New cassaine diterpenoid Amides with cytotoxic activities from the bark of Erythrophleum fordii

A phytochemical investigation of the bark of Erythrophleum fordii led to six new cassaine diterpenoid amides (2, 4 - 8), together with two known compounds of the same skeleton, norcassamide (1) and nor-erythrosuamide (3). The structures were mainly established on the basis of 1 D, 2D NMR and HR-MS analysis. The compounds 1, 2, 4, 6 - 8 exhibited selective cytotoxic activities (IC50 values < 10 mu M) against A2780, KB, Bel-7402, BGC-823, MCF-7, HCT-8, Hela, PC-3M, A549 and Ketr3 human cancer cell lines in the MTT test.