Use of 5-oxazolidine-2,4-dione C-glycoside derivatives as moisturizer for the skin

Abstract

The present invention relates to the cosmetic use, as moisturizer for keratin materials, preferably the skin, of one or more 5-oxazolidine-2,4-dione C-glycoside derivatives corresponding to formula (I) below, and also the solvates and/or the isomers (optical, geometric, tautomers) thereof and/or the salts thereof: (I) ##STR00001##

Claims

1. A process for moisturizing keratin material, which method comprises applying to the keratin material one or more 5-oxazolidine-2,4-dione C-glycoside derivatives corresponding to formula (I) below, and also the solvates thereof, the optical and geometric isomers and tautomers thereof and the organic or mineral base or acid salts thereof, ##STR00036## in which formula (I): S* denotes a monosaccharide sugar radical or denotes a polysaccharide sugar radical comprising from 2 to 5 saccharide units, each saccharide unit (the saccharide unit in the case of a monosaccharide or each saccharide unit in the case of polysaccharides) comprising one or more hydroxyl groups optionally substituted with a radical R′ chosen from: i) (C.sub.1-C.sub.6)alkyl or (C.sub.2-C.sub.6)alkenyl; or ii) an acetyl radical; or iii) a protective group (PG) for hydroxyl function(s); said monosaccharide radical possibly also being deoxygenated in position 2 (on its C.sub.2 carbon atom); said monosaccharide or polysaccharide radical possibly also comprising one or more amino groups NR.sub.bR.sub.c with R.sub.b and R.sub.c, which may be identical or different, representing a hydrogen atom, or an acetyl group, or a protective group for the amino function; said monosaccharide or polysaccharide radical being connected to the rest of the molecule by a bond between the C.sub.1 carbon atom of one of the sugars of said monosaccharide or polysaccharide radical, this bond possibly being α or β anomeric; R represents i) a hydrogen atom; ii) a (C.sub.1-C.sub.18)alkyl group; iii) an aryl(C.sub.1-C.sub.4)alkyl group optionally substituted with at least one hydroxyl and/or (C.sub.1-C.sub.4)alkoxy group; iv) a cycloalkyl group.

2. The process according to claim 1, in which the one or more 5-oxazolidine-2,4-dione C-glycoside derivatives corresponding to formula (I) comprise(s) a radical R chosen from: i) a hydrogen atom; ii) a (C.sub.1-C.sub.18)alkyl group.

3. The process according to claim 1, in which the one or more 5-oxazolidine-2,4-dione C-glycoside derivatives corresponding to formula (I) comprise(s) a sugar radical S* which represents a monosaccharide radical in which the heterocycle which forms it contains 4 or 5 carbon atoms, of formula S*′ below: ##STR00037## Ra representing a hydrogen atom, a (C1-C4)alkyl group; or a (poly)hydroxy(C1-C4)alkyl group or the hydroxyl function(s) of the (poly)hydroxy(C1-C4)alkyl group being substituted with A, it being understood that the R.sub.a radical is in the C.sub.5 position if the sugar unit is in pyranose form or in the C.sub.4 position if it is in furanose form; R.sub.b representing a hydrogen atom or a (C.sub.1-C.sub.4)alkyl group; R.sub.c representing a hydrogen atom, or a protective group for the amine function; R.sub.e represents a hydrogen atom or a —CH.sub.2—O—A group; A representing a hydrogen atom, a (C.sub.1-C.sub.6)alkyl group or a hydroxyl-function-protective group, or else, when n is greater than or equal to 2 and two groups A-O are contiguous, then two A groups can together form a linear or branched (C.sub.1-C.sub.6)alkylene chain; n is equal to 1, 2 or 3 and m is equal to 0 or 1.

