PHOTOACTIVE GRAFTED POLYSACCHARIDE AND USE THEREOF IN COSMETICS

Abstract

The invention relates to a polysaccharide polymer of formula (I):

PS—(O—CO-L-X).sub.a(OH).sub.b   (I) in which PS denotes the basic backbone of the polysaccharide bearing the hydroxyl groups; L is a divalent hydrocarbon-based group comprising from 1 to 20 carbon atoms; X denotes a photoactive group of azide or diazirine type; a denotes the content of OH groups substituted with the photoactive group; b denotes the content of unsubstituted free OH groups; a being between 0.02 and 0.5; b being between 0.5 and 0.98; and a+b=1.

The invention also relates to a composition comprising the polymer (I) in a physiologically acceptable medium, and also to a cosmetic process for caring for the skin, comprising the topical application to the skin of said composition and exposure of the treated skin to light radiation.

Claims

1. A polysaccharide polymer grafted with photoactive groups of azide or diazirine type of formula (I):
PS—(O—CO-L-X).sub.a(OH).sub.b   (I) in which PS denotes the basic backbone of the polysaccharide bearing the hydroxyl groups; L is a linear, branched or cyclic, saturated or unsaturated divalent hydrocarbon-based group comprising from 1 to 20 carbon atoms, which may be interrupted with one or more non-adjacent heteroatoms chosen from sulfur, oxygen, or —NH—, —COO—, —CONH—, —O—CO—NH— or —NH—CO—NH— groups, said divalent group optionally substituted with one or more groups chosen from hydroxyl, amine, thiol, carboxylic acid, amide, cyano, and acyl (C.sub.1-C.sub.4)amino groups; X denotes a photoactive group of azide or diazirine type; a denotes the content of OH groups substituted with the photoactive group; b denotes the content of unsubstituted free OH groups; a being between 0.02 and 0.5; b being between 0.5 and 0.98; and a+b=1; with the exception of compounds (I) for which: PS is dextran and -L-X═—(CH.sub.2).sub.5—N.sub.3 PS is hyaluronic acid and -L-X═—(CH.sub.2).sub.3—N.sub.3.

2. The polymer as claimed in claim 1, wherein the polysaccharide comprises one or more base units chosen from uronic acid, glucuronic acid and mannuronic acid.

3. The polymer as claimed in claim 1, wherein the polysaccharide is chosen from hyaluronic acid, chondroitin, chondroitin sulfate, alginic acid, heparin, heparin sulfate, xanthan gum, dextran and cellulose.

4. The polymer as claimed in claim 1, wherein the polysaccharide is hyaluronic acid or alginic acid.

5. The polymer as claimed in claim 1, wherein a is between 0.02 and 0.4 and b is between 0.6 and 0.98.

6. The polymer as claimed in claim 1, wherein L is chosen from the following groups: ##STR00020##

7. The polymer as claimed in claim 1, wherein the photoactive group X may be chosen from the following groups: ##STR00021##

8. The polymer as claimed in claim 1, wherein the group X-L- is chosen from: ##STR00022## ##STR00023## ##STR00024##

9. The polymer as claimed in claim 1, wherein it has a weight-average molecular weight ranging from 5000 to 1 000 000 daltons.

10. A composition comprising, in a physiologically acceptable medium, a grafted polysaccharide (I) as claimed in claim 1.

11. The composition as claimed in claim 10 the grafted polysaccharide (I) is present in a content ranging from 0.1% to 10% by weight, relative to the total weight of the composition.

12. The composition as claimed in claim 10, which comprises a cosmetic adjuvant chosen from water, emulsifiers, preserving agents, sequestrants, fragrances, thickeners, oils, waxes and film-forming polymers.

13. The composition as claimed in claim 10, which is in the form of an O/W emulsion or an aqueous gel.

14. A cosmetic process for caring for the skin, more particularly facial skin, in particular wrinkled skin, comprising: (i) a step consisting in applying to the skin a composition comprising, in a physiologically acceptable medium, a grafted polysaccharide (I), (ii) a step consisting in exposing the treated skin to light radiation, preferably for at least 5 seconds, the grafted polymer (I) being a polysaccharide polymer grafted with photoactive groups of azide or diazirine type of formula:
PS—(O—CO-L-X).sub.a(OH).sub.b   (I) in which PS denotes the basic backbone of the polysaccharide bearing the hydroxyl groups; L is a linear, branched or cyclic, saturated or unsaturated divalent hydrocarbon-based group comprising from 1 to 20 carbon atoms, which may be interrupted with one or more non-adjacent heteroatoms chosen from sulfur, oxygen, or —NH—, —COO—, —CONH—, —O—CO—NH— or —NH—CO—NH— groups, said divalent group being optionally substituted with one or more groups chosen from hydroxyl, amine, thiol, carboxylic acid, amide, cyano, and acyl (C.sub.1-C.sub.4)amino groups; X denotes a photoactive group of azide or diazirine type; a denotes the content of OH groups substituted with the photoactive group; b denotes the content of unsubstituted free OH groups; a being between 0.02 and 0.5; b being between 0.5 and 0.98; and a+b=1.

