WO2004010965A1 - Use of lignans for prevening or treating the sings of ageing of the skin - Google Patents

Abstract

The invention relates to the cosmetic use of at least one lignan of given formula, or of a plant extract containing it (such as an extract of flax seeds), in a composition suitable for topical application to the skin, containing a cosmetically acceptable medium, for preventing or treating the signs of ageing of the skin, in particular the loss of firmness, elasticity and/or tonicity of the skin and/or the formation of wrinkles and fine lines. The invention also relates to a topical cosmetic composition containing these lignans in combination with other anti-ageing active agents. Lastly, the invention relates to a cosmetic process for treating dry skin, comprising the topical application to the said skin of a composition containing at least one such lignan in a cosmetically acceptable medium.

Description

Use of lignans for preventing or treating the signs of ageing of the skin

The invention relates to the cosmetic use of at least one lignan of given formula, derived in particular from flax seeds, in a composition suitable for topical application to the skin, containing a cosmetically acceptable medium, for preventing or treating the signs of ageing of the skin, in particular the loss of firmness, elasticity and/or tonicity of the skin and/or the formation of wrinkles and fine lines.

The invention also relates to a topical cosmetic composition containing these lignans in combination with other anti-ageing active agents. Human skin consists of two compartments, namely a surface compartment, the epidermis, and a deep compartment, the dermis.

Natural human epidermis is composed mainly of three types of cells: keratinocytes, which form the vast majority, melanocytes and Langerhans cells. Each of these cell types contributes, by virtue of its intrinsic functions, towards the essential role played in the body by the skin.

The dermis gives the epidermis a solid support. It is also the epidermis' nourishing factor. It consists mainly of fibroblasts and of an extracellular matrix which is itself composed mainly of collagen, elastin and a substance known as ground substance, these components being synthesized by the fibroblasts. Leukocytes, mastocytes and tissue macrophages are also found therein. It also contains blood vessels and nerve fibres.

It is collagen fibres that give the dermis its firmness. Collagen fibres consist of fibrils sealed together, thus forming more than 10 different types of structures. The firmness of the dermis is mainly due to the highly efficient interlocking of the collagen fibres packed together in all directions. The collagen fibres contribute towards the firmness, elasticity and tonicity of the skin and/or mucous membranes.

Collagen fibres are under constant renewal, but this renewal decreases with age, leading to thinning of the dermis.

In addition, although very strong, collagen fibres are sensitive to certain enzymes known as collagenases, which are stimulated in particular by prolonged exposure to UN. Degradation of the collagen fibres leads to the development of flaccid and wrinkled skin, which people, preferring the appearance of smooth and taut skin, have always sought to combat.

The importance of collagen in the structure of tissues, particularly the skin and/or mucous membranes, and the importance of combating its degradation and/or of regenerating it in order thus to combat ageing and its consequences may thus be appreciated on reading the text hereinabove. The Applicant has now discovered, surprisingly and unexpectedly, that certain lignans, extracted in particular from flax seeds, increase the synthesis of collagen by the fibroblasts and are thus useful for combating the signs of ageing of the skin. Lignans constitute a vast group of natural products characterized by the coupling of two propylbenzene units via a β-β' bond. In other words, they thus have a , 3-dibenzylbutane structure. These compounds are present especially in a number of cereals, fruit and vegetables and in particular in plants such as flax (especially secoisolariciresinol and isolariciresinol) , chaparral (nordihydroguaiaretic acid) or sesame (sesaminol, sesamolinol and pinoresinol) , in the form of glycosides. These are the main sources of lignans. However, lignans are also found in schisandra, arborvitae, birthwort, morina, nutmeg, magnolia, forsythia and nettle.

The lignan that is most commonly known is nordihydroguaiaretic acid, which is an antioxidant used especially in retinol-based anti-ageing compositions, to prevent oxidation of the latter (EP-0 440 398) .

Glycosylated lignans derived from sesame have moreover been described as being useful for firming the skin and preventing the formation of wrinkles and slackening of the skin by scavenging OH° radicals (JP-09 095 417) . They are also well known as antioxidants and may be used in moisturizing and protective creams (US-5 993 795) .

