The present invention relates to the field of cosmetic products, more particularly intended for caring for keratin materials, in particular caring for the skin of the face and/or of the body.

More particularly, the present invention is directed towards proposing the use of novel resorcinol-based compounds for effectively depigmenting and/or lightening, or even bleaching, keratin materials, especially the skin of the face and/or of the body and/or for improving the complexion, especially the homogeneity and radiance thereof.

The term "skin" means all of the skin of the body, including the scalp, the mucous membranes, the semi-mucous membranes, and the skin appendages. The term "skin appendages" means the bodily hair, the eyelashes, the hair and the nails. More particularly, in the present invention, the skin of the neckline, the neck and the face, the hands, the underarms and especially the skin of the face, are considered.

The colour of human skin is mainly determined by the nature and concentration of a pigment, melanin. There are two types of melanin in epidermal cells, eumalanin, which is a brown-black coloured pigment, and pheo melanin, which is a yellow-orange coloured pigment. Melanin is synthesized by specific dendritic cells, called melanocytes, located in the basal layer of the epidermis. Melanogenesis, i.e. the formation of melanin, takes place in specific organelles, the melanosomes, which, loaded with melanin, are transferred to the neighbouring epidermal cells, the keratinocytes, via the dendrites.

The mechanism of melanogenesis is particularly complex and schematically involves the following main steps:

Tyrosine— > Dopa— > Dopaquinone— > Dopachrome— > Melanin Inside the melanosomes, three enzymes, namely tyrosinase, Tyrp 1 (for Tyrosinase-related protein 1) and Dct/Tyrp2 (for DOPAchrome tautomerase/Tyrosinase-related protein 2), play a major role in melanin production. More particularly, tyrosinase is the essential enzyme which regulates the first steps of eumelanin and pheomelanin synthesis.

The pigmentation of the skin of the face and/or of the body, and more particularly the pigmentation of the skin, depends on various factors, such as environmental factors linked to the seasons of the year, and the individual's origin.

In addition, at various periods of their life, some people see the appearance on their skin, and more especially on the hands, of darker and/or more highly coloured spots, which give the skin heterogeneity. These spots are also due to a high concentration of melanin in the skin.

A substance is acknowledged as being depigmenting if it acts directly on the vitality of the epidermal melanocytes where melanogenesis takes place, and/or if it interferes with one of the steps of melanin biosynthesis, either by inhibiting one of the enzymes involved in melanogenesis, or by inserting itself as a structural analogue of one of the chemical compounds of the melanin synthesis chain, which chain can then be blocked, thus ensuring depigmentation.

Arbutin and kojic acid are known as skin depigmenting agents. The compound 5-[(E)-2-(4-hydroxyphenyl)ethenyl]benzene-l,3-diol, which is an aromatic resorcinol, is also known as a skin depigmenting agent, especially in JP01038009.

Substances with efficient depigmenting action, especially better than that of the compound 5-[(E)-2-(4-hydroxyphenyl)ethenyl]benzene-l,3-diol, have been sought.

Certain resorcinol-based compounds are already known in the prior art for their depigmenting activity. In this regard, mention may be made in particular of FR2971249.

There remains a need for a new agent for bleaching keratin materials, especially the skin, which also makes it possible especially to improve the homogeneity of the complexion and to revive the radiance of the complexion, the action of which is as effective as those which are known, but which does not have their drawbacks, i.e. which is stable, non-toxic to the skin and effective even at low concentration.

In this regard, the Applicant Company has, surprisingly and unexpectedly, discovered that particular active agents have good depigmenting activity and also an action which allows them to prevent, reduce and/or treat impairment of the skin complexion or of the colour of the semi-mucous membranes, i.e. in particular an activity which allows them to improve the homogeneity of the complexion and to revive the radiance of the complexion, even at low concentration.

In this regard, the Applicant has discovered, surprisingly and unexpectedly, that certain resorcinol derivatives have good depigmenting activity, even at low concentration, without showing any cytotoxicity.

One subject of the invention is thus the compounds of formula (I) as defined below.

Similarly, a subject of the invention is a composition comprising, in a physiologically acceptable medium, at least one compound of formula (I) as defined below.

