A labile sulfur in trisulfide affects cytochrome P-450 dependent lipid peroxidation in rat liver microsomes.

The effects of trisulfide derivatives were studied on cytochrome P-450-dependent lipid peroxidation using rat liver microsomal systems. Cytochrome P-450-dependent lipid peroxidation was induced by carbon tetrachloride or tert-butylhydroperoxide and was evident by an increase in thiobarbituric acid-reactive substances (TBA-RS) and oxygen consumption. In these cytochrome P-450-dependent lipid peroxidation systems, pretreatment of microsome with trisulfide derivatives (cystine trisulfide and thiocyclam) significantly inhibited TBA-RS formation and oxygen consumption compared with disulfide or thiol analogs (cystine, nereistoxin, or cysteine). The labile sulfur contained in trisulfide disappeared during incubation with liver microsomes. In the CCl4-induced lipid peroxidation system, the cytochrome P-450 level and NAD(P)H-cytochrome P-450 reductase activity were significantly decreased by the addition of trisulfide derivatives. Therefore, in cytochrome P-450-dependent lipid peroxidation system, the potential effects of trisulfide appear to be mediated via enzyme inhibition. These results suggest that pretreatment of the trisulfide derivatives may affect the toxic function of exogenous xenobiotics or drugs, which are reduced by the liver enzyme cytochrome P-450 to radical species.