| abstract |
PURPOSE:To prepare a cosmetic having remarkably improved effect for the prevention of the skin darkening, spots, freckles, etc. caused by the inhibition of tyrosinase activity, by compounding an S,S-diacyl lipoic acid to a cosmetic base. CONSTITUTION:An S,S-diacyl lipoic acid of formula (R is straight- or branched- chain fatty acid acyl residue; R' is H or straight- or branched-chain alcohol alkyl residue) or its alkyl ester derivative, e.g. S,S-dibutanoyl lipoic acid, is compounded in a cosmetic composition in an amount of 0.01-5wt%, pref. 0.1- 1wt% of the cosmetic composition as a whole. The S,S-diacyl lipoic acid can be obtained by cleaving the disulfide bond of alpha-lipoic acid with a reducing agent in a solvent, and reacting the resultant dihydrolipoic acid with a desired fatty acid chloride in a non-polar solvent in the presence of a base. |