Tyrosinase Inhibitors from the Wood of Artocarpus heterophyllus

From the methanolic-soluble extract of the wood of Artocarpus heterophyllus, four new flavones, artocarmins A–D (1–4), and three new chalcones, artocarmitins A–C (5–7), have been isolated together with 13 known compounds. Their structures were determined on the basis of the spectroscopic data. Compounds 1–4, 6, 7, 9–16, and 20 displayed significant tyrosinase inhibitory activity. The most active compound, morachalcone A (12) (IC50, 0.013 μM), was 3000 times more active as a tyrosinase inhibitor than a positive control, kojic acid (IC50, 44.6 μM).