Polyhydroxylated Sterols from the South China Sea Gorgonian Verrucella umbraculum

Two new polyhydroxylated sterols, named verumbsteroids A and B (1 and 2, resp.), along with seven known analog, 3-9, were isolated from the gorgonian Verrucella umbraculum collected from the South China Sea. The structures and relative configurations of the new compounds were elucidated by comprehensive spectroscopic investigations. The absolute configuration of 1 was determined by using modified Mosher method with the acetonide derivative of 1. Compounds 1 and 3-5 were found to show cytotoxicities against five human tumor cell lines (HL-60, K562, HeLa, A-549, and HCT-116) with the IC50 values ranging from 2.76 to 9.62 mu m.