The invention also relates to the non-therapeutic cosmetic use of at least one compound of formula (I) as defined below as an active agent for depigmenting, lightening and/or bleaching keratin materials, especially the skin of the face and/or of the body, and/or for preventing, reducing and/or treating impairment of the skin complexion or of the colour of the semi-mucous membranes.

The inventors have in fact demonstrated that the abovementioned compounds of formula (I) as defined in the present invention have depigmenting, lightening or even bleaching activity on keratin materials, especially on the skin. More particularly, it has been shown, as detailed in the experimental section below, that these compounds of formula (I) reduce melanin synthesis.

In particular, the present invention relates to the cosmetic use of at least one compound of formula (I) as defined in the present invention or a cosmetically acceptable salt thereof for improving the homogeneity of the complexion and/or for reviving the radiance of the complexion.

The compounds of formula (I) as defined in the present invention or a cosmetically acceptable salts thereof are not, at the present time, known to be used for depigmenting, lightening or even bleaching keratin materials, especially the skin, or for improving the homogeneity of the complexion, or for reviving the radiance of the complexion.

A subject of the invention is also a non-therapeutic cosmetic treatment process for depigmenting, lightening and/or bleaching keratin materials, especially the skin of the face and/or the body, and/or for preventing, reducing and/or treating impairment of the skin complexion or of the colour of the semi-mucous membranes, comprising at least one step consisting in applying, to the skin of the face and/or the body, at least one composition comprising at least one compound of formula (I) as defined in the present invention.

For the purposes of the present invention, the term "preventing" or "prevention" means at least partially reducing the risk of occurrence of a given phenomenon, i.e., in the present invention, impairment of the skin complexion or of the colour of the semi-mucous membranes.

A subject of the invention is also the compounds of formula (I) as defined below for their dermato logical use for depigmenting the skin.

For the purposes of the present invention, the term "keratin materials" means human keratin materials, and in particular the skin, bodily hair, the eyelashes, head hair, the lips and the nails of human beings.

The term "skin" means all of the skin of the body, including the scalp, the mucous membranes and the semi-mucous membranes. More particularly, in the present invention, the skin of the neckline, the neck and the face, the hands, the underarms and especially the skin of the face, are considered.

The compounds of formula (I) in accordance with the invention may also make it possible to depigment and/or lighten bodily hair, the eyelashes, head hair, and also the lips and/or the nails.

More particularly, the term "keratin materials" denotes human skin.

One subject of the invention is thus the novel compounds of formula (I) corresponding to formula (I) below:

(I)

X denotes an oxygen atom O, a sulfur atom S or a radical NRa

Ri and R2 independently denote:

- a hydrogen atom H,

- a linear or branched, saturated Ci-C6 hydrocarbon-based radical, optionally substituted with one or more hydroxyl radicals,

- a linear or branched, unsaturated C2-C6 hydrocarbon-based radical, optionally substituted with one or more hydroxyl radicals, or

Ri and R2 may form, together with each carbon atom that bears them, a phenyl group optionally substituted with one or more radicals -ORb,

Ra and Rb independently denote:

- a hydrogen atom H,

- a linear or branched saturated Ci-C6 hydrocarbon-based radical, or

- an acetyl radical;

and also the salts thereof, the solvates thereof and the optical and/or geometrical isomers thereof, including enantiomers and diastereoisomers, and the racemic mixtures thereof, alone or as a mixture.

In the context of the present invention, the salts of the compounds of formula (I) comprise the conventional non-toxic salts of said compounds such as those formed from acid or base.

As salts of the compound of formula (I), mention may be made of the salts obtained by addition of the compound of formula (I) with a base, which may be organic or mineral. The base may thus be a mineral base, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonium hydroxide, magnesium hydroxide, lithium hydroxide, or sodium, potassium or calcium carbonate or hydrogen carbonate, for example. The base may also be 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 especially of 2-amino-2-methylpropanol, ethanolamine, triethanolamine, 2-dimethylaminopropanol, 2-amino-2-(hydroxymethyl)- 1 ,3-propanediol and 3-(dimethylamino)propylamine.

