WO2008058999A1

WO2008058999A1 - Novel siliceous dithiolane-based compounds and use thereof

Info

Publication number: WO2008058999A1
Application number: PCT/EP2007/062343
Authority: WO
Inventors: Xavier Marat; Karine Lucet-Levannier; Marie-Jocelyne Pygmalion
Original assignee: LOreal SA
Current assignee: LOreal SA
Priority date: 2006-11-17
Filing date: 2007-11-14
Publication date: 2008-05-22
Anticipated expiration: 2009-05-17

Abstract

The present invention relates to novel siliceous dithiolane-based compounds of formulae (I), (I') and (II), to their use for therapeutic or cosmetic purposes, especially as agents for protecting against oxidative stress, in particular for photoprotecting the skin, and also to cosmetic or dermatological compositions containing them.

Description

Novel siliceous dithiolane-based compounds and use thereof

The present invention relates to novel siliceous dithiolane-based compounds of formulae (I), (I') and (II) , to their use in compositions that are useful for treating or preventing disorders induced by oxidative stress, especially caused by sunlight, and to compositions containing them.

The skin is the outermost organ of our body and is thus the first target for environmental stress factors, most particularly represented by the ultraviolet radiation of sunlight, UVB and UVA. Specifically, acute or chronic exposure to sunlight is known to induce deleterious biological and clinical effects on the body.

Cutaneous damage associated with chronic (repeated irradiation) or acute (strong irradiation) exposure to UV-A or UV-B rays has been extensively studied; it is especially known that : - UV-B rays (290-300 nm; 5% of the total UV range), which have the highest-energy wavelengths, above all affect the epidermal cells (keratinocytes) , by acting on DNA;

UV-A rays (320-400 nm; 95% of the total UV range), which are more penetrating, reach the dermal cells such as the fibroblasts and act indirectly via the generation of free radicals; furthermore, prolonged exposure to ultraviolet radiation has the effect of stimulating the expression of collagenases, particularly type-1 matrix metalloprotease (MMP-I) .

At the cellular and molecular levels, the impact of UVB and UVA radiation induces various reactions, including direct and indirect induction of DNA lesions.

Among the types of direct induction of DNA lesions, some are specific to UV radiation, for instance pyrimidine dimers and 6,4 photo products. In the event of an error during repair by the specialized enzymatic systems (nucleotide excision repair NER, or global excision repair GER) , they may be responsible for mutations, which are themselves the cause of tumoural processes resulting in the development of skin cancers. A very high incidence of mutations characteristic of the impact of solar UV rays is, for that matter, found in the cells derived from these tumours. These DNA lesions are also the cause of apoptosis processes inducing the formation of characteristic cells in the epidermis: the "sunburn cells". It will also be noted that UV rays are responsible at the cellular level for the generation of reactive oxygen species, which are themselves the cause of many biological effects, for instance, the induction of oxidative damage to DNA (8-oxo guanine) or to numerous genes.

Finally, in addition to the effects mainly described on the two major cell types of the skin, namely the keratinocytes that form the stratified and differentiated epidermis, and the fibroblasts that are responsible for the synthesis and renewal of the dermal extracellular matrix, UV rays also have an impact on melanocytes (cells responsible for pigmentation) and the Langerhans cells, having an antigen-presenting immune function.

The deleterious effects of UV on the skin (erythema, photocarcinogenesis, photoageing, photo-immuno- suppression, pigmentation disorders, etc.) are induced by a direct action of UV rays on certain cellular chromophores such as DNA, but also by an indirect action. The reason for this is that the energy transported by the UV rays is capable of triggering the formation of activated oxygen species (AOS) , for instance singlet oxygen and the superoxide anion, via a photosensitization reaction involving endogenous photo- sensitizers such as riboflavins, bilirubins, phaeomelanin and porphyrin derivatives. Singlet oxygen and the superoxide anion undergo a cascade of reactions leading to the production of other AOSs, for instance hydrogen peroxide and hydroxyl radicals. The AOSs thus generated damage DNA, cell membranes and certain proteins (enzymes, transcription factors, etc.).

Cells are equipped with an enzymatic antioxidant defence (superoxide dismutases Cu-Zn and Mn, catalases, glutathione peroxidases, etc.) and non-enzymatic defences (vitamins E and C, thiols, including glutathione, β-carotene, trace elements, etc.), whose role is to maintain the intracellular redox potential, but this defence capacity may be exceeded during an intense oxidative stress.

Glutathione tripeptide (γ-L-glutamyl-L-cysteinyl- glycine or GSH) is the most ubiquitous and abundant of the non-protein low molecular weight thiols. The majority of the intracellular GSH exists in reduced form (GSH) . Glutathione disulfide (GSSG) represents less than 0.5% of the total GSH. In the majority of animal cells, the concentration of GSH is between 1 and 10 mM, whereas it is from about 0.5 to 10 μM in the plasma. The thiol function located on the cysteine residue gives it a redox potential (about -230 mV) that is predominant in metabolic redox phenomena. Its reductive and nucleophilic properties play a major role in protecting against the oxidative damage of lipids, proteins and nucleic acids. Under conditions of oxidative stress, its protective and detoxifying role results mainly from its coenzyme function for glutathione peroxidases and glutathione-S-transferases . It also participates in synergistic interactions with other components of the antioxidant protective system such as vitamin C, vitamin E and superoxide dismutases.

A reduction in the level of glutathione will thus affect the cellular redox balance. It is especially known that exposure to UV leads to a depletion of the level of intracellular GSH, thus increasing the sensitivity of cells to oxidative stress.

The skin may be protected from the harmful effects of UV radiation by using sunscreens. These products contain molecules that absorb the harmful wavelengths before they reach the skin and damage it, thus preventing the acute and chronic effects of exposure to UV.

However, sunscreens do not have a global action. Since there are no screening agents that allow total absorption of the harmful wavelengths (UVB, UVA and long UVA) , a photoprotection strategy based on induction of the endogenous antioxidant defence systems offers advantageous perspectives.

There is thus a real need to find additional solutions in this field in order to reconstitute the level of endogenous glutathione after exposure to UV. This may be envisaged by stimulating with an active agent the natural endogenous systems for cellular defence and/or repair after a UV stress.

Lipoic acid or thioctic acid (1, 2-dithiacyclopentane-3- valeric acid) is an endogenous dithiol widely found in plants and animals. It is a coenzyme for the metabolism of lipids and carbohydrates in mitochondrial multienzyme complexes such as pyruvate dehydrogenase and α-ketoglutarate dehydrogenase. Lipoic acid also increases the cellular level of glutathione via regeneration of oxidized glutathione (GSSG) and increasing the activity of γ-glutamylcysteine ligase (enzyme which controls GSH synthesis) .

The Applicant has now discovered that certain novel derivatives bearing a siliceous dithiolane unit, and in particular siliceous lipoic acid derivatives, make it possible to significantly increase the level of glutathione after induced UV depletion.

Thus, the present invention relates to compounds of general formulae (I) and (I'):

0)

(I¹)

in which:

A is a radical of formula (1) below:

(1)

in which: L is a divalent radical for attaching the radical A to the silicone chain, m represents an integer 0, 1, 2, 3, 4, 5, 6, 7 or 8, - X represents an oxygen, nitrogen or sulfur atom,

Y represents an oxygen or nitrogen atom, a group NR⁴ or a sulfur atom,

R⁴ represents a hydrogen, a linear C1-C20, or branched C3-C20, saturated or unsaturated C2-C20 alkyl, optionally substituted with an optionally substituted phenyl radical,

R denotes a linear C1-C30 or branched C3-C20 saturated, or C2-C20 unsaturated hydrocarbon-based group, a halogenated C1-C8 hydrocarbon-based group or a trimethylsilyloxy group;

B, which may be identical or different for the same compound, is chosen from the radicals R and A; r is an integer between 0 and 50 inclusive; s is an integer between 0 and 20 inclusive, and if s is 0, at least one of the two radicals B is A; u is an integer between 1 and 6 inclusive; t is an integer between 0 and 10 inclusive; it being understood that t + u is greater than or equal to 3.

Preferably, L corresponds to either of the formulae (a) and (a' ) below:

in whi ch :

Z is a linear or branched, saturated or unsaturated Ci-Cβ alkanediyl radical, optionally substituted with a hydroxyl or linear or branched, saturated or unsaturated C2-C8 alkyl radical;

Y' represents a hydrogen atom, a hydroxyl radical or a linear or branched, saturated or unsaturated Ci-Cs alkyl radical; p is 0 or 1.

Preferably, the radicals R, which may be identical or different, are chosen from linear Cl-ClO, or branched C3-C10, saturated or unsaturated alkyl radicals, the phenyl radical and the trifluoropropyl radical, at least 80% by number of the radicals R being a methyl radical .

In formulae (I) and (I') above, the preferred compounds are those for which: ° A is a radical of formula (1) above with m = 4;

⁰ L is such that Y' = H, Z = CH₂ and p = 1;

⁰ X represents an oxygen atom;

⁰ Y represents an oxygen or nitrogen atom, NR⁴ with

R⁴ representing a hydrogen, a linear C1-C20 or branched C3-C20, saturated or unsaturated alkyl, optionally substituted with an optionally substituted phenyl radical;

⁰ R is methyl;

⁰ B is methyl or a radical A; r is 0, 1, 2 or 3;

⁰ s is 0, 1, 2 or 3;

⁰ t + u is 3, 4 or 5.

In formulae (I) and (I') above, the compounds that are more particularly preferred are those for which:

⁰ A is a radical of formula (1) above with m = 4; ⁰ L is such that Y' = H, Z = CH₂ and p = 1; 0 X represents an oxygen atom; ⁰ Y represents an oxygen or nitrogen atom (NR⁴ with R⁴ = H) ;

⁰ R is methyl;

⁰ B is methyl or a radical A; ° r = 0; s = 0 or 1.