4. The process according to claim 1, in which the one or more 5-oxazolidine-2,4-dione C-glycoside derivatives corresponding to formula (I) comprise(s) a sugar radical S* which represents a polysaccharide radical constituted of 2 to 5 saccharide units linked together via an oxygen atom (oxy), 1.fwdarw.4 (C.sub.1 of one saccharide unit .fwdarw.C.sub.4 of the other saccharide unit) or 1.fwdarw.3 (C.sub.1 of one saccharide unit .fwdarw.C.sub.3 of the other saccharide unit) or 1.fwdarw.6 (C.sub.1 of one saccharide unit .fwdarw.C.sub.6 of the other saccharide unit), each saccharide unit of which is constituted of a heterocycle comprising 4 or 5 carbon atoms, of formula S*″ below: ##STR00038## in which formula S*″: Ra representing a hydrogen atom, a (C1-C4)alkyl group; or a (poly)hydroxy(C1-C4)alkyl group or the hydroxyl function(s) of the (poly)hydroxy(C1-C4)alkyl group being substituted with A, it being understood that the R.sub.a radical is in the C.sub.5 position if the sugar unit is in pyranose form or in the C.sub.4 position if it is in furanose form; R.sub.b representing a hydrogen atom or a (C.sub.1-C.sub.4)alkyl group; R.sub.c representing a hydrogen atom, or a protective group for the amine function; R.sub.e represents a hydrogen atom or a —CH.sub.2—O—A group; A representing a hydrogen atom, a (C.sub.1-C.sub.6)alkyl group or a hydroxyl-function-protective group, or else, when n is greater than or equal to 2 and two groups A-O are contiguous, then two A groups can together form a linear or branched (C.sub.1-C.sub.6)alkylene chain; n is equal to 1, 2 or 3 and m is equal to 0 or 1; p and q represent integers inclusively between 0 and 4, with p+q inclusively between 1 and 4, it being understood that the two sugar units between the square brackets q and p can be reversed, i.e. can represent the following sequence: ##STR00039##

5. The process according to claim 1, in which the one or more 5-oxazolidine-2,4-dione C-glycoside derivatives corresponding to formula (I) comprise(s) a sugar radical S* which represents a monosaccharide radical chosen from glucose, galactose, mannose, xylose, lyxose, fucose, arabinose, rhamnose, ribose, deoxyribose, quinovose, fructose, sorbose, talose, 2-deoxyglucose, threose, erythrose, N-acetylglucosamine, N-acetylgalactosamine, glucosamine and galactosamine.

6. The process according to claim 1, in which the one or more 5-oxazolidine-2,4-dione C-glycoside derivatives corresponding to formula (I) comprise(s) a sugar radical S* which represents a monosaccharide radical chosen from glucose, xylose and rhamnose.

7. The process according to claim 1, in which the one or more 5-oxazolidine-2,4-dione C-glycoside derivatives corresponding to formula (I) comprise(s) a sugar radical S* which represents a polysaccharide radical.

8. The process according to claim 1, in which the one or more 5-oxazolidine-2,4-dione C-glycoside derivatives corresponding to formula (I) is (are) chosen from the compounds of formulae (I′), (I″), (I″″), (I′a), (I″a) and (F″″a) below: ##STR00040## ##STR00041## and also the solvates thereof, the optical and geometric isomers and tautomers thereof and the salts thereof, in which formulae (I′), (I″), (I″″), (I′a), (I″a) and (I″′a): R′.sub.1 has the same definition as that of R for the compounds of formula (I); R′.sub.2 represents a hydrogen atom or the group —OR″ with R″; R″ represents i) (C.sub.1-C.sub.6)alkyl; or ii) an acetyl radical; or iii) a protective group (PG) for hydroxyl function(s); or iv) a hydrogen atom; R′″ represents a hydrogen atom, or a (C.sub.1-C.sub.4)alkyl group, or a —CH2—OR″ group with R″ as defined previously.

9. The process according to claim 1, in which the one or more 5-oxazolidine-2,4-dione C-glycoside derivatives corresponding to formula (I) are chosen from the following compounds: TABLE-US-00006 compound structure 1a 2a 3a 4a TABLE-US-00007 compound sugar structure 1 D- glucose 2 D- xylose 3 D- glucose 4 L- rhamnose 5 D- mannose 6 D- mannose 7 D- galactose 8 D- galactose and also the solvates thereof, and the organic or mineral base or acid salts thereof.

