Inhibitory effects of prenyl flavonoids isolated from Artocarpus communis on mushroom tyrosinase and melanin production in cultured melanoma cells

Eighteen prenylated flavones, six new compounds (1-6) and twelve known compounds (7-18), were isolated from the heartwood and cortex of Artocarpus communis. In the tyrosinase inhibition assay, norartocarpetin (8), artogomezianone (9), cudraflavone A (15), and artonin M (18) exhibited strong inhibitory activities in concentration-dependent manner, while artocommunol CG (3), artocommunol CI (5), artocarpin (7), and cyclocommunol (10) showed moderate inhibitory activities on mushroom tyrosinase. The inhibition kinetics, analyzed by Lineweaver-Burk plots, indicated for 8 and 9 to be a competitive inhibitor, and for 15 and 18 to be a mixed-type inhibitor. Compounds 7, 9, 15, and 18 also inhibited melanin production in B16 melanoma cells. These results suggest that some prenylflavones from A. communis may serve as candidates for skin- lightening agents.