WO2019077268A1 - Cosmetic composition for active prevention of the signs of ageing - Google Patents

Abstract

Cosmetic composition for active prevention of the signs of ageing. The present invention particularly relates to the cosmetic use of at least one extract from at least one iridaceous plant of the genus Iris, as an agent for preventing and/or delaying the appearance of the first signs of cutaneous ageing, in particular those linked with oxidation and/or glycoxidation phenomena brought about by an oxidising stress, and a cosmetic composition for topical application to the skin comprising at least (i) an extract from an iridaceous plant of the genus Iris, (ii) an extract from red algae and (iii) a tocopherol phosphate or one of the salts thereof.

Description

 Cosmetic composition of active prevention signs of age. TECHNICAL FIELD OF THE INVENTION

 The present invention relates to the field of skin aging, and more specifically the prevention of the appearance of the first signs of age otherwise known as 'pre-aging'.

STATE OF THE ART

 Skin aging has for many years mobilized research efforts to identify new assets and / or new technologies aimed at decreasing and / or correcting the signs of aging, in particular visible signs such as wrinkles, the loss of elasticity and sagging of the skin that appear and then increase with age and are particularly characteristic of mature skin.

 In the context of the present invention, we are interested in the active prevention of the appearance of the first signs of age, a field for which there still remains the need to develop new cosmetic compositions, in particular adapted to young skin ( 20-35 years). We speak of "pre-aging" or "pre-aging", upstream of chronological aging phenomena, also called intrinsic aging and photo-induced aging, also called extrinsic aging.

The skin is continually subjected to multiple aggressions that can accelerate its natural aging process. It is particularly sensitive to oxidative stress generated both by the normal functioning of our body and by external elements such as air pollution, solar radiation or even tobacco. This oxidative stress is characterized by the production of Reactive Oxygen Species (ROS) that can react with all cellular components, causing their modification by oxidation and an alteration of their function. This leads in particular to a gradual decrease in cell functions following the aggregation (bridging) of macromolecules. In order to counteract the action of the ROS, the cells have developed defense mechanisms, enzymatic or otherwise. We speak of 'natural system of antioxidant defense of the skin'. But these protective mechanisms are also disturbed during aging.

It was recently highlighted by the team of Radjei S et al. (Experimental Dermatology, 2016, 25, 475-494) the presence of an enzymatic glyoxalase system at the level of the epidermis, playing a protective role against oxidative damage induced by reactive oxygen species (ROS) such as the glyoxal (GO) and methylglyoxal (MG). The Glyoxalase removes glyoxal (GO) and methylgloxal (MG). Thus this enzyme prevents their accumulation and subsequent glycation phenomena, resulting from the reaction of carbonyl compounds such as GO and MG with skin proteins leading to advanced glycation products (AGE). The elimination of carbonyl compounds (glyoxal and methylglyoxal) is therefore essential to protect the skin from the glycation phenomena involved in skin aging.

 According to one particular embodiment, the 'natural antioxidant defense system of the skin' according to the invention involves glyoxalase. It is in this context that the Applicant has demonstrated, surprisingly, that an Iris extract was able to increase the activity of glyoxalase, thus allowing to act directly on the natural system of antioxidant defense of the skin to strengthen it and thus delay the appearance of signs of age.

 The use of an extract of Iris in cosmetics is already known, in particular from the Shiseido JPS60-201249 application published in 1987, to prevent advanced 'visible' signs of aging, in particular the roughness of the skin and the skin. sagging skin, rather characteristic of mature skin. Applications WO 97/003556 from the company L'OREAL and WO 02/234229 from the company SILAB are also known, the effects of an iris extract on the reduction of wrinkles via a skin tissue relaxation effect or an inhibition collagenase activity in the dermis, again targeting advanced signs of aging.

But to the knowledge of the Applicant, this is the first time that we demonstrate the effect of an Iris extract on the activity of glyoxalase and its role in the active prevention of the appearance of the first signs of age ('pre-aging').

SUMMARY OF THE INVENTION

A first subject of the invention therefore relates to a cosmetic composition for topical application to the skin comprising, in a physiologically acceptable medium, at least:

 (i) an iridescent extract of the genus Iris, chosen in particular from an extract of a species selected from the group consisting of Iris florentina, Iris germanica, Iris pallida or Iris pallasii, preferably Iris florentina,

(ii) an extract of red algae, preferably of the species Kappaphycus alvarezii and (iii) a tocopherol phosphate or a salt thereof, preferably a tocopheryl sodium phosphate.

Preferably the iridescent extract of the genus Iris is an extract of Iris florentina rhizome.

