COSMETIC COMPOSITION COMPRISING THIOPYRIDINONE COMPOUNDS AND AN INORGANIC REDUCING AGENT

Abstract

COSMETIC COMPOSITION COMPRISING THIOPYRIDINONE COMPOUNDS AND AN INORGANIC REDUCING AGENT. 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 inorganic reducing agent of formula (II). The present invention also relates to a composition comprising one or more thiopyridinone compounds with increased solubility of the thiopyridinone compound(s) over time. Figure for the abstract: none

Description

Title of the invention: COSMETIC COMPOSITION COMPRISING THIOPYRIDINONE COMPOUNDS AND AN INORGANIC REDUCING AGENT FIELD OF INVENTION

[0001] The present invention relates to the stabilization of a thiopyridinone compound. The present invention relates in particular to a composition comprising a thiopyridinone compound and an inorganic reducing agent that stabilizes the compound and its composition. CONTEXT OF THE INVENTION

[0002] Cosmetic products that provide flawless skin through cleansing, hydration, moisturizing, anti-aging, anti-wrinkle and brightening are highly sought after in everyday life.

[0003] At various times in their lives, some people notice the appearance of darker and / or more colored spots on their skin, particularly on their face and hands, giving their skin a heterogeneous appearance. These spots are due to a high concentration of melanin in the keratinocytes located on the surface of the skin.

[0004] The use of harmless topical depigmenting substances with good efficacy for treating pigmentation spots is particularly desirable. For example, arbutin, niacinamide, and kojic acid are known as skin depigmenting agents.

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

[0006] The thiopyridinone compound may exhibit strong depigmentation or bleaching effects by reducing melanin production.

[0007] There is nevertheless a need to develop a cosmetic composition comprising a thiopyridinone compound with increased stability, to confer skin lightening and whitening effects. Summary of the invention

[0008] According to one aspect of this disclosure, a composition, preferably a cosmetic composition, is proposed, comprising thiopyridinone compound(s) of formula (I) or (I'), and reducing agent(s), wherein the stability, preferably thermal stability and / or photostability, of the thiopyridinone compound(s) is increased. The inventors have discovered in a manner unexpected that the use of reducing agent(s) improves the stability, preferably thermal stability and / or photostability, of the compound of formula (I) or (I1) in the composition.

[0009] The present invention proposes a composition, preferably a cosmetic composition comprising: I. at least one compound chosen from a compound of formula (I) below, its tautomer of formula (F) below, their salts, solvates, hydrates, optical isomers, racemates or mixtures thereof: Formula (I) Formula (!')

[0010] in which,

[0011] Ri designates a radical chosen from: a. a hydrogen atom; b. a linear saturated alkyl group in the form of Ci-Cio or branched in the form of C3-CiO optionally substituted with one or more groups, which may be identical or different, chosen from: i. -O-R3; ii. -S-R3;

[0012] R 2 denotes a radical chosen from: a. a hydrogen atom; b. a linear saturated CrCi2, C3-Ci2 branched, or C3-C8 cyclic hydrocarbon group, optionally substituted with one or more groups, which may be identical or different, selected from i. -O-R3; ii. -S-R3; iii. -C(O)-O-R3 ; iv. an aryl group at C5-Ci2, optionally substituted with one or more hydroxyls and / or with one or more CrC8 alkoxy radicals, and

[0013] c) an aryl group in C5-Ci2, optionally substituted with one or more hydroxyls and / or with one or more CrC8 alkoxy radicals;

[0014] R 3 designates a radical chosen from: a. a hydrogen atom, and b. a linear saturated alkyl group in Ci-Cio or branched in C3-CiO;

[0015] and

[0016] (II) at least one inorganic reducing agent of formula (II), its mesomeric forms, and its solvates such as hydrates O R--S--O"M+ (II)

[0017] in which,

[0018] X represents a heteroatom chosen from an oxygen or a sulfur, preferably an oxygen;

[0019] m is 0 or 1;

[0020] M+ is a cation, preferably chosen from an alkali metal, an alkaline earth metal or an ammonium, more preferably chosen from an alkali metal such as sodium or potassium;

[0021] R represents a group chosen from:

[0022] i) -OH,

[0023] ü) -O-M'+ with M'+ as defined previously for M+,

[0024] iii) o ' II ~ ' s ix'U

[0025] in which,

[0026] • p is an inclusive integer chosen between 0 and 4, preferably 0, 1, 2 and more preferably 0 or 2;

[0027] • m1 is 0 or 1, preferably 1;

[0028] • X1 is such as defined for X, preferably X1 represents an oxygen atom; and

[0029] M' '+ is such as defined previously for M+, and M+, M'+, M”+ are identical or different, preferably identical.

[0030] According to another aspect of this disclosure, a cosmetic treatment process for keratinous material is proposed, the process comprising the application of the composition as disclosed herein to the keratinous material, preferably the skin.

[0031] According to another aspect of this disclosure, it is proposed that the composition as disclosed herein be used to bleach or depigment keratinous material, preferably skin.

[0032] According to yet another aspect of this disclosure, it is proposed to use at least one inorganic reducing agent of formula (II), its mesomeric forms, and its solvates such as hydrates O R--S--O'M' (II)

[0033] in which,

[0034] X represents a heteroatom chosen from an oxygen or a sulfur, preferably an oxygen;

[0035] m is 0 or 1;

[0036] M+ is a cation, preferably chosen from an alkali metal, an alkaline earth metal or an ammonium, more preferably chosen from an alkali metal such as sodium or potassium;

[0037] R represents a group chosen from:

[0038] i). -OH,

[0039] ü). -O-M'+ with M'+ as defined previously for M+,

[0040] iii) O _ JL ■ ■■■■■■ [S l ï." ■ SOM ! 11 [XU-

[0041] in which,

[0042] • p is an inclusive integer chosen between 0 and 4, preferably 0, 1, 2 and more preferably 0 or 2;

[0043] • m' is 0 or 1, preferably 1;

[0044] • X' is such that defined for X, preferably X' represents an oxygen atom; and

[0045] • M' '+ is such as defined previously for M+, and M+, M'+, M”+ are identical or different, preferably identical,

[0046] in a composition comprising at least one compound selected from the compounds of formula (I), its tautomer of formula (I'), their salts, optical isomers, racemates, solvates, hydrates or mixtures thereof:

[0047] formulas (I) and (I') in which:

[0048] R i designates a radical chosen from: a. a hydrogen atom; b. a linear saturated alkyl group in the form of Ci-Cio or branched in the form of C3-CiO optionally substituted with one or more groups, which may be identical or different, chosen from: i. -O-R3; ii. -S-R3;

[0049] R 2 denotes a radical chosen from: a. a hydrogen atom; b. a linear saturated hydrocarbon group in C1-C12 or branched in C3-C12 or cyclic in 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. an aryl group at C5-C12, optionally substituted with one or more hydroxyls and / or with one or more CrC8 alkoxy radicals;

[0050] c) an aryl group at C5-C12, optionally substituted with one or more hydroxyl groups and / or with one or more alkoxy radicals at C1-C8; and

[0051] R 3 designates a radical chosen from: a. a hydrogen atom; b. a linear saturated alkyl group in C1-C10 or branched in C3-C10,

[0052] to stabilize the compound of formula (I), its tautomer of formula (I1), their salts, optical isomers, racemates, solvates, hydrates, or mixtures thereof, in the composition.

[0053] These features, aspects, and advantages, as well as others, of the present subject will be better understood with reference to the following description and the attached claims. The purpose of this summary is to present a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject, nor be used to limit the scope of the claimed subject. DESCRIPTION OF THE INVENTION

[0054] Those skilled in the art will be aware that this disclosure is subject to variations and modifications other than those specifically described. It should be understood that this disclosure includes all such variations and modifications. The disclosure also includes all such steps, features, compositions, and compounds designated or indicated in this patent memorandum, individually or collectively, and any combination of one or more of these steps or features.

[0055] Definitions

[0056] For convenience, before describing this disclosure in more detail, certain terms used in the patent memorandum and examples are defined here. These definitions should be read in light of the rest of the disclosure and understood as by a person skilled in the art. The terms used here have meanings recognized and known to a person skilled in the art; however, for convenience and completeness, specific terms and their meanings are set out below.

[0057] The terms “include” and “comprising” are used in an inclusive and open sense, meaning that additional elements may be included. They are not intended to be interpreted as “consists solely of”.

[0058] The expression "at least one" is used to mean one or more and therefore includes individual components as well as mixtures / combinations.

[0059] Throughout this patent memorandum, unless the context otherwise requires, the term "include", and variations such as "includes" and "comprising", shall be understood to imply the inclusion of any element or step or group of elements or steps stated, but not the exclusion of any other element or step or group of elements or steps.