For their part, the glycosylated lignans derived from flax seeds are known to inhibit the production of melanin and thus bleach the skin

(JP2001-261 570) , as agents for increasing the activity of catalase and fibroblasts and the synthesis of hyaluronic acid, for preventing or treating UN-induced wrinkles and for reinforcing the elasticity of the skin (JP2001-114 636 and JP2001-122 733) .

Lignans, for example those derived from flax, have moreover been described as being useful in preventing osteoporosis and certain cancers, but also as anti-viral agents and fungicides. It has thus been proposed to use them to treat the symptoms of the menopause (EP-0 906 761) .

Lastly, patent application WO 02/080 702 discloses aglycone lignans, including secoisolariciresinol, which may be used in orally- administered compositions for combating ageing of the skin or as anti-inflammatories . These compounds are in particular included in foods.

However, to the Applicant's knowledge, it has never before been suggested that certain lignans in aglycone form, derived in particular from flax seeds, can be useful for combating ageing of the skin when they are applied topically to the skin. Thus, one subject of the invention is the cosmetic use of at least one lignan corresponding to formula (I) :

in which:

Ri and R₂ each represent a -CH₂-OH group or, taken together, form a furanone ring, R₃ and R₄ independently represent a hydroxyl group or an

-O-CH₃ group,

R₅, R₆ and R₇ independently represent a hydroxyl group or an -0-CH₃ group or a hydrogen atom, it being understood that at least one of the groups R₃ and R₄ and at least one of the groups R₅, R_e and R₇ represents an -0-CH₃ group,

R₈ and Rg each represent a hydrogen atom or together form a bond, or of a plant extract containing it, in a composition suitable for topical application to the skin and containing a cosmetically acceptable medium, for preventing or treating the signs of ageing of the skin, in particular the loss of firmness, elasticity and/or tonicity of the skin and the formation of wrinkles and fine lines.

A subject of the invention is also a cosmetic process for treating dry skin, comprising the topical application to the said skin of a composition containing at least one such lignan in a cosmetically acceptable medium.

For the purposes of the present invention, the term "cosmetically acceptable" means an inert medium that is compatible with the skin, its integuments and/or mucous membranes, which does not result in itching, stinging, tautness or redness liable to put the user off using the composition, and which has a pleasant appearance, odour and feel. The lignans corresponding to formula (I) above are advantageously chosen from: secoisolariciresinol, isolariciresinol and matairesinol .

Secoisolariciresinol is available, for example, from the company Apin Chemicals in powder form.

Rather than making use of purified lignans, it is possible in the present invention to use lignan- rich plant extracts. The plant extract used according to the invention may be obtained from any plant material cultivated in vivo or in vitro. The expression "in vivo cultivation" means any cultivation of conventional type, i.e. in the soil in the open air or in a greenhouse, or alternatively 'out of the soil. The expression "in vi tro cultivation" means all the techniques known to those_ skilled in the art for artificially obtaining a plant or part of a plant. The selection pressure imposed by the physicochemical conditions during the growth of plant cells in vitro makes it possible to obtain standardized plant material available throughout the year, in contrast with plants cultivated in vivo .

The lignans may especially be extracted from flax seeds, in particular from the species Linum usitatissinum, which thus constitutes the preferred source for supplying lignans of formula (I) or a plant extract according to the invention.

The extraction process used for extracting the lignans according to the invention in aglycone form usually comprises the following steps: a) the enzymatic hydrolysis of flax seeds in aqueous medium, or the extraction of flax seeds with an aqueous, alcoholic or aqueous-alcoholic solvent, and b) the acidic hydrolysis of the extract obtained in step (a) . The acidic hydrolysis step allows the lignans to be isolated in aglycone form. The solvent used in step (a) is generally chosen from water, ethanol and methanol, and mixtures thereof .

According to one preferred embodiment of the invention, the above process also comprises a preliminary step of defatting the flax seeds using an organic solvent such as n-hexane.

An example of such an extraction process is given in the publication by L. P. eagher et al . , Isolation and Characterization of the Lignans,

Isolariciresinol and Pinoresinol, in Flaxseed Meal, J. Agric. Food Chem. , 1999, 47, 3173-3180.

