On the cytotoxicity of oxidized phytosterols isolated from photoautotrophic cell cultures of Chenopodium rubrum tested on meal-worms Tenebrio molitor.

摘要

A bioassay to determine the cytotoxicity of sterol oxidation products (hydroperoxides) by measuring the mortality of T. molitor is described. Hydroperoxides were tested in concentrations of 10-5-10-2 M; mortality was observed (25% at a concentrationof 10-2 M after 23 h). A direct relation between activity and concentration was observed. 5,6-Epoxides of phytosterols and derived 3,5,6-trihydroxysteranes were isolated from C. rubrum cell cultures. Using 5,6-epoxycholesterol and 3,5,6-trihydroxycholestane as standards of known bioactivity, the toxicity of epoxides of sitosterol and stigmasterol, as well as the trihydroxy compounds thereof, were determined. The phytosterol derivatives were 5-times less active than the corresponding cholesterol oxidation products. 5,6-Epoxides and 5,6-chlorohydrins showed half of the activity of the corresponding 3,5,6-trihydroxyphytosterols. These developed highest cytotoxicity (40% mortality at a concentration of 5 X 10-3 M after 23 h). The activity of 5,6alpha- and5,6beta-epoxides was found to be equal. Metabolism and proposed biological function of oxidized phytosterols is discussed.