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

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. (C) 2012 Elsevier Ltd. All rights reserved.