N-acetylation and N-formylation of carcinogenic arylamines and related compounds in dogs.

When sulfanilamide, p-aminobenzoic acid, 4-amino-biphenyl, 2-aminofluorene or 1-aminopyrene was given orally to dogs, the corresponding N-acetyl and N-formyl derivates were isolated from urine or feces. These metabolites were identified unequivocally by comparison with an authentic sample by UV and mass spectrometry and their behaviour in TLC and HPLC. Dog intestinal flora and several bacterial strains exhibited both N-acetylating and N-formylating activities, in varying degrees, toward all of the arylamines tested. The metabolites formed by the intestinal bacteria were also isolated and identified unequivocally. The results suggest that the intestinal microflora plays an important role in the formation of N-acyl derivatives from arylamines in dogs.