Reduction of a variety of nitroaromatic compounds using NADH (and to lesser extent NADPH) as source of reducing equivalents; two electrons are transferred. Capable of reducing nitrofurazone, quinones and the anti-tumor agent CB1954 (5-(aziridin-1-yl)-2,4-dinitrobenzamide). The reduction of CB1954 results in the generation of cytotoxic species. 5,6,7,8-tetrahydropteridine + NAD(+) = 6,7-dihydropteridine + H(+) + NADH 5,6,7,8-tetrahydropteridine + NADP(+) = 6,7-dihydropteridine + H(+) + NADPH Subject to competitive inhibition by dicoumarol, nicotinic acid and acetate with respect to NADH. Subject to uncompetitive inhibition by dicoumarol, nicotinic acid and acetate with respect to nitrofurazone and nitrofurantoin. Homodimer. Belongs to the nitroreductase family.