Isolation and structural elucidation of crellastatins B-H : Cytotoxic bis(steroid) derivatives from the Vanuatu marine sponge Crella sp

Seven new cytotoxic dimeric steroids, namely crellastatins B-H (2-8), have been isolated from the Vanuatu sponge Crella sp. They have been structurally characterized on the basis of 2D-NMR (500 MHz) and FAB-MS data. All the new compounds show the same unprecedented junction between the monomeric units, formed via their side-chains, whereas they differ from A (1) in the hydroxylation pattern of the two tetracyclic cores. Like crellastatin A (1), crellastatins B-H (2-8) exhibit in vitro antitumor activity against human bronchopulmonary non-small-cell lung carcinoma cell lines (NSCLC) with IC50 values in the range of 2-10 μg/mL.