Another object of the invention is a cosmetic care method, intended in particular for young skin (subjects preferably between 20 and 35 years, preferably still between 20 and 30 years), for preventing and / or delaying the onset of first signs of cutaneous aging, in particular linked to the glycation and / or glycoxidation phenomena induced by oxidative stress, comprising the application to said skin of at least one cosmetic composition comprising at least one iridescent extract of the genus Iris selected in particular from an extract of a species selected from the group consisting of Iris florentina, Iris germanica, Iris pallida or Iris pallasii, preferably Iris florentina. According to one particular embodiment, said method comprises the application to said skin of at least one cosmetic composition for topical application to the skin comprising, in a physiologically acceptable medium, at least:

 (i) an iridescent extract of the genus Iris, chosen in particular from an extract of a species selected from the group consisting of Iris florentina, Iris germanica, Iris pallida or Iris pallasii, preferably Iris florentina,

(ii) an extract of red algae, preferably of the species Kappaphycus alvarezii and

 (iii) a tocopherol phosphate or a salt thereof, preferably a tocopheryl sodium phosphate.

Another subject of the invention therefore relates to the cosmetic use of at least one extract of at least one Iridaceae of the genus Iris, chosen especially from an extract of a species chosen from the group consisting of Iris florentina, Iris germanica, Iris pallida or Iris pallasii, preferably Iris florentina, as an agent for preventing and / or delaying the appearance of the first signs of skin aging, otherwise known as 'pre-aging', linked in particular to phenomena of oxidation and / or glycoxidation induced by oxidative stress. DETAILED DESCRIPTION OF THE INVENTION

 'Skin aging' is a normal physiological process, involving intrinsic factors (genetic, hormonal, disease ...) and extrinsic (UV, stress, climatic aggressions, pollution ...), and which increases during the life of an individual due to a decline in his defense system and his growing need for antioxidants.

 Changes in the stratum corneum, epidermis, epidermal junction and dermis vary with age and are manifested by 'visible signs' of aging, which progress with age , more or less quickly depending on the individual and his environment (intrinsic and extrinsic factors). These 'visible signs' of age include loss of elasticity, tone and / or firmness of the skin, wrinkles in the forehead, around the eyes and lips, in the neck, loss volumes of the face, and pigmentary spots.

By "pre-aging" in the sense of the present invention is meant the 'invisible signs' upstream of the appearance of the visible signs of age. These 'invisible signs' or 'cellular signs' of age, as opposed to 'visible signs', otherwise known as 'clinical signs' of age, include cellular damage induced by oxidative stress and in particular involving oxidation, glycation or glycoxidation of proteins.

It has been demonstrated that on skins of donors of different ages, the proportion of carbonylated and glycated proteins increases significantly with age (Petropoulos, I. et al., 2000): Increase of oxidatively modified The Journals of Gerontology Series a: Biological Sciences and Medical Sciences, 55 (5), B220-7.

The purpose of the invention and therefore to act on these cell phenomena of 'pre-aging', upstream of 'aging', in order to have a skin more resistant to the effects of oxidative stress, for a skin that looks younger more long time.

The present invention thus aims to strengthen the natural system of antioxidant defense of the skin and thus prevent and / or actively delay the appearance of the first signs of age ('pre-aging').

By 'early signs of age' are meant the very first signs of aging, distinct from the advanced clinical signs of aging, described above and in the prior art. These first signs result from the first cellular damage induced by oxidative stress and notably involving oxidation, glycation or glycoxidation of proteins. The invention thus relates in particular to the use of at least one extract of at least one Iridaceae of the genus Iris in a cosmetic composition, chosen especially from an extract of a species selected from the group consisting of Iris florentina, Iris germanica , Iris pallida or Iris pallasii, preferably Iris florentina, as an agent for preventing and / or delaying the appearance of the first signs of skin aging ('pre-aging').

According to a particular embodiment of the invention, the iridescent extract of the Iris genus is used in a content ranging from 0.0001% to 0.1% by weight of dry matter (active ingredient), preferably 0.001% by weight. % to 0.01% by weight of dry matter (active ingredient) relative to the total weight of the composition containing it.

According to one particular embodiment, the invention makes it possible to reduce the oxidation and / or glycoxidation phenomena induced by oxidative stress and thus prevent and / or delay the appearance of the first signs of age.

Thus according to a particular mode, the Iris extract prevents and / or delays the appearance of the first signs of skin aging related to oxidation and / or glycoxidation phenomena induced by oxidative stress. By "oxidative stress" according to the invention is meant in particular a stress resulting from the toxic effects of dicarbonyl compounds (eg glyoxal and methylglyoxal) on proteins. We speak more generally about 'oxidative stress' generated by the normal functioning of our organism and by external elements (pollution, UV radiation), which is characterized by the production of reactive oxygen species (ROS or ROS) that can react with all cellular components, in particular proteins and DNA, causing their modification by oxidation.

By "oxidation and / or glycoxidation phenomena" according to the invention ("glycation") is also generally meant the reaction of a reducing sugar (glucose) or the abovementioned dicarbonyl compounds (glyoxal and methylglyoxal), with proteins, leading to the formation of advanced glycation products (AGEs). The presence of these glycation adducts on the proteins causes their denaturation and the inactivation of the enzymes. According to a particular embodiment of the invention, the Iris extract of the invention strengthens the natural system of antioxidant defense of the skin.