The invention also relates to the compounds of formula (H) :

R2

(H) such that

^■ m represents an integer that may be 0, 1, 2, 3, 4, 5, 6, 7 or 8; ■ X represents an oxygen, nitrogen or sulfur atom;

^■ Y represents an oxygen or nitrogen atom, a group NR⁴ or a sulfur atom;

^■ v represents an integer that may be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10; ■ R¹, R² and R³ represent, independently of each other, a linear Cl-ClO or branched C3-C10, saturated or unsaturated alkyl radical, possibly comprising one or more halogen atoms (for example Cl, Br or F) , a phenyl radical or a benzyl radical; ■ D denotes hydrogen, a linear C1-C8 or branched C2-C8, saturated or unsaturated alkyl radical, a phenyl radical; the group Si (CH₃) ₃ with the proviso that when D is Si (CH₃) 3 then v = 0 and R¹, R² and R³ are methyl;

^■ W is a linear C1-C8 or branched C3-C8, saturated or unsaturated alkyl radical, or C2-C8 alkylene radical, optionally substituted with a hydroxyl;

^■ R⁴ represents a hydrogen, a linear C1-C20 or branched C3-C20, saturated or unsaturated alkyl, optionally substituted with an optionally substituted phenyl radical.

In formula (II) above, the preferred compounds are those for which:

^■ m = 4; X = 0;

Y = 0 or NR⁴;

R¹ to R³ denote linear C1-C4 or branched C3-C4 alkyl possibly comprising a phenyl radical, and more particularly methyl, ethyl, phenyl or -CH₂-Ph;

^■ R⁴ represents a hydrogen, a linear C1-C20 or branched C3-C20, saturated or unsaturated alkyl, optionally substituted with an optionally substituted phenyl radical; v = 0, 1 or 2;

^■ W is a methylene -CH₂- or -CHOH-CH₂- when v is other than 0;

D is -H or (CH₃)₃.

In formula (II) above, the compounds that are more particularly preferred are those such that: m = 4;

X = O; ° Y = O or NH;

⁰ R¹ to R³ denote C1-C4 alkyl and more particularly methyl;

⁰ W is a methylene -CH₂-.

In particular, the compounds according to the invention are :

1. (Trimethylsilyl) methyl 5- (1, 2-dithiolan-3- yl) pentanoate

2. 2- (Trimethylsilyl) ethyl 5- (1, 2-dithiolan-3-yl) - pentanoate

3. 3- (Trimethylsilyl) propyl 5- (1, 2-dithiolan-3-yl] pentanoate

4. [Ethyl (dimethyl) silyl] methyl 5- (1, 2-dithiolan-3- yl) pentanoate

5. 2-Hydroxy-3- (trimethylsilyl) propyl 5- (1,2- dithiolan-3-yl) pentanoate

6. [Dimethyl (phenyl) silyl] methyl 5- (1, 2-dithiolan-3- yl) pentanoate

7. [Benzyl (dimethyl) silyl] methyl 5- (1, 2-dithiolan-3- yl) pentanoate

8. 5- (1, 2-Dithiolan-3-yl) -N- [ (trimethylsilyl: methyl ] pentanamide

9. N- [bis (Trimethylsilyl) methyl] -5- (1, 2-dithiolan-3- yl) pentanamide

10. 5- (l,2-Dithiolan-3-yl) -N- [3- (trimethylsilyl: propyl ] pentanamide

11. 5- (l,2-Dithiolan-3-yl) -N- (3-{ 1, 3, 3, 3-tetramethyl- 1- [ (trimethylsilyl) oxy] disiloxanyl }propyl) pentanamide

12. N,N'-[(1,1,3, 3-Tetramethyldisiloxane-l, 3-diyi; dipropane-3, 1-diyl] bis [5- (1, 2-dithiolan-3-yl) - pentanamide]

The compounds of formulae (I), (I') and (II) may be obtained according to two general approaches.

The first conventionally uses a hydrosilylation reaction starting with the corresponding siloxane or silane derivative in which, for example, all the radicals A are hydrogen atoms. This derivative is referred to hereinbelow as the "SiH derivative".

The SiH groups may be present in the chain and/or at the chain ends. These SiH derivatives are products that are well known in the silicone industry and are generally commercially available. They are described, for example, in American patents US-A-3 220 972, US-A-3 697 473 and US-A-4 340 709.

The SiH derivatives corresponding to the compounds of formulae (I) and (I') may thus be represented by formulae (2) to (4) below:

H-SiR₁R₂R₃ (2)

(3)

(4)

in which :

Ri, R2 and R3 have the meaning given above for formulae (II) ,

R, r, s, t and u have the meaning given above for formulae (I) and (I'),

B' , which may be identical or different, are chosen from the radicals R and a hydrogen atom.

In order to prepare the compounds of the invention of formulae (I), (I') and (II) above, the process is performed in the following manner: a hydrosilylation reaction is performed on the SiH derivative of formula (2), (3) or (4) in the presence of a catalytically effective amount of a platinum catalyst on an organic dithiolane derivative chosen from those of formula (5) below:

(5)

in which X, Y and m have the same meaning as in formula (1) above and L' corresponds to one of the two formulae (b) and (b' ) below:

HC (^zv- (b¹)

in which Y' , Z and p have the same meanings as in formulae (a) and (a') above.

The hydrosilylation reaction is thus performed according to one of the following two reactions:

-SHH + CH₂=C — > ≡Si~CH₂-CH-

(grafting onto formula (b) ) or

(grafting onto formula (b' ) )

For example, on a lipoic derivative bearing an allylamide function:

A second route for preparing the compounds of formulae

(I) and (II) consists in performing esterification reactions or ester, thioester or amide formation reactions from carboxylic acid or from derivatives that are synthetically compatible with the chosen route.

These derivatives may be obtained via one of the four routes described in the following scheme taken with lipoic acid as the backbone:

in which Y, D, W, R₁ to R₃ and v have the same meanings as those indicated above for formula (II), Hal represents a halogen atom and more particularly chlorine, and M⁺ represents an alkali metal and more particularly sodium or potassium.

Reagents that may be mentioned include hydroxymethyl- trimethylsilane (RN 3219-63-4), 2- (trimethyl- s i lyl ) ethanol ( RN 2 91 6- 68 - 9 ) and 3 - ( t rime thy 1 - s i lyl ) propanol ( RN 2 917 - 47 - 7 ) , which are commercial products .

Halosilane derivatives that may be mentioned include chloropropyltrimethylsilane (RN 2344-83-4) and chloro- methyltrimethylsilane (RN 2344-80-1) sold by the company Wacker.

Mention may also be made of the following commercial products : iodomethyltrimethylsilane (RN 4206-67-1), (chloro- methyl)dimethylethylsilane (RN 3121-77-5), (chloro- methyl) dimethyl-n-butylsilane (RN 3121-75-3), (chloro- methyl) dimethylpentylsilane (RN 73013-39-5), (chloro- methyl) dodecyldimethylsilane (RN 70851-47-7), (chloro- methyl) triethylsilane (RN 757-34-6), 2-chloroethyl- trimethylsilane (RN 7787-87-3), bis (trimethyl- silyl)methylchloride (RN 5926-35-2), (chloro- methyl) dimethylphenylsilane (RN 1833-51-8), (chloro- methyl) diphenylmethylsilane (RN 18407-40-4) and (trimethylsilylmethyl) dimethylchloromethylsilane (RN 18306-73-5) .

Mention may be made of aminomethyltrimethylsilane (RN 18166-02-4) sold by the company Gelest, and also (phenyl) (trimethylsilyl) methylamine, bis (trimethyl- silyl) methylamine (RN 134340-00-4), and aminopropyl- trimethylsilane (RN 18187-14-9), and also other compounds cited by Speier JL, J. Org. Chem., 1971, 36, 21, 3120-3126 and Shina K, CAS AN 1961, 81299.

The particularly preferred compounds of formulae (I), (I') and (II) may be advantageously obtained from lipoic acid.

The Applicant has demonstrated that daily UV exposure (simulation of average UV daylight, L'Oreal concept, Christiaens FJ and al . , Standard ultraviolet daylight for nonextreme exposure conditions, Photochem

Photobiol, 2005) led to a decrease in the intracellular level of GSH on HaCaT cells (keratinocytes obtained from an adult human skin implant spontaneously immortalized in vitro) . The depletion was at a maximum

6 hours after exposure (about 40% decrease) and the basal state was regained 24 hours after the daily UV

(DUV) exposure.

The compounds according to the invention can prevent and/or correct this depletion of GSH, and can thus "boost" the endogenous antioxidant defence systems, in order to prepare the skin to better withstand a UV stress and to help it to repair itself. Their activity was compared with a reference compound, lipoic acid, which is known for increasing the level of GSH.

The Applicant has thus shown that the capacity for increasing the level of GSH of the compounds according to the invention is substantially higher than that of lipoic acid measured under the same conditions (see Example 5) .

The present invention also relates to the use of the compounds of general formulae (I), (I') and/or (II) as agents for stimulating the intracellular synthesis of glutathione and/or for maintaining an intracellular level of glutathione at an amount that is sufficient for preventing oxidative damage caused by free radicals on cells.

Thus, the use according to the invention can increase the cellular antioxidant defence systems, in particular the antioxidant defence systems of skin cells. The skin cells are especially fibroblasts, keratinocytes, melanocytes, Langerhans cells, etc. According to one advantageous use of the invention, the compounds of general formulae (I), (I') and (II) are useful as skin photoprotective agents.

This use may be useful whether the skin has undergone exposure to daylight of an intensity lower than the minimum erythemal dose and whose effects do not produce visible signs on the skin, or whether the UV-ray damage is visible, for example by the appearance of redness on the skin.

Consequently, the impairments range from simple discomfort such as a uniquely perceptible sensation of heating of the skin, to redness, or even irritation.

The term "skin" means the entire skin surface of the human body, including skin, mucous membranes and semi- mucous membranes, thus including the lips, the scalp, etc., and also the skin's appendages, especially the nails, bodily hair and head hair.

Thus, the compounds of general formulae (I), (I') and/or (II) are useful for preventing and/or treating UV stress and/or heating sensations caused by solar radiation, in particular UVA and/or UVB.

The compounds of general formulae (I), (I') and/or (II) are also useful for preparing a composition, comprising a physiologically acceptable medium, intended for preventing and/or treating skin impairments, such as skin redness and irritation, caused by solar radiation.

The compounds of general formulae (I), (I') and/or (II) are also useful for the preparation of a composition, comprising a physiologically acceptable medium, for preventing and/or treating DNA lesions caused by solar radiation and thus for preventing the development of cancers, in particular skin cancers. A subject of the invention is also the use of at least one compound of formula (I), (I') or (II) for the preparation of a composition containing a physiologically acceptable medium, the said composition being intended for preventing and/or treating skin and/or mucous membrane disorders induced by irradiation with UVA and/or UVB radiation.

