The chemical synthesis and biological oxidation of 7α-hydroxy[26-14C]cholesterol, 7-dehydro[26-14C]cholesterol and 26-hydroxy[26-14C]cholesterol

Publisher Website
Google Scholar
Abstract
26-Hydroxycholesterol was obtained by reducing the methyl ester of ([plus or minus])-3[beta]-hydroxycholest-5-en-26-oic acid, which was synthesized from 2 5-oxonorcholesterol. Methods for preparing 7[alpha] -hydroxycholesterol and 7-dehydrocholesterol were modified to allow the micro-scale preparation of these [14C]sterols from [26-14C]-cholesterol. 26-Hydroxycholesterol was oxidized more readily than l[alpha]-hydroxy-cholesterol, 7-dehydrocholesterol or cholesterol by mitochondrial preparations from livers of mice, rats, guinea pigs, common toads (Bufo vulgaris) and Caiman crocodylus. ([plus or minus])-3[beta]-Hydroxy [26-14c]cholest-5-en-26-oic acid was oxidized very rapidly to 14CO2 by mouse and guinea pig mitochondria without evident discrimination between the two optical isomers. An enzyme system that oxidizes 26-hydroxycholesterol to 3[beta]-hydroxycholest-5-en-26-oic acid was identified in the soluble extract of rat-liver mitochondria. This enzyme could use NADP in place of NAD but was not identical with liver alcohol dehydrogenase (EC 1.1.1.1). [26-14c]Cholesteryl 3[beta]-sulphate was not oxidized by fortified mouse-liver preparations that oxidized [26-14] cholesterol to 14CO2.