, and more preferably 5 or more.

[0123] It is preferable that the composition according to the present invention have a pH of 6.5 or less, and more preferably 6 or less.

[0124] It is preferable that the composition according to the present invention have a pH of from 4.5 to 6.5, and more preferably from 5 to 6.

[0125] The pH of the composition means the pH of the aqueous phase of the composition according to the present invention.

[0126] It may be preferable that at least one buffer or buffering agent also be used, as the pH adjusting agent, in combination with the acidifying agent and / or the basifying agent, in order to stabilize the pH of the composition according to the present invention.

[0127] As the buffer, any of commonly known buffers may be used. For example, salts of acids or bases, preferably salts of weak acids or weak bases, may be used. For example, sodium citrate or sodium lactate may be used as the buffer, if citric acid or lactic acid is used as the acidifying agent.Medium / Solvent

[0128] In an embodiment, the composition of the present invention, may advantageously comprise at least one medium / solvent, including water and / or organic medium / solvent.

[0129] In some embodiments, the composition may comprise water in varying amounts. For low viscosity applications of the composition, e.g., in form of leave- on lotion, a relatively high amount of water may be used. For example, water is used in a content of greater than or equal to 20% by weight relative to the total weight of composition. The water content in the low viscosity composition according to the invention preferably ranges from 20% to 99% by weight, or preferably from 30% to 95% by weight, or from 40% to 90% by weight, relative to the total weight of the composition. For high viscosity applications of the composition, e.g., in form of leave-on cream, a relatively lower amount of water may be used. The high viscosity composition according to the invention advantageously comprises water in a content of less than or equal to 40% by weight relative to the total weight of composition.

[0130] In some embodiments, the amount of water in the composition may be present in an amount of 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.

[0131] In some embodiments, the amount of water in the composition may be present in an amount of 99% by weight or less, preferably 95% by weight or less, and more preferably 90% by weight or less, relative to the total weight of the composition.

[0132] 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 morepreferably from 40% to 90% by weight, relative to the total weight of the composition.

[0133] In some embodiments, the composition may also comprise one or more organic medium / solvents, preferably water-soluble organic medium / solvents (solubility of greater than or equal to 5% in water at 25°C and at atmospheric pressure).

[0134] Examples of the organic medium / solvents that may be mentioned include alcohols: in particular monovalent alcohols such as ethyl alcohol, isopropyl alcohol, benzyl alcohol, and phenylethyl alcohol; diols such as ethylene glycol, propylene glycol, and butylene glycol; other polyols such as glycerol, sugar and sugar alcohols; and ethers such as ethylene glycol monomethyl, monoethyl, and monobutyl ethers, propylene glycol monomethyl, monoethyl, and monobutyl ether, and butylene glycol monomethyl, monoethyl, and monobutyl ethers.

[0135] The organic medium / solvents, when they are present in an amount ranging 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.

[0136] In some embodiments, the composition may also comprise other additives, active agents, carriers, adjuvants that are known in the art compatible to keratin material and are cosmetically acceptable.

[0137] In some embodiments, the composition of the present invention brightens or depigments a keratin material, preferably skin.

[0138] In other embodiments, the composition of the present invention may be useful for treating a keratin material, preferably skin to impart whitening or depigmenting effect.Preparation of the composition

[0139] In an embodiment, the present invention provides a process for preparing the composition. The compositions according to the invention can be manufactured by known processes, generally used in the cosmetic or dermatological field.

[0140] The process comprises mixing the above described essential and optional components by any known method. In an embodiment the composition of the present invention may be prepared by a process including the steps of mixing at least one compound of formula (I) or (T), with at least one reducing agent of formula (II), with water or any suitable solvent. Mixing include addition of other additives as required. The process involves mixing the components at any temperature, preferably at room temperature, more preferably at 30°C or more, at 40°C or more and more preferably at 50°C or more.

[0141] The composition of the according to the present invention may be in various forms but not limited to emulsion, solution, gel, or cream.MethodfUse of the composition

[0142] In an embodiment, the present invention provides a cosmetic method of treating a keratin material, the method comprising: applying the composition of the present invention on the keratin material, preferably skin.