According to a particular embodiment of the invention, the Iris extract of the invention increases the activity of the glyoxalase of skin cells, in particular epidermal stem cells.

By "epidermal stem cells" according to the invention is meant in particular cells with a high potential for clonogenicity localized preferentially at the level of the basal layer of the epidermis. The cells, which make up a small population of skin cells, have the highest ability to divide and form large colonies compared to other skin cells.

Iris extract

 According to a preferred embodiment of the invention, the extract of at least one Iridaceae of the genus Iris is chosen from an extract of a species chosen from the group consisting of Iris florentina, Iris germanica, Iris pallida or Iris pallasii, of preferably Iris florentina.

 According to a particular mode, it will be an extract of rhizome, preferably an extract of rhizome Iris florentina.

 The Iris extract may be mixed in powder form with a composition for topical application to the skin, or may be in the form of a liquid extract obtained by extraction in the presence of a suitable solvent, preferably at least one polar solvent cosmetically acceptable.

 Prior to the extraction stage itself, the plant material may have been dried and / or milled.

The extract may be prepared by various extraction methods known to those skilled in the art.

Advantageously, the extraction is preferably carried out by contacting the selected plant material with a polar solvent or a mixture of polar solvents. According to the present invention, the term "polar solvent" means that the solvent has a Polarity Index value that is equal to or greater than a value of 4. The polarity index is a quantity calculated on the basis of thermodynamic magnitudes. (of solubility and change of state) which highlights the more or less polar nature of a molecule. For the solvent polarity indices, refer to the article by LR SNYDER: Classification of the solvent properties of common liquids; Journal of Chromatography, 92 (1974), 223-230. Preferred polar solvents are those consisting of a compound comprising at least one polar covalent bond of OH type.

 As a particularly preferred polar solvent, a solvent or a mixture of solvents chosen from water is chosen, the C 1 -C 4 alcohols, such as ethanol, glycols, such as ethylene glycol, glycerol, butylene glycol and propylene glycol, and mixtures thereof.

According to a preferred embodiment, the plant material is extracted with water.

Extraction can be carried out under reflux or by maceration at room temperature.

Ultrasound during extraction is advantageously used in order to improve the mass yield of said extraction.

The extraction process advantageously comprises a filtration step for separating the liquid phase from the spent plant material.

The extraction cycle and then filtration can be repeated several times in order to exhaust the plant material of substances having an affinity for the extraction solvent.

 The extraction process may also comprise at least one fading and / or purification step, for example in the form of a treatment of the extract with a solution of at least one polar solvent in the presence of activated carbon particles. . This eliminates chlorophyll extracted by the solvent.

 The extraction process may further be completed by a step of partial or total elimination of extraction solvents.

 The extract can advantageously be concentrated by removing a part of the solvent or of the mixture of the extraction solvent.

It is thus possible to obtain an aqueous concentrate that does not contain a significant quantity of organic solvents, or else, by eliminating all the extraction solvent, to obtain a dry residue.

Alternatively, the product of the extraction step may be freeze-dried or atomized to be in the form of a powder.

The polar plant extract as described above may be used in a cosmetic composition in the form of a powder or may be put back in solution or in suspension in at least one cosmetically acceptable solvent, which may be identical to or different from that which has served to extraction.

According to a preferred variant, the concentrated Iris extract is redissolved in water. We speak of solution of Iris extract or aqueous extract of Iris according to the invention. The aqueous extract further advantageously comprises at least one antioxidant, in particular phenoxyethanol.

According to one particular embodiment, the Iris extract, in particular of Iris florentina, can be obtained by a process comprising the following steps:

 - the grinding of the rhizome of the plant,

 - extraction of vegetable matter by steam distillation,

- Filtration and optionally re-solution of the extract obtained in a solvent or a mixture of polar solvents.

The powder, concentrated liquid or diluted liquid (extract solution or aqueous extract) forms of the Iris extract may alternatively be used in the preparation of cosmetic compositions. According to a particular and preferred embodiment of the invention, the Iris extract according to the invention will be used in the form of Iris extract solution (aqueous extract) in the preparation of cosmetic compositions.

According to one particular preferred embodiment, the Iris extract is in the form of an aqueous extract of Iris florentina, preferably an aqueous extract of Iris florentina rhizome.

In particular, the Iris florentina extract obtained by hydrodistillation of the rhizome of Iris florentina is in solution in water and advantageously comprises an antioxidant, such as phenoxyethanol.

Use will advantageously extract Iris INCI 'Water and Iris Florentina root extract and phenoxyethanol' such as that marketed under the name Vegebios ^® Iris Florence 1 5P by Solabia. The amount of dry extract (dry matter = active ingredient) in this aqueous commercial solution is about 0.5% by weight of dry extract relative to the total weight of the commercial solution.

