Metabolism of 7‐nitrobenz[a]anthracene by intestinal microflora

Abstract

Pure cultures of anaerobic intestinal bacteria and mixed fecal microflora from human, rat, mouse, and pig were screened for the ability to metabolize 7‐nitrobenz[a]anthracene (7‐NO₂BA). Based on analysis by high‐performance liquid chromatography (HPLC) and by ultraviolet (UV), mass, and nuclear magnetic resonance (NMR) spectral techniques, the compounds were identified as 7‐aminobenz[a]anthracene (7‐NH₂BA) and benz[a]anthracene 7, 12‐dione (dione). Identification of 7‐NH₂BA as a metabolite of 7‐NO₂BA indicates that the anaerobic intestinal bacteria are capable of reducing 7‐NO₂BA to potentially bioactive intermediates. The reductive capacities of the mixed intestinal microflora were generally greater than those of pure cultures. Thus, metabolism of 7‐NO₂BA in the intestinal tract may 6e underestimated if pure cultures are used as the sole method for evaluating the potential hazard.