[0143] In some embodiments, the present invention provides a non-therapeutic cosmetic method of treating a keratin material, the method comprising: applying the composition of the present invention on the keratin material, preferably skin.

[0144] In other embodiments, the present invention provides use of the composition brightening or depigmenting a keratin material, preferably skin. In some embodiments, the composition is suitable for the treatment of darker and / or more coloured spots on the skin. In some embodiments, the composition is useful in providing necessary care to the skin, preferably brightening the skin, and / or reducing or lightening darker and / or more coloured spots on the skin.

[0145] In some embodiments, the present invention provides a cosmetic composition that may be applied once per day, twice per day, or more than once or twice per day. In some cases, the composition is applied in the evenings before bed. In other cases, the compositions are applied in the morning. In still other cases, the composition may be applied immediately after washing the skin. The compositions may be used once, or for a series of days, weeks, or months. For example, thecompositions may be used daily for a period of 1, 2, 3, 4, 5, 6, 7, 8 or more weeks, or months.

[0146] In an embodiment, the present invention provides use of: at least one reducing agent of formula (II), wherein the compound of formula (II) is selected from: a) an inorganic reducing agent of formula (IIA), its mesomeric forms, and its solvates such as hydrateswherein,X represents a heteroatom selected from oxygen or sulfur, preferably oxygen; m is 0 or 1 ;M+is a cation, preferably selected from alkali metal, alkaline earth metal or ammonium, more preferably selected from an alkali metal such as sodium or potassium;R represents a group selected from: i) -OH, ii) -O-M’+with M’+as previously defined for M+,in) wherein,• p is an integer inclusively selected between 0 and 4, preferably 0, 1, 2, and more preferably 0 or 2;• m’ is 0 or 1, preferably 1;• X’ is as defined for X, preferably X’ represents an oxygen atom; and• M”+is as previously defined for M+, and M+, M’+, M”+are identical or different, preferably identical, b) thiolated amino compound of formula (IIB)Ra-N(Rb)-CH(Rc)-(CH2)n-S-Rd (IIB) wherein,- n is an integer selected from 0 to 3;- Rarepresents a hydrogen atom or -C(Xa)-Ra' with Xa representing an oxygen or sulfur atom, preferably oxygen, and Ra' representing a linear or branched hydrocarbon chain, saturated or unsaturated, comprising from 1 to 8 carbon atoms, preferably saturated hydrocarbon such as (Ci-C6)alkyl, said chain being: i) optionally substituted by one or more groups chosen from (di)(Ci- C4)(alkyl)amino, and -C(O)OM, with M representing a hydrogen atom, or a cationic counterion preferably chosen from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+ and K+; and / or ii) optionally interrupted by one or more heteroatoms or groups chosen from O, S, N(Re), -C(O)-, -C(O)-N(Re)- or -N(Re)-C(O)-, with Rerepresenting a hydrogen atom or a (Ci-C4)alkyl group such as methyl, preferably Rerepresents a hydrogen atom;- Rb represents a hydrogen atom or a (Ci-C4)alkyl group such as methyl, preferably Rb represents a hydrogen atom;- Rcrepresents one of the following selected from: a) a hydrogen atom, b) -C(O)OM’ with M’ as defined previously for M; or c) -C(O)-N(Re')-Ra" with Ra" being as defined previously for Ra', preferably Ra" is different from Ra', more preferably Ra" represents (Ci-C4)alkyl optionally substituted with one or more -C(O)OM groups with M as defined above, preferably -C(O)OH;- Rd represents a hydrogen atom or -S-CH2-CH(Rf)-N(Rg)-Rh with Rf being as defined previously for Rc, Rgbeing as defined previously for Rb, and Rh being as defined previously for Ra, preferably Rd represents a hydrogen atom; it is understood that:- Rf is identical or different to Rc, preferably identical;- Rgis identical or different to Rb, preferably identical;- Rh is identical or different to Ra, preferably identical; and- M and M’ are identical or different, preferably identical, in a composition comprising at least one compound selected from compounds of formula (I), its tautomer of formula (I’), salts, optical isomers, racemates, solvates, hydrates, or mixtures thereof :(I) (I ) wherein in formulae (I) and (I’):- Ri denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C10 or branched C3-C10 alkyl group optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; ii) -S-R3;- R2 denotes a radical chosen from:a) a hydrogen atom; b) a saturated hydrocarbonated group linear C1-C12 or branched C3-C12 or cyclic C3-C8, optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; ii) -S-R3; iii) -C(O)-O-R3; iv) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci- Cs alkoxy radicals; c) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals; and- R3 denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C10 or branched C3-C10 alkyl group, to stabilize the compound of formula (I), its tautomer of formula (I’), salts, solvates, hydrates, optical isomers, racemates, or mixtures thereof, in the composition. The term “stabilize” has the same meaning as enhancing the stability.

