Alpneumines A-H, new anti-melanogenic indole alkaloids from Alstonia pneumatophora.

Eight new indole alkaloids, alpneumines A-H (1-8) were isolated from the Malaysian Alstonia pneumatophora (Apocynaceae) and their structures were determined by MS and 2D NMR spectroscopic methods. Alpneumines E and G (5 and 7), vincamine, and apovincamine showed anti-melanogenesis in B16 mouse melanoma cells.