As a variant, the lignans according to the invention may be obtained by acidic hydrolysis of glycosylated lignans obtained according to the process described in US-5 705 618. This process comprises the extraction of a commercially available defatted flax seed meal, using an aqueous-alcoholic mixture, followed by the removal of the residual solids and the removal of the lignan-rich alcoholic solvent, to obtain a concentrate that is subjected to a basic hydrolysis intended to decomplex the lignans. This hydrolysed concentrate is then subjected to a liquid/liquid fractionatiori, for example using an ethyl acetate/water mixture, or is passed through an ion-exchange resin to concentrate the lignans, which are then separated out by chromatography. The amount of lignan (s) 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 amount of lignan (s) representing from 0.001% to 10% of the total weight of the composition and preferably from 0.01% to 2% of the total weight of the composition may be used.

The composition according to the invention may be in any presentation form normally used in cosmetics and dermatology, and it may especially be in the form of an optionally gelled solution, a dispersion of the lotion type, optionally a two-phase lotion, an emulsion obtained by dispersing a fatty phase in an aqueous phase (O/W emulsion) or conversely (W/O emulsion) , or a triple emulsion (W/O/W or 0/W/O emulsion) or a vesicular dispersion of ionic and/or nonionic type. These compositions are prepared according to the usual methods .

This composition may be more or less fluid and may have the appearance of a white or coloured cream, an ointment, a milk, a lotion, a serum, a paste or a mousse. It may optionally be applied in the form of an aerosol. It may also be in solid form, in particular in the form of a stick or a patch. It may be used as a care product and/or as a makeup product for the skin. In a known manner, the composition of the invention may also contain adjuvants that are common in cosmetics, such as hydrophilic or lipophilic gelling agents, hydrophilic or lipophilic active agents, preserving agents, antioxidants, solvents, fragrances, fillers, screening agents, pigments, odour absorbers and dyestuffs. The amounts of these various adjuvants are those conventionally used in the field under consideration, for example from 0.01% to 20% relative to the total weight of the composition. Depending on their nature, these adjuvants may be introduced into the fatty phase, into the aqueous phase, or into lipid vesicles. In any case, these adjuvants, and also the proportions thereof, will be chosen so as not to harm the desired properties of the lignans according to the invention.

When the composition of the invention is an emulsion, the proportion of the fatty phase may range from 5% to 80% by weight and preferably from 5% to 5,0% by weight relative to the total weight of the composition. The oils, emulsifiers and co-emulsifiers used in the composition in emulsion form are chosen from those conventionally used in the field under consideration. The emulsifier and co-emulsifier are present in the composition in a proportion ranging from 0.3% to 30% by weight and preferably from 0.5% to 20% by weight relative to the total weight of the composition.

As oils that may be used in the invention, mention may be made of mineral oils (liquid petroleum jelly) , oils of plant origin (avocado oil or soybean oil) , oils of animal origin (lanolin) , synthetic oils (perhydrosqualene) , silicone oils (cyclomethicone) and fluoro oils (perfluoropolyethers) . Fatty alcohols (cetyl alcohol) , fatty acids and waxes (carnauba wax or • ozokerite) may also be used as fatty substances.

As examples of emulsifiers and co-emulsifiers that may be used in the invention, mention may be made of fatty acid esters of polyethylene glycol such as PEG-20 stearate, and fatty acid esters of glycerol such as glyceryl stearate.

Hydrophilic gelling agents that may be mentioned in particular include carboxyvinyl polymers (carbomer) , acrylic copolymers such as acrylate/alkylacrylate copolymers, polyacrylamides, polysaccharides, natural gums and clays, and lipophilic gelling agents that may be mentioned include modified clays, for instance bentones, metal salts of fatty acids, hydrophobic silica and polyethylenes .

According to one preferred embodiment of the invention, the composition also contains at least one compound chosen from: desquamating agents; moisturizers; depigmenting or propigmenting agents; antiglycation agents; NO-synthase inhibitors; agents for stimulating the synthesis of dermal or epidermal macromolecules and/or for preventing their degradation; agents for stimulating the proliferation of fibroblasts and/or keratinocytes or for stimulating the differentiation of keratinocytes; muscle relaxants; tensioning agents; antipollution agents and/or free- radical scavengers; agents acting on the capillary circulation; agents acting on the energy metabolism of cells; and mixtures thereof.

The concentration of these optional additional agents in the composition according to the invention may range from 0.0001% to 20% by weight and is preferably between 0.001% and 5% by weight relative to the total weight of the composition.

Examples of such additional compounds are given below.