The invention also relates to a cosmetic care method, in particular intended for young skin (subjects aged 20 to 35), for preventing and / or delaying the appearance of the first signs of skin aging, in particular linked to the phenomena of glycation and / or glycoxidation induced by oxidative stress, comprising the application to said skin of at least one cosmetic composition comprising at least one iridescent extract of the genus Iris selected in particular from an extract of a species selected from the group consisting of Iris florentina, Iris germanica, Iris pallida or Iris pallasii, preferably Iris florentina. According to one particular embodiment, the cosmetic composition comprising at least one iridescent extract of the Iris genus is applied to young skin, in particular to the skin of a subject having a period of 20 to 40 years, preferably 20 to 35 years, preferably still 20 to 30 years. According to a particular mode, the composition is applied to the skin of the body and / or of the face and / or of the neck, in particular the skin of the face and / or of the neck, in particular the skin of the face. According to one particular embodiment, the composition is applied to the skin of the face of a subject from 20 to 25 years old.

 According to a particular embodiment, the composition is applied to the skin of the face of a subject of 25 to 30 years.

According to another particular mode, the composition is applied to the skin of the face of a subject from 30 to 35 years.

According to a particular and preferred embodiment, the cosmetic treatment method according to the invention comprises the application on the skin of a composition comprising, in a physiologically acceptable medium, at least:

 (i) an iridescent extract of the genus Iris, preferably of the species Iris florentina, more preferably an extract of rhizome of Iris florentina,

 (ii) an extract of red algae, preferably of the species Kappaphycus alvarezii and

(iii) a tocopherol phosphate or a salt thereof, preferably a tocopheryl sodium phosphate.

 According to a particular and preferred embodiment, such a composition is applied to the skin of a subject having 20 to 40 years, preferably 20 to 35 years, more preferably 20 to 30 years. Additional assets

According to a preferred embodiment of the invention, the cosmetic composition further comprises at least one agent that protects and / or stimulates the activity of the cells of the epidermis, in particular epidermal stem cells. By "protective agent and / or stimulating the activity of the epidermal cells" according to the invention is meant in particular an agent capable of maintaining the number and / or the activity of the epidermal cells, for example under oxidative stress conditions. Such an agent may, for example, be selected for its effect on telomere protection, which delays the senescence of the cells. It is possible in particular to use as agent with protective effect and / or stimulating the activity of epidermal cells, an extract of red algae, a tocopherol phosphate or one of its salts, and preferably their mixture. By "red algae extract" according to the invention is meant in particular an extract obtained from the species Kappaphycus alvarezii.

In a particular embodiment, use a red algae extract (Kappahycus alvarezii) rich galactans, such as that sold by Silab under the name TELOSOMYL ^®. Such an extract, described in the patent application FR 3047172 (SILAB), is obtained by hydrolysis of a red algae powder of the Kappaphycus alvarezii species, separation of the soluble and insoluble phases, and filtration so as to collect the fraction aqueous composition comprising in particular biopolymers. This extract limits the alteration of the telosome, the protective cap of telomeres. Indeed, TELOSOMYL ^® stimulates the expression of telosome proteins, thus limiting the shortening of telomeres. TELOSOMYL ^® preserves the replicative potential of fibroblasts. Longevity is maintained, and programmed aging of the skin delayed.

 The content of red algae extract in the composition of the invention will in particular range from 0.001% to 1% by weight, preferably from 0.01 to 0.1% by weight of dry extract (active ingredient) relative to total weight of the composition.

By "protective agent and / or stimulating the activity of the epidermal stem cells" according to the invention is meant in particular an agent capable of maintaining the number and / or the activity of the epidermal stem cells, for example in an oxidative stress condition. Such an agent may for example be selected by a clonogenicity test which is based on the ability of the stem cells to adhere to a support and divide to form large colonies (> 4mm ² ).

 It is admitted that the homeostasis of the interfollicular epidermis, a skin compartment that is in constant renewal, is maintained by a small population of so-called stem cells, located in the basal cell layer of the epidermis.

In order to study this population of cells, the so-called clonogenicity test is based on the ability of these stem cells to adhere to a support and to divide to form a large population of daughter cells grouped as colonies (Barrandon et al. al., Proc Natl Acad Sci USA 84 (1987), 2302-2306). The analysis of the number and size of the colonies makes it possible to characterize the stem cells of the epidermis and to evaluate in particular the protective action of an active agent ('protective agent and / or stimulating the activity of epidermal stem cells') during stress.

 The first step of isolating these cells is to prepare a suspension of epidermal cells which is then seeded on a feeder layer of 3T3 fibroblasts whose mitotic activity is blocked by mitomycin.

