Chemical Constituents from Tabernaemontana bufalina Lour.

Investigation of the branches and leaves of Tabernaemontana bufalina Lour. led to afford an undescribed monoterpenoid indole alkaloid, namely (3R,7S,14R,19S,20R)-19-hydroxypseudovincadifformine (1), and nine known metabolites (2-10). Their structures were determined by analysis of their NMR and ESI-MS spectra, and modified Mosher's and calculated electronic circular dichroism (ECD) methods were used for establishing the absolute configuration of compound 1. Their cytotoxic activities were assayed using two cancer cell lines. As the results, cytotoxic activities on MDA-MB-231 and B16 cells showed IC50 values of 8.9 and 0.13 μm for 6, and of 20.3 and 11.7 μm for 9, respectively.