1. Desquamating agents The term "desquamating agent" means any compound capable of acting: either directly on desquamation by promoting exfoliation, such as β-hydroxy acids, in particular salicylic acid and its derivatives (including 5-n- octanoylsalicylic acid) ; α-hydroxy acids, such as glycolic acid, citric acid, lactic acid, tartaric acid, malic acid or mandelic acid; urea; gentisic acid; oligofucoses; cinnamic acid; extract of Saphora japonica; resveratrol; or on the enzymes involved in the desquamation or degradation of corneodesmosomes, glycosidases, stratum corneum chymotryptic enzyme (SCCE) , or even other proteases (trypsin, chymotrypsin-like) . Mention may be made of agents for chelating mineral salts: EDTA; N-acyl-N,N' ,N' -ethylenediaminetriacetic acid; amino- sulphonic compounds and in particular (N-2- hydroxyethylpiperazine-N-2-ethane) sulphonic acid (HEPES) ; 2-oxothiazolidine-4-carboxylic acid (procysteine) ; cc-amino acid derivatives of the type such as glycine (as described in EP-0 852 949, and sodium methyl glycine diacetate sold by BASF under the trade name Trilon M) ; honey; sugar derivatives such as O-octanoyl-6-D-maltose and N-acetylglucosamine . 2. Moisturizer

The term "moisturizer" means: either a compound acting on the barrier function, in order to maintain the moisturization of the stratum corneum, or an occlusive compound. Mention may be made of ceramides, sphingoid-based compounds, lecithins, * glycosphingolipids, phospholipids, cholesterol and its derivatives, phytosterols (stigmasterol, β-sitosterol or campesterol) , essential fatty acids, 1,2-diacyl- glycerol, 4-chromanone , pentacyclic triterpenes such as ursolic acid, petroleum jelly and lanolin; or a compound that directly increases the water content of the stratum corneum, such as trehalose and its derivatives, hyaluronic acid and its derivatives, glycerol, pentanediol, sodium pidolate, serine, xylitol, sodium lactate, polyglyceryl acrylate, ectoin and its derivatives, chitosan, oligosaccharides and polysaccharides, cyclic carbonates, N-lauroyl- pyrrolidonecarboxylic acid and N- -benzoyl-L-arginine; or a compound that activates the sebaceous glands, such as DHEA and its derivatives and vitamin D and its derivatives .

3. Depigmenting or propigmenting agent The depigmenting agents that may be incorporated into the composition according to the present invention comprise, for example, the following compounds: kojic acid; ellagic acid; arbutin and its derivatives 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-cholesteryloxycarbonyl-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 its salts and esters; ascorbic acid and its derivatives, especially ascorbyl glucoside; and plant extracts, in particular extracts of liquorice, of mulberry and of skullcap, without this list being limiting.

Propigmenting agents that may be mentioned include the extract of burnet {Sanguisorba officinalis) sold by the company Maruzen, and extracts of chrysanthemum ( Chrysanthemum mori folium) .

4. Anti-glycation agent

The term "anti-glycation agent" means a compound for preventing and/or reducing the glycation of skin proteins, in particular of dermal proteins such as collagen.

Examples of anti-glycation agents are plant extracts of the Ericacea family, such as an extract of blueberry ( Vaccinium angusti folium) ; ergothioneine and its derivatives; and hydroxystilbenes and their derivatives, such as resveratrol and 3, 3 ' , 5, 5' -tetra- hydroxystilbene . Resveratrol is particularly preferred for use in this invention.

5. NO-synthase inhibitor Examples of NO-synthase inhibitors that are suitable for use in the present invention especially comprise a plant extract of the species Vitis vinifera which is sold especially by the company Euromed under the name Leucocyanidines de raisins extra, or by the company Indena under the name Leucoselect^", or finally by the company Hansen under the name Extrait de marc de raisin; a plant extract of the species Olea europaea which is preferably obtained from olive tree leaves and is sold especially by the company Vinyals in the form of a dry extract, or by the company Biologia & Technologia under the trade name Eurol BT; and a plant extract of the species Gingko biloba which is preferably a dry aqueous extract of this plant sold by the company Beaufour under the trade name Gingko biloba extrait standard.