[0060] The term "including" is used to mean "including but not limited to". "Including" and "including but not limited to" are used interchangeably.

[0061] The term "INCI" is an abbreviation for 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 the ingredients of personal care products.

[0062] All percentages, parts, and ratios are based on the total weight of the compositions in this disclosure, unless otherwise stated. Ratios, concentrations, quantities, and other numerical data may be presented here in a range format. It should be understood that this range format is used solely for convenience and conciseness and should be interpreted flexibly as including not only the numerical values ​​explicitly stated as the range limits, but also as including all individual numerical values ​​or subranges encompassed within that range as if each numerical value and subrange were explicitly stated. For example, a range of percentages by weight from approximately 0.01% to 10% should be interpreted as including not only the explicitly stated limits from approximately 0.01% to approximately 10%, but also as including subranges, such as 0.02% to 0.05%, 1% to 10%, and so on, as well as individual quantities, including fractional quantities, within the specified ranges, such as 1.5%, 5.3%, and 9.25%, for example.

[0063] For the purposes of this disclosure, and unless otherwise indicated: a. A "linear CrCi2 or C3-Ci2 branched saturated hydrocarbon group" is equivalent to a "linear (C1-C12) or branched (C3-C12) alkyl group" which corresponds to a linear C1-C12 or C3-Ci2 branched saturated hydrocarbon group, and preferably to a linear Ci-Cio or C3-Ci0 branched hydrocarbon group, more preferably to a linear Ci-C6 or C3-C6 branched hydrocarbon group; preferably, the linear or branched groups may be selected from the methyl, ethyl, propyl, isopropyl, butyl, isobutyl and tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl groups. More preferably, the linear or branched saturated alkyl groups can be chosen from the methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and tert-butyl, pentyl, hexyl, heptyl and octyl groups, such as methyl, ethyl, n-pentyl, n-nonyl, isobutyl; b. a saturated hydrocarbon group "C3-C8 cyclic" is a mono- or bi-cyclic cycloalkyl group containing 3 to 8 carbon atoms and is in particular a monocyclic cycloalkyl group in C5 to C7 such as a cyclohexyl group; c. an "alkoxy radical" is an alkyl-oxy radical in which the alkyl radical is a linear hydrocarbon radical or branched in Ci-Ci6 and, preferably, in CrC8; 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 carbon-based group, monocyclic or bicyclic, fused or unfused, comprising from 5 to 12 carbon atoms, preferably from 6 to 10 carbon atoms, and in which at least one ring is aromatic; preferably, the aryl radical is a phenyl, a biphenyl, a naphthyl, more preferably a phenyl group; e. The expression "at least one" is equivalent to the expression "one or more"; and f. The term "included" for a concentration range means that the limits of that range are included within the defined range.

[0064] The salts of compounds of formula (I), (!'), (la) or (la') include conventional non-toxic salts of said compounds, such as those formed from an organic or inorganic acid or an organic or inorganic base.

[0065] As salts of compounds of formula (I), (!'), (la) or (la1), mention may be made of the 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 therefore include, for example, one or more alcohol functional groups; examples include 2-amino-2-methylpropanol, ethanolamine, triethanolamine, 2-dimethylaminopropanol, 2-amino-2-(hydroxymethyl)-1,3-propanediol, and 3-(dimethylamino)propylamine.

[0066] Other examples include amino acid salts, for instance lysine, arginine, guanidine, glutamic acid, and aspartic acid. Advantageously, the salts of compounds of formula (I) (when they include a carboxy group) can be selected from alkali metal or alkaline earth metal salts such as sodium, potassium, calcium, or magnesium salts and ammonium salts.

[0067] A "salt of an organic or inorganic acid" is more particularly chosen from among the salts chosen from a salt derived from i) hydrochloric acid HCl, 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) alkoxysulfinic acids: Alk-OS(O)OH such as methoxysulfinic acid and ethoxysulfinic acid; xi) aryloxysulfinic acids such as tolueneoxysulfinic acid and phenoxysulfinic acid; xii) phosphoric acid H3PO4; xiii) acetic acid CH3C(O)OH; xiv) triflic acid CF3SO3 H; and xv) tetrafluoroboric acid HBF4.

[0068] Acceptable solvates of the compounds described in the patent memorandum include conventional solvates such as those formed during the preparation of said compounds due to the presence of solvents. Examples include solvates due to the presence of water or linear or branched alcohols, such as ethanol or isopropanol.

[0069] Optical isomers of formula (I) or (!') are, in particular, enantiomers and diastereomers.

[0070] The mesomeric forms of formula (II) represent isomers of compounds of formula (II) resulting from the delocalization of electrons around heteroatoms such as oxygen and / or sulfur.

[0071] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by a person skilled in the art of this disclosure. Although all processes and materials similar or equivalent to those described herein may be used in the practice or testing of the disclosure, preferred processes and materials are hereby described.

[0072] This disclosure shall not be limited in scope by the specific embodiments described herein, which are intended for illustrative purposes only. Functionally equivalent products, compositions, and processes clearly fall within the scope of the disclosure as described herein.

[0073] Composition stabilizing the thiopyridinone compound

[0074] In one 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, their salts, solvates, hydrates, optical isomers, racemates or mixtures thereof:

[0075] wherein,

[0076] R i denotes a radical selected from: a. a hydrogen atom; b. a linear saturated alkyl group in the form of Ci-Cio or branched in the form of C3-CiO optionally substituted with one or more groups, which may be identical or different, chosen from: i. -O-R3; ii. -S-R3;

[0077] R 2 denotes a radical chosen from: a. a hydrogen atom; b. a linear saturated CrCi2, C3-Ci2 branched, or C3-C8 cyclic hydrocarbon group, optionally substituted with one or more groups, which may be identical or different, selected from i. -O-R3; ii. -S-R3; iii. -C(O)-O-R3 ; iv. an aryl group at C5-Ci2, optionally substituted with one or more hydroxyl groups and / or groups with one or more CrC8 alkoxy radicals, and

[0078] c) an aryl group in C5-Ci2, optionally substituted with one or more hydroxyls and / or with one or more alkoxy radicals in CrC8;

[0079] R 3 designates a radical chosen from: a. a hydrogen atom, and b. a linear saturated alkyl group in the form of Ci-Cio or branched in the form of C3-CiO; and

[0080] (II) at least one reducing agent of formula (II), its mesomeric forms, and its solvates such as hydrates O II R--S--O M' II 1X1

[0081] (II)

[0082] in which,

[0083] X represents a heteroatom chosen from an oxygen or a sulfur, preferably an oxygen;

[0084] m is 0 or 1;

[0085] M+ is a cation, preferably chosen from an alkali metal, an alkaline earth metal or an ammonium, more preferably chosen from an alkali metal such as sodium or potassium;

[0086] R represents a group chosen from:

[0087] i). -OH,

[0088] ü). -O-M'+ with M'+ as defined previously for M+,

[0089] iii) H r, [Xl^

[0090] in which,

[0091] • p is an inclusive integer chosen between 0 and 4, preferably 0, 1, 2 and more preferably 0 or 2;

[0092] • m' is 0 or 1, preferably 1;

[0093] • X' is such that defined for X, preferably X' represents an oxygen atom; and

[0094] • M' '+ is such as defined previously for M+, and M+, M'+, M”+ are identical or different, preferably identical;

[0095] The composition, preferably a cosmetic composition according to an embodiment of the present invention, includes at least one compound of formula (I) or (P), referred to as a "thiopyridinone-type compound" or "thiopyridinone compound." It may be preferable for the present invention to provide cosmetic compositions that include a combination of a thiopyridinone-type compound (I) or (I') with at least one reducing agent of formula (II), which improves the stabilization, preferably the thermal stabilization, of the thiopyridinone compounds and of the cosmetic composition comprising them.

[0096] The "stability" of the thiopyridinone compound can be determined by changing the amount of the thiopyridinone compound in the composition according to the present invention over a certain period of time. The "thermal stability" of the thiopyridinone compound can be determined by changing the amount of the thiopyridinone compound in the composition according to the present invention over a certain period of time, particularly when the composition is maintained for a relatively long period, such as two weeks, at room temperature or even at a high temperature such as above 40 °C. The "photostability" of the thiopyridinone compound can be determined by changing the amount of the thiopyridinone compound in the composition according to the present invention after exposure to light.Increased "stability", "thermal stability" or "photostability" means that the change in the amount of the thiopyridinone compound over time is more limited.