[0147] According to one embodiment of the invention, the composition comprises an aqueous phase. The composition is notably formulated as water-in-oil or oil-in- water emulsions or as multiple emulsions (oil-in-water-in-oil or water-in-oil-in- water triple emulsions (such emulsions are known and described, for example, by C. Fox in “Cosmetics and Toiletries” - November 1986 - Vol. 101 - pages 101-112)).

[0148] According to a particular embodiment of the invention, the composition is a direct emulsion, i.e. an emulsion of oil-in-water or O / W type.EXAMPLES

[0149] The disclosure will now be illustrated with working examples, which is intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice of the disclosed methods and compositions, the exemplary methods, devices, and materials are described herein. It is to be understood that this disclosure is not limited to particular composition, methods, and experimental conditions described, as such methods and conditions may apply. The present invention will be described in a more detailed manner by way of examples. However, these examples should not be construed as limiting the scope of the present invention.Example 1: Synthesis of compound 20

[0150] Compound 20 is synthesized as disclosed in example 2 of patent EP3 390 363.Example 2Cosmetic Compositions

[0151] A cosmetic composition (according to the invention) comprising the compound 20 of formula (I) with at least one reducing agent of formula (II) as described herein along with other additional ingredients was prepared by taking each of said ingredients in an amount as mentioned in Table 1 below. For Example the cosmetic composition EXI was prepared using 0.50 wt% of 2- mercaptonicotinoyl glycine, 0.2 wt% of reducing agent i.e., sodium thiosulphate, a total of 6.00 wt% of Glyceryl Stearate, PEG- 100 stearate, and PEG-40 stearate, 2.40 wt % of fatty alcohols, 6.00 wt% of hydrogenated polyisobutene, 1.20 wt% of preservatives, 0.20 wt% of chelating agent, 18.00 wt% of isohexadecane, 0.36 wt% of thickening agent and 0.36% wt of triethanol amine along with quantity sufficientwater. Similarly, Compositions EX2, EX3, and EX4 (according to the invention) were prepared with 0.2% wt each of sodium metabisulfite, sodium sulfite, and N- Acetyl cysteine respectively. Comparative composition CEX1 was also prepared in a similar manner including the ingredients without any reducing agent as mentioned in Table 1 below.Table 1Example 3Stability of compositions Thermal stability studies

[0152] The compositions as prepared in Example 1 were analyzed to determine its stability when stored at varying temperatures.

[0153] About 1.0g of each of the compositions independently was mixed with 50mL of water to prepare an aqueous solution of the composition. Methanol was added to the aqueous solution of the composition and was subjected to sonication followed by stirring for about 1.5 hours. The resulting solution was filtered. A portion of the filtered solution was subjected to HPLC-UPLC analysis to determine the amount of compound 20 (2-Mercaptonicotinoyl Glycine) at timing TO. Another portion of the filtered solution was placed in oven at 45°C for a period of 2 months and the presence of compound 20 at accelerated aging T2M@45°C was determined. One another portion of the filtered solution was stored in room temperature for 2 months and the presence of compound 20 in the solution T2M@RT was determined.

