THE INHIBITORY COMPONENTS FROM ARTOCARPUS-INCISUS ON MELANIN BIOSYNTHESIS

The inhibitory effects of methanol extracts of heartwood of 23 Papua N ew Guinean wood species on tyrosinase activity were examined. The extr act of Artocarpus incisus showed the strongest tyrosinase inhibitory a ctivity which was equivalent to kojic acid. The extract apparently inh ibited melanin biosynthesis of both cultured B16 melanoma cells withou t any cytotoxicity and in the back of a brown guinea pig without skin irritation. Thus, the potentiality of the extracts of heartwood of A. incisus both as material of a useful skin whitening agent and as a rem edy for disturbances in pigmentation is evident. Tyrosinase inhibitory activity-guided fractionation led to the isolation of seven active co mpounds including a new compound which has been characterized as methy l-1''-butenyl)-5,7,2',4'-tetrahydroxyflavone, named isoartocarpesin. O ther active compounds were (+)-dihydromorin, chlorophorin, (+)-norarto carpanone, 4-prenyloxyresveratrol, artocarbene, and artocarpesin. Thes e compounds are probably responsible for the melanin biosynthesis inhi bitory effects.