[0097] In certain embodiments, at least one reducing agent of formula (II) as described herein improves the stabilization, preferably thermal stabilization and / or photostabilization, of the compound of formula (I) or (I1) in the composition. In other embodiments, the composition according to the present invention exhibits increased stability, preferably thermal stability and / or photostability, of the thiopyridinone compound of formula (I) and (I1) it contains. In certain embodiments, the composition according to the present invention exhibits increased stability of the compound of formula (I) or (I') upon prolonged storage at room temperature.In some embodiments, the composition according to the present invention exhibits increased stability of the compound of formula (I) or (I'), even when the composition is maintained and stored for a longer period, such as two to three weeks at elevated temperatures such as 40 to 60 °C. In yet another embodiment, the increased stability of the compound of formula (I) or (I1) in the composition provides a . improved bioavailability to provide prolonged brightening or depigmenting effects on keratinous matter.

[0098] The present invention, according to one embodiment, provides methods for improving the stability of a thiopyridinone (I) or (I1) type compound in cosmetic compositions that are useful for treating keratinous material, for example, human facial and neck skin. In some embodiments, the present invention provides cosmetic skin treatment methods comprising applying the cosmetic composition of the present invention to the skin to impart a lightening or whitening effect. The cosmetic compositions are useful in non-therapeutic methods for treating brown spots and uneven skin texture. Thiopyridinone compounds of formula (I) or (T)

[0099] In one 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 (!') below, their salts, solvates, hydrates, optical isomers, racemates or mixtures thereof:

[0100] wherein,

[0101] Ri denotes a radical selected from: a. a hydrogen atom; and b. a linear saturated alkyl group in the form Ci-CiO or branched in the form C3-CiO optionally substituted with one or more groups, which may be identical or different, chosen from: i. -O-R3; and ii. -S-R3;

[0102] R 2 denotes a radical chosen from: a. a hydrogen atom; b. a linear saturated hydrocarbon group in C1-C12 or branched in C3-C12 or cyclic in C3-C8, optionally substituted with one or more groups, which may be the same or different, selected from i. -O-R3; ii. -S-R3; iii. -C(O)-O-R3 ; iv. an aryl group at C5-C12, optionally substituted with one or more hydroxyl groups and / or groups with one or more CrC8 alkoxy radicals, and a. an aryl group in C5-Ci2, optionally substituted with one or more hydroxyls and / or with one or more alkoxy radicals in CrC8;

[0103] R 3 designates a radical chosen from: a. a hydrogen atom, and b. a linear saturated alkyl group in Ci-Cio or branched in C3-CiO;

[0104] The compounds used according to the present invention therefore correspond to the formula (I) or the tautomer (!') below or to their salts, their optical isomers, racemates, and / or solvates such as hydrates, alone or in mixture. O

[0105] in formulas (I) and (!'):

[0106] R i designates a radical selected from: a. a hydrogen atom; b. a linear saturated alkyl group in the form of Ci-Cio or branched in the form of C3-CiO optionally substituted with one or more groups, which may be identical or different, selected from: i. -O-R3; ii. -S-R3;

[0107] R 2 designates a radical chosen from:

[0108] a) a hydrogen atom;

[0109] b) a linear saturated CrCi2 or C3-Ci2 branched or C3-C8 cyclic hydrocarbon group, optionally substituted with one or more groups, which may be identical or different, selected from: i. -O-R3; ii. -S-R3; iii. -C(O)-O-R3 ; iv. an aryl group at C5-Ci2, optionally substituted with one or more hydroxyl groups and / or groups with one or more CrC8 alkoxy radicals; and

[0110] c) an aryl group in C5-Ci2, optionally substituted with one or more hydroxyl groups and / or with one or more CrC8 alkoxy radicals [YES] in which

[0112] R 3 designates a radical chosen from: a. a hydrogen atom; b. a linear saturated alkyl group in Ci-Cio or branched in C3-CiO;

[0113] The compound (!') is the tautomeric form of compound (I) when an equilibrium between the tautomers exists according to the following scheme: Formula 0) Formula (H

[0114] In some embodiments, Ri represents a hydrogen atom.

[0115] In some embodiments, Ri represents a linear alkyl group (in Cr C10) or a branched alkyl group (C3-C10), in particular a linear alkyl group (C1-C6) or a branched alkyl group (C3-C6), such as methyl, ethyl, n-pentyl, n-nonyl, isobutyl groups, more preferably an ethyl group. In particular, said alkyl group of Rin' is unsubstituted.

[0116] In some embodiments, R2 represents a hydrogen atom.

[0117] In some embodiments, R2 represents a linear alkyl group (in Cr Cio) or a branched alkyl group (in C3-Ci0), in particular a linear alkyl group (in Ci-C6) or a branched alkyl group (in C3-C6), such as methyl, ethyl, n-pentyl, n-nonyl, isobutyl groups, more preferably a methyl or an ethyl; said alkyl group of R2 not being substituted.

[0118] In certain embodiments, R2 represents a linear alkyl group (CrClO) or a branched alkyl group (C3-CiO), in particular a linear alkyl group (Ci-C6) or a branched alkyl group (C3-C6), such as methyl, ethyl, n-pentyl, n-nonyl, or isobutyl groups, more preferably a methyl or ethyl group; said alkyl group being substituted with one or more groups selected from i), ii), iii), and iv) as defined above. Preferably, said alkyl group is substituted with one or two groups selected from i), ii), and iii), more preferably with one or two groups selected from i) and iii), or better yet, substituted with a group iii) such as a carboxyl group.

[0119] In some embodiments, another variant for the radical R2 is that said alkyl group is substituted with a group iv), in particular substituted with a phenyl group.

[0120] In some embodiments, R2 represents a cycloalkyl group (in C3-C8), preferably a cycloalkyl group (in C5-C7) such as a cyclohexyl.

[0121] In some embodiments, R2 represents a C5-Ci2 aryl group optionally substituted with one or more hydroxyl groups and / or with one or more CrC8 alkoxy radicals, preferably a phenyl group, in particular unsubstituted.

[0122] In some embodiments, R3 represents a hydrogen atom.

[0123] In some embodiments, R3 represents a linear saturated alkyl group in Ci-Cio or branched in C3-Ci0; in particular a linear alkyl group (in Ci-C6) or a branched alkyl group (in C3-C6), preferably an alkyl group (in CrC4) such as a methyl group.

[0124] In some embodiments, it may be preferable that the compounds of formula (I) and the tautomer (!') or their salts, their optical isomers, racemates, and / or solvates such as hydrates, alone or in mixture;

[0125] have the following meanings:

[0126] R i designates a radical chosen from: a. a hydrogen atom; b. a linear saturated alkyl group in the C1-C6 range or branched in the C3-C6 range, optionally substituted with one or more groups, which may be identical or different, chosen from: i. -O-R3; ii. -S-R3;

[0127] preferably optionally substituted with one or more groups i);

[0128] R 2 designates a radical chosen from: a. a hydrogen atom; b. a linear saturated hydrocarbon group in C1-C10 or branched in C3-C10 or cyclic in C3-C8 or C3-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 Ci-C4 alkoxy radicals such as a methoxy;

[0129] preferably substituted with one or more groups selected from i) and iii), preferably iii) such as a carboxy;

[0130] R 3 designates a radical chosen from: a. a hydrogen atom; b. a linear saturated alkyl group in C1-C6 or branched in C3-C6.

[0131] In certain embodiments, it may be preferable that the compounds of formula (I) and the tautomer (!') or their salts, their optical isomers, racemates, and / or solvates such as hydrates, alone or in mixture, have the following meanings:

[0132] R i designates a radical chosen from: a. a hydrogen atom; b. a linear saturated alkyl group in Ci-C4 or branched in C3-C4 optionally substituted with one or more groups, which may be identical or different, chosen from i) -OR3>plus preferably unsubstituted;

[0133] R 2 designates a radical chosen from: a. a hydrogen atom; b. a linear saturated hydrocarbon group in C1-C10 or branched in C3-C10 or cyclic in C3-C8 as in C5-C6, optionally substituted with one or more groups, which may be identical or different, chosen from: i. -O-R3; ii. -C(O)-O-R3 ;

[0134] iv) an aryl group in C5-Ci2, optionally substituted with one or more hydroxyls and / or with one or more alkoxy radicals in Ci-C4;

[0135] R 3 designates a radical chosen from: a. a hydrogen atom; b. a linear saturated CrC4 or C3-C4 branched alkyl group such as a methyl or ethyl group.

