Gusanlungionosides A-D, potential tyrosinase inhibitors from Arcangelisia gusanlung

Four new megastigmane glycosides, named gusanlungionosides A-D (1-4), together with 10 known compounds (5-14), were isolated from the stems of Arcangelisia gusanlung. The structures and absolute configurations of 1-4 were elucidated by comprehensive analysis of their NMR and CD data. Compounds 1-4 exhibited strong inhibitory effects not only on the mushroom tyrosinase activity in vitro but also on melanogenesis in cells.