The conjugation of phenylacetic acid in man, sub-human primates and some non-primate species

Abstract

14 C-Labelled phenylacetic acid has been administered to man, 14 species of sub-human primates and 11 non-primate species and their urine examined for metabolites. Four amino acid conjugates of this acid have been found in various species, namely, phenacetylglutamine, phenacetylglycine, phenacetyltaurine and diphenacetylornithine, but their occurrence varies with species. In the primates the occurrence of the glutamine and glycine conjugates appears to be correlated with their evolutionary status. Man excretes exclusively the glutamine conjugate, the Old World monkeys the glutamine conjugate and very small amounts of the glycine conjugate, the New World monkeys the glutamine conjugate and significant amounts of the glycine conjugate and the prosimians the glycine conjugate only. The non-primate mammalian species excrete the glycine conjugate and no glutamine conjugate. The two avian species examined also differed, since the pigeon excreted the glycine conjugate, whereas the domestic hen excreted mainly the ornithine conjugate with small amounts of the glycine conjugate. The conjugation of phenylacetic acid with taurine is reported for the first time. It occurs in all the species examined except the vampire bat and domestic hen, but its quantitative occurrence is haphazard amongst the species examined. It was found in significant amounts in the pigeon, ferret, bushbaby, capuchin monkey, squirrel monkey, mona monkey and baboon, but in minor amounts in other species.