6. Agent for stimulating the synthesis of dermal or epidermal macromolecules and/or for preventing their degradation Among the active agents for stimulating dermal macromolecules or for preventing their degradation, mention may be made of those that act: - either on collagen synthesis, such as extracts of Centella asiatica; asiaticosides and derivatives; ascorbic acid or vitamin C and its derivatives; synthetic peptides such as Iamin, biopeptide CL or the palmitoyloligopeptide sold by the company Sederma; peptides extracted from plants, such as the soybean hydrolysate sold by the company Coletica under the trade name Phytokine^"; and plant hormones such as auxins ; or on elastin synthesis, such as the extract of Saccharomyces cerivisiae sold by the .company LSN under the trade name Cytovitin ; and the extract of the alga Macrocystis pyrifera sold by the company SECMA under the trade name Kelpadelie^"; or on glycosaminoglycan synthesis, such as the product of fermentation of milk with Lactobacillus vulgaris, sold by the company Brooks under the trade

® name Biomm yogourth ; the extract of the brown alga Padina pavonica sold by the company Alban Mϋller under the trade name HSP3-; and the extract of Saccharomyces cerevisiae available especially from the company Silab under the trade name Firmalift or from the company LSN under the trade name Cytovitin^"; or on fibronectin synthesis, such as the extract of the zooplankton Salina sold by the company Seporga

® under the trade name GP4G ; the yeast extract available especially from the company Alban Mϋller under the trade name Drieline^"; and the palmitoyl pentapeptide sold by the company Sederma under the trade name Matrixil^";

¹ or on metalloprotease (MMP) inhibition, such as, more particularly, MMP 1, 2, 3 or 9. Mention may be made of: retinoids and derivatives, oligopeptides and lipopeptides, lipoamino acids, the malt extract sold by the company Coletica under the trade name Collalift^®; extracts of blueberry or of rosemary; lycopene; isoflavones, their derivatives or plant extracts containing them, in particular extracts of soybean (sold, for example, by the company Ichimaru Pharcos under the trade name Flavosterone SB-), of red clover, of flax, of kakkon, or of sage; or on the inhibition of serine proteases such as leukocyte elastase or cathepsin G. Mention may be made of: the peptide extract of Leguminosa seeds {Pisum sativum) sold by the company LSN under the trade name Parelastyl^"; heparinoids; and pseudodipeptides .

Among the active agents that stimulate epidermal macromolecules, such as fillagrin and keratins, mention may be made especially of the extract of lupin sold by the company Silab under the trade name Structurine^" ; the extract of beech Fagus sylvatica buds sold by the company Gattefosse under the trade name Gatuline^"; and the extract of the zooplankton Salina sold by the company Seporga under the trade name GP4G- . 7. Agent for stimulating the proliferation of fibroblasts or keratinocytes and/or keratinocyte differentiation

The agents for stimulating the proliferation of fibroblasts that may be used in the composition according to the invention may be chosen, for example, from plant proteins or polypeptides, extracts, especially of soybean (for example an extract of soybean sold by the company LSN under the name Eleseryl SH-VEG 8^" or sold by the company Silab under the trade name Raffermine^") ; and plant hormones such as giberrellins and cytokinins . The agents for stimulating keratinocyte proliferation that may be used in the composition according to the invention especially comprise retinoids such as retinol and its esters, including retinyl palmitate; phloroglucinol; extracts of nut cakes sold by the company Gattefosse; and extracts of Solanum tuberosum sold by the company Sederma.

The agents for stimulating keratinocyte differentiation comprise, for example, minerals such as calcium; the extract of lupin sold by the company Silab under the trade name Photopreventine^®; sodium beta- sitosteryl sulphate sold by the company Seporga under the trade name Phytocohesine^" ; and the extract of corn sold by the company Solabia under the trade name Phytovityl^®.

8. Muscle relaxant

Besides the sapogenin described above, the composition according to the invention may comprise other muscle relaxants, among which mention may be made in particular of alverine and its salts, especially alverine citrate, manganese gluconate and the hexapeptide argireline R sold by the company Lipotec.

