[Inhibition of cytochrome P-450 when exposed to nitro-compounds]

Changes in ESR signals from the active form of cyt P-450 in mouse liver samples after administration of some nitro compounds were studied by the ESR method. It is shown that administration of nitro compounds leads to the formation of nitrosyl cyt P-450-NO complexes and a decrease in the ESR signal from cyt P-450 within the first 1-2 h after administration, indicating the inhibition of enzyme activity. It is assumed the nitro compounds induced inhibition of cyt P-450 in the first hours after administration is responsible for the enhancement by imidazoles of the effect of some chemotherapeutic drugs.