Abstract:Cholesterol oxides generated during high temperature were characterized by gas chromatography-mass spectrometry (GC-MS). Silicon column chromatography was used to isolate the oxides, and their toxicity toward buffalo rat liver (BRL) cells was evaluated by MTT assay. The results indicated that there were five major cholesterol oxides generated under high temperature: 7α-hydroxycholesterol, 7β-hydroxycholesterol, 5,6 β-epoxycholesterol, 5,6α-epoxycholesterol, and 7-ketocholesterol. Single factor experiments showed that the maximum amount of cholesterol oxides were obtained after heating at 160 ℃ for 30 min; therefore, this condition was used for the preparation of cholesterol oxides in this study. The crude products were purified by silicon columns, and a cholesterol oxide product with a purity of about 90% was obtained (composition: 9.96% 7α-hydroxycholesterol, 23.24% 7β-hydroxycholesterol, 15.34% 5,6β-epoxycholesterol, 14.36% 5,6α-epoxycholesterol, 26.77% 7-ketocholesterol, 3.12% cholesterol, and 7.21% other impurities). According to the result of the MTT assay, the purified cholesterol oxides showed significant (p < 0.05) toxicity to BRL cells at a concentration of 80 μg/mL, and the cell viability after a treatment at a concentration of 100 μg/mL was only 7.49% of the viability of untreated control cells. The toxicity mechanism of cholesterol oxides needs to be further explored.