Solar irradiation or exposure is characterized by an exposure to sunlight, and may especially be an intense irradiation corresponding to exposure to zenithal sunlight or to solar radiation varying by an angle of 30° around this zenithal position and/or when the skin is subjected to UV radiation capable of inducing a solar erythema (redness commonly known as "sunburn") , and defined by a minimum erythemal dose (MED) . This dose varies as a function of the phototype of the individual and of the UVA/UVB ratio.

The invention is especially directed towards preventing or reducing damage induced in the skin, mucous membranes and/or the integuments of a mammal, in particular of a human being, by short exposure to erythemal doses of solar radiation.

These solar exposure conditions comprise UVA and/or UVB rays, at doses around the MED, in particular at a dose of greater than or equal to 1 MED.

As explained above, by virtue of their capacity for increasing the level of GSH, the compounds of formulae

(I), (I') and/or (II) according to the invention allow the establishment of the cutaneous antioxidant protective system.

Thus, the cosmetic use according to the invention of at least one compound of formulae (I), (I') and (II) in a composition containing a physiologically acceptable medium is particularly suitable for preparing the skin for exposure to sunlight.

According to the invention, a "physiologically acceptable medium" is either a cosmetically or pharmaceutically acceptable medium that is compatible with the skin, mucous membranes, the nails and/or the hair, or a medium that may be administered orally.

In particular, preparation of the skin for exposure to sunlight may be performed by the daily application to the skin of the said cosmetic composition for one week, and preferably two weeks, before the exposure to sunlight, just up to at least one day (between 6 and 18 hours) before the exposure to sunlight.

Whether they are of endogenous or exogenous origin, free radicals cause substantial oxidative damage, especially in cell membranes (lipid peroxidation causing degradation of the membrane permeability) , cell nuclei (destruction of DNA) and tissues, in particular connective tissue (degradation of elastin and collagen fibres, and depolymerization of polyuronic fibres) . This damage especially leads to drying-out and loss of firmness and elasticity of the skin (Grinwald et al . 1980, Agren et al . 1997).

Specialists currently consider that one of the causes of cellular ageing is the weakening of the defence capacities against free radicals and against the oxidation phenomena (especially the formation of superoxide ions) that they initiate.

Thus, more generally, the compounds of general formulae (I), (I') and/or (II) according to the invention are useful as indirect antioxidant compounds for preventing and/or limiting the formation of free radicals and/or for removing the free radicals present in cells, and may be used for any skin disorder caused by oxidative stress .

This activity of the compounds of general formulae (I), (I') and (II) is reinforced by the intrinsic antioxidant property of these compounds associated with their thiol function.

Thus, the use of the compounds according to the invention allows the clinical signs of ageing to be prevented and/or treated.

Ageing is a natural physiological phenomena whose clinical signs are generally reflected on the skin by the appearance of wrinkles and fine lines, by slackening of the cutaneous and subcutaneous tissues, by a loss of skin elasticity and by atony of the texture of the skin. The loss of firmness and tonicity of the skin, for instance wrinkles and fine lines, is at least partly accounted for by dermal atrophy and also flattening of the dermo-epidermal junction; the skin is less firm and more flaccid, and the thickness of the epidermis decreases.

In addition, the complexion of the skin is generally modified, and appears paler and yellowier. This phenomena appears to be due essentially to disorganization of the capillary circulation (less haemoglobin in the papillary dermis) . Another clinical sign of ageing is the dry and coarse appearance of the skin, which is due essentially to greater desquamation; by diffracting light rays, these squamae also contribute towards the somewhat greyish appearance of the complexion. Furthermore, numerous coloured and/or darker marks appear on the surface of the skin, and more especially on the hands, giving the skin heterogeneity. In general, these marks are due to a large production of melanin in the epidermis and/or the dermis of the skin. Moreover, diffuse irritation and occasionally telangiectasia may exist on certain areas of the skin.

Some of these signs are more particularly associated with intrinsic or physiological ageing, i.e. age- related ageing, whereas others are more specific to extrinsic ageing, i.e. ageing caused in general by the environment; this is more particularly a case of photo- ageing due to exposure to sunlight, light or any other radiation, or alternatively pollutants.

Thus, the subject of the invention is particularly suited towards the cosmetic use of at least one compound of general formulae (I), (I') and/or (II) according to the invention in a composition containing a physiologically acceptable medium, for preventing and/or treating loss of firmness and/or elasticity of the skin. Such a use especially allows the skin to regain a uniformly smooth appearance.

Another subject of the invention is the cosmetic use of at least one compound of general formulae (I), (I') and/or (II) according to the invention in a composition containing a physiologically acceptable medium, for preventing and/or treating a dull complexion and/or for reviving the complexion.

The invention is also suited to the cosmetic use of at least one compound of general formulae (I), (I') and/or (II) according to the invention in a composition containing a physiologically acceptable medium, for preventing and/or treating skin dehydration.

The subject of the invention is also more generally suited to the cosmetic use of at least one compound of general formulae (I), (I') and/or (II) according to the invention in a composition containing a physiologically acceptable medium, for preventing and/or treating the signs of ageing of the skin. The expression "signs of ageing of the skin" more particularly means pigmentation marks and/or hyperkeratosis marks and/or epidermal atrophy and/or skin roughness and/or skin dryness.

Another subject of the invention relates to the cosmetic use of at least one compound of general formulae (I), (I') and/or (II) in a composition containing a cosmetically acceptable medium, for preventing and/or treating the harmful effects of pollution on the skin.

It is known that the toxicity of atmospheric pollutants, especially gaseous pollutants such as sulfur dioxide, ozone and nitrogen oxides on the constituents of the skin (fibres, cells and enzymes) and on the sebum secreted by the skin is especially associated with their activity of free-radical initiators, which are a source of oxidation phenomena that cause cell damage in living beings.

The live cells, which are in direct and permanent contact with the external environment (especially the skin, the scalp and certain mucous membranes) , are particularly sensitive to these effects of gaseous pollutants, which are especially reflected by accelerated ageing of the skin, with a complexion that lacks radiance, and an early formation of wrinkles or fine lines, and also by a decrease in the vigour and a dull appearance of the hair.

As explained previously, an adverse effect of the presence of free radicals in the skin is that they cause peroxidation of lipids. With age (more particularly from the age of forty) , the accumulation of these peroxidized lipids is responsible for unpleasant body odour such as a rancid odour (Haze S. et al. J. Invest. Dermatol. 2001, 116 (4) : 520-4) . The subject of the invention is suited to the cosmetic use of at least one compound of general formulae (I),

(I') and/or (II) according to the invention in a composition containing a physiologically acceptable medium, for preventing and/or limiting and/or eliminating the peroxidation of skin lipids.

Thus, the subject of the invention is also useful for preventing and/or limiting and/or eliminating unpleasant body odour.

The compositions according to the invention may be intended for cosmetic and/or dermatological use. They may be compositions suitable for topical application, in particular external topical application to the skin, mucous membranes and/or the integuments.

According to another embodiment, the compositions according to the invention are suitable for the oral route, and are especially intended for oral cosmetic applications .

The amount of compound that may be used according to the invention obviously depends on the desired effect, and may thus vary within a wide range.

To give an order of magnitude, an extract as defined previously may be used topically in an amount representing from 0.001% to 20% of the total weight of the composition and preferentially in an amount representing from 0.01% to 10% of the total weight of the composition.

Formulation of the compositions

Preferably, the composition according to the invention comprising at least one compound of formulae (I), (I') and/or (II) is constituted of a cosmetically acceptable medium, i.e. a medium that has a pleasant colour, odour and feel and that does not cause any unacceptable discomfort .

The compositions are preferably cosmetic compositions or products. The term "cosmetic product" especially means any substance or preparation intended to be placed in contact with the various surface parts of the human body (epidermis, pilous and hair system, nails, lips and external genital organs) or with the teeth and the oral mucosae for the purpose, exclusively or mainly, for cleaning them, fragrancing them, modifying their appearance and/or correcting body odour and/or protecting them or keeping them in good condition (Amended Cosmetic Directive 76/768/EEC) .

The composition according to the invention may especially be in the form of an alcoholic, aqueous- alcoholic or oily solution, a suspension, a dispersion, a W/O, O/W or multiple emulsion, aqueous or anhydrous gels, or a vesicular dispersion of ionic or nonionic type. It may have a liquid, semi-liquid, pasty or solid consistency.

For topical application, the composition that may be used according to the invention may especially be in the form of an aqueous-alcoholic or oily solution or a dispersion of the lotion or serum type, emulsions of liquid or semi-liquid consistency of the milk type, obtained by dispersing a fatty phase in an aqueous phase (O/W) or conversely (W/O) or multiple emulsions, a free or compacted powder to be used in unmodified form or to be incorporated into a physiologically acceptable medium, or suspensions or emulsions of soft consistency of the aqueous or anhydrous cream or gel type, or alternatively microcapsules or microparticles, or vesicular dispersions of ionic and/or nonionic type. It may thus be in the form of an ointment, a tincture, a cream, a pomade, a powder, a patch, an impregnated pad, a solution, an emulsion or vesicular dispersion, a lotion, a gel, a spray, a suspension, a shampoo, an aerosol or a mousse. It may be anhydrous or aqueous. It may also consist of solid preparations constituting soaps or cleansing bars.

These compositions are prepared according to the usual methods .

According to another embodiment of the invention, the composition is suitable for oral use, in particular "cosmetic oral" use.

For oral use, the composition may especially be in the form of wafer capsules, gel capsules, coated tablets, granules, plain tablets, chewable pastes, gels or drinkable syrups or in any other form known to those skilled in the art.

The amounts of the various constituents of the compositions that may be used according to the invention are those conventionally used in the fields under consideration.

Combinations

The compositions according to the invention may also contain agents for reinforcing or complementing the activity of the compound of formula (I), (I') or (II), and especially at least one compound chosen from antioxidants, antipollution agents, anti-UVA screening agents, anti-UVB screening agents, depigmenting agents and agents for stimulating DNA repair.

