Leptogorgins A-C, Humulane Sesquiterpenoids from the Vietnamese Gorgonian sp.

Leptogorgins A-C (-), new humulane sesquiterpenoids, and leptogorgoid A (), a new dihydroxyketosteroid, were isolated from the gorgonian sp. collected from the South China Sea. The structures were established using MS and NMR data. The absolute configuration of was confirmed by a modification of Mosher's method. Configurations of double bonds followed from NMR data, including NOE correlations. This is the first report of humulane-type sesquiterpenoids from marine invertebrates. Sesquiterpenoids leptogorgins A () and B () exhibited a moderate cytotoxicity and some selectivity against human drug-resistant prostate cancer cells 22Rv1.