[0136] In some embodiments, it may be preferable that the compounds of formula (I) and the tautomer (!') or their salts, their optical isomers, racemates, and / or solvates such as hydrates, alone or in mixture;

[0137] have the following meanings:

[0138] R, is a hydrogen atom; and

[0139] R 2 designates a radical chosen from: a. a hydrogen atom; b. a linear saturated hydrocarbon group in C1-C5 or branched in C3-C5 or cyclic in C3-C8 as in C5-C6, optionally substituted with one or more groups, which may be identical or different, chosen from ii) -C(O)-O-R3,

[0140] preferably substituted with a group ii) -C(O)-O-R3 ; and

[0141] R 2 is even more preferably a linear saturated hydrocarbon group in C|-C 4 or branched in C3 -C 4 substituted with a iii) -C(O)-OR3 group, and

[0142] R 3 designates a radical chosen from: a. a hydrogen atom; b. a linear saturated alkyl group in C1-C4 or branched in C3-C4 such as a methyl or ethyl group.

[0143] In a preferred embodiment, the compounds of formula (I) and the tautomer (!') are chosen from the compounds of formula (la) and also their tautomers of formula (la') below, their salts, their solvates and their optical isomers, and their racemates, alone or in mixture:

[0144] In formulas (la) and (la'), Ri and R3 have the same meaning as for compounds of formula (I) and (!') and X denotes an alkylene radical -(CH2)n-, n being an integer from 1 to 10 inclusive, preferably from 1 to 6, more preferably from 1 to 4, such that 1, preferably R3 represents a hydrogen atom.

[0145] 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, alone or in mixture: N' Structure Chemical Name N* CAS 1 s<"' X'?? H N-ethyl-2-thioxo-1,2-dihydropyridine-3-carboxamide 91859-75-5 2 7 ' f---x\ N-methyl-2-thioxo* 1,2-dihydroxypyridine-3-carboxamide 91859-74-4 3 ]j ' !^-Gcty^2-thfoxcs- 1,2-dshydropyridine-3-carboxamide& 91859-77-7 if W ff A. YY N-benzyi-2-thioœœ- 1,2-dihydropyndine-3-c3rboxamide 91859-79-9 .,........, .......ff V N-phenyl-2-thtoxo-1 „2-d8iÿdropyridin»-3-caFboxamide 104857-16-1 6 ,z\- W ;' k N-cy dob exyî-2-thîoxO' 12-dihydfBpyndine-3-carboxamide 91859-78-3 ^.,-Y- N42-(4r4rtéthG«yp^^ dhyij-2-thioxo-i 2-dihÿdropyrkfce-î-tarboxamide 923682-88-6 8 ; H M-(2-methy^pfopyi)-2-thioxo- 1,2-dÊ^ÿdrepyndme- 3-csfboxamsde 1100 027-79-9 9 H-pentyl-2-thioxo-1,2-dihydf70-GpyTtdàie-77-3-353xam H-nanyl-2-thæxûi- 1 J'-dshydfcpyndhe- 3-carboxamide 103114M4-6 11 / 'X ;< VN“v •: $ > H Ni-(2-hy dwyéîhyl)- 2-thioxo- 1 ;2-Xrme Xr'amid3izhyzhyndhyl-1 bLN-diéÜiyt 2-mercaptobrcotmamide 13 X < ;N-éthyh^-Ç2^ydroxyê^^ 2-lfiioxo- 1 2-dhydfopyddsne- S-cafiscxamâde 14 , ...Âx IM-(2.3-dlhyJroxypf 2-ïhtoxo- 12-dshydropyrfdsne-3-cafboxarmdie 15 H jj ■•••:•: kh0 ;.3-dihydro.x^ 2-y§)-2-thjoxa- 1,2-dihÿdrQpyrIdine-3-cafboxamfde 16 Y'' X CH, Y ' " n '" N ;! * N-[(2-1hk)XG- 1. Cd&y dropyridîn-3-yil) d' ethyl 17 'Vy. Y'' N-[(2-thiexo- 1,2-dîhydropyridh-3-yl) ethyl 18 N-methyl lN-[(2-th»xo-1 2-d»hydropyrtdjn-3-yt) ethyl 19 IJ IM-[(2-di©X8“- 1,2-dlhydrQpyrtdin-3-yf) ethyl 20 JH IM-[(2WesE>~ 1 .l^hydropyrtdln-S-yi) çarbonyOglydne 21 H M-methy f N - [{2-thtoxo-1,2-djh yd ig pv r îdi n-3-yl) 22 .A:. ..-x, Y!j...... H-buty!-2-th§àxo- i ,2-dÊhydmpyndme-3-cabbaxanàde

[0146] In a preferred embodiment, the compounds are chosen in particular from: rr Structure Nom cosmique CAS 1 H ht-éthyf^-thioxo- 1,2<§hydropyridîne-3-csrboxamIde 91859-75-5 2 / / \\ W—yÇ A IM-méthyi-2-thsoxG- 1 j4^hydrQpyrkfee- 3-carboxamfde 91859-74-4 4 if V ji M-benzyl-2-thioxQ-1,2-dïhydrepyrtdsne-3-carboxamtde 91859-79-9 g Ay-j--'’ ^XX' M-cy dob exyi-2-thîoxo-1,2-dïhydrepyndme-3-carbaxamtde 91859-70 7 A .--x XX X 'jS* 'A-'’ -.^.- J X --¼ N ^-(4-<néthoxyphény Ps g^y!]-2-th®xo-1 J-cïihydropyddhie-3-cafbexamîde 923682-88-6 9 %-À M-penM-2-t:hîoxo-1 ^-dbydfcpyridme-3-carboxamjde 330667-57-7 11 CS fT z\ î | CM ^8 H N-(2 hydrxyylhyl)- 2-ttimœ- 1,2-dihydfopyTtdme- 3-carboxarrtide: 12 H 2 - mef cajj to^ icotiïsamide 14 § ” i N-(2,3-dixo-1hydroxyhipff ?2-dshydfspyrfdhe- 3-carboxamîde 15 : ' $ HJ^hydroxyprapan-2-yl)-2 -îNoxo 1 ; 4'éihyfe 17 Œ- Y * , zX, N-^x-^ioxs- 1 2-d^ dropyridùv3-yl) ç a à? 18 fvVT K ; M-méthy f N 2-thfoxo- 1,2-dlhy dropyndm-3-yt) 19 lj SV N-[(2-thisxo- 1 2-dîhydrGpyïtdsn-3-yt) 29  M-[(2-thfexo- 1 y2-diJdinhydyl-pydnyl)» 21 Py'S^y'" < £'HH N-méthyW{(2-thjoxo-1, Z-dthydtdpÿrtdân-3-ÿi) ^Ij^xOglydne

[0147] In a more preferred embodiment, among these compounds, the following compounds are particularly preferred: N' Structure Chemical Name N" CAS 1 X--' H M-ethyl-24hsoxo- 1,2-dEhydropyridine-î^afboxamàde 91859-7 5-6 9 ...-•'>x .-'•'"'•-x hi-penlyl-2-thtoxo- 1,2-dlhydropyridlne-ÎKartsoxamlde 33Û667-57-7 16 A.VXX ,vs\- Z.--Sx ^--:1- VY *• > ■; % «.< ;• •\ .K- ° H <C IM-[(2-îhfoxs- 1 2^hydropyridsri-3-yJ) 18 1 0 'T î T ’ V£ X N-méthyl-N-[(2-fhSoxo-1,2-dshydropyridîri-3- 19 x. ' Xx ' xx. ' |j ï H M-[(2-thioxo- 1 %2-dthydropyndin-3-yl) OŒteÜMfe d’éih yfe 28 M4(2-t)fexs- 142<8hydropyrld5n-3-yl) carboqyfjglydne 21 >x 1 Œ ff H N- methyl RH(2-th»xc-12-dlhydropy nsfe-3-yl) SgitaxOg^ciïie

[0148] In a much more preferred embodiment, the following compounds are more particularly used: Structure Kom chemical Ns CAS 18 1 'j. f î N-methyl1-N4(2-thiox$- 1 2-dihydrûpyridln-3-y^ SAfbwy Ê] giyd naj ed ëthy 1 e 19 Û | 20 J 8) H-[(24hksxo- 1,2-dihydrcpyndm-3-yi) carbonyijglydne 21 1 A ..... / fi U K4métyi-N4(2-thiox^ 1 ;2-djhydFQpyridsm3-yii

[0149] In a most preferred embodiment, the compound according to the present invention is as follows:

[0150] All the above compounds can be obtained by a chemical process known to those skilled in the art, from commercially available reagents.

[0151] In one embodiment, the (1) thiopyridinone compound of formula (I) or (I1) can be prepared according to the process described, for example, in EP-A-3 390 363 or WO 2017 / 102349.

[0152] The (1) thiopyridinone compound may be an active ingredient or active compound in cosmetic or dermatological products. The term "active ingredient" or "active compound" used herein refers to an ingredient or compound that possesses an active cosmetic or dermatological property, such as antioxidant, bleaching, UV-filtering, and antibacterial effects. The (1) thiopyridinone compound used in the present invention may act as a depigmenting, lightening, bleaching, or whitening agent, and thus the composition according to the present invention may be used as a skin-lightening product or as a cosmetic composition for lightening keratinous material.

