Protection of superoxide-induced cholesterol oxidation by antioxidants in protic conditions

It was found in previous experiments that superoxide in the presence of added hydrogen peroxide in protic conditions produces oxysterols. The oxysterols formed under these conditions were 7β-ketocholesterol, 7α-hydroxycholesterol and 7β-hydroxycholesterol. In the present experiments, the inhibitory effects of three antioxidants, α-tocopherol (α-T), butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), on the oxidation of cholesterol in the presence of superoxide anion, water and hydrogen peroxide were investigated. It was found that BHA had the highest antioxidant activity on cholesterol oxidation, followed by α-T and BHT. The presence of antioxidants markedly retarded the formation of 7-ketocholesterol. The formation of 7β-hydroxycholesterol or 7α-hydroxycholesterol was also reduced, but to a lesser degree.