Excretion and metabolism of phenol, 4-nitrophenol and 2-methylphenol by the frogs Rana temporaria and Xenopus laevis

Abstract

1. Rana and Xenopus excrete 90–95% dose, and metabolize 50–65% dose of phenol, 4-nitrophenol and 2-methylphenol within 24 h, to about the same extent.

2. Kinetic data for the excretion of phenols from both species fit a two-compartment model. The elimination constants of Rana and Xenopus are not significantly different.

3. Metabolism is mostly conjugation by glucuronidation and sulphation of the original phenols. Additionally, oxidations leading to dihydroxyphenols and benzoic acid from 2-methylphenol, and reduction of 4-nitrophenol occur, followed by conjugation.

4. There is an important difference between the metabolite patterns of Rana and Xenopus in that the latter is unable to glucuronidate phenols. As the amount of metabolites produced is similar in both species, Xenopus compensates for its inability to glucuronidate by increasing other metabolites.