Alkaloids from Melodinus yunnanensis.

Ten monoterpenoid indole alkaloids, namely meloyine, 19S-methoxytubotaiwine N₄-oxide, 16,19-epoxy-Δ¹⁴-vincanol, 14β-hydroxymeloyunine, meloyunine, Δ¹⁴-vincamenine N₄-oxide, 16β,21β-epoxy-vincadine, 14β,15β-20S-quebrachamine, 3-oxo-voaphylline, 2α,7α-dihydroxy-dihydrovoaphylline, and 32 known alkaloids were isolated from leaves and twigs of Melodinus yunnanensis. Their structures were elucidated based on 1- and 2-D NMR, FTIR, UV, and MS spectroscopic data. Meloyine I showed weak cytotoxic activity against four human cancer cell lines: MCF-7 breast cancer, SMMC-7721 hepatocellular carcinoma, HL-60 myeloid leukemia, and A-549 lung cancer.