10. A composition comprising one or more compounds chosen from the compounds of formulae (I′), (I″), (I″″), (I′a), (I″a) and (F″″a) below: ##STR00054## ##STR00055## and also the solvates thereof, the optical and geometric isomers and tautomers thereof and the salts thereof, in which formulae (I′), (I″), (I″″), (I′a), (I″a) and (I″″a): R′.sub.1 represents i) a hydrogen atom; ii) a (C.sub.1-C.sub.18)alkyl group; iii) an aryl(C.sub.1-C.sub.4)alkyl group optionally substituted with at least one hydroxyl and/or (C.sub.1-C.sub.4)alkoxy group; or iv) a cycloalkyl group); R′.sub.2 represents a hydrogen atom or the group —OR” with R″ as defined below; R″ represents i) (C.sub.1-C.sub.6)alkyl; or ii) an acetyl radical; or iii) a protective group (PG) for hydroxyl function(s); or iv) a hydrogen atom; R′″ represents a hydrogen atom, or a (C.sub.1-C.sub.4)alkyl group, or a —CH.sub.2—OR″ group with R″.

11. The composition according to claim 10, in which the one or more compound(s) are present in amounts ranging from 0.01% to 10% by weight relative to the total weight of the composition.

12. A composition comprising one or more 5-oxazolidine-2,4-dione C-glycoside derivatives corresponding to formula (I) below, and also the solvates thereof, the optical and geometric isomers and tautomers thereof and the organic or mineral base or acid salts thereof, ##STR00056## in which formula (I): S* denotes a monosaccharide sugar radical or denotes a polysaccharide sugar radical comprising from 2 to 5 saccharide units, each saccharide unit (the saccharide unit in the case of a monosaccharide or each saccharide unit in the case of polysaccharides) comprising one or more hydroxyl groups optionally substituted with a radical R′ chosen from: i) (C.sub.1-C.sub.6)alkyl or (C.sub.2-C.sub.6)alkenyl; or ii) an acetyl radical; or iii) a protective group (PG) for hydroxyl function(s); said monosaccharide radical possibly also being deoxygenated in position 2 (on its C.sub.2 carbon atom); said monosaccharide or polysaccharide radical possibly also comprising one or more amino groups NR.sub.bR.sub.c with R.sub.b and R.sub.c, which may be identical or different, representing a hydrogen atom, or an acetyl group, or a protective group for the amino function; said monosaccharide or polysaccharide radical being connected to the rest of the molecule by a bond between the C.sub.1 carbon atom of one of the sugars of said monosaccharide or polysaccharide radical, this bond possibly being α or β anomeric; R represents i) a hydrogen atom; ii) a (C.sub.1-C.sub.18)alkyl group; iii) an aryl(C.sub.1-C.sub.4)alkyl group optionally substituted with at least one hydroxyl and/or (C.sub.1-C.sub.4)alkoxy group; iv) a cycloalkyl group and one or more additional moisturizing active agents other than the compounds of formula (I).

13. A compound of formula (I) and also the solvates thereof, the optical and geometric isomers and tautomers thereof and the organic or mineral base or acid salts thereof, ##STR00057## in which formula (I): S* denotes a monosaccharide sugar radical or denotes a polysaccharide sugar radical comprising from 2 to 5 saccharide units, each saccharide unit (the saccharide unit in the case of a monosaccharide or each saccharide unit in the case of polysaccharides) comprising one or more hydroxyl groups optionally substituted with a radical R′ chosen from: i) (C.sub.1-C.sub.6)alkyl or (C.sub.2-C.sub.6)alkenyl; or ii) an acetyl radical; or iii) a protective group (PG) for hydroxyl function(s); said monosaccharide radical possibly also being deoxygenated in position 2 (on its C.sub.2 carbon atom); said monosaccharide or polysaccharide radical possibly also comprising one or more amino groups NR.sub.bR.sub.c with R.sub.b and R.sub.c, which may be identical or different, representing a hydrogen atom, or an acetyl group, or a protective group for the amino function; said monosaccharide or polysaccharide radical being connected to the rest of the molecule by a bond between the C.sub.1 carbon atom of one of the sugars of said monosaccharide or polysaccharide radical, this bond possibly being α or β anomeric; R represents i) a hydrogen atom; ii) a (C.sub.1-C.sub.18)alkyl group; iii) an aryl(C.sub.1-C.sub.4)alkyl group optionally substituted with at least one hydroxyl and/or (C.sub.1-C.sub.4)alkoxy group; iv) a cycloalkyl group.

