| abstract |
Disclosed are a compound useful as a skin whitening agent, which has excellent melanin production inhibitory activity, and an external preparation for the skin containing the compound. A skin whitening agent of the present invention contains a compound represented by general formula (1) or a pharmacologically acceptable salt thereof as an active ingredient. (In the formula, A represents a C1-6 alkyl, a C5-6 cycloalkyl, a benzyl, a benzylcarbonyl, a benzoyl, a phenyl, a pyridyl or a pyrimidyl; Ra represents H, a C1-6 alkyl or C2-6 alkenyl; --- represents a single bond or a double bond; n represents 1 or 2; Y represents S or O; and R3 and R4 each represents H, a C1-6 alkyl, a hydroxy C1-6 alkyl, a C2-7 acyl, a phenyl, a pyridyl, a pyrimidyl or the like; provided that when the heterocyclic ring including Y is a thiazoline ring, R4 = Ra = H, X1 = X2 = CH and p = 0 or R5 is a C1-6 alkyl, at least one R3 is a group other than a C1-3 alkyl.) |