Synthesis and assessment of the relative toxicity of the oxidised derivatives of campesterol and dihydrobrassicasterol in U937 and HepG2 cells.

ABSTRACT

The cytotoxic effects of the oxidised derivatives of the phytosterols, stigmasterol and ß-sitosterol, have previously been shown to be similar but less potent than those of the equivalent cholesterol oxides in the U937 cell line. The objective of the present study was to compare the cytotoxic effects of the oxidised derivatives of synthetic mixtures of campesterol and dihydrobrassicasterol in both the U937 and HepG2 cell lines. The parent compounds consisted of a campesterol dihydrobrassicasterol mix at a ratio of 21 (2CMP1DHB) and a dihydrobrassicasterolcampesterol mix at a ratio of 31 (3DHB1CMP). The 2CMP1DBH oxides were more cytotoxic in the U937 cells than the 3DBH1CMP oxides but the difference in cytotoxicity was less marked in the HepG2 cells. The order of toxicity of the individual oxidation products was found to be similar to that previously observed for cholesterol, ß-sitosterol and stigmasterol oxidation products in the U937 cell line. There was an increase in apoptotic nuclei in U937 cells incubated with the 7-keto and 7ß-OH derivatives of both 2CMP1DHB and 3DHB1CMP and also in the presence of 3DHB1CMP-3ß,5α,6ß-triol and 2CMP1DHB-5ß,6ß-epoxide. An additional oxidation product synthesised from 2CMP1DHB, 5,6,22,23-diepoxycampestane, was cytotoxic but did not induce apoptosis. These results signify the importance of campesterol oxides in the overall paradigm of phytosterol oxide cytotoxicity.