The interactions of hydrazine derivatives with rat-hepatic cytochrome P-450

1. The ability of different classes of hydrazine derivatives to modify cytochrome P-450 function during turnover as judged by loss of absorbance at 416 nm, loss of CO-reactive cytochrome P-450, or destruction of haem has been studied.

2. Addition of monosubstituted hydrazines to rat-liver microsomes caused considerable loss of CO-reactive cytochrome P-450 and haem destruction; monosubstituted hydrazides caused mainly loss of CO-reactive cytochrome P-450, most likely due to abortive complex formation. Metabolism of 1,1-disubstituted hydrazines by microsomal cytochrome P-450 resulted in loss of CO-reactive cytochrome P-450 only, with no haem destruction. The 1,2-disubstituted hydrazines and hydrazides, procarbazine and iproniazid, acted similarly to the monosubstituted hydrazines, while 1,2-dimethyl-hydrazine elicited no response, cither in observable spectral changes or loss of CO-reactive cytochrome P-450.

3. Synthetic diazene intermediates of phenylhydrazine and N-aminopiperidine reacted rapidly with microsomal cytochrome P-450 to form a spectral intermediate resembling the putative iron porphyrin-diazenyl complex. The decomposition of certain iron porphyrin-diazenyl derivatives apparently leads to destruction of the porphyrin prosthetic group, most likely due to haem alkylation.