Chemistry and antibacterial activity of nitrobenzofurans

Thirteen 2-methylbenzofurans were synthesized and their antibacterial activity was investigated. 2-Methyl-3-nitrobenzofuran and analogs containing 7-NO2, 5-NO2, 7-Br, 7-CONH2, and 7-CF3 substituents are bacteriostatic. The spectrum of activity of these compounds is similar to nitrofurazone; however, a strain of E. coli Br which has increased resistance to nitrofurazone did not show increased resistance to 3,7-dinitro-2-methylbenzofuran (1). The 3-nitro-2-methylbenzofurans are labile in solution (T1/2 0.8-3.5 hr at 37 degrees, pH 7.0). The solvolysis product of 1 was identified as alpha,6-dinitro-o-cresol (15). The 3-nitrobenzofurans are more potent in minimal media than in Penassay broth. This greater potency can be abolished by addition of casamino acids and tryptophan to the minimal media.