Occurrence of Cholest-4-en-3-one in Red Alga, Meristotheca papulosa

Abstract

Hitherto, little is known about the occurrence of Δ4-3-keto-steroids in the plant kingdom. In this study, an attempt to clarify the occurrence of keto-steroid in the red alga, Meristotheca papulosa was carried out. The algal keto-steroid isolated by a column chromatography and thin-layer chromato-graphy gave m. p. 75-79°C, MW (mass spectrum): 384, p-phenylenediamine reaction: positive, 2, 4-dinitrophenylhydrazine reaction: positive. Ultraviolet absorption spectral and mass spectral analyses suggested the structure of Δ4-3-keto-steroid. This algal steroid was identified as cholest-4-en-3-one by a thin-layer, paper, and gas-liquid chromatography. Moreover, it was ascertained that the labeled cholest-4-en-3-one was formed as a metabolite of cholesterol-14C by algal tissues. The cholest-4-en-3-one, an intermediate in the bioconversion of cholesterol to steriod hormones, has not yet been shown in animals and plants. However, in the case of alga, it is suggested that cholesterol is oxidized to cholest-4-en-3-one for lack of steroid C20-C22 lyase in the red alga.