[0153] The (1) thiopyridinone compound can be used as an agent for depigmenting, lightening, bleaching or whitening the skin, body hair, eyelashes or hair, and also the lips and / or nails, and preferably the skin, in particular for removing pigmentation spots or age spots and / or as an anti-tanning agent.

[0154] 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.

[0155] 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.

[0156] In certain embodiments, the quantity 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.

[0157] 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.

[0158] It may be preferable for the composition according to the present invention to comprise (1) at least one thiopyridinone compound. Two (1) or more thiopyridinone compounds may be used in combination. Thus, only one type of (1) compound of thiopyridinone or a combination of different types of (1) thiopyridinone compounds may be used.

[0159] The (1) thiopyridinone compound is selected from the compounds of formula (I) below, the tautomers of formula (T) below, their salts, their solvates, such as their hydrates, their optical isomers, their racemates and mixtures thereof: O (D (I)

[0160] In these formulas (I) and (!'):

[0161] Ri designates a radical selected from: a. a hydrogen atom; b. a linear saturated alkyl group in the form of Ci-Cio or branched in the form of C3-CiO optionally substituted with one or more groups, which may be identical or different, selected from: i. -O-R3; ii. -S-R3;

[0162] R 2 designates a radical chosen from:

[0163] a) a hydrogen atom;

[0164] b) a linear saturated hydrocarbon group in C1-C12 or branched in C3-C12 or cyclic in C3-C8, optionally substituted with one or more groups, which may be identical or different, selected from: i. -O-R3; ii. -S-R3; iii. -C(O)-O-R3 ; iv. an aryl group at C5-C12, optionally substituted with one or more hydroxyl groups and / or groups with one or more CrC8 alkoxy radicals; and a. c) an aryl group in C5-Ci2, optionally substituted with one or more hydroxyl groups and / or with one or more CrC8 alkoxy radicals

[0165] in which

[0166] R 3 designates a radical chosen from: a. a hydrogen atom; b. a linear saturated alkyl group in Ci-Cio or branched in C3-Ci0.

[0167] Inorganic reducing agent of formula (II)

[0168] In one embodiment, the composition of the present invention comprises at least one (2) reducing agent of formula (II), its mesomeric forms, and its solvates such as hydrates O R--S--O'M'

[0169] (II)

[0170] in which,

[0171] X represents a heteroatom chosen from an oxygen or a sulfur, preferably an oxygen;

[0172] m is 0 or 1;

[0173] M+ is a cation, preferably selected from an alkali metal, an alkaline earth metal or an ammonium, more preferably selected from an alkali metal such as sodium or potassium;

[0174] R represents a group chosen from:

[0175] i) -OH,

[0176] ü) -O-M'+ with M'+ as defined previously for M+,

[0177] iii) Q

[0178] in which,

[0179] • p is an inclusive integer chosen between 0 and 4, preferably 0, 1, 2 and more preferably 0 or 2;

[0180] • m' is 0 or 1, preferably 1;

[0181] • X' is such that defined for X, preferably X' represents an oxygen atom; and

[0182] • M”+ is such as defined previously for M+, and M+, M'+, M”+ are identical or different, preferably identical.

[0183] In certain embodiments, the composition comprises at least one (2) reducing agent of formula (II) in which,

[0184] X of formula (II) represents a heteroatom selected from an oxygen or a sulfur, preferably an oxygen;

[0185] m of formula (II) is 0 or 1;

[0186] M+ of formula (II) is a cation, preferably a sodium or a potassium;

[0187] R of formula (II) represents a group chosen from

[0188] i) -OH,

[0189]

[0190] ii) -O-M'+ with M'+ as defined previously for M+, iii) 0 H ' 1S]~ S 'OM p H

[0191]

[0192]

[0193]

[0194]

[0195]

[0196] in which, • p is 0 or 2; • m' is 0 or 1; • X1 is as defined for X, preferably X1 represents an oxygen atom; and M+, M'+, M”+ are identical. In certain embodiments, wherein in (2) reducing agent of formula (II)

[0197]

[0198]

[0199]

[0200] R represents a group selected from: i) -OH, ii) -O-M'+ with M'+, iii) O II F il

[0201]

[0202]

[0203]

[0204]

[0205]

[0206] P- wherein, • p is 0 or 2; • m' is 0 or 1; • X' represents an oxygen atom; and M+, M'+ and M”+ are identical and selected from a sodium or a potassium.In some embodiments, wherein in (2) reducing agent of formula (II)

[0207]

[0208]

[0209]

[0210] X of formula (II) represents a sulfur; m in formula (II) is 1; M+ in formula (II) is a sodium or a potassium; R of formula (II) represents a group selected from i. -OH, and ü- -O-M'+ with M'+,

[0211]

[0212] M+, and M'+ are identical. In some embodiments, the compounds of formula (II) may be found in their delocalized or marginal mesomeric limiting forms,

[0213] when m = 0, then . RS{OM^O€*RS(=O)-O-M+

[0214] and

[0215] when m = 1, then the mesomeric limiting forms are Rs(o-^)(=x)m=o ,rs(=ô)(=x^-m* rs^ôxx-m^û

[0216] where, M+, M'+, M"+ are present to ensure the electroneutrality of the molecule of formula (II).

[0217] In a preferred embodiment, the (2) reducing agent may be selected from sodium bisulfite, sodium metabisulfite, sodium sulfite, sodium thiosulfate, sodium sulfate, potassium metabisulfite, potassium sulfite, potassium thiosulfate, potassium sulfate or potassium tetrathionate.

[0218] In a preferred embodiment, the (2) reducing agent may be selected from sodium bisulfite, sodium metabisulfite, sodium sulfite, sodium thiosulfate, or sodium sulfate.

[0219] In one embodiment, the composition of the present invention comprises a reducing agent of formula (II) which 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.

[0220] In certain embodiments, the composition of the present invention according to one embodiment comprises a reducing agent of formula (II) which 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.

[0221] In certain embodiments, the quantity of (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. pH correcting agent

[0222] In one embodiment, the composition of the present invention may comprise at least one pH-correcting agent (pH adjuster). Two or more pH-correcting agents may be used in combination. Thus, a single type of pH-correcting agent or a combination of different types of pH-correcting agents may be used.

[0223] As a pH correcting agent, at least one acidifying agent and / or at least one alkalizing agent (alkaline agent) may be used.

[0224] The acidifying agent may be a monovalent or polyvalent acid, such as divalent.

[0225] Acidifying agents may be, for example, mineral (inorganic) acids such as hydrochloric acid, sulfuric acid, phosphoric acid, or acids organics such as carboxylic acids, for example tartaric acid, citric acid and lactic acid, as well as sulfonic acids.

[0226] The alkalizing agent may be a monovalent or polyvalent base, such as divalent. Alkalizing agents may be mineral (inorganic) or organic, or hybrid.

[0227] Mineral alkalizing agents may be selected 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.

[0228] Organic alkalizing agents may be selected from organic amines having 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 this is the pKb corresponding to the highest basicity functional group. Furthermore, the organic amines do not include any alkyl or alkenyl fatty chain comprising more than ten carbon atoms.

[0229] The organic alkalizing agent may be chosen, for example, from the alkanolamines, oxyethylenated and / or oxypropylenated ethylenediamines, amino acids and amine compounds of formula (III) below:

[0230] in which

[0231] W represents a divalent Ci-C6 alkylene radical optionally substituted with one or more hydroxyl groups or a Ci-C6 alkyl radical, and optionally interrupted by one or more heteroatoms such as O and N, and

[0232] Rx, Ry, Rz and Rt, which may be identical or different, represent a hydrogen atom or an alkyl radical in Ci-C6, hydroxyalkyl in Ci-C6 or aminoalkyl in CrC6.

[0233] Examples of formula (III) amine compounds that may be mentioned include 1,3-diaminopropane, 1,3-diamino-2-propanol, spermine and spermidine.

[0234] The term "alkanolamine" designates an organic amine comprising a primary, secondary or tertiary amine function, and one or more linear or CrC8 branched alkyl groups bearing one or more hydroxyl radicals.

[0235] Alkanolamines such as monoalkanolamines, dialkanolamines or trialkanolamines comprising one to three C1-C4 hydroxyalkyl radicals Identical or different compounds may be appropriate for the present invention. Among such compounds, one may cite monoethanolamine (MEA), diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, N-dimethylaminoethanolamine, 2-amino-2-methyl-l-propanol, triisopropanolamine, 2-amino-2-methyl-l,3-propanediol, 3-amino-l,2-propanediol, 3-dimethylamino-l,2-propanediol and tris(hydroxymethylamino)methane.