The compounds of formulae (I), (I') and (II) according to the invention may also be advantageously combined with extracts (total biomass, culture medium, ribosomal fraction, cell membrane fraction, LPS fraction, lipid A, etc.) of non-fruiting, non-photosynthetic filamentous bacteria such as Vitreoscilla filiformis or alternatively {2- (acetyl (3-trifluoromethylphenyl) - amino] -3-methylbutyrylamino } acetic acid.

It is thus possible, for example, to use an antioxidant chosen from: vitamin E (tocopherol) and derivatives thereof, including the acetate, linoleate or nicotinate, preferably at concentrations of about from 0.1% to 5%, γ-orizanol (0.1% to 5%) - lysine pidolate or arginine pidolate (0.5% to 10%), plant extracts such as extract of balm (0.01% to 2%), extract of silymarin (0.01% to 2%), extract of Ginkgo biloba (0.05% to 2%), extract of sage (0.05% to 2%), extract of cola nuts (0.05% to 2%), extract of rutin (0.1% to 2%) or extract of thyme (0.1% to 2%), the percentages being given as dry matter, carotenoids, such as α- and β-carotene or lycopene in a purified form or in an extract (for example tomato puree with a lycopene titre reaching a final lycopene concentration of between 10^~12% to 10% and more preferentially from 10^"7% to 0.1%), proanthocyanidol oligomers from pine, hawthorn or grape (0.1% to 2%) , - di-tert-butylhydroxybenzylidenecamphor (0.1% to

green tea (0.1% to 2%), caffeine (0.1% to 5%) , glycerol (2% to 30%) , - mannitol (2% to 30%), carnosine (0.1% to 2%), superoxide dismutase (100 to 10 000 IU/100 g) , guanosine (0.01% to 1%), microalgae containing ethoxyquine such as Hematococcus (0.005% to 1%), pentasodium aminotrimethylenephosphonate (0.001% to 0.5%) , lactoperoxidase (0.01% to 0.1%), vitamin C and derivatives thereof, lactoferrin (0.01% to 0.1%), isopropyl (benzyl { 2- [benzyl (2-isopropoxy-2-oxo- ethyl) amino] ethyl } amino) acetate, - phloretin, hesperidin, neohesperidindihydrochalcone, ferulic acid,

Eukarions (including EUK-8, EUK-134 and EUK-189 developed by Proteome Systems) ,

L-2-oxo-4-thiazolidinecarboxylic acid ergothioneine, caffeic acid,

Desferal, - 4, 4' - (2, 3-dimethylbutane-l, 4-diyl) dibenzene-1, 2- diol .

A mixture of several antioxidants may also be used.

Mention may also be made of free-radical scavengers, in particular bioflavonoids; coenzyme QlO or ubiquinone; certain enzymes such as catalase, glutathione peroxidase and quinone reductases; glutathione; benzylidenecamphor; benzylcyclanones; substituted naphthalenones; pidolates; phytanetriol; lignans; melatonin; hydroxylated chalcones, and also reduced derivatives thereof.

Preferably, the antioxidant is chosen from vitamin C, vitamin E, isopropyl (benzyl { 2- [benzyl (2-isopropoxy-2- oxoethyl) amino] ethyl } amino) acetate, ferulic acid, phloretin and SOD.

The term "anti-pollution agent" means any compound capable of trapping ozone, monocyclic or polycyclic aromatic compounds such as benzopyrene and/or heavy metals such as cobalt, mercury, cadmium and/or nickel. The term "free-radical scavenger" means any compound capable of trapping free radicals. As ozone-trapping agents that may be used in the composition according to the invention, mention may be made in particular of vitamin C and its derivatives including ascorbyl glucoside; phenols and polyphenols, in particular tannins, ellagic acid and tannic acid; epigallocatechin and natural extracts containing it; extracts of olive tree leaf; extracts of tea, in particular of green tea; anthocyans; extracts of rosemary; phenol acids, in particular chorogenic acid; stilbenes, in particular resveratrol; sulfur-containing amino acid derivatives, in particular S-carboxy- methylcysteine; ergothioneine; N-acetylcysteine; chelating agents, for instance N, N' -bis (3, 4, 5-tri- methoxybenzyl) ethylenediamine or one of its salts, metal complexes or esters; carotenoids such as crocetin; and various starting materials, for instance the mixture of arginine, histidine ribonucleate, mannitol, adenosine triphosphate, pyridoxine, phenylalanine, tyrosine and hydrolysed RNA, sold by Laboratoires Serobiologiques under the trade name CPP LS 2633-12F^®, the water-soluble fraction of corn sold by the company Solabia under the trade name Phytovityl^®, the mixture of extract of fumitory and of extract of lemon sold under the name Unicotrozon C-49^® by the company Induchem, and the mixture of extracts of ginseng, of apple, of peach, of wheat and of barley, sold by the company Provital under the trade name Pronalen Bioprotect^®.

As agents for trapping monocyclic or polycyclic aromatic compounds, which may be used in the composition according to the invention, mention may be made in particular of tannins such as ellagic acid; indole derivatives, in particular 3-indolecarbinol; extracts of tea, in particular of green tea, extracts of water hyacinth or Eichornia crassipes; and the water-soluble fraction of corn sold by the company Solabia under the trade name Phytovityl^®. Finally, as heavy-metal-trapping agents that may be used in the composition according to the invention, mention may be made in particular of chelating agents such as EDTA, the pentasodium salt of ethylenediaminetetramethylenephosphonic acid, and N, N'- bis (3, 4, 5-trimethoxybenzyl) ethylenediamine or one of the salts, metal complexes or esters thereof; phytic acid; chitosan derivatives; extracts of tea, in particular of green tea; tannins such as ellagic acid; sulfur-containing amino acids such as cysteine; extracts of water hyacinth (Eichornia crassipes) ; and the water-soluble fraction of corn sold by the company Solabia under the trade name Phytovityl^®.

Advantageously, the compositions according to the invention contain at least one UVA-screening agent and/or at least one UVB-screening agent, preferably a combination of at least one UVA-screening agent and of at least one UVB-screening agent.

Sunscreens are molecules that absorb UV radiation and thus prevent it from reaching the skin cells. They can absorb either mainly UVB or mainly UVA, depending on their nature. There are two major categories of sunscreens, either organic, or mineral (zinc oxide or titanium oxide) . By using them in cosmetic compositions in combination and in a sufficient amount, they can block a large proportion of the UV radiation.

However, it is commonly accepted that, in order to be effective, these formulations must be used under good application conditions (sufficient amount, frequent renewal and uniform spreading) . These application conditions are not always adhered to by the user, which increases the risk of an appreciable amount of UV radiation reaching the skin cells, and thus of giving rise to the biological effects mentioned above. Furthermore, in order to obtain absorption with respect to all the wavelengths of the UVB + UVA solar UV spectrum, several molecules that absorb in complementary wavelength ranges need to be combined.

The compositions in accordance with the invention may also comprise at least one organic photoprotective agent and/or at least one mineral photoprotective agent, which is (are) active in the UVA and/or UVB range (absorbers) , and which is (are) water-soluble or liposoluble, or even insoluble in the commonly used cosmetic solvents.

The additional organic screening agents are chosen especially from anthranilates; salicylic derivatives; camphor derivatives; benzophenone derivatives; β, β-diphenylacrylate derivatives; benzotriazole derivatives; benzalmalonate derivatives; benzimidazole derivatives; imidazolines; bis-benzoazolyl derivatives as described in patents EP 0 669 323 and US 2 463 264; p-aminobenzoic acid (PABA) derivatives; methylene- bis (hydroxyphenylbenzotriazole) derivatives as described in patent applications US 5 237 071, US 5 166 355, GB 2 303 549, DE 197 26 184 and EP 893 119; screening polymers and screening silicones such as those described especially in patent application WO 93/04665; dimers derived from α-alkyl- styrene, such as those described in patent application DE 198 55 649; 4, 4-diarylbutadienes such as those described in patent applications EP 0 967 200, DE 197 46 654, DE 197 55 649, EP 1 008 586, EP 1 133 980 and EP 133 981, and mixtures thereof.

As examples of additional organic screening agents, mention may be made of those denoted hereinbelow under their INCI name:

para-Aminobenzoic acid derivatives:

PABA,

Ethyl PABA, Ethyl dihydroxypropyl PABA,

Ethylhexyl dimethyl PABA sold in particular under the name Escalol 507 by ISP, Glyceryl PABA, PEG-25 PABA sold under the name Uvinul P25 by BASF.

Salicylic derivatives:

Homosalate sold under the name Eusolex HMS by Rona/EM

Industries, Ethylhexyl salicylate sold under the name Neo Heliopan

OS by Haarmann & Reimer,

Dipropylene glycol salicylate sold under the name

Dipsal by Scher,

TEA salicylate, sold under the name Neo Heliopan TS by Haarmann & Reimer.

β, β-Diphenylacrylate derivatives :

Octocrylene sold in particular under the trade name Uvinul N539 by BASF, Etocrylene sold in particular under the trade name Uvinul N35 by BASF.

Benzophenone derivatives:

Benzophenone-1 sold under the trade name Uvinul 400 by BASF,

Benzophenone-2 sold under the trade name Uvinul D50 by

BASF,

Benzophenone-3 or Oxybenzone sold under the trade name

Uvinul M40 by BASF, Benzophenone-4 sold under the trade name Uvinul MS40 by

BASF;

Benzophenone-5,

Benzophenone-6 sold under the trade name Helisorb 11 by

Norquay, Benzophenone-8 sold under the trade name Spectra-Sorb

UV-24 by American Cyanamid,

Benzophenone-9 sold under the trade name Uvinul

DS-49 by BASF,

Benzophenone-12, Diethylaminohydroxybenzoylhexyl benzoate sold under the trade name Uvinul A Plus by BASF.

Benzylidenecamphor derivatives: 3-Benzylidenecamphor manufactured under the name Mexoryl SD by Chimex,

4-Methylbenzylidenecamphor sold under the name Eusolex 6300 by Merck,

Benzylidenecamphorsulfonic acid manufactured under the name Mexoryl SL by Chimex,

Camphorbenzalkonium methosulfate manufactured under the name Mexoryl SO by the company Chimex,

Terephthalylidenedicamphorsulfonic acid manufactured under the name Mexoryl SX by Chimex, Polyacrylamidomethylbenzylidenecamphor manufactured under the name Mexoryl SW by Chimex.