[0154] The details of the HPLC-UV assays are as follows:Apparatus / ReagentsHPLC Conditions

[0155] The amount of the compound 20 of formula (I) in each of the solutions were determined and % values of compound 20 of formula (I) measured are tabulated in Table 2 .Table 2

[0156] From Table 2 above it could be observed that the inventive compositions EXI to EX4 were more stable at room temperature as well as at elevated temperature, and the comparative composition CEX1 was found to be less stable. This was because in the presence of the reducing agent (inorganic reducing agent of formula (II A) or thiolated amino compound of formula (IIB)) the stability of the compound of formula (I) was increased, thereby resulting in an increasingly stable cosmetic composition, when compared to comparative composition CEX1. In particular it could be noted that the inventive composition EXI comprising sodium thiosulphate, increased the stabilization of the thiopyridinone compound at all temperatures (RT and at higher temperature) for a prolonged period of time.Further, the inventive composition EX4 comprising N-Acetyl cysteine of formula (IIB) improved the stabilization of thiopyridinone compound of formula (I) and hence the corresponding composition was much more thermally stable, compared to the comparative composition CEX1 which was devoid of N-Acetyl cysteine.

[0157] Therefore, the composition according to the present invention comprising reducing agent exhibited enhanced stability of thiopyridinone compound, provided a stable composition with extended shelf life at room temperature as well as at accelerated conditions. Photostability studies

[0158] The compositions as prepared in Example 1 were analyzed to determine its photostability when exposed to UV radiation.

[0159] Each of the compositions EXI, (inventive) and comparative composition CEX1 was independently coated on an inert support. The coated supports were exposed to UV radiation of 5J / cm2for about 1 hour. The exposed compositions were then dissolved in an organic solvent and the solutions were analyzed HPLC or UPLC chromatographic methods.

[0160] The amount of compound 20 of formula (I) in each of the compositions was measured by HPLC-UV assay at two timings as mentioned below. Timing (1): Just after the preparation of the composition.Timing (2): Solution of the compositions after UV exposure.

[0161] The details of the HPLC-UV assays are as follows:Apparatus / ReagentsHPLC Conditions

[0162] The amount of compound 20 of formula (I) remaining in each of the compositions before (Timing 1) and after UV exposure (Timing 2) were determined by HPLC-UV assay and the difference in the amount of compound of formula (I) was computed.

[0163] The % values of compound 20 of formula (I), remained in UV exposed compositions EXI, and CEX1 are shown in Table 3 below.Table 3

[0164] It was found that the composition EXI, which comprised sodium thiosulphate (inorganic reducing agent of formula (IIA)) was more effective and stable than the comparative composition CEXl.The composition of the present invention comprising inorganic reducing agent of formula(II) as described herein provided thiopyridinone compounds both increased thermal stability and photostability, and thereby resulted in cosmetic compositions with extended life even when stored at varied temperatures.

Claims

I / We claim :

