3 beta-O-Glycosylated 16 beta-acetoxy-9 beta-H-lanosta-7,24-diene-3 beta,18,20 beta-triol, an intermediate metabolite from the sea cucumber Eupentacta fraudatrix and its biosynthetic significance

摘要

A novel oligoglycoside cucumarioside A(8) with unprecedented hydroxy group at C-18 was isolated from sea cucumber Eupentacta fraudatrix and its structure elucidated. The presence of hydroxy group at C-18 indicates that the glycoside is a "hot" metabolite that allows clarification of some peculiarities of 4.4,14-trimethylsterol glycoside biosynthetic pathways. A hypothetical scheme of biosynthesis of triterpene glycosides in sea cucumbers is proposed where direct formation of lanostane derivatives with a 7(8)-double bond from prosteroid cation is possible