[0236] The 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 among the carboxylic acid, sulfonic acid, phosphonic acid or phosphoric acid functions. The amino acids may be in neutral or ionic form.

[0237] Amino acids that can be used in the present invention include, in particular, 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.

[0238] It may be preferable for the amino acids to be basic amino acids comprising an additional amine function optionally included in a ring or in a ureido function.

[0239] Such basic amino acids may preferably be chosen from those corresponding to formula (IV) below:

[0240] in which

[0241] R of formula (IV) represents a group chosen from:

[0242] -(CH2)3-NH2,

[0243] -(CH2)2-NH2,

[0244] -(CH2)2-NH-CO-NH2, and

[0245] Compounds corresponding to formula (IV) include histidine, lysine, arginine, omithine and citrulline.

[0246] The organic alkalizing agent may be chosen from among heterocyclic organic amines. In addition to histidine, which has already been mentioned among the amino acids, pyridine, piperidine, imidazole, triazole, tetrazole, and benzimidazole may be mentioned in particular.

[0247] The organic alkalizing agent can also be chosen from amino acid dipeptides. Examples of amino acid dipeptides that can be used in the present invention include carnosine, anserine, and balein.

[0248] The organic alkalizing agent can also be chosen from compounds comprising a guanidine function. As amines of this type that can be used in the present invention, in addition to arginine, which has already been mentioned as an amino acid, creatine, creatinine, 1,1-dimethylguanidine, 1,1-diethylguanidine, glycocyamine, metformin, agmatine, N-amidinoalanine, 3-guanidinopropionic acid, 4-guanidinobutyric acid and 2-([amino(imino)met hyl]aminojethane-1 -sulfonic acid.

[0249] In a preferred embodiment of the present invention, the organic alkalizing agent may be selected from amino acids, preferably basic amino acids, and more preferably, arginine, lysine, histidine, or mixtures thereof. Even more preferably, the organic alkalizing agent may be arginine.

[0250] Hybrid compounds that may be mentioned include salts of the amines mentioned above with acids such as carbonic acid or hydrochloric acid. Guanidine carbonate or monoethanolamine hydrochloride may be used in particular.

[0251] In some embodiments, the amount of the pH correcting agent in the composition may be greater than or equal to 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.

[0252] In some embodiments, the amount of pH correcting agent in the composition may be less than or equal to 15% by weight, preferably 10% by weight or less and, more preferably, 5% by weight or less, relative to the total weight of the composition.

[0253] In a preferred embodiment, the pH correcting agent may be present in an amount 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.

[0254] It is preferable that the composition according to the present invention has a pH of 4.5 or more, and more preferably of 5 or more.

[0255] It is preferable that the composition according to the present invention has a pH of 6.5 or less, and more preferably of 6 or less.

[0256] It is preferable that the composition according to the present invention has a pH of 4.5 to 6.5, and more preferably of 5 to 6.

[0257] The pH of the composition corresponds to the pH of the aqueous phase of the composition according to the present invention.

[0258] It may be preferable that at least one buffer or buffering agent also be used, as a pH correcting agent, in combination with the acidifying agent and / or the alkalizing agent, in order to stabilize the pH of the composition according to the present invention.

[0259] Any commonly known buffer 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 a buffer if citric acid or lactic acid is used as the acidifying agent. Medium / solvent

[0260] In one embodiment, the composition of the present invention may advantageously comprise at least one medium / solvent, including water and / or an organic medium / solvent.

[0261] In some embodiments, the composition may comprise water in varying amounts. For low-viscosity applications of the composition, for example as a leave-on lotion, a relatively high amount of water may be used. For example, water is used at a content greater than or equal to 20% by weight relative to the total weight of the composition. The water content in the low-viscosity composition according to the invention 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, for example as a leave-on cream, a relatively lower amount of water may be used. The high-viscosity composition according to the invention advantageously comprises water at a content less than or equal to 40% by weight relative to the total weight of the composition.

[0262] In some embodiments, the amount of water in the composition may be 20% by weight or more, preferably 30% by weight or more, and more preferably 40% by weight or more, relative to the total weight of the composition.

[0263] In some embodiments, the amount of water in the composition may be 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.

[0264] In a preferred embodiment, the amount of water in the composition can be from 20% to 99% by weight, preferably from 30% to 95% by weight, and more preferably from 40% to 90% by weight, relative to the total weight of the composition.

[0265] In some embodiments, the composition may also include one or more organic media / solvents, preferably organic media / solvents soluble in water (solubility greater than or equal to 5% in water at 25°C and atmospheric pressure).

[0266] Examples of organic media / solvents that may be cited 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, a sugar and sugar alcohols; and ethers such as monomethyl, monoethyl and monobutyl ethers of ethylene glycol, monomethyl, monoethyl and monobutyl ethers of propylene glycol, and monomethyl, monoethyl and monobutyl ethers of butylene glycol.

[0267] The organic media / solvents, if any, 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.

[0268] In some embodiments, the composition may also include other additives, active agents, carriers, adjuvants which are known in the art to be compatible with keratinous material and are cosmetically acceptable.

[0269] In certain embodiments, the composition of the present invention lightens or depigments a keratinous material, preferably the skin.

[0270] In other embodiments, the composition of the present invention may be useful for treating keratinous material, preferably skin, in order to confer a whitening or depigmenting effect. Preparation of the composition

[0271] In one 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.

[0272] The process includes mixing the essential and optional components described above by any known method. In one embodiment, the composition of the present invention can be prepared by a process including the steps of mixing at least one compound of formula (I) or (I'), with at least one inorganic reducing agent of formula (II), with water or any suitable solvent. The mixing includes the addition of other additives if necessary. The process implies mixing the components at any temperature, preferably at room temperature, more preferably at 30°C or above, at 40°C or above and more preferably at 50°C or above.

[0273] The composition according to the present invention may be in various forms, including but not limited to an emulsion, a solution, a gel, or a cream. Method / Use of the composition

[0274] In one embodiment, the present invention proposes a cosmetic treatment method for keratinous material, the method comprising: the application of the composition of the present invention to the keratinous material, preferably the skin.

[0275] In certain embodiments, the present invention proposes a non-therapeutic cosmetic treatment method for keratinous material, the method comprising: the application of the composition of the present invention to the keratinous material, preferably the skin.

[0276] In other embodiments, the present invention proposes using the composition to lighten or depigment keratinous material, preferably skin. In some embodiments, the composition is suitable for treating darker and / or more pigmented spots on the skin. In some embodiments, the composition is useful for providing necessary skin care, preferably for lightening the skin and / or reducing or lightening darker and / or more pigmented spots on the skin.

[0277] In some embodiments, the present invention provides a cosmetic composition that can be applied once a day, twice a day, or more than once or twice a day. In some cases, the composition is applied in the evening before bedtime. In other cases, the compositions are applied in the morning. In still other cases, the composition can be applied immediately after washing the skin. The compositions can be used once, or for a series of days, weeks, or months. For example, the compositions can be used daily for a period of 1, 2, 3, 4, 5, 6, 7, 8 weeks or more, or months.

[0278] In one embodiment, the present invention proposes the use of:

[0279] at least one inorganic reducing agent of formula (II), its mesomeric forms, and its solvates such as hydrates O r—s—o'm* (he)

[0280] in which,

[0281] X represents a heteroatom chosen from an oxygen or a sulfur, preferably an oxygen;

[0282] m is 0 or 1;

[0283] M+ is a cation, preferably chosen from an alkali metal, an alkaline earth metal or an ammonium, more preferably chosen from an alkali metal such as sodium or potassium;

[0284] R represents a group chosen from:

[0285] i) -OH,

[0286] ü) -O-M'+ with M'+ as defined previously for M+,

[0287] iii) Q p it ' ' >

[0288] in which,

[0289] • p is an inclusive integer chosen between 0 and 4, preferably 0, 1, 2 and more preferably 0 or 2;

[0290] • m1 is 0 or 1, preferably 1;

[0291] • X1 is such as defined for X, preferably X1 represents an oxygen atom; and

[0292] • M' '+ is such as defined previously for M+, and M+, M'+, M”+ are identical or different, preferably identical,

[0293] in a composition comprising at least one compound selected from the compounds of formula (I), its tautomer of formula (I1), their salts, optical isomers, racemates, solvates, hydrates or mixtures thereof: (I)

[0294] formulas (I) and (I') in which:

[0295] R i designates a radical chosen from: a. a hydrogen atom; b. a linear saturated alkyl group in the C1-C10 configuration or branched in the C3-C10 configuration, optionally substituted with one or more groups, which may be identical or different, chosen from: i. -0-R3 ; ii. -S-R3;

[0296] R 2 denotes a radical chosen from:

[0297] a) a hydrogen atom;

[0298] b) a linear saturated hydrocarbon group in C1-C12 or branched in C3-C12 or cyclic in C3-C8, optionally substituted with one or more groups, which may be identical or different, selected from: i. -O-R3; ii. -S-R3; iii. -C(O)-O-R3 ; iv. an aryl group at C5-Ci2, optionally substituted with one or more hydroxyls and / or with one or more CrC8 alkoxy radicals;

[0299] c) an aryl group in C5-Ci2, optionally substituted with one or more hydroxyl groups and / or with one or more CrC8 alkoxy radicals; and

[0300] R 3 designates a radical chosen from: a. a hydrogen atom; b. a linear saturated alkyl group in the form of Ci-Cio or branched in the form of C3-CiO,

[0301] for stabilizing the compound of formula (I), its tautomer of formula (I1), salts, solvates, hydrates, optical isomers, racemates, or mixtures thereof, in the composition. The term "stabilize" has the same meaning as enhance stability.