1. A composition, preferably a cosmetic composition, comprising: i) at least one compound selected from a compound of Formula (I) below, its tautomer of formula (I’) below; salts, solvates, hydrates, optical isomers, racemates, or mixtures thereof:Formula (I) Formula (F) wherein,- Ri denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear Ci-Cio or branched C3-C10 alkyl group optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; ii) -S-R3;- R2 denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C12 or branched C3-C12 or cyclic C3-C8 hydrocarbonated group, optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; ii) -S-R3; iii) -C(O)-O-R3;iv) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals, and c) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals;- R3 denotes a radical chosen from: a) a hydrogen atom, and b) a saturated linear C1-C10 or branched C3-C10 alkyl group; and ii) at least one inorganic reducing agent of formula (II) wherein the compound of formula (II) is selected from: a) an inorganic reducing agent of formula (HA), its mesomeric forms, and its solvates such as hydrateswherein,X represents a heteroatom selected from oxygen or sulfur, preferably oxygen; m is 0 or 1;M+is a cation, preferably selected from alkali metal, alkaline earth metal or ammonium, more preferably selected from an alkali metal such as sodium or potassium;R represents a group selected from: i) -OH,ii) -0-M’+with M’+as previously defined for M+,111) wherein,• p is an integer inclusively selected between 0 and 4, preferably 0, 1, 2, and more preferably 0 or 2;• m’ is 0 or 1, preferably 1;• X’ is as defined for X, preferably X’ represents an oxygen atom; and• M”+is as previously defined for M+, and M+, M’+, M”+are identical or different, preferably identical or, b) a thiolated amino compound of formula (IIB), its optical, geometric isomers, solvates, hydrates, salts of bases, or of acids thereof,Ra-N(Rb)-CH(Rc)-(CH2)n-S-Rd(HB) wherein, n is an integer selected from 0 to 3;- Rarepresents a hydrogen atom or -C(Xa)-Ra' with Xarepresenting an oxygen or sulfur atom, preferably oxygen, and Ra' representing a linear or branched hydrocarbon chain, saturated or unsaturated, comprising from 1 to 8 carbon atoms, preferably saturated hydrocarbon such as (Ci-Ce)alkyl, said chain being: i) optionally substituted by one or more groups chosen from (di)(Ci- C4)(alkyl)amino, and -C(0)0M, with M representing a hydrogen atom, or acationic counterion preferably chosen from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+ and K+; and / or ii) optionally interrupted by one or more heteroatoms or groups chosen from O, S, N(Re), -C(O)-, -C(O)-N(Re)- or -N(Re)-C(O)-, with Rerepresenting a hydrogen atom or a (Ci-C4)alkyl group such as methyl, preferably Rerepresents a hydrogen atom;- Rb represents a hydrogen atom or a (Ci-C4)alkyl group such as methyl, preferably Rb represents a hydrogen atom;- Rc represents one of the following selected from: a) a hydrogen atom, b) -C(O)OM’ with M’ as defined previously for M; or c) -C(O)-N(Re')-Ra" with Ra" being as defined previously for Ra', preferably Ra" is different from Ra', more preferably Ra" represents (Ci-C4)alkyl optionally substituted with one or more -C(O)OM groups with M as defined above, preferably -C(O)OH;- Rd represents a hydrogen atom or -S-CH2-CH(Rf)-N(Rg)-Rh with Rf being as defined previously for Rc, Rgbeing as defined previously for Rb, and Rh being as defined previously for Ra, preferably Rd represents a hydrogen atom; it is understood that:- Rf is identical or different to Rc, preferably identical;- Rgis identical or different to Rb, preferably identical;- Rh is identical or different to Ra, preferably identical; and- M and M’ are identical or different, preferably identical.

2. The composition as claimed in claim 1, whereinRi of formula (I) and formula (I’) represents a hydrogen atom, orRi of formula (I) and formula (I’) represents a linear (Ci-Cio)alkyl group or branched (C3-Cio)alkyl group, especially a linear (Ci-C6)alkyl group or branched (Cs-Cejalkyl group, preferably selected from methyl, ethyl, n-pentyl, n-nonyl, or isobutyl, more preferably ethyl, particularly said alkyl group of Ri is not substituted.

3. The composition according to any one of the preceding claims, whereinR2 of formula (I) and formula (I’) represents a hydrogen atom; orR2 of formula (I) and formula (F) represents a linear (Ci-Cio)alkyl group or branched (C3-Cio)alkyl group, especially a linear (Ci-C6)alkyl group or branched (C3-C6)alkyl group, preferably selected from methyl, ethyl, n-pentyl, n-nonyl, or isobutyl, more preferably methyl or ethyl group; said alkyl group of R2 being not substituted.

4. The composition according to any one of the preceding claims, whereinR2 of formula (I) and formula (I’) represents a linear (Ci-Cio)alkyl group or branched (C3-Cio)alkyl group, especially a linear (Ci-C6)alkyl group or branched (C3-C6)alkyl group, preferably selected from methyl, ethyl, n-pentyl, n-nonyl, or isobutyl, more preferably methyl or ethyl; said alkyl group being substituted by one or more groups selected from i), ii), iii) and iv) as defined in claim 1, preferably said alkyl group being substituted by one or two groups selected from i), ii) and iii), more preferably by one or two groups selected from i) and iii), better substituted by one group iii) as carboxy.

5. The composition according to any one of the preceding claims, whereinR2 of formula (I) and formula (I’) represents a (C3-Cs)cycloalkyl group, preferably a (Cs-Cvlcycloalkyl group such as cyclohexyl; orR2 of formula (I) and formula (I’) represents a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals, preferably a phenyl group particularly not substituted.

