5,8-Epidioxysterols and related derivatives from a Chinese Soft Coral Sinularia flexibilis

Chromatographic separation of the methanolic extract of the marine soft coral, Sinularia flexibilis, resulted in the isolation and characterization of four new sterols, 5α,8α-epidioxygorgosta-6-en-3β-ol (1), 5α,8α-epidioxygorgosta-6,9(11)-dien-3β-ol (2), 22α,28-epidioxycholesta-5,23(E)-dien-3β-ol (3) and its C-22 epimer (4), along with nine known sterols. The structures of the new compounds were determined on the basis of extensive spectroscopic data (IR, MS, 1H and 13C NMR, HMQC, HMBC, and NOESY) analyses.