| abstract |
A dopa oxidase activity inhibitor, a melanin production inhibitor, a skin whitening agent or an external preparation for the skin, which contains, as an active ingredient, Peristrophe japonica , an organic solvent extract thereof, a compound represented by formula (I) or a salt of the compound. (In formula (I), R 1 and R 2 each represents a hydroxyl group or an alkoxy group having 1-4 carbon atoms, or alternatively R 1 and R 2 combine together to form a methylenedioxy group; R 3 and R 4 each represents a hydroxyl group or an alkoxy group having 1-4 carbon atoms, or alternatively R 3 and R 4 combine together to form a methylenedioxy group; R 5 represents a hydrogen atom, a hydroxyl group, an alkoxy group having 1-5 carbon atoms, an acyl group having 1-4 carbon atoms or a sugar residue such as (D-Apio-β-D-furanosyl)oxy; and R 6 and R 7 each represents a hydrogen atom and R 8 and R 9 combine together to represent an oxygen atom, or alternatively R 8 and R 9 each represents a hydrogen atom and R 6 and R 7 combine together to represent an oxygen atom.) |