6. The composition according to any one of the preceding claims, whereinR3 of formula (I) and formula (I’) represents a hydrogen atom; orR3 of formula (I) and formula (I’) represents a saturated linear C1-C10 or branched C3-C10 alkyl group; particularly a linear (C 1 -Cejal ky 1 group or a branched (Cs-Cejalkyl group, preferably (Ci-C4)alkyl group such as methyl group.

7. The composition according to any one of the preceding claims, whereinRi of formula (I) and formula (T) represents a radical chosen from: a) a hydrogen atom; b) a saturated linear Ci-Ce or branched C3-C6 alkyl group optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; ii) -S-R3; preferably optionally substituted with one or more groups i);R2 of formula (I) and formula (T) represents a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C10 or branched C3-C10 or cyclic C3-C8 such as C5-C6 hydrocarbonated group, optionally substituted with one or more groups, which may be identical or different, chosen from:i) -O-R3; ii) -SR3; iii) -C(O)-O-R3; iv) a phenyl group optionally substituted with one or more hydroxyls and / or with one or more C1-C4 alkoxy radicals such as methoxy; preferably substituted with one or more groups selected from i) and iii), preferably iii) such as carboxy;R3 of formula (I) and formula (I’) represents a radical chosen from: a) a hydrogen atom; b) a saturated linear Ci-Ce or branched C3-Ce alkyl group; preferentially, the compounds of formula (I) and tautomer of formula (I’), salts, solvates, hydrates, optical isomers, racemates, or mixtures thereof, have the following meanings:Ri of formula (I) and formula (I’) represents a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C4 or branched C -C4 alkyl group optionally substituted with one or more groups, which may be identical or different, chosen from i) -OR3, more preferably not substituted;R2 of formula (I) and formula (I’) represents a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C10 or branched C3-Cio or cyclic C3-Cs such as C5-C6 , hydrocarbonated group, optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; iii) -C(O)-O-R3;iv) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more C1-C4 alkoxy radicals; andRs of formula (I) and formula (I’) represents a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C4 or branched C3-C4 alkyl group such as methyl or ethyl .

8. The composition according to any one of the preceding claims, wherein, the (1) compound is selected from the compounds 1 to 24, its tautomers, salts, solvates, hydrates, optical isomers, racemates, or mixtures thereof, particularly the 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, and more preferably 20:

9. The composition according to any one of the preceding claims, wherein the compound of formula (I) or its tautomer of formula (I’), its salts, solvates, hydrates, optical isomers, racemates, or mixtures thereof, is in an amount ranging 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.

10. The composition as claimed in claim 1, whereinX of formula (IIA) represents a heteroatom selected from oxygen or sulfur, preferably oxygen; m of formula (IIA) is 0 or 1 ;M+of formula (IIA) is a cation, preferably is sodium or potassium;R of formula (IIA) represents a group selected from i) -OH, ii) -O-M’+with M’+as previously defined for M+,iii) wherein,• p is 0 or 2;• m’ is 0 or 1;• X’ is as defined for X, preferably X’ represents an oxygen atom; andM+, M’+, M”+are identical.

11. The composition according to any one of the preceding claims, whereinR of formula (IIA) represents a group selected from i) -OH, ii) -O-M’+with M’+,iii) wherein,• p is 0 or 2;• m’ is 0 or 1;• X’ is represents an oxygen atom; andM+, M’+, and M”+are identical selected from sodium or potassium.

12. The composition according to any one of the preceding claims, whereinX of formula (IIA) represents sulphur; m of formula (IIA) is 1 ;M+of formula (IIA) is sodium or potassium;R of formula (IIA) represents a group selected from i) -OH, and ii) -O-M’+with M’+,M+, and M’+are identical.

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 tetra thionate.

