METABOLISM OF 7-NITROBENZ[A]ANTHRACENE BY INTESTINAL MICROFLORA

Pure cultures or 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-NO(2)BA). 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-NH(2)BA) and benz[a]anthracene 7,12-dione (dione). Identification of 7-NH(2)BA as a metabolite of 7-NO(2)BA indicates that the anaerobic intestinal bacteria are capable of reducing 7-NO(2)BA to potentially bioactive intermediates. The reductive capacities of the mixed intestinal microilora were generally greater than those of pure cultures. Thus, metabolism of 7-NO(2)BA in the intestinal tract may be underestimated if pure cultures are used as the sole method for evaluating the potential hazard.