9. Tensioning agent

The term "tensioning agent" means a compound capable of exerting tension on the skin, the effect of which is to .temporarily fade out irregularities on the skin's surface, such as wrinkles and fine lines. Among the tensioning agents that may be used in the composition according to the present invention, mention may be made especially of:

(1) synthetic polymers, such as polyurethane latices or acrylic-silicone latices, in particular those described in patent application EP-1 038 519, such as a propylthio (polymethyl acrylate) , propylthio (polymethyl methacrylate) and propylthio (polymethacrylic acid), grafted polydimethylsiloxane, or alternatively a propylthio (polyisobutyl methacrylate) and propylthio (polymethacrylic acid) grafted polydimethylsiloxane. Such grafted silicone polymers are sold especially by the company 3M under the trade names VS 80, VS 70 or L021. (2) polymers of natural origin, especially (a) polyholosides, for example (i) in the form of starch derived especially from rice, corn, potato, cassava, pea, Triticum aestivum wheat, oat, etc. or (ii) in the form of carrageenans , alginates, agars, gelans, cellulose-based polymers and pectins, advantageously as an aqueous dispersion of gel microparticles, and (b) latices consisting of shellac resin, sandarac gum, dammar resins, elemi gums, copal resins and cellulose- based derivatives, and mixtures thereof, (3) plant proteins and protein hydrolysates, in particular from corn, rye, Tri ticum aestivum wheat, buckwheat, sesame, spelt, pea, bean, lentil, soybean and lupin,

(3) mixed silicates, especially phyllosilicates and in particular Laponites, (4) wax microparticles chosen, for example, from carnauba wax, candelilla wax and alfalfa wax, (5) colloidal particles of mineral filler with a number-average diameter of between 0.1 and 100 nm and preferably between 3 and 30 nm, chosen, for example, from: silica, cerium oxide, zirconium oxide, alumina, calcium carbonate, barium sulphate, calcium sulphate, zinc oxide and titanium dioxide.

10. Anti-pollution agent or free-radical scavenger 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 chlorogenic acid; stilbenes, in particular resveratrol; sulphur- containing amino acid derivatives, in particular S-carboxymethylcysteine; ergothioneine; N-acetyl- cysteine; chelating agents for instance N,N' -bis (3 , 4, 5- trimethoxybenzyl) 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, phenyl- alanine, tyrosine and hydrolysed RNA, sold by the 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 Eichhornia 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; sulphur-containing amino acids such as cysteine; extracts of water hyacinth {Eichhornia crassipes) ; and the water-soluble fraction of corn sold by the company Solabia under the trade name Phytovityl .

The free-radical scavengers that may be used in the composition according to the invention comprise, besides certain anti-pollution agents mentioned above, vitamin E and its derivatives such as tocopheryl acetate; bioflavonoids; coenzyme Q10 or ubiquinone; certain enzymes, for instance catalase, superoxide dismutase, lactoperoxidase, glutathione peroxidase and quinone reductases; glutathione; benzylidenecamphor; benzylcyclanones; substituted napthaienones ; pidolates; phytanetriol ; gamma-oryzanol ; lignans; and melatonin. 11. Agents acting on the capillary circulation

The active agents acting on the capillary circulation (vasoprotective or vasodilating agents) are found especially among flavonoids, ruscogenins, esculosides, escin extracted from common horse chestnut, nicotinates, heperidine methyl chalcone, essential oils of lavender or of rosemary, and extracts of Ammi Visnaga . 12. Agents acting on the energy metabolism of cells

This expression means active agents acting on the energy metabolism of the skin, such as, for example, and in a non-limiting manner, ATP synthesis, and also those involved in the respiratory chain of the cell or in the energy reserves'. Mention may be made in this respect of coenzyme Q10 (ubiquinone) , cytochrome C, creatine or phosphocreatine.

As mentioned previously, the composition according to the invention may also contain UVA and/or UNB screening agents, in the form of organic or mineral compounds, the latter optionally being coated to make them hydrophobic .