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 as claimed in claim 1, wherein- n of formula (IIB) is 1 or 2;- Raof formula (IIB) represents a hydrogen atom or -C(Xa)-Ra' with Xa representing an oxygen atom, and Ra' representing a linear or branched hydrocarbon chain, saturated or unsaturated, comprising from 1 to 8 carbon atoms, preferably saturated hydrocarbon such as (Ci-C6)alkyl, said chain being: i) optionally substituted by one or more groups chosen from (di)(Ci- C4)(alkyl)amino, and -C(O)OM, with M representing a hydrogen atom, or a cationic counterion such as Na+ and K+; and / or ii) optionally interrupted by one or more heteroatoms or groups chosen from O, S, N(Re), -C(O)-, -C(O)-N(Re)- or -N(Re)-C(O)-, with Rerepresenting a hydrogen atom or a (Ci-C4)alkyl group such as methyl, preferably Rerepresents a hydrogen atom;- Rb of formula (IIB) represents a hydrogen atom;- Rcof formula (IIB) represents one of the following selected from: a) a hydrogen atom, b) -C(O)OM’ with M’ as defined previously for M; or c) -C(O)-N(Re')-Ra" with Ra" being as defined previously for Ra', preferably Ra" is different from Ra', more preferably Ra" represents (Ci-C4)alkyl optionally substituted with one or more -C(O)OM groups with M as defined above, preferably -C(O)OH;- Rd of formula (IIB) represents a hydrogen atom or -S-CH2-CH(Rf)- N(Rg)-Rh with Rf being as defined previously for Rc, Rgbeing as defined previously for Rb, and Rh being as defined previously for Ra, preferably Rd represents a hydrogen atom.

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

17. The composition according to any one of the preceding claims, wherein Ra, Rb, and Rcof formula (IIB) represents hydrogen atom.

18. The composition according to any one of the preceding claims, wherein,- n of formula (IIB) is 1 or 2;- Raof formula (IIB) represents hydrogen atom or -C(Xa)-Ra' with Xa representing an oxygen or sulfur atom, preferably oxygen, and Ra' representing a linear or branched hydrocarbon chain, saturated or unsaturated, comprising from 1 to 8 carbon atoms, preferably saturated hydrocarbon such as (Ci-C6)alkyl, more preferably (Ci- C4)alkyl such as methyl;-Rb, and Rd of formula (IIB) represents hydrogen atom; and-Rc of formula (IIB) represents -C(O)OM’ with M’ representing a hydrogen atom, or a cationic counterion preferably chosen from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+ and K+.

19. The composition according to any one of the preceding claims, wherein n of formula (IIB) is 1 or 2;Rd of formula (IIB) represents -S-CH2-CH(Rf)-N(Rg)-Rh;Ra, Rb, Rg and Rh of formula (IIB) independently represents hydrogen atom; andRcand Rf of formula (IIB) represents -C(O)OM’ with M’ representing a hydrogen atom, or a cationic counterion preferably chosen from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+and K+.

20. The composition according to any one of the preceding claims, wherein,-n of formula (IIB) is 1;-Raof formula (IIB) represents -C(Xa)-Ra' with Xa representing an oxygen or sulfur atom, preferably oxygen, and Ra' representing a linear or branched hydrocarbon chain, saturated or unsaturated, comprising from 1 to 8 carbon atoms, preferably saturated hydrocarbon such as (Ci-C6)alkyl, more preferably (Ci-C4)alkyl such as methyl;-Rb, and Rd of formula (IIB) represents hydrogen atom; and-Rc of formula (IIB) represents -C(0)0M’ with M’ representing a hydrogen atom, or a cationic counterion preferably chosen fromalkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+and K+.

21. The composition according to any one of the preceding claims, wherein the thiolated amino compound of formula (IIB) its optical, geometric isomers thereof, is in form of a salt with a mineral acid such as HHal with Hal representing 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-acetyl cysteine, cysteine, homocysteine, cystine, cysteine hydrochloride, cysteamine hydrochloride, 20 glutathione, or butyroyl glutathione.

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

24. The composition according to any one of the preceding claims, wherein the reducing agent is in an amount ranging 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.

25. The composition according to any one of the preceding claims, wherein the composition comprises water in an amount ranging 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.

26. The composition according to any one of the preceding claims, wherein the composition whitens or depigments a keratin material, preferably skin.

27. A cosmetic method of treating a keratin material, the method comprising: applying the composition according to any one of the preceding claims on the keratin material, preferably skin.

