Catalyzes the reduction of nitroaromatic compounds using NADPH. Has a broad electron acceptor specificity. Reduces nitrofurazone by a ping-pong bi-bi mechanism possibly to generate a two-electron transfer product. Major oxygen-insensitive nitroreductase in E.coli. Binds 1 FMN per monomer. Homodimer. Belongs to the flavin oxidoreductase frp family.