14. The compound of formula (I) according to claim 13, comprising a radical R chosen from: i) a hydrogen atom; ii) a (C.sub.1-C.sub.18)alkyl group.

15. A cosmetic process for moisturizing keratin materials which comprises applying to said keratin materials a composition as defined in claim 10.

16. The cosmetic process according to claim 15, wherein said composition is applied to dry skin and/or to a cutaneous region chosen from: the hands, the face, the neck, the feet, the legs, the arms and forearms.

17. A process for the synthesis of compounds of formula (I), ##STR00058## in which formula (I): S* denotes a monosaccharide sugar radical or denotes a polysaccharide sugar radical comprising from 2 to 5 saccharide units, each saccharide unit (the saccharide unit in the case of a monosaccharide or each saccharide unit in the case of polysaccharides) comprising one or more hydroxyl groups optionally substituted with a radical R′ chosen from: i) (C.sub.1-C.sub.6)alkyl or (C.sub.2-C.sub.6)alkenyl; or ii) an acetyl radical; or iii) a protective group (PG) for hydroxyl function(s); said monosaccharide radical possibly also being deoxygenated in position 2 (on its C.sub.2 carbon atom); said monosaccharide or polysaccharide radical possibly also comprising one or more amino groups NR.sub.bR.sub.c with R.sub.b and R.sub.c, which may be identical or different, representing a hydrogen atom, or an acetyl group, or a protective group for the amino function; said monosaccharide or polysaccharide radical being connected to the rest of the molecule by a bond between the C.sub.1 carbon atom of one of the sugars of said monosaccharide or polysaccharide radical, this bond possibly being α or β anomeric; R represents i) a hydrogen atom; ii) a (C.sub.1-C.sub.18)alkyl group; iii) an aryl(C.sub.1-C.sub.4)alkyl group optionally substituted with at least one hydroxyl and/or (C.sub.1-C.sub.4)alkoxy group; iv) a cycloalkyl group, according to scheme (1) below: ##STR00059## in which (II) denotes a monosaccharide represented by: ##STR00060## or a polysaccharide PS—OH, in which Ra represents a hydrogen atom, a (C1-C4)alkyl group or a (poly)hydroxy(C1-C4)alkyl group or the hydroxyl function(s) of the (poly)hydroxy(C1-C4)alkyl group being substituted with A; it being understood that the R.sub.a radical is in the C.sub.5 position if the sugar unit is in pyranose form or in the C.sub.4 position if it is in furanose form; R.sub.b representing a hydrogen atom or a (C.sub.1-C.sub.4)alkyl group; R.sub.c representing a hydrogen atom, or a protective group for the amine function-; R.sub.e represents a hydrogen atom or a —CH.sub.2—O—A group; A representing a hydrogen atom, a (C.sub.1-C.sub.6)alkyl group or a hydroxyl-function-protective group, or else, when n is greater than or equal to 2 and two groups A-O are contiguous, then two A groups can together form a linear or branched (C.sub.1-C.sub.6)alkylene chain; n is equal to 1, 2 or 3 and m is equal to 0 or 1, p′ and q′ representing an integer inclusively between 0 and 4, with p′+q′ inclusively between 0 and 4 it being understood that the two units between square brackets can be reversed; PS—OH denoting a polysaccharide having the structure (gg) below: ##STR00061## step 1 comprising reacting a monosaccharide or a polysaccharide PS—OH of formula (II) with a barbituric acid derivative (III) by heating optionally at a temperature of between 30° C. and 100° C., so as to give the compound comprising a sugar unit (IV); step 2 comprising reacting the compound (IV) with a chemical oxidizing agent or else a biological agent, it being understood that, if A represents a hydrogen atom and it is desired to have a protective group PG, then a protection step is added, that, if R.sub.b and R.sub.c of NR.sub.bR.sub.c optionally present on the monosaccharide or the polysaccharide (II) represent hydrogen atoms and it is desired to protect the amino group(s), a protection step is carried out, that, if the group R comprises a function sensitive to these synthesis steps, a protection/deprotection sequence is added, wherein, under certain reaction temperature and time conditions during step 2, optionally the intermediate (V) according to step 2a is isolated: ##STR00062## wherein step 2b comprises treating the compound (V) in a polar solvent or solvent mixture) with a boiling point of between 40° C. and 100° C. at atmospheric pressure to give a C-glycoside compound of formula (I).

