Tirucallane-type alkaloids from the bark of Dysoxylum laxiracemosum.

Eight novel tirucallane-type alkaloids (1-8) and 11 known compounds were isolated from a methanol extract of the bark of Dysoxylum laxiracemosum. The structures of 1-8 were elucidated using extensive NMR spectrometric and mass spectroscopic methods. Compounds 1 and 5, named laxiracemosins A and E, showed significant cytotoxicity against five human cancer cell lines.