Phenylbenzimidazole derivatives

Phenylbenzimidazolesulfonic acid sold especially under the trade name Eusolex 232 by Merck,

Disodium phenyldibenzimidazoletetrasulfonate sold under the trade name Neo Heliopan AP by Haarmann & Reimer.

Phenylbenzotriazole derivatives: Drometrizole trisiloxane sold under the name Silatrizole by Rhodia Chimie, methylenebis (benzotriazolyl) tetramethylbutylphenol sold in solid form under the trade name MIXXIM BB/100 by Fairmount Chemical, or in micronized form as an aqueous dispersion under the trade name Tinosorb M by Ciba Specialty Chemicals.

Anthranilic derivatives:

Menthyl anthranilate sold under the trade name Neo Heliopan MA by Haarmann & Reimer.

Imidazoline derivatives: Ethylhexyldimethoxybenzylidenedioxoimidazoline propionate .

Benzalmalonate derivatives: Polyorganosiloxane containing benzalmalonate functions, for instance Polysilicone-15, sold under the trade name Parsol SLX by Hoffmann LaRoche.

4, 4-Diarylbutadiene derivatives: 1, 1-Dicarboxy (2, 2' -dimethylpropyl) -4,4- diphenylbutadiene,

Benzoxazole derivatives:

2, 4-Bis [5-1 (dimethylpropyl) benzoxazol-2-yl (4- phenyl) imino] -6- (2-ethylhexyl) imino-1, 3, 5-triazine sold under the name Uvasorb K2A by Sigma 3V and mixtures thereof.

The preferential organic UV-screening agents present in the compositions are chosen from: Ethylhexyl salicylate,

Homosalate,

Octocrylene,

Phenylbenzimidazolesulfonic acid,

Disodium phenyldibenzimidazoletetrasulfonate, Benzophenone-3,

Benzophenone-4 ,

Benzophenone-5, n-Hexyl 2- (4-diethylamino-2-hydroxybenzoyl) benzoate,

4-Methylbenzylidenecamphor, Terephthalylidenedicamphorsulfonic acid,

Methylenebis (benzotriazolyl) tetramethylbutylphenol,

Drometrizole trisiloxane,

Polysilicone-15,

1, 1-Dicarboxy (2, 2' -dimethylpropyl) -4,4- diphenylbutadiene,

2, 4-Bis [5-1 (dimethylpropyl) benzoxazol-2-yl (4- phenyl) imino] -6- (2-ethylhexyl) imino-1, 3, 5-triazine, and mixtures thereof. The additional mineral photoprotective agents are chosen from pigments and even more preferentially nanopigments (mean size of the primary particles: generally between 5 nm and 100 nm and preferably between 10 nm and 50 nm) of treated or untreated metal oxides such as, for example, nanopigments of titanium oxide (amorphous or crystallized in rutile and/or anatase form) , or of iron oxide, zinc oxide, zirconium oxide or cerium oxide.

The treated nanopigments are pigments that have undergone one or more surface treatments of chemical, electronic, mechanochemical and/or mechanical nature with compounds as described, for example, in Cosmetics & Toiletries, February 1990, Vol. 105, pp. 53-64, such as amino acids, beeswax, fatty acids, fatty alcohols, anionic surfactants, lecithins, sodium, potassium, zinc, iron or aluminium salts of fatty acids, metal (titanium or aluminium) alkoxides, polyethylene, silicones, proteins (collagen or elastin) , alkanolamines, silicon oxides, metal oxides, sodium hexametaphosphate, alumina or glycerol.

The treated nanopigments may more particularly be titanium oxides treated with: silica and alumina, such as the products Micro- titanium Dioxide MT 500 SA and Microtitanium dioxide MT 100 SA from the company Tayca, and the products Tioveil Fin, Tioveil OP, Tioveil MOTG and Tioveil IPM from the company Tioxide, alumina and aluminium stearate, such as the product Microtitanium Dioxide MT 100 T from the company Tayca, - alumina and aluminium laurate, such as the product Microtitanium Dioxide MT 100 S from the company Tayca, iron oxides and iron stearate, such as the product Microtitanium Dioxide MT 100 F from the company Tayca, silica, alumina and silicone, such as the products Microtitanium Dioxide MT 100 SAS, Microtitanium Dioxide MT 600 SAS and Microtitanium Dioxide MT 500 SAS from the company Tayca, - sodium hexametaphosphate, such as the product Microtitanium Dioxide MT 150 W from the company Tayca, octyltrimethoxysilane, such as the product T-805 from the company Degussa, alumina and stearic acid, such as the product UVT-M160 from the company Kemira, alumina and glycerol, such as the product UVT-M212 from the company Kemira, alumina and silicone, such as the product UVT-M262 from the company Kemira.

Other titanium oxide nanopigments treated with a silicone are preferably Tiθ2 treated with octyltrimethylsilane and for which the mean size of the elementary particles is between 25 and 40 nm, such as the product sold under the trade name T 805 by the company Degussa Silices, Tiθ2 treated with a polydimethylsiloxane and for which the mean size of the elementary particles is 21 nm, such as the product sold under the trade name 70250 Cardre UF TiO2SI3 by the company Cardre, anatase/rutile Tiθ2 treated with a polydimethylhydrogenosiloxane and for which the mean size of the elementary particles is 25 nm, such as the product sold under the trade name Microtitanium Dioxide USP Grade Hydrophobic by the company Color Techniques.

The uncoated titanium oxide nanopigments are sold, for example, by the company Tayca under the trade names Microtitanium Dioxide MT 500 B or Microtitanium Dioxide MT 600 B, by the company Degussa under the name P 25, by the company Wackher under the name Oxyde de titane transparent PW, by the company Miyoshi Kasei under the name UFTR, by the company Tomen under the name ITS and by the company Tioxide under the name Tioveil AQ. The uncoated zinc oxide nanopigments are, for example: those sold under the name Z-Cote by the company

Sunsmart ; those sold under the name Nanox by the company Elementis; those sold under the name Nanogard WCD 2025 by the company Nanophase Technologies.

The coated zinc oxide nanopigments are, for example: - those sold under the name Zinc Oxide CS-5 by the company Toshibi (ZnO coated with polymethylhydrogenosiloxane) ; those sold under the name Nanogard Zinc Oxide FN by the company Nanophase Technologies (as a 40% dispersion in Finsolv TN, C12-C15 alkyl benzoate) ; those sold under the name Daitopersion ZN-30 and Daitopersion ZN-50 by the company Daito (dispersions in cyclopolymethylsiloxane/oxyethylenated polydimethylsiloxane, containing 30% or 50% of nanozinc oxides coated with silica and polymethylhydrogenosiloxane) ; those sold under the name NFD Ultrafine ZnO by the company Daikin (ZnO coated with perfluoroalkyl phosphate and copolymer based on perfluoroalkylethyl as a dispersion in cyclopentasiloxane) ; those sold under the name SPD-Zl by the company Shin-Etsu (ZnO coated with silicone-grafted acrylic polymer, dispersed in cyclodimethylsiloxane) ; those sold under the name Escalol ZlOO by the company ISP (alumina-treated ZnO dispersed in an ethylhexyl methoxycinnamate/PVP-hexadecene copolymer/methicone mixture) ; those sold under the name Fuji ZnO-SMS-IO by the company Fuji Pigment (ZnO coated with silica and polymethylsilsesquioxane) ; those sold under the name Nanox Gel TN by the company Elementis (ZnO dispersed at a concentration of 55% in C12-C15 alkyl benzoate with hydroxystearic acid polycondensate) . The uncoated cerium oxide nanopigments are sold under the name Colloidal Cerium Oxide by the company Rhδne- Poulenc .

The uncoated iron oxide nanopigments are sold, for example, by the company Arnaud under the names Nanogard WCD 2002 (FE 45B) and Nanogard Iron FE 45 BL AQ, Nanogard FE 45R AQ, Nanogard WCD 2006 (FE 45R) or by the company Mitsubishi under the name TY-220.

The coated iron oxide nanopigments are sold, for example, by the company Arnaud under the names Nanogard WCD 2008 (FE 45B FN), Nanogard WCD 2009 (FE 45B 556), Nanogard FE 45 BL 345 and Nanogard FE 45 BL or by the company BASF under the name Transparent Iron Oxide.

Mention may also be made of mixtures of metal oxides, especially of titanium dioxide and of cerium dioxide, including the silica-coated equal-weight mixture of titanium dioxide and of cerium dioxide, sold by the company Ikeda under the name Sunveil A, and also the alumina, silica and silicone-coated mixture of titanium dioxide and of zinc dioxide, such as the product M 261 sold by the company Kemira, or the alumina, silica and glycerol-coated mixture of titanium dioxide and of zinc dioxide, such as the product M 211 sold by the company Kemira .

The nanopigments may be introduced into the particles according to the invention in unmodified form or in the form of pigmentary paste, i.e. as a mixture with a dispersant, as described, for example, in document GB-A-2 206 339.

The additional photoprotective agents are generally present in the compositions according to the invention in proportions ranging from 0.01% to 20% by weight relative to the total weight of the composition, and preferably ranging from 0.1% to 10% by weight relative to the total weight of the composition.

The depigmenting or antipigmenting agents that may be incorporated into the composition according to the invention comprise, for example, the following compounds: kojic acid; ellagic acid, arbutin and derivatives thereof such as those described in patent applications EP-895 779 and EP-524 109; hydroquinone; aminophenol derivatives such as those described in patent applications WO 99/10318 and WO 99/32077, and in particular N-cholsteryloxycarbonyl-para-aminophenol and N-ethyloxycarbonyl-para-aminophenol; iminophenol derivatives, in particular those described in patent application WO 99/22707; L-2-oxothiazolidine-4- carboxylic acid or procysteine, and also the salts and esters thereof; calcium D-pantethinesulfonate, ascorbic acid and derivatives thereof, especially ascorbyl glucoside; and extracts of plants, in particular of liquorice, of mulberry, of skullcap and of Bacopa monnieri, without this list being limiting.

A vitamin E derivative that may be used is especially tocopheryl acetate.

The agents for stimulating DNA repair are especially agents that promote its repair, such as photolyase and/or endonuclease T4.