15. The process as claimed in claim 14, wherein the polysaccharide comprises one or more base units chosen from uronic acid, glucuronic acid and mannuronic acid.

16. The process as claimed in claim 14, wherein the polysaccharide is chosen from hyaluronic acid, chondroitin, chondroitin sulfate, alginic acid, heparin, heparin sulfate, xanthan gum, dextran and cellulose.

17. The process as claim 14, wherein the polysaccharide is hyaluronic acid or alginic acid.

18. The process as claimed in claim 14, wherein a is between 0.02 and 0.4 and b is between 0.6 and 0.98.

19. The process as claimed in claim 14, wherein L is chosen from the following groups: ##STR00025##

20. The process as claimed in claim 14, wherein the photoactive group X may be chosen from the following groups: ##STR00026##

21. The process as claimed in claim 14, wherein the group X-L- is chosen from: ##STR00027## ##STR00028## ##STR00029##

22. The process as claimed in claim 14, wherein it has a weight-average molecular weight ranging from 5000 to 1 000 000 daltons.

23. The process as claimed in claim 14, wherein the grafted polysaccharide (I) is present in a content ranging from 0.1% to 10% by.

24. The process as claimed in claim 14, in which the step consisting in applying light radiation is performed after or at the same time as (simultaneously with) the step consisting in applying the cosmetic composition comprising the grafted polysaccharide (I).

25. The process as claimed in claim 14, in which step (ii) consisting in applying light radiation is performed after step (i) consisting in applying the cosmetic composition comprising the grafted polysaccharide (I).

26. The process as claimed in claim 14, wherein the light radiation is natural light or artificial light with a wavelength of between 360 and 600 nm.

27. The process as claimed in claim 14, in which the light radiation has a source chosen from arc lamps such as xenon lamps and mercury lamps; fluorescent lamps; incandescent lamps; LEDs and lasers.

28. The process as claimed in claim 14, in which the exposure time to the light radiation is at least 5 seconds.

29. The process as claimed in claim 14, wherein it is intended for attenuating wrinkles.

Description

SYNTHESIS EXAMPLE 1 (POLYMER 1)

Hyaluronic Acid 6% Functionalized with Diazirine Groups

[0079] ##STR00017##

[0080] 210 mg of hyaluronic acid (Hyacare® 50 from Evonik) were dissolved in 4.2 ml of distilled water in a round-bottomed flask covered with aluminum foil to prevent exposure to light. 50 mg of succinimidyl 4,4′-azipentanoate (sulfo-SDA from the company ThermoScientific) were added, with stirring at a temperature of 5° C. The reaction mixture was stirred for 24 hours while allowing the temperature to rise to 22° C., and maintaining the pH between 6 and 7 by addition of aqueous 0.5 M sodium hydroxide solution and aqueous 0.5 M hydrochloric acid solution.

[0081] 210 mg of hyaluronic acid (Hyacare® 50 from Evonik) were dissolved in 4.2 ml of distilled water in a round-bottomed flask covered with aluminum foil to prevent exposure to light. 50 mg of succinimidyl 4,4′-azipentanoate (sulfo-SDA from the company ThermoScientific) were added, with stirring at a temperature of 5° C. The reaction mixture was stirred for 24 hours while allowing the temperature to rise to 22° C., and maintaining the pH between 6 and 7 by addition of aqueous 0.5 M sodium hydroxide solution and aqueous 0.5 M hydrochloric acid solution.

[0082] The reaction mixture was then introduced into a dialysis tube (Spectra/Por Dialysis Membrane MWCO 3500) and dialyzed in 5 liters of osmosed water for 48 hours, the water being replaced 8 times during this dialysis operation.

[0083] The residue deposited in the dialysis tube was extracted with distilled water and lyophilized to obtain a fibrous yellow solid product (250 mg).