The salts may also denote salts of addition with amino acids, for instance lysine, arginine or guanidine.

Advantageously, the salts of the compounds of formula (I) may be chosen from alkali metal or alkaline-earth metal salts such as sodium, potassium, calcium or magnesium salts; ammonium salts.

The solvates comprise conventional solvates such as those formed during the preparation of said compounds due to the presence of solvents. Examples that may be mentioned include solvates due to the presence of water or of linear or branched alcohols, such as ethanol or isopropanol.

The optical isomers are especially enantiomers and diastereoisomers.

A "Cx-Cy hydrocarbon-based radical" denotes a radical comprising from x to y carbon atoms. Such a hydrocarbon-based radical may be linear and saturated and typically contain from 1 to 6 carbon atoms or from 1 to 2 carbon atoms such as a methyl or ethyl radical. It may also be linear and unsaturated (ethylenic double bond) and typically contain from 2 to 6 carbon atoms or from 2 to 4 carbon atoms. It may also be branched and typically contain from 3 to 6 carbon atoms or from 3 to 5 carbon atoms.

Unless otherwise indicated, a "Cx-Cy hydrocarbon-based radical" denotes a saturated linear alkyl group comprising from x to y carbon atoms.

Preferentially, the linear saturated or branched hydrocarbon-based radicals are chosen from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl and hexyl.

More preferentially, the saturated linear or branched hydrocarbon-based radicals are chosen from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl and hexyl, more preferentially from methyl and ethyl, and even more preferentially methyl.

A "Cx-Cy alkyl radical" denotes a saturated Cx-Cy hydrocarbon-based radical. Such a hydrocarbon-based radical may be linear and saturated and typically contain from 1 to 6 carbon atoms or from 1 to 2 carbon atoms such as a methyl or ethyl radical. It may also be branched and typically contain from 3 to 6 carbon atoms or from 3 to 5 carbon atoms. Unless otherwise indicated, a "Cx-Cy alkyl radical" denotes a saturated linear alkyl group comprising from x to y carbon atoms.

The saturated linear or branched Ci-C6 hydrocarbon-based radical and the unsaturated linear or branched C2-C6 hydrocarbon-based radical according to the invention may optionally be substituted with one or more hydroxyl radicals, especially with one to three hydroxyl radicals, in particular with one hydroxyl radical.

An "aryl group" denotes an unsaturated or partially unsaturated monocyclic carbocyclic group, containing 6 carbon atoms, which is a phenyl group, and which is optionally substituted with one or more identical or different radicals -ORb as defined above, especially 1 to 3 radicals -ORb, preferably one radical -ORb as defined above.

Preferentially, Ri and R2 form, together with each carbon atom that bears them, a phenyl group optionally substituted with one or more identical or different radicals -ORb as defined above, especially 1 to 3 radicals -ORb, preferably one radical -ORb as defined above, and more preferentially said phenyl radical is unsubstituted.

In a particularly preferred manner, Ri and R2 form, together with each carbon atom that bears them, an unsubstituted phenyl group.

In one particular embodiment according to the invention, the compounds of formula (I) and also the salts thereof, the solvates thereof and the optical and/or geometrical isomers thereof, including enantiomers and diastereoisomers, and the racemic mixtures thereof, alone or as a mixture, are such that:

X denotes an oxygen atom O, a sulfur atom S or a radical NRa;

Ri and R2 independently denote:

- a hydrogen atom H,

- a linear saturated Ci-C6 hydrocarbon-based radical, or

Ri and R2 may form, together with each carbon atom that bears them, a phenyl group optionally substituted with one or more radicals -ORb,

Ra and Rb independently denote:

- a hydrogen atom H,

- a linear saturated C1-C2 hydrocarbon-based radical,

- an acetyl radical.

Preferentially, the compounds of formula (I) and also the salts thereof, the solvates thereof and the optical and/or geometrical isomers thereof, including enantiomers and diastereoisomers, and the racemic mixtures thereof, alone or as a mixture, are such that:

X denotes an oxygen atom O, a sulfur atom S or a radical NRa;

Ri and R2 independently denote:

- a hydrogen atom H,

- a linear saturated C1-C4 hydrocarbon-based radical such as methyl or ethyl, or

Ri and R2 may form, together with each carbon atom that bears them, a phenyl group optionally substituted with one or more radicals -ORb, and in particular an unsubstituted phenyl radical.