 This support makes it possible: (1) to select the basal cells of the epidermis containing the stem cells and (2) to ensure the growth of cells with a high dividing capacity which then form colonies of daughter cells. The cells with the highest ability to divide and form large colonies (> 4mm2) are from the epidermal strain population. Smaller colonies do not come from stem cells.

As protecting agent and / or stimulating the activity of epidermal stem cells, there may be mentioned in particular tocopherol phosphate or a salt thereof, the protective effect on stem cells is illustrated below in the examples.

By "vitamin E phosphate" or "tocopherol phosphate" according to the invention is meant in particular a tocopherol phosphate in the form of a base or a cosmetically acceptable salt. In the case of a tocopherol phosphate salt, an alkali metal salt, preferably sodium salt, is preferred.

 Advantageously, the tocopherol phosphate is alpha-tocopherol phosphate, beta-tocopherol phosphate, delta-tocopherol phosphate or gamma-tocopherol phosphate, and more particularly alpha tocopherol phosphate, otherwise known as alpha tocopheryl phosphate.

 A tocopherol phosphate or a salt thereof can thus advantageously be used in the composition of the invention, in combination with the Iris extract of the invention, to obtain a protective effect of epidermal stem cells.

 An extract of Iris forentina is preferably combined with the tocopherol phosphate or a salt thereof, preferably a sodium tocopheryl phosphate of the INCI name: sodium tocopheryl phosphate. The content of tocopherol phosphate in the composition of the invention will in particular range from 0.001% to 0.1% by weight, preferably from 0.01% to 0.1% by weight relative to the total weight of the composition.

The composition may further comprise other tocopherol derivatives, such as tocopherol esters other than tocopherol phosphate, to produce an antioxidant effect. protective of the cosmetic composition but devoid of biological effect. For example, tocopherol acetate may be mentioned as the antioxidant tocopherol ester of the composition.

Thus, according to a preferred embodiment of the invention, the cosmetic composition of the invention comprises an iridescent extract of the genus Iris and at least one agent that protects and / or stimulates the activity of the epidermal cells chosen from the group consisting of a red algae extract, tocopherol phosphate or one of its salts and preferably their mixture.

The cosmetic composition of the invention will advantageously comprise:

 an Iridaceae extract of the genus Iris chosen in particular from an extract of a species chosen from the group consisting of Iris florentina, Iris germanica, Iris pallida or Iris pallasii, preferably Iris florentina, for its effect at the molecular level by decreasing the production of reactive oxygen species;

 a red alga extract for its effect at the cellular level by an action on the protection of the telomeres, which delays the entry into senescence of the cells;

 a tocopherol phosphate, in particular alpha-tocopherol phosphate, or one of its salts, for its effect at the tissue level by an action on the protection of the stem cells. The invention therefore also relates to a cosmetic composition for topical application to the skin comprising, in a physiologically acceptable medium, at least:

 (i) an iridescent extract of the genus Iris selected in particular from an extract of a species selected from the group consisting of Iris florentina, Iris germanica, Iris pallida or Iris pallasii, preferably Iris florentina,

 (ii) an extract of red algae, preferably of the species Kappaphycus alvarezii and

(iii) a tocopherol phosphate or a salt thereof, preferably a tocopheryl sodium phosphate.

According to a particular and preferred embodiment, the iridescent extract of the genus Iris is an extract of rhizome of Iris florentina.

The contents of Iridaceae extract, red algae extract and tocopherol phosphate are as described above. In particular, the iridescent extract of the Iris genus is used in the composition of the invention in a content ranging from 0.001% to 0.1% by weight of dry matter, preferably from 0.001% to 0.01% by weight. % by weight of dry matter relative to the total weight of the composition. The content of red algae extract in the composition of the invention will in particular range from 0.001% to 1% by weight, preferably from 0.01 to 0.1% by weight of dry extract (active ingredient) relative to total weight of the composition.

 The content of tocopherol phosphate in the composition of the invention will in particular range from 0.001% to 0.1% by weight, preferably from 0.01% to 0.1% by weight relative to the total weight of the composition.

According to a particular and preferred embodiment, the iridescent extract of the genus Iris, the red algae extract and the tocopherol phosphate are packaged in the same cosmetic composition.

The cosmetic composition of the invention may also comprise other active agents which may be chosen in particular from hydrating agents such as hyaluronic acid or glycerol, smoothing agents or else anti-wrinkle agents such as adenosine, complexes of natural or synthetic polymers producing on the skin tensor films at the time of application to the skin, or else anti-aging agents, more particularly extracts of plants obtained by methods known to those skilled in the art and which act on biological targets of the superficial or deep layers of the skin in particular, the epidermis, and the dermis, to maintain the elasticity of the skin, to produce a plumping effect, to ensure the renewal or the repair of tissues, the maintenance skin barrier or acting on the complexion of the skin. It can also be lightening or whitening active acting on the tasks that can appear with age, especially on the hands.

galenic

 The cosmetic composition of the invention will generally comprise at least one cosmetically acceptable excipient.

