Prophylactic or ameliorating agent for pigmentation

A prophylactic or ameliorating method for pigmentation, comprising applying a compound represented by the following general formula (1), an isomer thereof, and/or a pharmacologically acceptable salt thereof to a subject for which prophylaxis or amelioration for pigmentation is needed in an amount effective to provide prophylaxis or amelioration of pigmentation:

• wherein:
• R1 represents a hydrogen atom or a linear chain or branched alkyl group having 1 to 8 carbon atom(s);
• R2 represents a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 8 carbon atom(s), a substituted or unsubstituted aromatic group, a substituted or unsubstituted polycyclic fused aromatic group, or a substituted or unsubstituted heterocyclic group having a 5 to 12 carbon atoms;
• R3 represents a substituted or unsubstituted aromatic group, a substituted or unsubstituted polycyclic fused aromatic group, or a substituted or unsubstituted heterocyclic group having a 5 to 15 carbon atoms, wherein the substituent of R3 is an alkyl group having 1 to 6 carbon atom(s), an alkoxy group having an alkyl chain having 1 to 6 carbon atom(s), an alkylamino group having an alkyl chain(s) having 1 to 6 carbon atom(s), a halogen atom, a halogenated alkyl group, a hydroxy group, or an amino group;
• n represents an integer of 1 or 2, and m represents an integer of 0 to 3.