18. A compound of formula (V), and also the solvates and/or isomers and/or salts thereof, having the general formula below ##STR00063## wherein—S* denotes a monosaccharide sugar radical or denotes a polysaccharide sugar radical comprising from 2 to 5 saccharide units, each saccharide unit (the saccharide unit in the case of a monosaccharide or each saccharide unit in the case of polysaccharides) comprising one or more hydroxyl groups optionally substituted with a radical R′ chosen from: i) (C.sub.1-C.sub.6)alkyl or (C.sub.2-C.sub.6)alkenyl; or ii) an acetyl radical; or iii) a protective group (PG) for hydroxyl function(s); said monosaccharide radical possibly also being deoxygenated in position 2 (on its C.sub.2 carbon atom); said monosaccharide or polysaccharide radical possibly also comprising one or more amino groups NR.sub.bR.sub.c with R.sub.b and R.sub.c, which may be identical or different, representing a hydrogen atom, or an acetyl group, or a protective group for the amino function; said monosaccharide or polysaccharide radical being connected to the rest of the molecule by a bond between the C.sub.1 carbon atom of one of the sugars of said monosaccharide or polysaccharide radical, this bond possibly being α or β anomeric; and R represents i) a hydrogen atom; ii) a (C.sub.1-C.sub.18)alkyl group; iii) an aryl(C.sub.1-C.sub.4)alkyl group optionally substituted with at least one hydroxyl and/or (C.sub.1-C.sub.4)alkoxy group; iv) a cycloalkyl group.

19. The compound according to claim 18, which is TABLE-US-00008 compound sugar structure 9 D- glucose .

20. The process according to claim 1 wherein the keratin material is skin.

Description

EXAMPLES

A) Synthesis Examples

4.1 Synthesis of Compounds 1, 2, 3, 4 and 9

Example 1

Synthesis of Compound 1

(1) ##STR00031##

(2) Step 1. Barbituric acid (10.7 g, 83 mmol) is added, with stirring, to a solution of D-glucose (15 g, 83 mmol) in water (170 ml), then NaHCO.sub.3 is added to pH 7. After neutralization, the mixture is heated at 80° C. for 5 h. The reaction is monitored by TLC in dichloromethane/MeOH 6:4+1% acetic acid. The reaction mixture is added dropwise to acetone (850 ml) with rigorous stirring. The precipitate obtained is filtered off and then washed 3 times in acetone, and the solid 10 obtained is dried under vacuum. It is isolated in the form of a yellow powder. The .sup.1H NMR spectra and the mass spectrometry are in accordance with the expected structure.

(3) Step 2. Hydrogen peroxide at 50% (137 mmol) is added, with stirring, to a solution of compound 10 (21.4 g, 68.5 mmol) in water (60 ml). The reaction mixture is brought to 70° C. for 4 h 30. The reaction is monitored by TLC (BuOH/H.sub.2O/AcOH 6:2:2). The mixture is then added dropwise at ambient temperature to 600 ml of acetone. The residue formed is filtered off, then dissolved in water and the solution is concentrated to dryness. The powder obtained is washed twice in acetone, to give the compound 1 in the form of a pale yellow powder. The .sup.1H NMR spectra and the mass spectrometry are in accordance with the expected structure.

