Skin dyeing compositions comprising dihydroxyacetone and a flavylium salt non substituted in position 3

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DESCRIPTION

Compositions for coloring the skin comprising dihydroxyacetone and an unsubstituted flavillium salt at position 3.

The present invention relates to cosmetic and / or dermatological compositions intended for artificial coloring of the skin, characterized in that it comprises, in a cosmetically acceptable support, dihydroxyacetone (DHA) and at least one compound of the flavylium salt type , unsubstituted in position 3, and substituted by at least one hydroxyl or alkoxy radical, obtained synthetically or from a plant extract that contains it or also from an enriched plant extract that contains it.

The invention also relates to the applications of these compositions in coloring the skin.

Nowadays, looking good is important and tanned skin is always a sign of good health. However, natural tanning is not always desirable insofar as it requires prolonged exposures to UV radiation, in particular UV-A radiation that cause darkening of the skin, but on the other hand, are likely to induce an alteration of it, particularly in the case of sensitive skin or skin continuously exposed to solar radiation. It is therefore desirable to find an alternative to natural tanning that is compatible with the requirements of such skin types.

Most of the cosmetic products intended for artificial tanning of the skin are based on mono- or polycarbonylated compounds that allow, by interaction with the amino acids of the skin, the formation of colored products.

To this end, it is known that dihydroxyacetone, or DHA, is a particularly interesting product that is commonly used in cosmetics as an agent for artificial tanning of the skin; applied on the latter, particularly on the face, it allows to obtain a tanning or darkening effect similar in appearance to that which can result from prolonged exposure to the sun (natural tanning) or under a UV lamp.

A drawback of DHA is the slowness with which the coloration develops: it is indeed necessary to count several hours (3 to 5 hours in general) for the coloration to be revealed. Furthermore, the coloration produced on the skin by DHA is often judged too yellow by users.

Thus, new compounds and new compositions are always being investigated that allow the skin to artificially confer a coloration similar to a natural tan in a simple, effective, fast and risk-free way.

Anthocyanin dyes have long been known as food and pharmaceutical dyes. These anthocyanins are present in nature in the form of heterosides called anthocyanosides and of genins, called anthocyanidins. These anthocyanins are derived from 2-phenyl-benzopyrilium or flavillium and are particularly present in the plant in the form of salts. Anthocyanins are red, purple or blue compounds that generally color flowers, fruits and sometimes leaves. The observed color depends both on the structure of genin mainly and on the conditions of the environment where the anthocyanin dyes are found.

Now, as a consequence of important research carried out in the field of artificial skin coloring, the Applicant Firm has now discovered that the association of DHA and one or more particular compounds of the type of flavillium salt not substituted in the position 3 allowed to confer an artificial coloring more similar to a natural tan immediately after applying the product to the skin. Indeed, the applicant firm has verified that the aforementioned association made it possible to obtain in relation to a self-bridging of the carbonylated type such as DHA used alone, a rise in color on the skin in a much shorter time (for example after 30 minutes ). In addition, the indicated association allows obtaining a tone close to a natural tan and stable over time.

The present invention therefore has as its object a new cosmetic and / or dermatological composition, intended for the artificial coloring of the skin similar to a natural tan, characterized by the fact that it comprises, in a cosmetically acceptable support: DHA and at least one compound of the flavylium salt type, unsubstituted in position 3, and substituted by at least one hydroxyl or alkoxy radical, obtained synthetically or from a plant extract that contains it or also from a enriched plant extract.

The present invention also has as its object the new use of the association of DHA and of at least one compound of the flavillium salt type, unsubstituted in position 3 and substituted by at least one hydroxyl or alkoxy radical, obtained synthetically, or from a plant extract, or an enriched plant extract, in cosmetic and / or dermatological compositions in order to give the skin an artificial coloration similar to a natural tan.

