Modification of cytochrome P-450, NADPH-cytochrome c reductase and aryl hydrocarbon hydroxylase activities by schistosomicidal drugs

This study was planned to investigate the modification of the mouse microsomal monooxygenase enzymes using various schistosomicidal drugs. Enzymes investigated were cytochrome P-450, NADPH-cytochrome c reductase and aryl hydrocarbon hydroxylase (AHH). Administration of oxamniquine and niridazole increased, whereas praziquantel and hycanthone lowered the cytochrome P-450 content. An apparent increase in the activity of NADPH-cytochrome c reductase was only observed with oxamniquine. The in vivo and in vitro effects of schistosomicidal drugs on the activity of AHH were investigated using benzo(a)pyrene (BP) as substrate. Oxamniquine and niridazole significantly increased the AHH activity in vivo and in vitro, while the antimonial drugs enhanced the enzyme activity only in vivo. On the other hand, praziquantel and hycanthone lowered the AHH activity only in vivo. Metrifonate did not show any effect either in vivo or in vitro. The mechanisms by which these drugs modify the AHH activity are discussed in the text.