By "cosmetically acceptable excipient" is meant a substance devoid of any cosmetic or biological effect as such, but useful for the incorporation of the active agent into the cosmetic composition, the shaping of said composition, or to its stability over time. The excipient is advantageously chosen from solvents, co-solvents (ethanol, glycerol, benzyl alcohol), thickeners, diluents, antioxidants, dyes, chemical or physical filters against UVA-type solar radiation. and UVB such as synthesis filters associated or not with filters consisting of particles capable of attenuating the effects of this radiation on the skin, self-tanning agents, pigments, fillers, preservatives, perfumes, absorbers odor, cosmetic or pharmaceutical active ingredients, essential oils, vitamins, essential fatty acids, surfactants, film-forming polymers, trace elements, film-forming polymers, chemical or mineral filters, moisturizing agents or water thermals, natural polymers such as polysaccharides or polypeptides, cellulose derivatives, or synthetic polymers, and optionally in addition to at least one other cosmetic active agent.

The cosmetic composition according to the invention advantageously comprises an aqueous phase and may advantageously be in any of the forms normally used for topical application, in the form of an aqueous, hydro-alcoholic or oily solution, of an oil-in-oil emulsion. water or water-in-oil, an aqueous gel, or in any other form for topical application.

 This composition may be more or less fluid and have the appearance of a white or colored cream, an ointment, a milk, a lotion, a serum, a paste, a mousse or a gel. It can optionally be applied to the skin in the form of an aerosol or by means of a patch or a mask or an applicator.

 Advantageously, the cosmetic composition according to the invention is an emulsion in the form of a day cream, a night cream, a sunscreen or an after-sun cream.

 According to one particular embodiment, the composition according to the invention is a cream present in a cosmetic kit comprising in addition at least one serum comprising at least one antioxidant. The invention will now be illustrated by the following nonlimiting examples.

Unless otherwise indicated, the percentages are expressed by weight relative to the total weight of said composition. EXAMPLES

Example 1 Effect of an Iris Extract on the Activity of Glyoxalase 1.1 Materials and Methods

 Cell culture

 250000 KHN967 P6 cells are seeded in 6 wells (Costar) in the complete Epilife medium (Life Technologies). During 4 days at 37 ° C in a humid atmosphere with 5%. Each point is made in triplicate.

Treatment

 The VEGEBIOS® IRIS FLORENCE 1.5P solution comprises 0.5% by weight of dry matter of Iris florentina rhizome, is added to 0.31% by weight in the complete Epilife medium and then filtered through 0.22μΜ.

The medium is replaced by this treatment medium for 6 hours.

Protein extraction

 After treatment, the cell mats are washed with 1X PBS (Invitrogen) to remove dead cells, various cell debris and serum from the trypsin inhibitor medium.

 500 μl of TrypLE ™ Express Enzyme (Invitrogen) are added and left for 10 minutes at 37 ° C to dissociate the cells.

 The cells are collected in a Protein LoBind Eppendorf tube. The wells are rinsed with 500 μl of supplemented DMEM and added to each tube. After centrifugation at 1500 x g for 5 minutes, the cell pellet is rinsed twice with 1 ml of 1X PBS buffer. The cell pellets are taken up in 70 μl of Cellytic Lysis Buffer (Sigma) and are stored at -80 ° C.

The cell extracts are thawed and the lysis of the cells is mechanically completed by sonification with Bioruptor (Diagenode); in 5 cycles of 8 seconds ON 'and 30 seconds OFF' at 4 ° C. The supernatants are recovered and stored at 4 ° C. after centrifugation for 15 minutes, 4 ° C., 14,000 × g. Protein Dosage (PC Protein Assay, Biorad)

 Reagent B (500-01 14)

 Reagent A (500-01 13)

 Reagent S (500-01 15)

Reagents B, A and S are the reagents of said Biorad DC protein assay kit.

• Preparation of the standard and reagent range

BSA stock solution: 5mg / ml (Sigma, A2153, 4 ° C), aliquoted and frozen at -20 ° C.

The range is prepared in Eppendorf tubes stored at 4 ° C maximum 2 months.

Table 1:

Reagent A is prepared extemporaneously (stable for one week); 20 μί of reagent S are added to 1 ml of reagent A (the reagent S is added if the samples contain detergents).

 Reagents A, B and S of the kit are stored at room temperature. • Protocol

 In a 96-well plate (Costar) are introduced in quadruplicate:

- 5 μΙ of H ₂ 0 for the zero - 5 μΙ lysis buffer for sample blank

 - 5 μΙ of stock solution for the range

 - 5 μΙ of sample to be assayed (diluted to 1 / 2.5) 25 μΙ of reagent A 'are introduced into each well and stirred vigorously.

 After 5 minutes, 200 μl of reagent B are added to each well.

 After stirring the plate; the absorbance is read at 750 nm after 15 minutes.