The present invention also has as its object an artificial coloring process similar to the natural tanning of the skin, characterized in that it consists in applying an effective amount of the association of DHA and of at least one compound of the flavillium salt type, unsubstituted in position 3, and substituted by at least one hydroxyl or alkoxy radical, obtained synthetically, or from a plant extract, or from a plant extract enriched in cosmetic compositions.

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The compositions and uses according to the invention make it possible to obtain an artificial coloring similar to to a natural tan in a short period of time. Thus, an immediate coloration is obtained that allows a visualization of the application and consequently a better homogeneity in the spread of the composition on the skin and consequently of the resulting coloration. Furthermore, the artificial coloring obtained on the skin according to the invention is extremely similar to natural tanning.

Within the scope of the present invention, by "composition intended for artificially coloring the skin" is understood to be a formulation with a particular affinity for the skin that allows it to give the latter a long-lasting, non-covering coloration (that is, it does not has a tendency to dull the skin) and must not be removed either with water or with the aid of a solvent, and which is resistant to both rubbing and washing by a solution containing surfactants. Such a long-lasting coloration therefore differs from the superficial and momentary coloration provided, for example, by a make-up product,

Other features, aspects, and advantages of the present invention will appear upon reading the detailed description that follows.

The compositions according to the present invention generally lead within 30 minutes after application to fair skin at a rate of 2 mg / cm² at an obscuration characterized in the colorimetric measurement system (L *, a *, b *) by an AL * ranging from -0.5 to -20. More preferably, AL * will range from -0.5 to -15.

The compositions according to the present invention provide after 30 minutes after application to the skin at a rate of 2 mg / cm² a coloration on fair skin that is defined in the colorimetric measurement system (L *, a *, b *), by an Aa * / Ab * ratio ranging from 0.5 to 3 and even more particularly 0.8 to 2.

According to the present invention, "by fair skin" is understood, non-tanned skin of which its colorimetric characteristics can be defined by its ITA angle as defined in the publication by A. Chardon et al. "Skin Color Typology and Suntanning Pathways" and presented at the 16th IFSCC congress October 8-10 1990 in New-York, and in Int. J. Cosm. Sci. 13 191-208 (1991). Light skin such as those defined in this classification have an ITA angle between 35 and 55.

In the colorimetric measurement system (L *, a *, b *):

L * represents luminance or clarity, a * represents the red-green axis (-a * = green, + a * = red) and b * represents the yellow-blue axis (-b * = blue, + b * = yellow) . Thus, a * and b * express the tonality of the skin.

AL * translates the darkening of the color: the more negative the AL *, the darker the color with:

AL * = L * uncolored skin - L * colored skin

The Aa * / Ab * relation translates the red / yellow balance and therefore the tonality with:

Aa * = a * uncolored skin - a * colored skin Ab * = b * uncolored skin - b * colored skin

Among the compounds of the flavillium salt type unsubstituted in position 3 according to the invention, those that correspond to the following formula (I) are preferably used:

<img file="ES2239656T3_D0001.tif" />

formula (I) in which:

- R₁ designates an OH or C alkoxy radical₁-C₈, linear or branched, saturated or unsaturated

- R₂, R₃, R₄, identical or different, designate H or R₁, it being understood that at least one of the radicals R₁ to R₄ designates OH,

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- X is an organic or mineral anion and preferably a derivative of mineral acid such as for example a halide such as bromide or chloride or also a derivative of an organic acid such as for example acetate, borate, citrate, tartrate, lactate, bisulfate, sulfate , phosphate.

The compounds of formula (I) particularly preferred according to the present invention are selected from the group of those for which, in formula (I), Ri designates OH or OCH₃.

Mention may be made, in particular, of the chlorides of the following compounds:

- 4 ', 5,7-trihydroxyflavillium, commonly referred to as "apigeninidine chloride",

- 3 ', 4', 7-trihydroxyflavylium,

- 4'-hydroxyflavylium,

- 4 ', 7-dihydroxyflavillium,

- 3 ', 4'-dihydroxyflavillium,

- 3 ', 4'-dihydroxy-7-methoxy-flavilium,

- 3 ', 4', 5,7-tetrahydroxyflavillium,

- 3 ', 4', 5 ', 5,7-pentahydroxyflavillium.

