Melosuavine I, an apoptosis-inducing bisindole alkaloid from Melodinus suaveolens.

A new bisindole alkaloid, melosuavine I (1) possessing an aspidosperma-aspidosperma dimeric skeleton, was isolated from the leaves of Melodinus suaveolens. The structure with absolute configuration of 1 was elucidated by a combination of MS, NMR and computational methods. MTT assays indicated that 1 exhibited significant cytotoxicity on human breast cancer BT549 cells with an IC50 value of 0.89 µM. Further study showed that 1 inhibited BT549 cell proliferation by inducing apoptosis through activation of caspase 3 and p53, and down-regulation of Bcl-2.