Coumarin compounds as melanogenesis modifiers and uses thereof

A method for inhibiting melanogenesis or a method for promoting skin lightening in a mammal in need thereof, comprising administering to the mammal an effective amount of either lonchocarpic acid or a compound of formula I:

• wherein
• R3 is selected from the group consisting of halo, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, unsubstituted phenyl, 3,4-dihydroxyphenyl, 4-methoxyphenyl, 3,4-dimethoxyphenyl, and substituted or unsubstituted heteroaryl;
• R4 is selected from the group consisting of H, halo, hydroxy, alkoxy, alkenyloxy, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, and substituted or unsubstituted phenyl;
• each R5, R6, and R8 is independently selected from the group consisting of H, halo, hydroxy, alkoxy, alkenyloxy, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, and substituted or unsubstituted phenyl;
• R7 is selected from the group consisting of H, halo, hydroxy, alkoxy, alkenyloxy, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, and heterocycloalkyl;
• or R7 is —P(═O)(alkoxy)2, or —P(═S)(alkoxy)2;
• or R6 and R7 or R7 and R8 are joined to form a 5- or 6-membered heterocycloalkyl or heterocycloalkenyl;
• and the heterocycloalkyl or heterocycloalkenyl is unsubstituted or substituted with one or more groups selected from the group consisting of alkyl, alkenyl, hydroxyalkyl, acyloxyalkyl, hydroxy, and alkoxy;
• and
• provided that the compound is other than robustic acid;
• or pharmaceutically acceptable salts, solvates, isomers, tautomers, metabolites, analogs, isotopic variants or prodrugs thereof.