[0084] The product was stored in an amber-colored flask at −20° C.

[0085] The .sub.1H NMR analysis in deuterated water: 6% grafting

SYNTHESIS EXAMPLE 2 (POLYMER 2)

Hyaluronic Acid 11% Functionalized with Azide Groups

[0086] ##STR00018##

[0087] 1.63 g (0.01 mol) of 4-azidobenzoic acid were mixed with 100 ml of distilled water in a brown-glass round-bottomed flask. The solution was stirred vigorously and 1.9 g (0.01 mol) of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) were then added, followed by addition of 68 mg (0.5 mmol) of N-hydroxybenzotriazole (HOBt). The pH was adjusted to pH 5.2 by addition of aqueous 0.1 M sodium hydroxide solution. The solution was stirred vigorously for 50 minutes, and a solution of hyaluronic acid (Hyacare® 50 from Evonik) (2 g in 70 ml of distilled water) was then added. The solution was stirred at room temperature (25° C.) for 3 days.

[0088] The reaction mixture was then introduced into a dialysis tube (Spectra/Por Dialysis Membrane MWCO 3500) and dialyzed in 5 liters of water for 48 hours, the water being replaced 4 times during this dialysis operation.

[0089] The residue deposited in the dialysis tube was extracted with distilled water and lyophilized to obtain a fibrous yellow solid product.

[0090] This recovered solid was washed at room temperature in a brown round-bottomed flask using acetone, for 2 hours (100 ml per extraction, 3 extractions being performed).

[0091] The solid residue was then filtered off for 5 minutes and then dried under vacuum at room temperature for 12 hours. 1.8 g of a beige-colored solid product (powder) were thus obtained.

[0092] The product was stored in an amber-colored flask at −20° C.

[0093] The 1H NMR analysis in deuterated water: 11% grafting

SYNTHESIS EXAMPLE 3 (POLYMER 3)

Alginic Acid 10% Functionalized with Diazirine Groups

[0094] ##STR00019##

[0095] 0.65 g (3.68 mol) of alginic acid (Kelcosol from ISP) were mixed with 33 ml of distilled water in a brown-glass round-bottomed flask. The pH was adjusted to pH 3.4-3.6 by addition of aqueous 0.2 M hydrochloric acid solution. The solution was stirred vigorously and 0.71 g (3.68 mmol) of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) in water (3 mL) was then added, followed by 800 mg (3.68 mmol) of N-hydroxysulfosuccinimide. After stirring for 5 minutes, N-(2-aminoethyl)-4-(3-(trifluoromethyl)-3H-diazirin-3-yl)benzamide (1.0 g) was added. The pH was adjusted to pH 4.7 by addition of aqueous 0.2 M hydrochloric acid solution. The solution was stirred at room temperature (25° C.) for 40 hours and then poured into acetone (300 mL). The white precipitate was recovered by filtration. The powder was placed in 40 mL of water and then introduced into a dialysis tube (Spectra/Por Dialysis Membrane MWCO 3500) and dialyzed in 5 liters of water for 3 days, the water being replaced 3 times during this dialysis operation. The product was recovered by lyophilization to give a white powder (600 mg). The product was stored in an amber-colored flask at −20° C.

[0096] The 1H NMR analysis in deuterated water: 10% grafting

EXAMPLE 1

Demonstration of the Tensioning Effect of Polymers 1 and 2

[0097] The following compositions were prepared:

[0098] Composition 1: aqueous solution containing 5% by weight of AM of hyaluronic acid (Hyacare® 50 from Evonik)

[0099] Composition 2: aqueous solution containing 5% by weight of AM of polymer 1

[0100] Composition 3: aqueous solution containing 5% by weight of AM of polymer 2

[0101] Composition REF: aqueous composition of Hybridur® 875 polymer dispersion from Air Products (aqueous dispersion containing 40% by weight of particles of an interpenetrated network of polyurethane and acrylic polymers) at 7% AM.

[0102] The tensioning power of polymers 1 and 2 was compared, in vitro with a reference tensioning polymer: Hybridur® 875 polymer dispersion from Air Products (aqueous dispersion containing 40% by weight of particles of an interpenetrated network of polyurethane and acrylic polymers) and also with reference to hyaluronic acid (Hyacare® 50 from Evonik).

[0103] The tensioning effect is measured by an in vitro retraction test. This test consists in quantifying in vitro the tensioning power of a material deposited on an elastomeric substrate (Kimtech nitrile reference 90627 from Kimberley Clark) having a modulus of about 20 MPa and a thickness of 100 μm.