Example 2

Synthesis of Compound 2

(4) ##STR00032##

(5) Step 1. According to the process described in example 1, the intermediate 11 is obtained from D-xylose and barbituric acid. The .sup.1H NMR spectra and the mass spectrometry are in accordance with the expected structure 11.

(6) Step 2. 15 g of 11 (0.053 mol) in 35 ml of water were placed in a 100 ml three-necked round-bottomed flask equipped with a condenser, an argon inlet, a bubbler, a thermometer and a magnetic stirrer. 10.9 ml of 30% aqueous hydrogen peroxide in water (0.106 mol) were then added. The reaction medium is stirred at ambient temperature and the reaction is monitored by TLC with water/acetonitrile 8:2.

(7) After stirring overnight, the starting product is consumed, but the peroxide test is positive. The reaction medium is heated at 80° C. for 3 hours (negative peroxide test), cooled to ambient temperature and then poured into a round-bottomed flask containing 250 ml of ethanol, before being concentrated to dryness in a rotary evaporator.

(8) The paste obtained is taken up with acetone using a mortar, to give the compound 2 in the form of a light beige powder. The .sup.1H NMR spectra and the mass spectrometry are in accordance with the expected structure.

Example 3

Synthesis of Compound 3

(9) ##STR00033##

(10) Step 1. According to the process described in example 1, the intermediate 12 is obtained from D-glucose and 1,3-dimethylbarbituric acid. The .sup.1H NMR spectra and the mass spectrometry are in accordance with the expected structure 12.

(11) Step 2. An aqueous solution of Na.sub.2EDTA (13 mg in 90 ml of water, C=4.10.sup.−4 M, 0.036 mmol) is added, with stirring, to a solution of 12 (10.0 g, 32.0 mmol) in 140 ml of acetonitrile.

(12) After a few minutes, the mixture is cooled in an ice bath and then 25 ml of acetone are added. An oxone (48.0 g, 78.1 mmol)/NaHCO.sub.3 (20.0 g, 238 mmol) mixture is then slowly added. Stirring is continued overnight at ambient temperature, then the reaction mixture is filtered. After evaporation under vacuum, the residue is taken up in methanol, and the insoluble matter is filtered off. The filtrate is evaporated under vacuum and then purified on silica gel (dichloromethane/MeOH 8:2). The compound 3 is obtained in the form of a white solid. The .sup.1H NMR spectra and the mass spectrometry are in accordance with the expected structure.

Example 4

Synthesis of Compound 4

(13) ##STR00034##

(14) Step 1. According to the process described in example 1, the intermediate 13 is obtained from L-rhamnose and 1,3-dimethylbarbituric acid. The .sup.1H NMR spectra and the mass spectrometry are in accordance with the expected structure 13.

(15) Step 2. An aqueous solution of Na.sub.2EDTA (7 mg in 46 ml of water, 0.019 mmol) is added, with stirring, to a solution of 13 (5.0 g, 15.4 mmol) in 80 ml of acetonitrile. After a few minutes, the mixture is cooled in ice and then 13 ml of acetone are added. An oxone (25.2 g, 41.0 mmol)/NaHCO.sub.3 (10.5 g, 125 mmol) mixture is then carefully added at a rate of approximately ⅔ of a spatula every 10 min. The pH is stabilized at approximately 7.3. Stirring is continued overnight at ambient temperature, then the reaction mixture is filtered. After evaporation under vacuum, the residue is purified on silica gel by elution with an increasing gradient of MeOH in dichloromethane. The compound 4 is obtained in the form of a yellow oil. The .sup.1H NMR spectra and the mass spectrometry are in accordance with the expected structure.

Example 5

Synthesis of Compound 9

(16) ##STR00035##

(17) An aqueous solution of Na.sub.2EDTA (0.4 mM, 1 ml, 0.35 μmol) is added, with stirring, to a solution of 12 (100 mg, 0.294 mmol) in 1.5 ml of acetonitrile. After a few minutes, the mixture is cooled in ice and then 0.26 ml of acetone are added. An oxone (0.5 g, 0.814 mmol)/NaHCO.sub.3 (0.2 g, 2.38 mmol) mixture is then carefully added all at once. The pH is stabilized at approximately 8. After 2 h of stirring, the reaction mixture is filtered and concentrated under vacuum in order to obtain 70 mg of compound 9 in the form of a white paste. The .sup.1H NMR spectra and the mass spectrometry are in accordance with the expected structure 9.

