Formation and metabolism in vitro of 5,6-epoxides of cholesterol and β-sitosterol

• Main Authors: Leif Aringer, Peter Eneroth
• Format: Article
• Language: English
• Published: Elsevier 1974-07-01
• Series: Journal of Lipid Research
• Subjects: lipid peroxidation; epoxide hydrolase; cholestane-3β,5α,6β-triol; cholesterol-7α-hydroxylase; inhibition by 5,6-epoxysterols and 3β,5α,6β-trihydroxysterols; hydroxyalkylated Sephadex LH-20
• Online Access: http://www.sciencedirect.com/science/article/pii/S0022227520367870

The formation of 5α,6α- and 5β,6β-epoxides of cholesterol and β-sitosterol in rat liver subcellular fractions has been studied. The results show that the epoxidation seems to occur only in connection with the nonspecific tissue oxidation of the sterols. The β-epoxides were formed in three- to fourfold excess over the α-epoxides. Both cholesterol epoxides were efficiently converted by a microsomal hydrolase into the 3β,5α,6β-triol. The conversion was less extensive with β-sitosterol epoxides, especially the β-epoxide. The possible biological significance in the formation of the sterol epoxides and the triols was evaluated by their ability to inhibit the microsomal cholesterol 7α-hydroxylase. Only the cholesterol epoxides and especially the β-epoxide were active in this respect.