Crellastatin A: a cytotoxic bis-steroid sulfate from the Vanuatu marine sponge Crella sp

A new nonsym. dimeric steroid, crellastatin A (I), was isolated from the Vanuatu Island marine sponge Crella sp. Structural assignment was accomplished through extensive 2D NMR spectroscopy. The stereochem. of I was established from an anal. of ROESY expts. and from mol. mechanics and dynamics calcns. I, which possesses an unprecedented connection through the side chains, exhibits in vitro cytotoxic activity against NSCLC-N6 cells (IC50 of 1.5 mg/mL)