The composition may also contain moisturizers, NO- synthase inhibitors, free-radical scavengers or agents for stimulating the synthesis of epidermal macromolecules and/or for preventing their degradation.

The amounts of these various components will be adapted by a person skilled in the art.

Example 1 - Preparation of (trimethylsilyl) methyl 5- (1, 2-dithiolan-3-yl)pentanoate

4.23 g (20.5 mmol) of 5- (1, 2-dithiolan-3-yl) pentanoic acid and 2.9 ml (22.5 mmol) of (trimethylsilyl) methanol are introduced into 5 ml of toluene in a 25 ml three- necked flask on which is mounted a condenser and a thermometer. 0.11 ml (2.05 mmol) of 98% sulfuric acid is added and the mixture is then heated at T = 80⁰C for 2 hours 30 minutes. After cooling to room temperature, the reaction medium is taken up in 100 ml of ethyl acetate and then washed with water and with saturated sodium chloride solution, and the organic phase is dried over sodium sulfate, filtered and then concentrated under a vacuum of P = 240 mbar at 40⁰C.

After purification on a column of silica, eluting with 95/5 heptane/ethyl acetate, 2 g of (trimethylsilyl) methyl 5- (1, 2-dithiolan-3-yl) pentanoate are isolated (yield = 33%) .

The quasimolecular ions [M+H]+, [M+Na]+, [M+Na-CH3OH] +, [2M+Na]+ and the fragment [M+H-C4H12OSi] + of the expected molecule C12H24O2S2Si, M = 292, are mainly detected. The expected product is not detected on ESI-.

Anal. Calculated for C12H24O2S2Si C 49.27, H 8.27, O 10.94, Si 9.6, S 21.92 Found: C(49.44); H(8.3); S(21.72) 1H NMR (DMSO-de)

Example 2 - Preparation of the compounds

N- [bis (trimethylsilyl) methyl] -5- (1, 2-dithiolan-3-yl) - pentanamide, 5- (1, 2-dithiolan-3-yl) -N- [3- (trimethylsilyl) propyl] pentanamide and N,N'-[ (1, 1, 3, 3-tetra- methyldisiloxane-1, 3-diyl) dipropane-3, l-diyl]bis [5- (1, 2-dithiolan-3-yl) pentanamide]

The synthesis of the three compounds N- [bis (trimethylsilyl) methyl] -5- (1, 2-dithiolan-3-yl) - pentanamide, 5- (1, 2-dithiolan-3-yl) -N- [3- (trimethylsilyl) propyl] pentanamide and N, N' - [ (1, 1, 3, 3-tetra- methyldisiloxane-1, 3-diyl) dipropane-3, 1-diyl] bis [5- (1, 2-dithiolan-3-yl) pentanamide] is performed starting with a common intermediate: 1- { [5- (1, 2-dithiolan-3- yl) pentanoyl] oxy}pyrrolidine-2, 5-dione, the synthesis of which will first be described.

0. Synthesis of 1- { [5- (1, 2-dithiolan-3-yl) pentanoyl] - oxy}pyrrolidine-2, 5-dione

30 g (145 mmol) of 5- (1, 2-dithiolan-3-yl) pentanoic acid and 16.85 g (0.145 mol) of N-hydroxysuccinimide are suspended in 200 ml of anhydrous acetonitrile in a dry 500 ml three-necked flask under nitrogen, on which are mounted a condenser, a thermometer and a pressure- equalized dropping funnel. A solution of 30 g (145 mmol) of N, N' -dicyclohexylcarbodiimide in 50 ml of anhydrous acetonitrile is introduced dropwise at T = 0-5⁰C, followed by addition of 20 ml (145 mmol) of triethylamine . The reaction medium is stirred at 0-5⁰C for 1 hour and then left at room temperature for 24 hours .

After filtering off the insoluble white matter, the reaction mixture is concentrated under a vacuum P = 200 mbar at 40⁰C and then taken up in about 500 ml of ethyl acetate. The organic phase is washed with water, with saturated sodium hydrogen carbonate solution and with saturated sodium chloride solution. The organic phase is then dried over sodium sulfate, filtered and then concentrated under a vacuum P = 240 mbar at 40⁰C.

The crude product obtained (30 g) is recrystallized from 150 ml of hot ethanol. After drying over P₂O₅ under vacuum, 25.8 g of 1- { [5- (1, 2-dithiolan-3-yl) - pentanoyl] oxy}pyrrolidine-2, 5-dione are obtained as a crystalline yellow solid (yield = 60%) .

1. Synthesis of N- [bis (trimethylsilyl) methyl] -5- (1, 2- dithiolan-3-yl) pentanamide

A solution of 1.5 g (5 mmol) of 1- { [5- (1, 2-dithiolan-3- yl) pentanoyl ] oxy}pyrrolidine-2 , 5-dione in 20 ml of anhydrous acetonitrile and then 0.86 g (5 mmol) of 1 , 1-bis (trimethylsilyl) methanamine and 0.68 ml (5 mmol) of triethylamine are introduced into a 50 ml two-necked flask under nitrogen.

The mixture is stirred at room temperature for 20 hours, concentrated under a vacuum P = 200 mbar at 40⁰C and then taken up in 100 ml of dichloromethane . The organic phase is washed with water and then with saturated sodium chloride solution. The organic phase is then dried over sodium sulfate, filtered and then concentrated under a vacuum P = 700 mbar at 40⁰C.

After purification on a column of silica, eluting with 8/2 heptane/ethyl acetate, 0.68 g of N- [bis (trimethyl- silyl) methyl] -5- (1, 2-dithiolan-3-yl) pentanamide is obtained as a yellow oil (yield = 40%) .

The ESI+ and ESI- analysis makes it possible to confirm the molecular mass of the expected product C15H33NOS2Si2, M = 363 (detection of [M+H]+, [M+Na]+, [2M+Na]+, [M-H]-, [M+Cl]-, [2M+3H+Na]+ and of the fragment [M-H-H2S]-) . Uncharacterized secondary ions of very low intensity are also present on ESI+ and ESI-.

Anal. Calculated for C15H33NOS2Si2 : C 49.5, H 9.1,

N 3.9, O 4.4, S 17.6, Si 15.4.

Found: C(49.90); H(9.47); N(3.75); S(17.22)

¹H NMR (DMSO-de)

2. Synthesis of 5- (l,2-dithiolan-3-yl) -N- [3-

(trimethylsilyl) propyl] pentanamide

5- (l,2-Dithiolan-3-yl) -N- [3- (trimethylsilyl) propyl] - pentanamide is obtained from 3- (trimethylsilyl) propan- 1-amine, the synthesis of which is described below.

2. a. Synthesis of 3- (trimethylsilyl)propan-1-amine in two steps

2.6 g (14 mmol) of potassium phthalimide are suspended in 20 ml of anhydrous N, N-dimethylformamide in a dry

50 ml three-necked flask under argon, on which are mounted a condenser and a thermometer, and 2.3 ml

(13 mmol) of chloropropyltrimethylsilane are introduced dropwise into the reaction medium. The mixture is heated at T = 85°C for 20 hours, allowed to cool to room temperature and then concentrated under a vacuum P = I mbar at 40⁰C. The crude product is taken up in 100 ml of ethyl ether. After filtering off the salts, the ether phase is washed with water and then dried over sodium sulfate, filtered and concentrated under a vacuum P = 700 mbar at 40⁰C. 2.7 g of 2- [3- (trimethylsilyl) propyl] -lH-isoindole-1, 3 (2H) -dione are thus obtained in a yield of 71%.

For the phthalimide reduction step, 2.16 g (8.3 mmol) of 2- [ 3- (trimethylsilyl) propyl ] -lH-isoindole-1 , 3 (2H) - dione are dissolved at 40⁰C in 100 ml of a 6/1 isopropanol/water mixture. 1.57 g (41 mmol) of sodium borohydride are gradually added at room temperature and the reaction medium is stirred for 20 hours.

9 ml of acetic acid are then added slowly, and the mixture is refluxed for 3 hours. The reaction medium is concentrated under a vacuum P = 40 mbar at 40⁰C and the residue is taken up in 100 ml of water. In acidic medium (pH 4-5), the aqueous phase is washed with ether, the pH is brought to about 12-14 with aqueous

20% ammonia solution and it is then extracted with ethyl acetate. After washing with saturated sodium chloride solution, the organic phase is dried over sodium sulfate, filtered and then concentrated under a vacuum P = 240 mbar at 40⁰C. 0.5 g of

3- (trimethylsilyl) propan-1-amine is thus obtained

(yield = 41%) .

5- (l,2-Dithiolan-3-yl) -N- [3- (trimethylsilyl) propyl] - pentanamide is obtained in a yield of 66% by introducing one equivalent of 1- { [5- (1, 2-dithiolan-3- yl) pentanoyl] oxy}pyrrolidine-2, 5-dione per 1 eq of 13- (trimethylsilyl) propan-1-amine .

Analysis by ESI+ and ESI- makes it possible to confirm the molecular mass of the expected product C14H29NOS2Si, M = 319 (detection of [M+H]+, [M+Na]+, [2M+H]+, [2M+Na]+, [M-H]-, [M+Cl]-, [M+CH3COO] - and of the fragment by ESI- m/z = 272 [M-H-H2S]-).

Anal. Calculated for C14H29NOS2Si : C 52.6, H 9.1,

N 4.4, O 5.0, S 20.1, Si 8.8.

Found: C (52.47); H (9.10); N (4.51);

¹H NMR (DMSO-de)

3. Synthesis of N, N' - [ (1, 1, 3, 3-tetramethyldisiloxane- 1, 3-diyl) dipropane-3, 1-diyl] bis [5- (1, 2-dithiolan-3- yl) pentanamide]

The compound N, N' - [ (1, 1, 3, 3-tetramethyldisiloxane-l, 3- diyl) dipropane-3, 1-diyl] bis [5- (1, 2-dithiolan-3-yl) - pentanamide] was synthesized by introducing two equivalents of 1- { [5- (1, 2-dithiolan-3-yl) pentanoyl] - oxy}pyrrolidine-2 , 5-dione per 1 equivalent of 1, 3-bis (3-aminopropyl-l, 1,3, 3-tetramethyldisiloxane . Yield = 37%.

