A new sterol, sutinasterol ((24R)-24-ethyl-26,26-dimethyl-3β-hydroxycholesta-7,25(27)-diene) with a side chain arising from quadruple biomethylation has been isolated from the marine sponge Xestospongia sp. Since it represents the bulk (94%) of the sterol fraction, it presumably plays a biological role in membrane function. Four minor sterols were also characterized, one of which appears to be a biosynthetic intermediate of sutinasterol. A second trace sterol contains a side chain that is the result of five biomethylations and is the largest sterol isolated from natural sources to date. The structures of these sterols were deduced from spectral data (1H and 13C NMR and MS). A crystal structure study of sutinasterol was performed to determine the stereochemistry of the C24 ethyl group.
ASJC Scopus subject areas
- Organic Chemistry