Vobasinyl-Iboga Alkaloids from Tabernaemontana elegans Cell Cycle Arrest and Apoptosis-Inducing Activity in HCT116 Colon Cancer Cells.
Phytochemical investigation of the roots of the African medicinal plant Tabernaemontana elegans led to the isolation of three new (1-3) and two known (4 and 5) bisindole alkaloids of the vobasinyl-iboga type. The structures of 1-3 were assigned by spectroscopic methods, mainly using 1D and 2D NMR experiments. All of the isolated compounds were evaluated for their cytotoxicity against HCT116 colon and HepG2 liver carcinoma cells by the MTS metabolism assay. Compounds 1-3 and 5 were found to be cytotoxic to HCT116 colon cancer cells, displaying IC