Microsomal metabolism of pyrrolizidine alkaloids: N-oxidation of seneciphylline and senecionine.

H S Ramsdell, D R Buhler

Index: Toxicol. Lett. 37(3) , 241-9, (1987)

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Abstract

In vivo pretreatment of rats with phenobarbital or beta-naphthoflavone reduced the specific activity of microsomal pyrrolizidine alkaloid N-oxide formation. Heat pretreatment of microsomes under conditions intended to selectively inactivate the flavin-containing monooxygenase did not lower the rate of N-oxidation. Incubation in the presence of cytochrome P-450 inhibitors diminished the microsomal formation of N-oxide. The observations are consistent with the hypothesis that pyrrolizidine alkaloid N-oxidation