The quasimolecular ions [M+H]+, [M+Na]+, [M-H]-, [M+Cl]- and the fragments [M+H-C13H27NO2S2Si] + and [M-H-C13H25NOS2Si] - of the expected molecule C26H52N2O3S4Si2, M = 624 are mainly detected. Detection of weak signals by ESI+ and ESI- in the mass range 65-800 possibly corresponding to impurities.

Anal. Calculated for C26H52N2O3S4Si2 C 50.0, H 8.4, N 4.5, O 7.7, S 20.5, Si 9.0. Found: C(49.55); H(8.46); N(4.4); 1H NMR (DMSO-d₆)

Example 3 - Preparation of 5- (1, 2-dithiolan-3-yl) -N- [ (trimethylsilyl) methyl] pentanamide

0.2 ml (1.5 mmol) of 1-chloro-N, N-2-trimethylpropenyl- amine are added dropwise to a solution of 0.3 g (1.5 mmol) of 5- (1, 2-dithiolan-3-yl) pentanoic acid in 10 ml of anhydrous tetrahydrofuran in a dry 50 ml two- necked flask under argon. The reaction medium is stirred for one hour at room temperature, and a mixture of 0.3 ml (2.25 mmol) of aminomethyltrimethylsilane and 0.3 ml (2.25 mmol) of triethylamine is then added dropwise. The resulting mixture is stirred magnetically for 20 hours, the insoluble white material is filtered off and the filtrate is concentrated under a vacuum P = 350 mbar at 40⁰C. After filtering through silica, eluting with dichloromethane, 0.24 g of 5- (1, 2-dithiolan-3-yl) -N-

[ (trimethylsilyl) methyl] pantanamide is isolated

(yield = 70%) .

Analysis by ESI+ and ESI- makes it possible to confirm the molecular mass of the expected product C12H25NOS2Si, M = 291 (detection of [M+H]+, [M+Na]+,

[2M+Na]+, [M-H]-, [M+Cl]-]- and of the fragment

[M-H-H2S] -) .

Anal. Calculated for C12H25NOS2Si : C 49.4, H • 6, N 4.8, O 5.5, Si 9.6, S 22.0

Found: C(49.24); H(8.71); N(4.76); S(22.31); 1H NMR (DMSO-de)

Example 4 - Preparation of 5- (1, 2-dithiolan-3-yl) -N- (3-{l, 3, 3, 3-tetramethyl-l- [ (trimethylsilyl) oxy] - disiloxanyl}propyl) pentanamide

0.4 ml (3 mmol) of 1-chloro-N, N-2-trimethylpropenyl- amine is added dropwise to a solution of 0.620 g

(3 mmol) of 5- (1, 2-dithiolan-3-yl) pentanoic acid in 5 ml of anhydrous tetrahydrofuran in a dry 50 ml two- necked flask under argon. The reaction medium is stirred for one hour 30 minutes at room temperature and is then added dropwise to a mixture of 0.924 g

(3.3 mmol) of siloxane amine and 0.63 ml (4.5 mmol) of triethylamine in 5 ml of anhydrous THF. The mixture is stirred magnetically for 20 hours, the insoluble white material is filtered off and the filtrate is concentrated under vacuum.

After flash chromatography on silica, eluting with dichloromethane, followed by evaporation under vacuum, 1.1 g of 5- (l,2-dithiolan-3-yl) -N- (3-{l, 3, 3, 3-tetra- methyl-1- [ (trimethylsilyl) oxy] disiloxanyl ] propyl) - pentanamide are isolated (yield = 80%) .

Analysis of ESI+ and ESI- makes it possible to confirm the molecular mass of the expected product C18H41NO3S2Si3, M = 467 1H NMR (DMSO - d₆)

Example 5 - Measurement of the activity towards increasing the level of GSH of the compounds according to the invention

The study consisted in evaluating at the cellular level the protective effect of the reference molecule, lipoic acid, and also of the lipoic acid derivatives according to the invention, towards the UVD-induced depletion of intracellular GSH.

To do this, HaCaT cells were exposed to UVD and the level of intracellular GSH was then measured, thus allowing evaluation of the possible protection afforded by the addition to the culture medium of the lipoic acid derivatives according to the invention.

The UVD corresponds to the radiation of non-zenithal sunlight and to an average spectral illumination: it stimulates the radiation received by the skin of an individual in the course of a day and not solely to that corresponding to exposure to zenithal sunlight. Devices for reproducing this radiation are described in FR 2 863 356.

The evaluation technique uses a fluorescent probe, monochlorobimane (MCB) . MCB has the particular feature of having, unlike other bimane compounds such as monobromobimane, more selective reactivity towards glutathione: the blue fluorescent compound measured

(GSH-monochlorobimane) results from an enzymatic reaction catalysed by glutathione-S-transferase . The specificity of MCB towards GSH in our keratinocyte model (HaCaT line) was confirmed previously.

Pretreatment of cells with the reference molecule, lipoic acid, for 24 hours at 1 mM affords approximately 100% protection against the UVD-induced depletion of GSH (see Figure 1 showing the evaluation of the protective effect of lipoic acid at 1 mM in the MCB test on HaCaT: the measurement of the level of intracellular GSH is performed on keratinocytes that are or are not pretreated with lipoic acid at 1 mM and exposed to UVD at t = 0, t = 6 h and t = 24 h after the exposure to UVD) ; this protection is about 83% at 500 μM and about 10% at 100 μM.

The two lipoic acid derivatives, (trimethylsilyl) methyl 5- (1, 2-dithiolan-3-yl) pentanoate and 5- (1, 2-dithiolan- 3-yl) -N- [3- (trimethylsilyl) propyl] pentanamide, evaluated under the same operating conditions, give the keratinocytes protection of about 40% at 100 μM. The protection afforded by these two active agents against the depletion of GSH induced by the daily UV is higher than that of the reference molecule, lipoic acid (cf. Figure 2 : evaluation of the protective effect of the lipoic acid derivatives at 0.1 mM in the MCB test on HaCaT: the measurement of the level of intracellular GSH is performed on keratinocytes that are or are not pretreated with the active agents and exposed to UVD, t = 6 h after the UVD exposure) .

Example 6 - Measurement of the protection afforded against DNA damage Solar UV is capable of giving rise to extensive oxidative damage in skin cells, and especially in DNA.

The nucleic acids absorb the UVB photons, thus inducing DNA damage directly. Although UVA is not directly absorbed by DNA, it has a genotoxic action mediated by reactive oxygen species.

The comet test makes it possible to quantify the UV- induced DNA damage (in this case UVA) : the breaking of strands and oxidative DNA lesions (alkali-labile sites cleaved under alkaline conditions) are detected.

The principle of this test is based on the capacity of denatured and cleaved DNA fragments to migrate outside the cell nuclei, under the influence of an electric field, whereas undamaged DNA remains confined in the nucleus. The damaged DNA fragments form a trail behind the nucleus of the cells. The cells then take the appearance of "comets". The "tail" of each comet is proportionately larger and stronger the greater the DNA damage incurred. (Alapetite C. et al . , 1996, Int. J. Rad. Bio.; Klaude M, et al . , 1996, Mut . Res.; Lehmann J. et al., 1998, Mut. Res.; Singh NP. et al . , 1988, Exp. Cell Res. ) .

The study consisted in evaluating the photoprotective effect of 2 molecules derived from lipoic acid, (trimethylsilyl) methyl 5- (1, 2-dithiolan-3-yl) pentanoate

(compound of Example 1) and 5- (1, 2-dithiolan-3-yl) -N-

[3- (trimethylsilyl) propyl] pentanamide (compound of

Example 2-2) with respect to UVA-induced DNA damage.

To do this, normal human fibroblasts (NHF) were placed in contact with the active agents for 24 hours. The cells were then detached, included in an agarose gel and then deposited on a microscope slide. Following the UVA exposure (for 30 minutes) , the cells were subjected to a cell lysis (so as to keep intact only the genetic material) , to a DNA-denaturing step and then to an electrophoresis to make the damaged DNA migrate. The level of damaged DNA was measured using a fluorescence microscope combined with specialized image analysis software.

Pretreatment of the cells with the molecule (trimethylsilyl) methyl 5- (1, 2-dithiolan-3-yl) pentanoate gives the fibroblasts a protection of 42% at 1 μM and 50% at 10 μM (cf . Figure 3) .

5- (l,2-Dithiolan-3-yl) -N- [3- (trimethylsilyl) propyl] - pentanamide was evaluated under the same operating conditions. It affords a protection of 18% at 1 μM and of 47% at 10 μM (cf . Figure 4) .

These two compounds thus have the capacity for protecting against UV-induced DNA degradation.

Summary table:

Example 7 - Formulations Antisun composition (oil-in-water emulsion)

^■ Compound of Example 1, 2, 3 or 4 3 g

^■ 80/20 mixture of cetylstearyl alcohol and 3 g of oxyethylenated cetylstearyl alcohol

(33 EO units) sold by the company Tensia under the trade name Dehsconet® 390

^■ Glyceryl mono- and distearate mixture 2 g sold under the trade name Cerasynth® SD by the company ISP

^■ Cetyl alcohol 1.5 g

^■ Polydimethylsiloxane sold under the name 1.5 g DC200Fluid® by the company Dow Corning

^■ Glycerol 15 g

^■ Parleam = hydrogenated isoparaffin 20 g (6-8 mol of isobutylene) by the company

NOF Corporation

^■ Preserving agents qs

^■ Demineralized water qs 77 g

The fatty phase containing the compound is heated at about 70 - 80⁰C until completely melted. The water is then added in a single portion at 80⁰C with vigorous stirring. Stirring is continued for 10 to 15 minutes, the mixture is then allowed to cool with moderate stirring to about 40⁰C and the preserving agents are added.

Antisun composition (oil-in-water emulsion)

^■ Compound of Example 1, 2, 3 or 4 2 g

(33 EO units) sold by the company Tensia under the trade name Dehsconet® 390

^■ Cetyl alcohol 2.5 g C12-C15 alkyl benzoate sold under the 20 g trade name Finsolv TN by Witco

^■ Glycerol 15 g

^■ Preserving agents qs

^■ Demineralized water qs 97 g

This cream is prepared according to the standard techniques for preparing emulsions by dissolving the screening agent in the fatty phase containing the emulsifiers, heating this fatty phase to 70-80⁰C and adding, with vigorous stirring, the water heated to the same temperature. Stirring is continued for 10 to 15 minutes and the mixture is then allowed to cool with moderate stirring, and the fragrance and preserving agent are finally added at about 40⁰C.

