Studies on the effectiveness of mammalian and bacterial beta-glucuronidase enzymes in the hydrolysis of urinary beta-glucosiduronides of some tryptophan metabolites excreted in urine.

The effectiveness of E. coli and bovine liver beta-glucuronidases in the hydrolysis of the urinary beta-glucosiduronides of tryptophan metabolites was studied. Some of these metabolites demonstrate carcinogenic activity in the mouse bladder. Moreover, the effect of the prolonged contact of these conjugates to the urinary enzyme was investigated in the first and second voiding urine samples. The former urine was that retained in the bladder during sleep (about 8 hours) and the latter was collected 3 hours after the first. It is found that both enzymes have no important role in releasing the free carcinogens from their glucosiduronides. The presence of free carcinogens could be attributed to the spontaneous hydrolysis of some labile conjugates. However, the prolonged contact of the freely active substances during the sleeping hours with the epithelium of the bladder may enhance the process of bladder carcinogenicity. The increased accumulation of these metabolites in the first voiding urine could be interpreted in terms of their rate of excretion rather than by the enzymatic hydrolysis of their conjugates.