Failure of ascrobic acid to inhibit the metabolic N-oxidation of the bladder carcingen 4-biphenylamine.

The effect of L-ascorbic acid on the in vivo metabolic N-oxidation of the bladder carcinogen 4-biphenylamine has been investigated in the dog. Gas chromatographic analysis of the urines of dogs receiving concomitant oral doses of L-ascorbic acid and 4-biphyenylamine showed no significant difference in the N-oxidized metabolites when compared to dogs receiving arylamine alone. The results indicate that pretreatment with large doses of L-ascorbic acid has no effect on the metabolic N-oxidation of 4-biphenylamine or on the urinary concentration of these metabolites. The failure of L-ascrobic acid to lower the urinary concentration of these presumed proximate urinary carcinogens casts doubt on its efficacy in bladder tumor prophylaxis.