Novel monoterpenoid indole alkaloids from Melodinus yunnanensis

Abstract

Five monoterpenoid indole alkaloids, namely meloyines A-B (1–2), meloyines II-III (3–4), and 10-O-glucosyl-scandine (5) together with thirty-four known alkaloids were isolated from leaves and twigs of Melodinus yunnanensis. Alkaloid 1 was characterized as an unprecedented skeleton with a 6/5/5/6/6/4 ring system, and alkaloids 3–4 were dimeric monoterpenoid quinolone alkaloids. Their structures were elucidated based on 1D and 2D- NMR, FTIR, UV, and MS spectroscopic data. The cytotoxic activity of new alkaloids were evaluated against three human cancer cell lines.