[0302] According to one embodiment of the invention, the composition comprises an aqueous phase. The composition is in particular formulated as water-in-oil or oil-in-water emulsions or as multiple emulsions (triple oil-in-water-in-oil or water-in-oil-in-water emulsions (such emulsions are known and described, for example, by C. Fox in "Cosmetics and Toiletries" - November 1986 - Vol. 101 - pages 101-112)).

[0303] According to a particular embodiment of the invention, the composition is a direct emulsion, that is to say, an oil-in-water or O / W emulsion. EXAMPLES

[0304] The disclosure will now be illustrated by practical examples, which are intended to demonstrate how the disclosure works and are not intended to impose restrictive limitations on the scope of this disclosure. Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by a person skilled in the art of this disclosure. Although processes and materials similar or equivalent to those described herein may be used in the practice of the disclosed processes and compositions, examples of processes, devices, and materials are described herein. It should be It is understood that this disclosure is not limited to a particular composition, specific processes, and experimental conditions described, insofar as such processes and conditions may be applicable. The present invention will be described in more detail by means of examples. However, these examples shall not be construed as limiting the scope of the present invention. Example 1: Synthesis of compound #20

[0305] Compound 20 is synthesized as disclosed in Example 2 of patent EP3 390 363. Example 2: Cosmetic compositions

[0306] A cosmetic composition (according to the invention) comprising compound 20 of formula (I) with at least one inorganic reducing agent of formula (II) as described herein, with other additional ingredients, was prepared by taking each of said ingredients in an amount as mentioned in Table 1 below. For example, cosmetic composition EX1 was prepared using 0.50% by weight of 2-mercaptonicotinoylglycine, 0.2% by weight of reducing agent, i.e. sodium thiosulfate, a total of 6.00% by weight of glyceryl stearate, PEG-100 stearate, and PEG-40 stearate, 2.40% by weight of fatty alcohols, 6.00% by weight of hydrogenated polyisobutene, 1.20% by weight of preservatives, 0.20% by weight of chelating agent, 18.00% by weight of isohexadecane, 0.36% by weight of thickening agent and 0.36% by weight of triethanolamine, with a sufficient amount of water.Similarly, compositions EX2 and EX3 (according to the invention) were prepared with 0.2% by weight of sodium metabisulfite and sodium sulfite, respectively. The comparative composition CEX1 was also prepared in a similar manner, including the ingredients without any inorganic reducing agents as mentioned in Table 1 below.

[0307] [Tables 1] Ingredients / INCI (% by weight) EX1 EX2 EX3 CEX1 Compound 20 of formula (I) 2-Mercaptonicotinoyl Glycine 0.50 0.50 0.50 0.50 Inorganic reducing agent Sodium Thiosulfate 0.2 0 0 0 Sodium Metabisulfite 0 0.2 0 0 Sodium Sulfite 0 0 0.2 0 Glyceryl Stearate (and) PEG-100 Stearate 3.00 3.00 3.00 3.00 PEG-40 Stearate 3.00 3.00 3.00 3.00 Fatty Alcohols 2.40 2.40 2.40 2.40 Hydrogenated Polyisobutene 6.00 6.00 6.00 6.00 Preservatives 1.20 1.20 1.20 1.20 Chelating Agent 0.20 0.20 0.20 0.20 Isohexadecane 18.00 18.00 18.00 18.00 Thickening agent 0.36 0.36 0.36 0.36 Triethanolamine 0.36 0.36 0.36 0.36 Water / Aqua Qs 100 Qs 100 Qs 100 Qs 100 Example 3: Stability of compositions Thermal stability studies

[0308] The compositions as prepared in Example 1 were analyzed to determine their stability when stored at different temperatures.

[0309] Approximately 1.0 g of each composition was independently mixed with 50 mL of water to prepare an aqueous solution of the composition. Methanol was added to the aqueous solution of the composition and subjected to sonication followed by stirring for approximately 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 time T0. Another portion of the filtered solution was placed in an oven at 45°C for a period of 2 months, and the presence of compound 20 at accelerated aging (T2M) at 45°C was determined. Another portion of the filtered solution was stored at room temperature for 2 months, and the presence of compound 20 in the T2M solution at room temperature was determined.

[0310] The details of the HPLC-UV assays are as follows: Device / Reagents

[0311] [Tables2] High-performance liquid chromatography (UPLC) system, RP18 HPLC column, 1.7, 2.1 mm x 100 mm, eluent A 0.1% phosphoric acid Eluent B Methanol HPLC conditions

[0312] [Tables3] UV detector 296 nm Column temp. 30°C Flow rate 0.4 ml / min Injection volume 1 µL Mobile phase Gradient mode A: 0.1% phosphoric acid in water B: methanol

[0313] The quantity of compound 20 of formula (I) in each of the solutions was determined and the % values ​​of compound 20 of formula (I) measured are presented in Table 4.

[0314] [Tables4] Composition Compound 20 of formula (I) remaining (% by weight) T2M at TA T2M at 45°C EX1 (invention) 100 100 EX2 (invention) 100 97.7 EX3 (invention) 100 93.3 CEX1 (comparative) 88.9 84.4

[0315] According to Table 4 above, it can be seen that compositions EX1 to EX3 of the invention were more stable at room temperature, as well as at elevated temperatures, and that the comparative composition CEX1 proved to be less stable. Indeed, in the presence of the inorganic reducing agent, the stability of the compound of formula (I) increased, thus resulting in an increasingly stable cosmetic composition compared to the comparative composition CEX1. In particular, it can be seen that composition EX1 of the invention, comprising sodium thiosulfate, increased the stabilization of the thiopyridinone compound at all temperatures (at room temperature and at higher temperatures) for an extended period of time.Therefore, the composition according to the present invention comprising a reducing agent exhibited increased stability of the thiopyridinone compound, providing a stable composition with a prolonged shelf life at room temperature as well as under accelerated conditions. Photostability studies

[0316] The compositions prepared in Example 1 were analyzed to determine their photostability upon exposure to UV radiation.

[0317] Each of the compositions EX1 (invention) and the comparative composition CEX1 were independently coated onto an inert support. The coated supports were exposed to UV radiation of 5 J / cm² for approximately 1 hour. The exposed compositions were then dissolved in an organic solvent, and the solutions were analyzed by HPLC or UPLC chromatographic methods.

[0318] The quantity of compound 20 of formula (I) in each of the compositions was measured by HPLC-UV assay at two time points as mentioned below.

[0319] Instant (1): Just after the composition has been prepared

[0320] Instant (2): Solution of compositions after exposure to UV.

[0321] The details of the HPLC-UV assays are as follows: Device / Reagents

[0322] [Tables5] High-performance liquid chromatography (UPLC) system, RP18 HPLC column, 1.7, 2.1 mm x 100 mm. Eluent A: 0.1% phosphoric acid. Eluent B: Methanol. HPLC conditions

[0323] [Tableauxô] UV detector 296 nm Column temp. 30°C Flow rate 0.4 ml / min Injection volume 1 µL Mobile phase Gradient mode A: 0.1% phosphoric acid in water B: methanol

[0324] The quantity of compound 20 of formula (I) remaining in each of the compositions before (Time 1) and after exposure to UV (Time 2) was determined by HPLC-UV assay and the difference in quantity of compound of formula (I) was calculated.

[0325] The % values ​​of compound 20 of formula (I), remaining in compositions EX1 and CEX1 exposed to UV, are presented in Table 7 below.

[0326] [Tables7] Composition of compound 20 of formula (I) remaining after UV exposure (% by weight): EX1 (invention) 96% CEX1 (comparative) 86%

[0327] It was found that composition EX1, which included sodium thiosulfate (reducing agent), was more effective and stable than the comparative composition CEX1. The composition of the present invention comprising an inorganic reducing agent of formula (II), as described herein, conferred both increased thermal and photostability to the thiopyridinone compounds, and thus resulted in cosmetic compositions with a prolonged shelf life even when stored at varying temperatures.

