Species variations in the metabolism of acetophenone oxime by hepatic enzymes

The metabolism of acetophenone oxime was investigated in liver homogenates obtained from rats, rabbits, mice and hamsters. Significant species variations were observed in anaerobic metabolism studies both in qualitative and quantitative respects. In all cases, the oxime was initially reduced to the corresponding hydroxylamine. Whereas, the hydroxylamine was resistant to further transformation in rat, subsequent reduction to amine was observed in rabbit, mouse and hamster. Hydroxylamine reduction in rat was however observed in animals pretreated with phenobarbital, 3-methylcholanthrene or carbon tetrachloride. Enzymes catalyzing oxime and hydroxylamine reduction were present in both microsomal and cytosol fractions of liver. Highest reductase activity was observed in rat and mouse. Oxime reductase was not stimulated by either phenobarbital or 3-methylcholanthrene, but was inhibited by carbon tetrachloride.