Claims

1. Compound of general formulae (I) and (I'

0)

(I¹)

in which:

A is a radical of formula (1) below:

(1)

in which:

L is a divalent radical for attaching the radical A to the silicone chain, m represents an integer 0, 1, 2, 3, 4, 5, 6, 7 or 8,

X represents an oxygen, nitrogen or sulfur atom, - Y represents an oxygen or nitrogen atom, a group NR⁴ or a sulfur atom,

R denotes a linear C1-C30 or branched C3-C20 saturated, or C2-C20 unsaturated hydrocarbon-based group, a halogenated C1-C8 hydrocarbon-based group or a trimethylsilyloxy group; • B, which may be identical or different for the same compound, is chosen from the radicals R and A; r is an integer between 0 and 50 inclusive; s is an integer between 0 and 20 inclusive, and if s is 0, at least one of the two radicals B is A; u is an integer between 1 and 6 inclusive; t is an integer between 0 and 10 inclusive; it being understood that t + u is greater than or equal to 3.

2. Compound according to Claim 1, characterized in that L corresponds to one of the formulae (a) and (a' ) below:

in which:

3. Compound according to Claim 1 or 2, characterized in that the radicals R, which may be identical or different, are chosen from linear Cl-ClO or branched C3-C10, saturated or unsaturated alkyl radicals, the phenyl radical and the trifluoropropyl radical and that at least 80% by number of the radicals R are methyl radicals .

4. Compound according to any one of the preceding claims, characterized in that:

⁰ A is a radical of formula (1) above with m = 4;

⁰ L is such that Y' = H, Z = CH₂ and p = 1; ° X represents an oxygen atom;

⁰ Y represents an oxygen or nitrogen atom, NR⁴ with

R⁴ representing a hydrogen, a linear C1-C20 or branched

C3-C20, saturated or unsaturated alkyl, optionally substituted with an optionally substituted phenyl radical;

⁰ R is methyl;

⁰ B is methyl or a radical A;

⁰ r is 0, 1, 2 or 3;

⁰ s is 0, 1, 2 or 3; ° t + u is 3, 4 or 5.

5. Compound according to any one of the preceding claims, characterized in that:

⁰ A is a radical of formula (1) above with m = 4; ° L is such that Y' = H, Z = CH₂ and p = 1;

⁰ X represents an oxygen atom;

⁰ Y represents an oxygen or nitrogen atom (NR⁴ with

R⁴ = H) ;

⁰ R is methyl; ⁰ B is methyl or a radical A; r = 0; s = 0 or 1.

6. Compound of general formula (II) :

⁽H⁾ in which

^■ m represents an integer that may be 0, 1, 2, 3, 4, 5, 6, 7 or 8;

^■ X represents an oxygen, nitrogen or sulfur atom;

^■ Y represents an oxygen or nitrogen atom, a group NR⁴ or a sulfur atom;

^■ v represents an integer that may be 0 , 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10;

^■ R¹, R² and R³ represent, independently of each other, a linear Cl-ClO or branched C3-C10, saturated or unsaturated alkyl radical, possibly comprising one or more halogen atoms (for example Cl, Br or F) , a phenyl radical or a benzyl radical;

^■ D denotes hydrogen, a linear C1-C8 or branched C2-C8, saturated or unsaturated alkyl radical, a phenyl radical; the group Si (CH₃) ₃ with the proviso that when D is Si (CH₃) ₃ then v = 0 and R¹, R² and R³ are methyl; ■ W is a linear C1-C8 or branched C3-C8, saturated or unsaturated alkyl radical, or C2-C8 alkylene radical, optionally substituted with a hydroxyl;

7. Compound according to Claim 6, characterized in that:

^■ m = 4; X = O; ■ Y = 0 or NR⁴;

R¹ to R³ denote linear C1-C4 or branched C3-C4 alkyl possibly comprising a phenyl radical, and more particularly methyl, ethyl, phenyl or -CH₂-Ph; v = 0, 1 or 2; ■ R⁴ represents a hydrogen, a linear C1-C20 or branched C3-C20, saturated or unsaturated alkyl, optionally substituted with an optionally substituted phenyl radical;

D is -H or (CH₃)₃; ■ W is a methylene -CH₂- or -CHOH-CH₂- when v is other than 0.

8. Compound according to Claim 6 or 7, characterized in that ° m = 4; X = O;

⁰ Y = O or NH;

⁰ R¹ to R³ denote C1-C4 alkyl and more particularly methyl; ° W is a methylene -CH₂-.

9. Compound according to any one of the preceding claims, characterized in that it is obtained from lipoic acid.

10. Compound according to any one of the preceding claims, chosen from:

1. (Trimethylsilyl) methyl 5- (1, 2-dithiolan-3- yl) pentanoate; 2. 2- (Trimethylsilyl) ethyl 5- (1, 2-dithiolan-3-yl) - pentanoate;

3. 3- (Trimethylsilyl)propyl 5- (1, 2-dithiolan-3-yl) - pentanoate;

4. [Ethyl (dimethyl) silyl] methyl 5- (1, 2-dithiolan-3- yl) pentanoate;

5. 2-Hydroxy-3- (trimethylsilyl) propyl 5- (1,2- dithiolan-3-yl) pentanoate;■ 6. [Dimethyl (phenyl) silyl] methyl 5- (1, 2-dithiolan-3- yl) pentanoate;

7. [Benzyl (dimethyl) silyl] methyl 5- (1, 2-dithiolan-3- yl) pentanoate;

8. 5- (1, 2-Dithiolan-3-yl) -N- [ (trimethylsilyl) - methyl] pentanamide;

9. N- [bis (Trimethylsilyl) methyl] -5- (1, 2-dithiolan-3- yl ) pentanamide ;

10. 5- (l,2-Dithiolan-3-yl) -N- [3- (trimethylsilyl) - propyl ] pentanamide ; 11. 5- (l,2-Dithiolan-3-yl) -N- (3-{l, 3, 3, 3-tetramethyl- 1- [ (trimethylsilyl) oxy] disiloxanyl }propyl) pentanamide; 12. N,N'-[(1,1,3, 3-Tetramethyldisiloxane-l, 3-diyl) - dipropane-3, 1-diyl] bis [5- (1, 2-dithiolan-3-yl) - pentanamide] .

11. Use of at least one compound according to any one of Claims 1 to 10, as an agent for stimulating the intracellular synthesis of glutathione and/or for maintaining an intracellular level of glutathione at an amount that is sufficient for preventing oxidative damage caused by free radicals on cells.

12. Use of at least one compound according to any one of Claims 1 to 10, for increasing the cellular antioxidant defence systems.

13. Use according to Claim 11 or 12, as a photo- protective agent for the skin.

14. Use according to Claim 11 or 12, for preparing the skin for exposure to sunlight.

15. Use according to any one of Claims 11 to 14, for preventing and/or treating the heating sensations caused by solar radiation.

16. Use of at least one compound according to any one of Claims 1 to 10, for the preparation of a composition for preventing and/or treating redness and/or irritation caused by solar radiation.

17. Use of at least one compound according to any one of Claims 1 to 10, for the preparation of a composition for preventing and/or treating DNA lesions caused by solar radiation.

18. Use of at least one compound according to any one of Claims 1 to 10, for the preparation of a composition for preventing and/or treating skin and/or mucous membrane disorders induced by an intense irradiation with UVA and/or UVB rays.

19. Use of at least one compound according to any one of Claims 1 to 10, for preventing and/or limiting the formation of free radicals and/or for removing the free radicals present in cells.

20. Use according to Claim 19, for preventing and/or treating skin damage caused by oxidative stress.

21. Use according to Claim 19 or 20, for preventing and/or treating the harmful effects of pollution on the skin .

22. Use according to any one of Claims 19 to 21, for preventing and/or treating loss of firmness and/or elasticity of the skin.

23. Use according to any one of Claims 19 to 21, for allowing the skin to regain a uniformly smooth appearance .

24. Use according to any one of Claims 19 to 21, for preventing and/or treating a dull complexion and/or for promoting the radiance of the complexion.

25. Use according to any one of Claims 19 to 21, for preventing and/or treating cutaneous dehydration.

26. Use according to any one of Claims 19 to 21, for preventing and/or treating the signs of ageing of the skin.

27. Use according to Claim 26, for preventing and/or treating pigmentation marks and/or hyperkeratosis marks and/or epidermal atrophy and/or skin roughness and/or skin dryness.

28. Use according to any one of Claims 19 to 21, for preventing and/or limiting and/or eliminating peroxidation of the skin lipids.

29. Use according to Claim 28, for preventing and/or limiting and/or eliminating unpleasant body odour.

30. Use according to any one of Claims 10 to 29, characterized in that the composition is for external topical use.

31. Use according to Claim 30, characterized in that the said compound according to any one of Claims 1 to 10 is present in the composition at a concentration of from 0.001% to 20% relative to the total weight of the composition .

32. Use according to Claim 31, characterized in that the said compound is present in the composition at a concentration of from 0.01% to 10% relative to the total weight of the composition.

33. Use according to any one of Claims 10 to 29, characterized in that the composition is an oral composition .

34. Use according to Claim 33, characterized in that the said compound is present in an amount of between 0.1 and 100 mg per dosage intake.

35. Composition comprising, in a physiologically acceptable medium, at least one compound according to any one of Claims 1 to 10.

36. Composition according to Claim 35, characterized in that it also comprises at least one compound chosen from antioxidants, antipollution agents, anti-UVA screening agents, anti-UVB screening agents, depigmenting agents and agents for stimulating DNA repair .

37. Composition according to Claim 36, characterized in that the antioxidant is chosen from vitamin C, vitamin E, isopropyl (benzyl { 2- [benzyl (2-isopropoxy-2- oxoethyl) amino] ethyl } amino) acetate, ferulic acid, phloretin and SOD.

38. Cosmetic process for preparing the skin for sunlight, comprising at least one step of administering at least one compound according to any one of Claims 1 to 10.