Inhibition of beta-glucuronidase by chlorinated hydroquinones and benzoquinones

An earlier study of the metabolism of pentachlorophenol has shown that a metabolite, tetrachloro-p-hydroquinone, possessed pronounced inhibitory action on the activity of beta-glucuronidase from bacterial origin. Several other chlorinated hydroquinones and benzoquinones have now been studied with regard to their ability to inhibit beta-glucuronidase of various origin in vitro and in vivo. All the studied chlorinated hydroquinones and benzoquinones were found to be potent inhibitors of beta-glucuronidase of bacterial origin. D-glucaric acid-1.4-lactone was included for comparison and was found to be less active than the other studied compounds. The inhibition was found to be competitive in nature. No inhibitory effect of the benzo- and hydroquinones studied in vitro or in vivo could be demonstrated on beta-glucuronidase from livers. The result calls for precaution when using bacterial beta-glucuronidase to split urinary conjugates of glucuronic acid.