The organic screening agents may be chosen especially from: anthranilates, in particular menthyl anthranilate; benzophenones, in particular benzophenone-1, benzophenone-3 , benzophenone-5, benzophenone-6, benzophenone-8 , benzophenone-9, benzophenone-12 and, preferably, benzophenone-2 (oxybenzone) or benzophenone-4 (Uvinul MS40 available from BASF); benzylidenecamphors , in particular 3-benzylidenecamphor, benzylidenecamphorsulphonic acid, camphor benzalkonium methosulphate, polyacrylamido- methylbenzylidenecamphor, terephthalylidenedicamphor- sulphonic acid and, preferably, 4-methylbenzylidenecamphor (Eusolex 6300 available from Merck) ; benzimidazoles, in particular benzimidazilate (Neo Heliopan AP available from Haarmann & Reimer) , or phenylbenzimidazolesulphonic acid (Eusolex 232 available from Merck) ; benzotriazoles, in particular drometrizole trisiloxane, or methylenebis- benzotriazolyltetramethylbutylphenol (Tinosorb M available from Ciba) ; cinnamates, in particular cinoxate, DEA methoxycinnamate, diisopropyl methyl- cinnamate, glyceryl ethylhexanoate dimethoxycinnamate, isopropyl methoxycinnamate, isoamyl cinnamate and, preferably, ethocrylene (Uvinul N35 available from BASF) , octyl methoxycinnamate (Parsol MCX available from Hoffmann LaRoche) , or octocrylene (Uvinul 539 available from BASF); dibenzoylmethanes, in particular butylmethoxydibenzoylmethane (Parsol 1789) ; imidazolines, in particular ethylhexyl dimethoxybenzylidene dioxoimidazoline; PABAs, in particular ethyl dihydroxypropyl PABA, ethylhexyldimethyl PABA, glyceryl PABA, PABA, PEG-25 PABA and, preferably, diethylhexylbutamidotriazone (Uvasorb HEB available from 3V Sigma) , ethylhexyl- triazone (Uvinul T150 available from BASF) or ethyl PABA (benzocaine) ; salicylates, in particular dipropylene glycol salicylate, ethylhexyl salicylate, homosalate or TEA salicylate; triazines, in particular anisotriazine (Tinosorb S available from Ciba) ; drometrizole trisiloxane. The mineral screening agents preferably consist of zinc oxide and/or titanium dioxide, preferably of nanometric size^', optionally coated with alumina and/or stearic acid.

The examples that follow are given for purely illustrative purposes and are not intended to limit the scope of this invention. Unless otherwise mentioned, the proportions referred to in the compositions below correspond to weight percentages .

EXAMPLES

Example 1: Effect of secoisolariciresinol on collagen synthesis

Principle of the method:

The study consists in evaluating the synthesis of collagen with secoisolariciresinol (Apin Chemical) , by measuring the incorporation of radioactive proline into normal human dermal fibroblast cultures .

Human dermal fibroblasts used at the eighth passage are inoculated into 96-well plates for 80% confluence and are cultured in DMEM medium with 10% foetal calf serum, according to standard cell culturing methods. After a preincubation period, the cells are placed in contact with the product for 48 hours. The radioactive precursor, L- (2, 3-3H) roline (Amersham, 49 Ci/mmol) is then introduced into the culture medium (16.6 μCi/ml) . The labelling time is 24 hours. The synthesized collagen is then extracted by adding chaotropic buffer. The proteins are precipitated with trichloroacetic acid and then collected on filters (Skatron filters and collector) . The precipitates are washed and then counted by liquid scintillation.

Vitamin C (Sigma A 0278) at a final concentration of 20 ug/ml is used as a positive reference . Inter-group comparisons were performed by analysis of variance (ANOVA) using Dunnett's multiple comparison test. Results :

The results are collated in Table 1 below.

Table 1 Stimulation of the incorporation of proline

These results show that secoisolariciresinol significantly stimulates the synthesis of collagen by cultured human dermal fibroblasts.

Example 2 : Fluid containing oleosomes

Phase A

Stearyl heptanoate and stearyl octanoate 5.5

Plant oils _ 11.6

UNA-screening agent 1.9

Cyc1opentasi1oxane 3.7

Sucrose tristearate 2

Oxyethylenated sorbitan monostearate (4 EO) 1.35

Stearic acid 1 Oxyethylenated hydrogenated castor oil (60 EO) 2.5

Tocopheryl acetate 0.5

Phase B

Secoisolariciresinol 0.05 Preserving agents 0.29 Triethanolamine 0.50 %

Disodium EDTA 0.05 %

Glycerol 3 %

Water qs 100 %

This composition may be prepared in the following manner: phases A and B are heated separately to 65°C and are then cooled to room temperature (25°C) . Phase B is then introduced into phase A to obtain an O/W emulsion, which is then subjected to high-pressure homogenization (500b, 1 to 3 times) .

This fluid is useful, when applied daily to the face and neck, for preventing and treating the signs of ageing of the skin, and in particular the loss of firmness of the skin.

