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

Pure cultures or anaerobic intestinal bacteria and mixed fecal microfl ora from human, rat, mouse, and pig were screened for the ability to m etabolize 7-nitrobenz[a]anthracene (7-NO(2)BA). Based on analysis by h igh-performance liquid chromatography (HPLC) and by ultraviolet (UV), mass, and nuclear magnetic resonance (NMR) spectral techniques, the co mpounds were identified as 7-aminobenz[a]anthracene (7-NH(2)BA) and be nz[a]anthracene 7,12-dione (dione). Identification of 7-NH(2)BA as a m etabolite of 7-NO(2)BA indicates that the anaerobic intestinal bacteri a are capable of reducing 7-NO(2)BA to potentially bioactive intermedi ates. 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.