Effect of cholesterol alpha and beta epoxides on cell killing and transformation

V-79 Chinese hamster lung fibroblasts and C3H-10T1/2 mouse embryo cells were used to study the toxicity and transformation effects of the 5 alpha,6 alpha, and 5 beta,6 beta-epoxy derivatives of cholesterol. Both epoxides were found to be carcinogenic, and the transformation frequency increased with epoxide concentration and exposure time. The 5 beta,6 beta-epoxide caused a higher level of transformation than the alpha-isomer, and this is consistent with its greater toxicity.