Among these compounds, apigeninidin chloride (4 ', 5,7-trihydroxyflavylium chloride) and 3', 4 ', 7-trihydroxyflavylium chloride are also more particularly preferred.

A particular form of the invention consists in using apigeninidine chloride in the form of a plant extract, easily prepared by extraction, and isolated, from Sorghum caudatum leaves according to the procedures described in patents CN 1064284A and CN1035512C or any variant of these procedures.

It can also be extracted from the stems, seeds, or leaves of Sorghum Bicolor, the petals of Gesneria Fulgens, as well as the species Blechum Procerum and Sorgho in association with Colletotrichum Graminicola.

A particularly preferred form of the invention is an extract that comes from the leaves of Sorghum Bicolor obtained by a hydro-alcoholic extraction in an acid medium at an extraction temperature ranging from 30 to 40 ° C with a volume ratio of solvent / mass of Sorghum Bicolor leaves ranging from 10 to 30. The indicated Shorghum plant extract titrates approximately 0.05 to 50% by weight of apigeninidin chloride.

Compounds of the flavillium salt type, unsubstituted in position 3, and substituted by at least one hydroxyl or alkoxy radical, according to the invention, can be easily obtained synthetically, and at low cost, particularly by the well-known method of R. Robinson and D. Pratt J. Chem. Soc. 745 (1923). The indicated method involves condensing an orthohydroxybenzaldehyde or its substitution derivatives on an acetophenone or its substitution derivatives, to obtain, by selecting the substituents, the desired compounds of formula (I).

Taking apigeninidine chloride (4 ', 5,7-trihydroxyflavylium chloride) as an example, the synthesis scheme (i) can be as follows:

<img file="ES2239656T3_D0002.tif" />

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Taking 3 ', 4', 7-trihydroxyflavylium chloride as an example, the synthesis scheme (ii) can be as follows:

<img file="ES2239656T3_D0003.tif" />

Various synthetic routes, well known in the prior art, lead to apigeninidin.

One method consists, for example, in preparing, in a first step, trimethylapigeninidine, by condensation of commercial 4,6-dimethoxy-2-hydroxybenzaldehyde on commercial 4-methoxyacetophenone at 0 ° C in anhydrous ether medium, and saturation with HCl anhydrous, to obtain after filtration a red-orange precipitate of trimethylapigeninidine. In a second stage, in hydrolyzing the trimethylapigeninidine obtained in the previous stage in apigeninidine chloride, carrying out the reaction in medium Hl and phenol and AgCl in solution in methanol. Such a synthesis method is described by R. Robinson and A. Robertson in J. Chem. Soc. 1951 (1926) and 2196 (1927).

Another method consists of condensing 2,4,6-trihydroxybenzaldehyde on 4-hydroxyacetophenone at 0 ° C in anhydrous solvent medium (ethyl acetate for example), and saturation with anhydrous HCl, to obtain apigeninidine chloride. Such a method is described by R. Robinson et A. Robertson in J. Chem. Soc. 1528 (1928).

Another method of preparing apigeninide chloride is to reduce a flavone, naringenin, or its triacetylated derivative, by NaBH.₄, then in oxidizing the product obtained by chloranil (1,4-tetrachloro benzoquinone). The indicated method is described by JG Sweeny and GA lacobucci in the journal Tetrahedron 33 2923-2927 (1977).

The most particularly preferred method, according to the present invention, consists in condensing 2,4-dihydroxy-6-benzoyloxybenzaldehyde on 4-hydroxyacetophenone at 0 ° C in anhydrous ethyl acetate medium, saturating with anhydrous HCl, and then debenzoylating the product obtained by soda, in order to obtain apigeninidin chloride in high yield, following scheme (i) described above. The indicated method is described by R. Robinson and JC Bell in J. Chem. Soc. 813 (1934).