Assay of glvoxalase I activity (GLQ1)

 · Reagents

 - 100 mM sodium phosphate buffer pH 6.6:

 200ml of monophase phosphate solution (Sigma) at 100mM are adjusted to pH 6.6 with a dibasic phosphate solution (Sigma) about 6.6ml.

 - Methylglyoxal (MG) solution at 10mM:

 15.8 μl from the solution of Methylglyoxal at approximately 40% in water (Sigma) are added to 10 ml of 100 mM sodium phosphate buffer pH 6.6.

 - Solution of L-Glutathione reduced (GSH) at 10mM:

 30.7 mg of Glutathione reduced (Sigma) are solubilized in 10 ml of the phosphate buffer. · Protocol

 The protein lysates are thawed and then centrifuged at 4 ° C. at 150,000 × g for 15 minutes.

 In a 96-well UV-Star Plate (Dutscher) plate, 15 μg of protein per well is deposited.

 The reaction mixture is prepared extemporaneously and incubated for 5 min at 37 ° C.

 Table 2:

The formation of lactoyiglutathione absorbed at 240 nm is measured every minute for 10 min on the Fluostar Omega spectrophotometer (BMG) in an atmosphere at 37 ° C. 1.2 Results

Using the Mars software, the slope corresponding to the reaction rate is calculated in the exponential phase (at the initial T time and the final T time) from the fluorescence emitted in Fluorescence Units (FU) every 2 minutes. after subtraction of the fluorescence emitted in the White.

• Speed AAbs / AT

 = test 2 0nm- white ABS 7 0nml final- [ABS test 7 0nm 'white ABS 7 initial 0nm

 Final T-T

• Activity = Speed / mg of protein · Active effect in%

 = (Activity treated - control activity) X 100

 Sample activity

The results are shown in Table 3 below.

Table 3

 significant when p <0.01

Methylglyoxal (MG) in the presence of reduced glutathione (GSH) as cofactor at 2μΜ each are incubated 5min at 37 ° C in 50mM sodium phosphate buffer at pH 6.6 to produce hemithioacetate, the substrate of Glyoxalase 1 (GL01). After addition of 1 g of epidermal lysate protein, the activity of the enzyme is evaluated by measuring every minute for 10 minutes the increase in absorbance measured at 240 nm bound to S-Dlactoylglutathion formed.

 Depending on the assay conditions the Iris florentina extract significantly increases the glyoxalase activity by 17%.

Example 2 Effect of Alpha Tocopheryl Phosphate on the Protection of Epidermal Stem Cells

To study the effect of alpha tocopheryl phosphate on an epidermal stem cell population, the so-called clonogenicity test is based on the ability of these stem cells to adhere to a support and to divide into a population. large number of daughter cells grouped in colonies (Barrandon et al., Proc Natl Acad Sci USA 84 (1987), 2302-2306). The analysis of the number and size of the colonies makes it possible to characterize the stem cells of the epidermis and in particular to evaluate the protective action of an active agent during a stress.

 The first step of isolating these cells is to prepare a suspension of epidermal cells which is then seeded on a feeder layer of 3T3 fibroblasts whose mitotic activity is blocked by mitomycin.

 This support makes it possible: (1) to select the basal cells of the epidermis containing the stem cells and (2) to ensure the growth of cells with a high dividing capacity which then form colonies of daughter cells. The cells with the highest ability to divide and form large colonies (> 4mm2) are from the epidermal strain population. The smaller colonies are not derived from stem cells The protective effect of alpha tocopheryl phosphate is demonstrated by this method of culture. In a first step, the keratinocytes are treated with 1 μg / ml of alpha tocopheryl phosphate for 24 h and then subjected to oxidative stress by hydrogen peroxide for 15 min. They are reseeded at very low density which allows their individualized growth. After 7 days of culture, the cell colonies formed from each keratinocyte are stained, counted by image analysis according to their size to evaluate the amount of stem cells of the initial cell culture.

It is noted that the treatment with alpha tocopheryl phosphate under these conditions makes it possible to maintain the large number of large colonies (greater than 4 mm 2) during an oxidative stress of + 104% compared to the number of large colonies in the absence of treatment. As large colonies are derived from stem cells, alpha tocopheryl phosphate thus protects this particular cell population. Example 3 Formulations

Day cream (oil-in-water emulsion) The following composition is prepared

 Rhizome extract of iris florentina (1) 0.005% (% M.S *)

 Extract of Kappaphycus Alvarezii (2) 0.03% (% M.S *)

 Tocopheryl sodium phosphate 0.02%

 Glyceryl stearate + PEG-100 stearate 5.0%

 Hydrogenated Polyisobutene 4.0%

 Magnesium ascorbyl phosphate 3.0%

 Tricaprylate / glycerol caprate 3.0%

 Squalane 3.0%

 Glycerin 3.0%

 Shea butter 1, 5%

 Cetearyl octanoate 1, 5%

 Cetyl alcohol 1, 0%

 Stearyl alcohol 1, 0%

 Dimethicone 1, 0%

 0.3% xanthan gum

 0.1% citric acid

 Sodium citrate 0.1%

 Adenosine 0.05%

 Neutralizer, Perfume, Preservatives qs.