[0104] 26 μl of each polymer composition were deposited on a rectangular specimen (9×40 mm) of elastomer. Some of the treated specimens were irradiated for 1 minute with an Oriel sun simulator machine from the company Oriel-Lot.

[0105] After 3 hours of drying at 22±3° C. and 40±10% relative humidity, the tensioning effect exerted by the polymer deposited on the specimen is directly linked to the decrease in width at the center of the specimen. The tensioning effect (TE1) may then be quantified in the following manner:

tensioning effect (TE1) in %=(L.sub.0−L.sub.1/L.sub.0)×100

[0106] L.sub.0=initial width 9 mm

[0107] and L.sub.1=width after 3 hours of drying

[0108] The persistence with respect to synthetic sweat of the observed tensioning effect was then evaluated.

[0109] The deposits were rinsed by spraying onto the strip, at a distance of 5 cm, 10 μl of aqueous 0.9 M NaCl solution (synthetic sweat).

[0110] The deposits were dried for 3 hours at 22±3° C. and 40±10% relative humidity, and the tensioning effect after washing (TE2) was measured again by measuring the width L.sub.2 of the specimen.

Tensioning effect (TE2) in %=(L.sub.0−L.sub.2/L.sub.0)×100

[0111] with L.sub.2=width of the specimen after rinsing and 3 hours of drying.

[0112] The following results were obtained:

TABLE-US-00003 Tensioning Tensioning effect effect (TE1) (TE2) Irradiated (before (after Example Composition Polymer (yes/no) washing) washing) A 1 Hyaluronic No 33% 11% acid B 2 Polymer 1 No 66% 33% C 2 Polymer 1 Yes 66% 66% D 3 Polymer 2 No 55% 22% E 3 Polymer 2 Yes 55% 55% F REF Hybridur ® No 55% 22% 875 polymer dispersion

[0113] The results obtained show that the polymer of Example 1 and that of Example 2 according to the invention, after irradiation of the deposit (Examples C and E), make it possible to obtain a good tensioning effect before and after washing. The tensioning effect obtained thus shows good persistence with respect to sweat.

EXAMPLE 4

[0114] An antiwrinkle gel having the following composition is prepared:

TABLE-US-00004 polymer of synthesis example 1  2 g hydroxyethylcellulose (Natrosol ® 250 HHR CS from  0.3 g Ashland) Preserving agents qs Water qs 100 g

[0115] The composition obtained is applied to the face and the surface of the treated skin is then irradiated with white light (Lite-Pad lamp from the company Reicorp) for 5 minutes. The treatment applied makes it possible to effectively smooth out the wrinkles.

EXAMPLE 5

[0116] An antiwrinkle gel having the following composition is prepared:

TABLE-US-00005 polymer of example 2  1 g hydroxyethylcellulose (Natrosol ® 250 HHR CS from  0.3 g Ashland) Preserving agents qs Water qs 100 g

[0117] The composition obtained is applied to the face and the surface of the treated skin is then irradiated with white light (Lite-Pad lamp from the company Reicorp) for 15 minutes. The treatment applied makes it possible to effectively smooth out the wrinkles.

EXAMPLE 6

Demonstration of the Tensioning Effect of Polymer 3

[0118] The tensioning power of polymer 3 was evaluated according to the protocol described in example 1.

[0119] Composition 4: aqueous solution containing 2% by weight of AM of polymer 3

[0120] The following results were obtained:

TABLE-US-00006 Tensioning Tensioning effect effect (TE1) (TE2) Irradiated (before (after Example Composition Polymer (yes/no) washing) washing) G 4 Polymer 3 No 55% 22% H 4 Polymer 3 Yes 55% 55% F REF Hybridur ® No 55% 22% 875 polymer dispersion

[0121] The results obtained show that the polymer of example 3, after irradiation of the deposit (example H), makes it possible to obtain a good tensioning effect before and after washing. The tensioning effect obtained thus shows good persistence with respect to sweat.

EXAMPLE 7

[0122] An antiwrinkle gel having the following composition is prepared:

TABLE-US-00007 polymer of example 3  1 g hydroxyethylcellulose (Natrosol ® 250 HHR CS from  0.3 g Ashland) Preserving agents qs Water qs 100 g

[0123] The composition obtained is applied to the face and the surface of the treated skin is then irradiated with white light (Lite-Pad lamp from the company Reicorp) for 15 minutes. The treatment applied makes it possible to effectively smooth out the wrinkles.