Ra and Rb independently denote

- a hydrogen atom H,

- a methyl radical, or

- an acetyl radical.

Preferably, the compounds of formula (I) and also the salts thereof, the solvates thereof and the optical and/or geometrical isomers thereof, including enantiomers and diastereoisomers, and the racemic mixtures thereof, alone or as a mixture, are such that:

X denotes an oxygen atom O, a sulfur atom S or an NH radical;

Ri and R2 independently denote a hydrogen atom H,

or

Ri and R2 may form, together with each carbon atom that bears them, a phenyl group.

In a particularly preferred embodiment according to the invention, the compounds of formula (I) and also the salts thereof, the solvates thereof and the optical and/or geometrical isomers thereof, including enantiomers and diastereoisomers, and the racemic mixtures thereof, alone or as a mixture, are such that:

Ri denotes a hydrogen atom H,

R2 denotes a hydrogen atom H,

X denotes an oxygen atom O, a sulfur atom S or an NH radical.

In another particularly preferred embodiment according to the invention, the compounds of formula (I) and also the salts thereof, the solvates thereof and the optical and/or geometrical isomers thereof, including enantiomers and diastereoisomers, and the racemic mixtures thereof, alone or as a mixture, are such that:

X denotes an oxygen atom O, a sulfur atom S or an NH radical,

Ri and R2 form, together with each carbon atom that bears them, a C6 aryl group.

According to a first preferred variant, the compounds of formula (I) and also the salts thereof, the solvates thereof and the optical and/or geometrical isomers thereof, including enantiomers and diastereoisomers, and the racemic mixtures thereof, alone or as a mixture, are such that Ri and R2 are identical and each denote a hydrogen atom, X, Ra and Rb having the definitions given previously or hereinbelow, in the preferences.

According to this variant, preferably, X denotes an oxygen atom O, a sulfur atom S or an NH radical.

As examples of compounds of formula (I) according to this variant, mention may be made of the compounds A, B and C described hereinbelow, and also the salts and solvates thereof, alone or as a mixture.

According to a second preferred variant, the compounds of formula (I) and also the salts thereof, the solvates thereof and the optical and/or geometrical isomers thereof, including enantiomers and diastereoisomers, and the racemic mixtures thereof, alone or as a mixture, are such that Ri and R2 form, together with each carbon atom that bears them, a phenyl group optionally substituted with one or more radicals -ORb, X, Ra and Rb having the definitions given previously or hereinbelow, in the preferences.

According to this variant, preferably, Ri and R2 form, together with each carbon atom that bears them, a phenyl group that is not substituted with a radical -ORb.

As examples of compounds of formula (I) according to this second variant, mention may be made of the compounds C, D and E described hereinbelow, and also the salts and solvates thereof, alone or as a mixture.

As examples of compounds of formula (I) according to this form of the invention, mention may be made of the compounds A, B, C, D, E and F described hereinbelow, and also the salts and solvates thereof, alone or as a mixture.

WE CLAIMS

1. Compounds of formula (I):

(I)

in which:

X denotes an oxygen atom O, a sulfur atom S or a radical NRa;

Ri and R2 independently denote:

- a hydrogen atom H,

- a linear or branched, saturated Ci-C6 hydrocarbon-based radical, optionally substituted with one or more hydroxyl radicals,

- a linear or branched, unsaturated C2-C6 hydrocarbon-based radical, optionally substituted with one or more hydroxyl radicals, or

Ri and R2 form, together with each carbon atom that bears them, a phenyl group optionally substituted with one or more radicals -ORb,

Ra and Rb independently denote:

- a hydrogen atom H,

- a linear or branched saturated Ci-C6 hydrocarbon-based radical, or

- an acetyl radical;

and also the salts thereof, the solvates thereof and the optical and/or geometrical isomers thereof, including enantiomers and diastereoisomers, and the racemic mixtures thereof, alone or as a mixture.