28. Use of the composition according to any one of the preceding claims for whitening or depigmenting a keratin material, preferably skin.

29. Use of at least one reducing agent of formula (II), wherein the compound of formula (II) is selected from: a) inorganic reducing agent of formula (IIA), its mesomeric forms, and its solvates such as hydrateswherein,X represents a heteroatom selected from oxygen or sulfur, preferably oxygen; m is 0 or 1 ;M+is a cation, preferably selected from alkali metal, alkaline earth metal or ammonium, more preferably selected from an alkali metal such as sodium or potassium;R represents a group selected from: i) -OH, ii) -O-M’+with M’+as previously defined for M+,iii) wherein,• p is an integer inclusively selected between 0 and 4, preferably 0, 1, 2, and more preferably 0 or 2;• m’ is 0 or 1, preferably 1;• X’ is as defined for X, preferably X’ represents an oxygen atom; and• M”+is as previously defined for M+, and M+, M’+, M”+are identical or different, preferably identical,or, b) thiolated amino compound of formula (IIB)Ra-N(Rb)-CH(Rc)-(CH2)n-S-Rd (IIB) wherein,- n is an integer selected from 0 to 3;- Rarepresents a hydrogen atom or -C(Xa)-Ra' with Xa representing an oxygen or sulfur atom, preferably oxygen, and Ra' representing a linear or branched hydrocarbon chain, saturated or unsaturated, comprising from 1 to 8 carbon atoms, preferably saturated hydrocarbon such as (Ci-C6)alkyl, said chain being: i) optionally substituted by one or more groups chosen from (di)(Ci- C4)(alkyl)amino, and -C(0)0M, with M representing a hydrogen atom, or a cationic counterion preferably chosen from alkali metals, alkaline earth metals and ammonium, more preferably alkali metals such as Na+ and K+; and / or ii) optionally interrupted by one or more heteroatoms or groups chosen from O, S, N(Re), -C(O)-, -C(O)-N(Re)- or -N(Re)-C(O)-, with Rerepresenting a hydrogen atom or a (Ci-C4)alkyl group such as methyl, preferably Rerepresents a hydrogen atom;- Rb represents a hydrogen atom or a (Ci-C4)alkyl group such as methyl, preferably Rb represents a hydrogen atom;- Rcrepresents one of the following selected from: a) a hydrogen atom, b) -C(0)0M’ with M’ as defined previously for M; or c) -C(O)-N(Re')-Ra" with Ra" being as defined previously for Ra', preferably Ra" is different from Ra', more preferably Ra" represents (Ci-C4)alkyl optionally substituted with one or more -C(0)0M groups with M as defined above, preferably -C(O)OH;- Rd represents a hydrogen atom or -S-CH2-CH(Rf)-N(Rg)-Rh with Rf being as defined previously for Rc, Rgbeing as defined previously for Rb, and Rhbeing as defined previously for Ra, preferably Rd represents a hydrogen atom; it is understood that:- Rf is identical or different to Rc, preferably identical;- Rgis identical or different to Rb, preferably identical;- Rh is identical or different to Ra, preferably identical; and- M and M’ are identical or different, preferably identical, in a composition comprising at least one compound selected from compounds of formula (I), its tautomer of formula (I’), salts, optical isomers, racemates, solvates, hydrates, or mixtures thereof :wherein formulae (I) and (I’):- Ri denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C10 or branched C3-C10 alkyl group optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; ii) -S-R3;- R2 denotes a radical chosen from: a) a hydrogen atom; b) a saturated hydrocarbonated group linear C1-C12 or branched C3-C12 or cyclic C3-C8 , optionally substituted withone or more groups, which may be identical or different, chosen from: i) -O-R3; ii) -S-R3; iii) -C(O)-O-R3; iv) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals; c) a C5-C12 aryl group optionally substituted with one or more hydroxyls and / or with one or more Ci-Cs alkoxy radicals; and- R3 denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C1-C10 or branched C3-C10 alkyl group, to stabilize the compound of formula (I), its tautomer of formula (I’), salts, optical isomers, racemates, solvates, hydrates, or mixtures thereof, in the composition.

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