The concentration of compound of the flavillium salt type, as described according to the present invention, preferably ranges from about 0.0001 to 10%, and even more preferably from 0.001 to 5% by weight, relative to the total weight of the composition.

DHA is generally present in the compositions according to the invention in proportions ranging from 0.1 to 10% by weight relative to the total weight of the composition, and preferably from 0.2 to 8% by weight with in relation to the total weight of the composition.

The compositions according to the present invention can comprise, in addition to the classical cosmetic adjuvants, particularly selected from fatty substances, organic solvents, ionic or non-ionic thickeners, softeners, antioxidants, anti-free radical agents, opacifiers, stabilizers, emollients, silicones, α-hydroxy acids, anti-foam agents, moisturizing agents, vitamins, perfumes, preservatives, surfactants, fillers, polymers, propellants, alkalizing or acidifying agents, colorants, or any other ingredient commonly used in the cosmetic and / or dermatological field, in particular for the manufacture of sunscreen compositions in the form of emulsions.

The fatty substances can consist of an oil or a wax or their mixtures. By oil, it is meant a compound that is liquid at room temperature. By wax, it is meant a compound solid or substantially solid at room temperature, and whose melting point is generally greater than 35 ° C.

As oils, mention may be made of mineral oils (paraffin); vegetables (sweet almond oil, macadamine, currant seeds, jojoba); synthetics such as perhydrosqualene, fatty alcohols, acids or esters (such as C₁₂-C₁₅ sold under the trade name "Finsolv TN" by the Finetex company, octyl palmitate, isopropyl lanolate, triglycerides of which capric / caprylic acids), oxyethylenated or oxypropylene fatty esters and ethers; siliconized (cyclomethicone, polydimethylsiloxanes or PDMS) or fluorinated, polyalkylenes.

As waxy compounds, paraffin, carnauba wax, beeswax, hydrogenated castor oil can be mentioned.

Among the organic solvents, mention may be made of the lower alcohols and polyols.

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According to a particularly preferred form, the compositions according to the invention contain at least 5% by weight relative to the weight of the composition of one or more polyhydroxy solvents. The latter can be selected from glycols and glycol ethers such as ethylene glycol, propylene glycol, butylene glycol, dipropylene glycol or diethylene glycol. And more particularly, the compositions according to the invention contain a mixture of at least three different polyhydroxy solvents and even more particularly a mixture constituted by propylene glycol, butylene glycol, and dipropylene glycol.

The thickeners can be particularly selected from cross-linked polyacrylic acids, guar gums and modified or unmodified celluloses such as hydroxypropylated guar gum, methylhydroxyethylcellulose and hydroxypropylmethyl cellulose.

Well understood, the person skilled in the art will try to select the possible complementary compound (s) mentioned above and / or their amounts in such a way that the advantageous properties intrinsically related to the association according to the invention are not, or substantially, altered by the or the additions considered.

The compositions according to the invention can be prepared according to techniques well known to those skilled in the art, in particular those intended for the preparation of emulsions of the oil-in-water or water-in-oil type.

This composition can be presented in particular in the form of an emulsion, simple or complex (H / E, E / H, H / E / H or E / H / E) such as a cream, a milk, or in the form of a gel or of a cream gel, in the form of a lotion, powder or solid stick and, if necessary, be packaged in an aerosol and presented in the form of a foam or a spray.

Preferably, the compositions according to the invention are in the form of an oil-in-water or a water-in-oil emulsion.

When it comes to an emulsion, its aqueous phase may comprise a non-ionic vesicular dispersion prepared according to known procedures (Bangham, Standish and Watkins. J. Mol. Biol. 13, 238 (1965), FR 2 315 991 and FR 2 416 008).

Specific, but in no way limiting, examples illustrating the invention are given below.

Example 1

An extract of Sorghum Bicolor was prepared which titrated 20-30% apigeninidine chloride according to the following preparation procedure:

An extract from Sorghum Bicolor leaves was obtained by hydro-alcoholic extraction (95 ° ethanol) in an acid medium (0.2% HCl) at an extraction temperature of 35 ° C with a volume of solvent / mass of leaves ratio de Sorghum Bicolor de 15. The Sorghum plant extract was dried in an oven for 24 h at 40 ° C and sieved at 200 μιη.

