Marine sterols. VIII. Isolation and structure of sarcosterol, a new sterol with a delta17(20)-double bond from the soft coral Sarcophyton glaucum.

The sterol mixture of the southern Japan's soft coral, Sarcophyton glaucum, was found to contain 11 sterols including a novel sterol, 23,24 xi-dimethylcholesta-5,22-dien-3 beta-ol and a new diunsaturated C29 sterol. 22,23-Dihydrobrassicasterol and gorgosterol were the major components in free- and esterified sterols respectively. Brassicasterol was found in S. glaucum, in contrast to the ubiquity of 24-epibrassicasterol in the marine invertebrates in the northern districts. The new sterol (sarcosterol) was isolated; its structure as 23 xi, 24 xi-dimethylcholesta-5, 17(20)-trans-dien-3 beta-ol was based on spectra evidence and comparison with cholesta-5, 17(20)-trans-dien-3 beta-ol.