(18) B): Evaluation of the Moisturizing Potential on Isolated Stratum Corneum by Measurement with a Corneometer

(19) A test was performed to evaluate the moisturizing potential of the compounds of the invention formulated in an aqueous solution to an amount of 5% by weight relative to the total weight of the composition.

(20) The technique makes it possible to measure the dielectric capacitance of the stratum corneum (SC), which depends on the mean dielectric permittivity value of the tissue. The dielectric permittivity varies greatly with the amount of water contained in the SC.

(21) The SC samples are conditioned at 75% relative humidity and at 25° C. before/during the measurements and the treatment. The capacitance measurement is performed using a Corneometer™ (Courage & Khazaka, Germany).

(22) The compound tested, compounds 1, 2 and 3 according to the invention or a moisturizing active agent such as glycerol (humectant positive control), is dissolved in a water/n-propanol mixture (80/20) and the solution is deposited onto the SC at a rate of 5 μl/cm.sup.2 followed by air-drying for a total duration of 4 h.

(23) A measurement is taken at T0h, before the treatment, and a measurement T4h is taken after total drying of the treatment.

(24) The variation in the level of moisturization between T0h and T4h is calculated for each condition tested and compared to the references (carrier control and positive control) and to its T0h. The experiments are carried out on at least two different batches of SC and three samples of SC per condition tested.

(25) The variation in the corneometer signal (HCM) after treatment is calculated for each SC sample: DHCMi=HCMi(T4h)−HCMi(T0h).

(26) The results are then expressed as relative percentage in relation to the references, the carrier control and the glycerol positive control corresponding to a level of 0% and 100%, respectively.

(27) Thus, for each experiment, the following are measured: For the carrier control: DHCMi.sub.carrier=HCMi.sub.carrier(T4h)−HCMi.sub.carrier(T0h) For the positive control: DHCMi.sub.glycerol=HCMi.sub.glycerol(T4h)−HCMi.sub.glycerol(T0h) For the active agent: DHCMi.sub.active agent=HCMi.sub.active agent(T4h)−HCMi.sub.active agent(T0h) % DHCMi.sub.active agent=(DHCMi.sub.active agent−DHCMi.sub.carrier)/((DHCMi.sub.glycerol−DHCMi.sub.carrier) As specified above, according to this mode of calculation: % DHCMi.sub.carrier=0% % DHCMi.sub.glycerol=100%

(28) The moisturizing potential of an active agent is therefore determined as relative percentage in relation to the positive control.

(29) The mean of the relative percentages % DHCMi.sub.active agent are listed in the table below for compounds 1, 2 and 3 tested at 5%, compared to glycerol at 5%:

(30) TABLE-US-00004 Products tested in a Mean water/n-propanol mixture DHCMi.sub.active agent corr Carrier control  0% Glycerol at 5% by weight 100% Compound 1 according to the  88% invention at 5% by weight Compound 2 according to the  63% invention at 5% by weight Compound 3 according to the  51% invention at 5% by weight

(31) It emerges from this test that the dielectric capacitance of the stratum corneum (SC) is high with compounds 1, 2 and 3 used according to the invention. In particular, the dielectric capacitance of the stratum corneum (SC) is of the same order with compound 1 used according to the invention in comparison with that obtained with glycerol at the same concentration.

C) Example 8

Skincare Cream

(32) TABLE-US-00005 % by weight Compound 1    4% Glyceryl monostearate  0.8% Cetyl alcohol  2.0% Stearyl alcohol  5.0% Polyoxyethylene (20 OE) stearate  3.0% Crosslinked acrylic acid (Carbopol 941)  0.3% Caprylic/capric triglycerides  12.0% Preservatives qs Water qs 100.0%

(33) When applied to the skin, the illustrated cosmetic formulation shows a good moisturizing effect on the skin.