Bengamides revisited: New structures and antitumor studies

The structural chemistry and biological activity of the bengamide class of compounds have been further characterized. Extracts prepared from recollect ed Jaspis cf. coriacea from five sites in Fiji were pooled. Six new bengami des, M (7b), N (8a), O (8b), P (9a), Q (9b), and R (10), were identified, a ccompanied by the known bengamides A (1a), B (1b), E (3a), F (3b), Y (5), Z (6), L (7a), G (11a), H (11b), and I (12). The structures of the new compo unds were determined from spectroscopic data, and some were additionally co nfirmed by semisynthesis. Cytotoxicity screening data were obtained from th e NCI-DTP 60 cell screen for bengamides A, B, and P. Bengamides A and B wer e more potent than bengamide P, with average IC50 values of 0.046, 0.011, a nd 2.70 FM, respectively. The in vitro antitumor activity against MDA-MB-43 5 human mammary carcinoma was also determined for natural bengamides A, B, E, F, P, M, O, and Z and for synthetic samples of B and O. The best activit y was observed for the natural bengamides A (IC50 = 1 nM) and O (IC50 = 0.3 nM).