抄録
All the biological activities of nitrofuran derivatives, including antibacterial action, mutagenicity, and carcinogenicity, are considered to be initiated by the enzymic reduction of their nitro groups. Enzymic reduction of 2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide (AF-2) was compared with those of p-nitrobenzoate and New Coccine by using a bacterial enzyme, rat liver microsomes, and cytosol. The nitroreductions of AF-2 and p-nitrobenzoate by bacterial enzyme depended on NADPH and NADH to the same extent, but only the NADPH-dependent nitroreduction of p-nitrobenzoate was stimulated by flavin mononucleotide (FMN). On the other hand, the reduction of New Coccine depended more on NADH than NADPH and stimulation by FMN was also found in the NADPH-dependent reduction. In both microsomal and bacterial enzymes, the nitroreduction of AF-2 was hardly inhibited by quinacrine, SKF 525A, CO, and air, while that of p-nitrobenzoate was strongly inhibited by them. In cytosol, the nitroreduction of AF-2 and p-nitrobenzoate was clearly inhibited by these compounds, the inhibitory effect of which was to the same extent in both substrates. These results suggest that the mechanism of nitroreduction of AF-2 in liver microsomal and bacterial enzymes is somewhat different from that of p-nitrobenzoate, while in liver cytosol, the nitro groups of AF-2 and p-nitrobenzoate are mainly reduced by xanthine oxidase through the same mechanism.
