Two new indole alkaloids, winphyllines A (1) and B (4), along with four known alkaloids, Nb-demethylechitamine (2), 17-O-acetylnorechitamine (3), 12-methoxyechitamidine (5), and N(4)-demethylastogustine (6), were isolated from the methanol extract of the twigs of Alstonia rostrata. The structures of 1 and 4 were elucidated by means of HRMS and NMR spectroscopic methods. The in vitro cytotoxic activity of the isolated alkaloids against several human cancer cell lines was evaluated.
Keywords: Alstonia rostrata; Apocynaceae; monoterpene indole alkaloid.