2. Compounds according to the preceding claim, in which:

X denotes an oxygen atom O, a sulfur atom S or a radical NRa;

Ri and R2 independently denote:

- a hydrogen atom H,

- a linear saturated Ci-C6 hydrocarbon-based radical, or

Ri and R2 form, together with each carbon atom that bears them, a phenyl group optionally substituted with one or more radicals -ORb,

Ra and Rb independently denote:

- a hydrogen atom H,

- a linear saturated C1-C2 hydrocarbon-based radical,

- an acetyl radical.

3. Compounds according to one of the preceding claims, in which: X denotes an oxygen atom O, a sulfur atom S or a radical NRa;

Ri and R2 independently denote:

- a hydrogen atom H,

- a linear saturated C1-C2 hydrocarbon-based radical, or

Ri and R2 form, together with each carbon atom that bears them, a phenyl group optionally substituted with one or more radicals -ORb,

Ra and Rb independently denote

- a hydrogen atom H,

- a methyl radical, or

- an acetyl radical.

4. Compounds according to Claim 1, in which:

X denotes an oxygen atom O, a sulfur atom S or a radical NRa;

Ri and R2 independently denote:

- a hydrogen atom H,

or

Ri and R2 form, together with each carbon atom that bears them, a phenyl group,

Ra denotes a hydrogen atom H.

5. Compounds according to one of the preceding claims, chosen from:

and also the salts thereof, the solvates thereof and/or the optical isomers thereof, including enantiomers and diastereoisomers, and the racemic mixtures thereof, alone or as a mixture.

6. Composition comprising, in a physiologically acceptable medium, at least one compound of formula (I) according to any one of the preceding claims.

7. Composition according to the preceding claim, characterized in that compound (I) is present in a content of between 0.01% and 10% by weight, preferably between 0.1 % and 5% by weight and preferentially from 0.5%> to 3% by weight, relative to the total weight of the composition.

8. Composition according to either of Claims 6 and 7, characterized in that it comprises at least one adjuvant chosen from the group formed by organic solvents, especially C2-C6 alcohols; oils, especially hydrocarbon-based oils and silicone oils; waxes, pigments, fillers, dyes, surfactants, emulsifiers; cosmetic active agents, organic or mineral photoprotective agents, polymers, thickeners, preserving agents, fragrances, bactericides, ceramides, odour absorbers and antioxidants.

9. Composition according to any one of Claims 6 to 8, characterized in that it comprises at least one active agent chosen from desquamating agents; calmatives, organic or mineral photoprotective agents, moisturizers; depigmenting agents other than the compounds of the invention; anti-glycation agents; NO-synthase inhibitors; agents for stimulating the synthesis of dermal or epidermal macro molecules and/or for preventing their degradation; agents for stimulating fibroblast and/or keratinocyte proliferation or for stimulating keratinocyte differentiation; tensioning agents; anti-pollution agents and/or free-radical scavengers; agents acting on the microcirculation; agents acting on the energy metabolism of cells; and mixtures thereof.

10. Non-therapeutic cosmetic process for depigmenting, lightening and/or bleaching keratin materials, especially the skin of the face and/or the body, and/or for preventing, reducing and/or treating impairment of the skin complexion or of the colour of the semi-mucous membranes, comprising at least one step consisting in applying, to the skin of the face and/or the body, at least one composition comprising at least one compound of formula (I) as defined according to any one of Claims 1 to 5 or of a composition containing same according to any one of Claims 6 to 9.

11. Process according to the preceding claim, for depigmenting, lightening and/or bleaching the skin.

12. Non-therapeutic cosmetic use of a compound of formula (I) as defined according to any one of Claims 1 to 5 or of a composition containing same according to any one of Claims 6 to 9, as an active agent for depigmenting, lightening and/or bleaching keratin materials, in particular the skin of the face and/or of the body, and/or for preventing, reducing and/or treating impairment of the skin complexion or of the colour of the semi-mucous membranes.

13. Cosmetic use according to Claim 12, for making the complexion homogeneous and/or reviving the radiance of the complexion.