The yield of this extraction is 22.42% in coloring matter.

The title of the extract thus obtained is 21% by weight of apigeninidine chloride.

This example demonstrates the intensity of the coloration obtained with an extract of Sorghum Bicolor associated with DHA according to the present invention as well as the speed with which this coloration develops in relation to a composition containing DHA alone as a skin coloring agent.

This example shows that the coloration obtained by combining DHA with a Sorghum Bicolor extract according to the present invention makes it possible to obtain a high intensity of color immediately after application and stable over time.

The Applicant Firm has made the following compositions (the amounts are expressed as a percentage by weight relative to the total weight of the composition):

Composition A (outside the invention)

-Polidimethyl / methyl siloxane POE / POP (396/4) (OE / OP 18/18) A 10% D5 10 g

- Cyclopentadimethylsiloxane 12.5 g

- Mixture of natural tocopherols / soybean oil 0.1 g

- Dihydroxyacetone (DHA) 4 g

- Sodium chloride 2 g

- Propylene glycol 23 g

- Butylene glycol 5 g

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- Dipropylene glycol 10 g

- Trisodium citrate 0.542 g

- Citric acid 0.209 g

- Demineralized water 32,649 g

Composition B (invention)

-Polidimethyl / methyl siloxane POE / POP (396/4) (OE / OP 18/18) A 10% D5 10 g

- Cyclopentadimethylsiloxane 12.5 g

- Mixture of natural tocopherols / soybean oil 0.1 g

- Demineralized water 32.55 g

- Sodium chloride 2 g

- Propylene glycol 23 g

- Butylene glycol 5 g

- Dipropylene glycol 10 g

- Sorghum Bicolor extract as prepared above 0.1 g

- Dihydroxyacetone 4 g

- Trisodium citrate 0.542 g

- Citric acid 0.208 g

Assessment protocol

Compositions A and B were applied at a rate of 2 mg / cm³ on an area of ​​7 x 4.5 cm² delimited on the back of 6 volunteers whose skin color characterized by the ITA angle is between 35 and 55.

The following five series of colorimetric measurements were carried out with the aid of a Minolta CR-300 colorimeter:

- 1 °) before application of the composition,

- 2 °) 30 minutes after application,

- 3 °) 2 hours after application,

- 4th) 4 hours after application.

The results were expressed in the system (L *, a *, b *) in which L * represents light, a * represents the red-green axis (-a * = green, + a * = red) and b * represents the axis yellow-blue (-b * = blue, + b * = yellow). Thus, a * and b * express the tonality of the skin.

For the evaluation of the intensity of the coloration, it is interested in AL * which translates the darkening of the color: the more negative is AL *, the darker the color with:

AL * = L * uncolored skin - L * colored skin

For the tonality of the coloration obtained, he is interested in the ratio Aa * / Ab * that translates the red / yellow balance and therefore the tonality with;

Aa * = a * uncolored skin - a * colored skin Ab * = b * uncolored skin - b * colored skin

The results obtained are indicated in the following table (I):

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TABLE (I)

<td></td><td>Composition A (comparative) AL *</td><td>Composition B (invention) AL *</td><td>Composition B (invention) Aa * / Ab *</td>

<td>30 minutes</td><td> -0,4</td><td> -1,6</td><td> 0,8</td>

<td>2 hours</td><td> -1,1</td><td> -2,0</td><td> 0,7</td>

<td>4 hours</td><td> -2,5</td><td> -2,7</td><td> 0,9</td>

It was thus found that 30 minutes after application, composition B contained DHA and the coloring plant extract allowed to obtain a darkening very similar to that obtained with composition A, which contained only DHA after 4 hours.

Composition B, which contains DHA and the coloring vegetable extract, also made it possible to obtain a tone similar to a natural tan and constant over time.