Example 3: Water-in-oil cream

Phase A

Hydrogenated polyisobutene 5.5 %

Isostearyl neopentanoate ' 3.5 %

PEG stearate (20 EO) 1 %

PEG glyceryl stearate (100 EO) 2 %

Cetyl alcohol 0.5 %

Stearic acid 1 %

Matairesinol 0.01 % Phase A '

C c1omethicone 11

Phase B

Preserving agents 0.2 Triethanolamine 0.03 Water qs 100

Phase C

Polyacrylamide and isoparaffin and Laureth-7 1 %^'

(Sepigel 305 from SEPPIC)

The above composition may be prepared in the following manner: phase A is heated with stirring until homogeneous. After cooling, phase A' is added and phase B is then heated with stirring, followed by adding phase A, with continued stirring. After cooling to 50°C, phase C is incorporated into the emulsion.

An anti-wrinkle cream that may be used as a night cream is obtained.

Claims

1. Cosmetic use of at least one lignan corresponding to formula (I) :

in which:

Ri and R₂ each represent a -CH₂-OH group or, taken together, form a furanone ring,

R₃ and R₄ independently represent a hydroxyl group or an

-0-CH₃ group,

R₅, R₆ and R₇ independently represent a hydroxyl group or an -0-CH₃ group or a hydrogen atom, it being understood that at least one of the groups R₃ and R and at least one of the groups R₅, R₆ and R₇ represents an -0-CH₃ group,

Rs and R₉ each represent a hydrogen atom or together form a bond, or of a plant extract containing it, in a composition suitable for topical application to the skin and containing a cosmetically acceptable medium, for preventing or treating the signs of ageing of ■ the skin.

2. Use according to Claim 1, characterized in that the said lignan is chosen from: secoisolariciresinol, isolariciresinol and , matairesinol .

3. Use according to Claim 1 or 2, characterized in that the said plant extract is an extract of flax seeds.

4. Use according to Claim 3, characterized in that the said extract of flax seeds is obtainable by a process comprising the following steps: a) the enzymatic hydrolysis of flax seeds in aqueous medium, or the extraction of flax seeds with an aqueous, alcoholic or aqueous-alcoholic solvent, and b) the acidic hydrolysis of the extract obtained.

5. Use according to Claim 4, characterized in that the solvent used in step (a) is chosen from^* water, ethanol and methanol, and mixtures thereof.

6. Use according to Claim 4 or 5, characterized in that the said process also comprises a preliminary step of defatting the flax seeds using an organic solvent such as n-hexane.

7. Use according to any one of Claims 1 to 6, characterized in that the said signs of ageing of the skin are chosen from: loss of firmness, elasticity and/or tonicity of the skin and the formation of wrinkles and fine lines.

8. Use according to any one of Claims 1 to 7, characterized in that the said lignan represents from 0.001% to 10% of the total weight of the composition.

9. Use according to Claim 8, characterized in that the said lignan represents from 0.01% to 2% of the total weight of the composition.

10. Composition suitable for topical application to the skin, comprising, in a cosmetically acceptable medium, at least one lignan corresponding to formula (I) :

in which:

Ri and R₂ each represent a -CH₂-OH group or, taken together, form a furanone ring,

R₃ and R₄ independently represent a hydroxyl group or an

-0-CH₃ group, R₅, R₆ and R₇ independently represent a hydroxyl group or an -0-CH₃ group or a hydrogen atom, it being understood that at least one of the groups R₃ and R₄ and at least one of the groups R₅, R₆ and R₇ represents an -0-CH₃ group,

R₈ and R₉ each represent a hydrogen atom or together form a bond, or a plant extract containing it, and at least one compound chosen from: desquamating agents; moisturizers; depigmenting or propigmenting agents; antiglycation agents; NO-synthase inhibitors; agents for stimulating the synthesis of dermal or epidermal macromolecules and/or for preventing their degradation; agents for stimulating the proliferation of fibroblasts and/or keratinocytes or for stimulating , the differentiation of keratinocytes; muscle relaxants; tensioning agents; antipollution agents and/or free- radical scavengers; agents acting on the capillary circulation; agents acting on the energy metabolism of cells; and mixtures thereof.

11. Cosmetic process for treating dry skin, comprising the topical application to the said skin of a composition containing, in a cosmetically acceptable medium, at least one lignan of formula (I) as defined in Claim 1.