abstract |
An inhibitor of endothelin action or a skin-whitening agent, comprising a compound represented by Formula (1) or a salt thereof as an active ingredient. n n n n n n n n n n n n wherein in Formula (1), R 1 represents a formyl group or an alkyl group having 1 to 4 carbon atom(s), and R 2 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atom(s). |