 Water qs. 100%

 % M.S *:% dry matter in the total composition.

 (1): VEGEBIOS IRIS FLORENCE 1.5P at 0.5% by weight of extract dry matter

(2) TELOSOMYL®, 0.6% extract solids The aqueous phase and the oily phase are prepared separately and then mixed in the conventional emulsion formulation mode.

The use of this cream, through its action its antioxidant action and the protection of the extracellular matrix also helps to mitigate or delay the first signs of aging of the skin in young people under 35 years. Lightening Face Serum

A serum is prepared according to the composition below:

Rhizome extract of iris florentina (1) 0.01% (M. S *)

 Extract of Kappaphycus Alvarezii (2) 0, 05% (M. S *)

 Tocopheryl sodium phosphate 0.02%

 Glycerin 2%

 0.25% xanthan gum

 Polymethylsilsesquioxane 2%

 2% ethyl alcohol

 Lactic acid 1%

 Polyacrylate 0.50%

 Dimethicone copolyol 0.25%

 Neutralizer, Fragrance, Preservative qs

 Water qs 100%

% M. S *:% dry matter in the total composition.

(1): VEGEBIOS IRIS FLORENCE 1.5P at 0.5% by weight of extract dry matter

(2) TELOSOMYL®, 0.6% extract dry matter

A serum drop, applied on the face usually before the application of face cream. This serum is usually used for one to two weeks

Claims

Cosmetic composition for topical application to the skin comprising, in a physiologically acceptable medium, at least:  (i) an iridescent extract of the genus Iris, chosen in particular from an extract of a species selected from the group consisting of Iris florentina, Iris germanica, Iris pallida or Iris pallasii, preferably Iris florentina, (ii) an extract of red algae, preferably of the species Kappaphycus alvarezii and  (iii) a tocopherol phosphate or a salt thereof, preferably a tocopheryl sodium phosphate. Cosmetic composition according to Claim 1, characterized in that the extract of at least one Iridaceae of the genus Iris is an extract of rhizome of Iris florentina. Cosmetic composition according to Claim 1 or Claim 2, characterized in that the iridescent extract of the Iris genus is used in a content ranging from 0.001% to 0.1% by weight of dry matter, preferably 0.001% by weight. % to 0.01% by weight of dry matter relative to the total weight of the composition. Cosmetic composition according to any one of Claims 1 to 3, characterized in that the content of extract of red algae ranges from 0.001% to 1% by weight, preferably from 0.01 to 0.1% by weight of dry extract (active ingredient) relative to the total weight of the composition. Cosmetic composition according to any one of Claims 1 to 4, characterized in that the content of tocopherol phosphate ranges from 0.001% to 0.1% by weight, preferably from 0.01% to 0.1% by weight. relative to the total weight of the composition. 6. Cosmetic treatment method for preventing and / or delaying the appearance of the first signs of skin aging, in particular related to the phenomena of glycation and / or glycoxidation induced by oxidative stress, comprising the application on said skin of at least one cosmetic composition as defined in any one of claims 1 to 5. Cosmetic treatment method according to claim 6, characterized in that the cosmetic composition is applied to a young skin, in particular a subject having 20 to 40 years, in particular 20 to 35 years, preferably 20 to 30 years. Cosmetic use of at least one extract of at least one Iridaceae of the genus Iris, chosen especially from an extract of a species selected from the group consisting of Iris florentina, Iris germanica, Iris pallida or Iris pallasii, preferably Iris florentina, as an agent for preventing and / or delaying the appearance of the first signs of cutaneous aging linked in particular to oxidation and / or glycoxidation phenomena induced by oxidative stress. Cosmetic use according to claim 8, in which the Iris extract enhances the natural system of antioxidant defense of the skin, in particular by increasing the activity of the glyoxalase of the skin cells, in particular epidermal stem cells. 10. Use according to one of claims 8 or 9, wherein the iridescent extract of the genus Iris is used in a content ranging from 0.001% to 0.1% by weight of dry matter, preferably 0.001%. % to 0.01% by weight of dry matter relative to the total weight of the composition. 1 1. Cosmetic treatment method for preventing and / or delaying the appearance of the first signs of skin aging, in particular related to the phenomena of glycation and / or glycoxidation induced by oxidative stress, comprising the application to the skin of a subject having 20 at 40, especially 20 to 35 years, preferably from 20 to 30 years, of at least one cosmetic composition comprising at least one Iridaceae extract of the genus Iris chosen in particular from an extract of a species selected from the group consisting of Iris florentina, Iris germanica, Iris pallida or Iris pallasii, preferably Iris florentina.