Marine steroids. Part I. Structures of the principal aglycones from the saponins of the starfish, Marthasterias glacialis

Abstract

The principal aglycones obtained by hydrolysis of the saponins of M. glacialis are identified as 3β,6α-dihydroxy-5α-cholesta-9(11),24-dien-23-one and 3β,6α-dihydroxy-5α-cholest-9(11)-en-23-one. These are the first 23-oxo-cholestanes to be isolated from natural sources. On catalytic hydrogenation they yield 3β,6α-dihydroxy-5α-cholestan-23-one, which has been synthesised from stigmasterol.