Hydroxylated amide skin moisturizer

A composition comprising, in a physiologically acceptable medium, a compound of formula (II):

• wherein
• (i) R1 and R2 represent a hydrogen atom, or
• (ii) R1 represents a hydrogen atom and R2 represents a saturated C1-C6 or unsaturated C2-C6 linear alkyl group or saturated or unsaturated C3-C6 branched alkyl group, substituted with one or more groups, which may be identical or different, selected from the group consisting of —OH, —SiMe3, —CO2R6 and —F;
• or
• (iii) R1 and R2 represent a saturated C1-C6 or unsaturated C2-C6 linear alkyl group or saturated or unsaturated C3-C6 branched alkyl group, optionally substituted with one or more groups, which may be identical or different, selected from the group consisting of −OR5, —SiMe3, —CO2R6 and —F;
• or
• (iv) R1 and R2 form, together with the nitrogen atom which bears them, a saturated heterocycle with 5 to 7 ring members and optionally comprising another heteroatom chosen from sulphur and oxygen, this heterocycle being optionally substituted with 1 to 3 linear C1-C4 or branched C3-C4 alkyl group(s) optionally substituted with one or more OH groups;
• R5 representing a hydrogen atom, or a linear C1-C3 or branched C3 saturated, or C2-C3 unsaturated alkyl group;
• R6 representing a hydrogen atom or a linear C1-C4 or branched C3-C4 saturated alkyl group;
• R3 represents a hydrogen atom or a linear C1-C6 saturated alkyl group, or —OR3 represents a phosphate group;
• it being possible for the two groups R3 to form, together, an isopropylidene group;
• R4 represents a hydrogen atom or —OR4 represents a phosphate group;
• with the proviso that 2,3,4-trihydroxybutanamide is excluded,
• a salt thereof, an isomer thereof, or a salt thereof;
• and at least one cosmetic ingredient selected from the group consisting of an oil, a wax, a thickener, a film-forming polymer, a preserving agent, a fragrance, a filler, a UV-screening agent, a bactericide, an odour absorber, a dyestuff, a cosmetic active agent, a plant extract, an antioxidant, sand a surfactant.