Claims

1. Demands Composition, preferably a cosmetic composition, comprising: (I) at least one compound selected from a compound of formula (I) below, its tautomer of formula (F) below, their salts, solvates, hydrates, optical isomers, racemates or mixtures thereof: Formula (I) Formula (F) in which, R i of formula (I) and of formula (I1) represents a radical chosen from: a) a hydrogen atom; b) a linear saturated alkyl group in the C1-C6 range or optionally branched in the C3-C6 range, substituted with one or more groups, which may be identical or different, selected from: i) -O-R3; ii) -S-R3; preferably optionally substituted with one or more groups i); R 2 of formula (I) and of formula (!') represents a radical chosen from: a) a hydrogen atom; b) a linear or branched saturated hydrocarbon group in C3-C1 or cyclic in C3-C8 as in C5-C6, optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; ü) -SR3; iii) -C(O)-O-R3; (iv) a phenyl group optionally substituted with one or more hydroxyl groups and / or with one or more C1-C4 alkoxy radicals such as a methoxy; preferably substituted with one or more groups chosen from i) and iii), preferably iii) such as a carboxy; R 3 of formula (I) and formula (!') represents a radical chosen from: a) a hydrogen atom; b) a linear saturated alkyl group in the C1-C6 range or a branched C3-C6 range; and (II) at least one inorganic reducing agent of formula (II), its mesomeric forms, and its solvates such as hydrates O _________O ________ P (II) in which, X represents a heteroatom chosen from oxygen or sulfur, preferably oxygen; m is 0 or 1; M+ is a cation, preferably chosen from an alkali metal, an alkaline earth metal, or an ammonium, more preferably chosen from an alkali metal such as sodium or potassium; R represents a group chosen from: i) -OH, ii) -O-M'+ with M'+ as defined previously for M+, iü) o —£ S]—S---OM" '' ? H [X Jaf in which, • p is an inclusive integer chosen between 0 and 4, preferably 0, 1, 2 and more preferably 0 or 2; • m1 is 0 or 1, preferably 1; • X1 is such that X1 is defined for X, preferably X1 represents an oxygen atom; and ​• M”+ is such as defined previously for M+, and M+, M'+, M”+ are identical or different, preferably identical. Composition according to claim 1, wherein, the (1) compound is chosen from compounds 1 to 24, their tautomers, salts, solvates, hydrates, optical isomers, racemates or mixtures thereof, in particular 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: 8" CtSHnique Structure -x * ^.,,¼ ■ - S-csrtxjxHiTtide 2 / y •• v " x' / N-œethyl-24hMKS- 1,2-dihyskQpyrkfee-3-t^ 3 N-oc^f8-24hto»- 4 / ""'•v. / ""' 'S- ^-berzyP2-thiexü- 1,2-iaB^dr<qj^dme-3-cætotamîcie 5 '—- N-phé!^t-2-S^oxo> i ,2-di^'âMpyriMkre^carte^ s 4 ^-cÿekrhexyl-2-8ïiœ&-t :2-dihydropyr Hsne^ca^^ 7 ,--x. .•-x, ,.-¼ ,7 2-îhsa<o-t 3-carbûs siride B N-(2-mé»p / ^û^> 2^^xp-t,2-dihydrop^à4ie-3-caÆ^^ 9 s-.s S ■ N-^ei3fyi-24hiss:&-1J^dftÿ«fropyrMme-3-cæîx^^ 10 <art^^ 11 X" '"'X, X H ■N-^Z^iyite^êîh&VZ-tiiox^ 1 ^Biyà’^ytane-a^a^GxaînIde 12 s$ N.N-OM 2-n®rcapîonicçtënam«ie 13 X T "s N-éthyVfH24îy<lFoxyè^ l;2-dibÿdropÿiM&»e-3-ca^ 14 vl<" 'Xt'' dshydrffipyfîdw-3-£ÆF^ 15..-.'IH. i £ ... oa " \s' "-S ■N-O3- <W*sxypropQrF2^^ 2-1hsoxfi-1.2..®y^^ 3-c3rtx»iamtô8 15 <:■ ’-■ A ...... A A ... i A r A / ••A Mr2-thsox<H r2-dihydrap.^ carbcwttKIi^ 17 aÀ N^^àxc-l.S-ditiÿdrop^iiin-a-il) 15 ... À .... ... iî "T T r ■< ,> \V. ^^W(24tas-1,2-àhydf«wf Min-3-y5 caffeGfiyllglosl® 1& ..... 1..... ..^ ..- Œ iï MN“R2-a^0XS-1;.2-.^ 20 i: N-[{ 2-Swî«3- 1.2-dihydrapy^in^ caf&asy®ydne 21 rArY >r"' ^s. H 1,2-® yclrapy ridsnAJ-^ cæbGoygg^dr» hKa-meîtW' t 1, 2 xnpï;Ed iih J rasb' ornée [Revendication 3] [Revendication 4]

5. N-bütÿf-2-^»xo-1 ; 2-dîhy^rspysdne-S-cartaomkfe A composition according to any one of the preceding claims, wherein the compound of formula (I) or its tautomer of formula (I1), its salts, solvates, hydrates, optical isomers, racemates, or mixtures thereof, is present in an amount 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. A composition according to any one of the preceding claims, wherein: R of formula (II) represents a group chosen from i) -OH, ii) -O-M'+ with M'+, iii) in which, • p is 0 or 2; • m' is 0 or 1; • X' represents an oxygen atom; and M+, M'+ and M”+ are identical and chosen from sodium or potassium. Composition according to any one of the preceding claims, wherein: X in formula (II) represents sulfur; m in formula (II) is 1; M+ in formula (II) is sodium or potassium; R in formula (II) represents a group chosen from i) -OH, and ii) -O-M'+ with M'+, M+, and M'+ are identical.

6. Composition according to any one of the preceding claims, wherein the inorganic reducing agent is selected from sodium bisulfite, sodium metabisulfite, sodium sulfite, sodium thiosulfate or sodium sulfate.

7. Composition according to any one of the preceding claims, wherein the inorganic reducing agent is in an amount 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.

8. Cosmetic process for treating keratinous material, the process comprising: applying the composition according to any one of claims 1 to 7 to the keratinous material, preferably the skin.

9. Use of the composition according to any one of claims 1 to 7 for bleaching or depigmenting keratinous material, preferably skin.

10. Use of at least one inorganic reducing agent of formula (II), of its mesomeric forms, and of its solvates such as hydrates O R--S--O (II) in which, X represents a heteroatom selected from an oxygen or a sulfur, preferably an oxygen; m is 0 or 1; M+ is a cation, preferably chosen from an alkali metal, an alkaline earth metal, or an ammonium, more preferably chosen from an alkali metal such as sodium or potassium; R represents a group chosen from: i) -OH, ii) -O-M'+ with M'+ as defined previously for M+, iii) Q y $ in which, • p is an inclusive integer chosen between 0 and 4, preferably 0, 1, 2 and more preferably 0 or 2; • m' is 0 or 1, preferably 1; • X' is such that defined for X, preferably X' represents an oxygen atom; and • M”+ is as defined previously for M+, and M+, M'+, M”+ are identical or different, preferably identical, in a composition comprising at least one compound selected from the compounds of formula (I), its tautomer of formula (I1), their salts, optical isomers, racemates, solvates, hydrates or mixtures thereof: (I) (D formulas (I) and (I') in which: R i designates a radical chosen from: a) a hydrogen atom; b) a linear saturated alkyl group in the form of Ci-Cio or branched in the form of C3-CiO optionally substituted with one or more groups, which may be identical or different, chosen from: i) -O-R3; ü) -S-R3 ; R 2 denotes a radical chosen from: a) a hydrogen atom; b) a linear saturated hydrocarbon group in C1-C12 or branched in C3-C12 or cyclic in C3-C8, optionally substituted with one or more groups, which may be identical or different, selected from: i) -O-R3; ii) -S-R3; iii) -C(O)-O-R3; (iv) an aryl group in C5-Ci2, optionally substituted with one or more hydroxyl groups and / or with one or more CrC8 alkoxy radicals; c) a C5-C12 aryl group, optionally substituted with one or more hydroxyl groups and / or with one or more CrC8 alkoxy radicals; and R 3 designates a radical chosen from: a) a hydrogen atom; b) a linear saturated alkyl group in Ci-CiO or branched in C3-CiO, to stabilize the compound of formula (I), its tautomer of formula (P), their salts, optical isomers, racemates, solvates, hydrates, or mixtures thereof, in the composition.