摘要：Cholesterol α-epoxide (5, 6α-epoxy-5α-cholestan-3β-ol), cholesterol β-epoxide (5, 6β-epoxy-5β-cholestan-3β-ol), and cholestanetriol (5α-cholestane-3β, 5, 6β-triol) were isolated from plasma and liver of rabbits by high performance liquid chromatography and identified by gas-chromatography-mass spectrometry. The 5, 6-oxygenated cholestanols in the plasma and liver of rabbits fed for two months on a diet supplimented with cholesterol were elevated to 2-5 times and 5-8 times the normal level, respectively. Among the 5, 6-oxygenated steroids, the β-epoxide existed at the highest level in tissues of both control and cholesterol-fed rabbits. The ratios of the β-epoxide to the α-epoxide were 2-3 in all the examined biological specimens just as the previously demontsrated ones in the in vitro lipid peroxidation-mediated reaction of cholesterol. These results strongly suggest that the epoxidation of the cholesterol double bond in the animal may be mediated by lipid peroxidation. The elevated 5, 6-oxygenated cholestanol levels on long term cholesterol feeding will be discussed in relation to a possible physio ogical role of cholestanetriol in regulation of tissue cholesterol levels.
