The Conjugation of Indolylacetic Acid in Man, Monkeys and other Species

Abstract

Indol-3-yl[2-¹⁴C]acetic acid has been administered to 18 species of animals including man, and the urinary metabolites examined by radiochromatogram scanning. Man received 500 mg orally and the other animals 100 mg/kg by intraperitoneal injection.

In most species, 50–90% of the administered ¹⁴C was excreted in the urine in 48 h. 14–76% of the indolylacetic acid was excreted unchanged in 48 h.

In man, the ¹⁴C excreted in 48 h consisted of about 50% unchanged indolylacetic acid, 30% indolylacetylglucuronide and 10–20% indolylacetyl-glutamine. No glycine conjugate was detected.

The glutamine conjugate was excreted only by the Old World (3 species) and New World (3 species) monkeys and man.

The glycine conjugate was excreted by all species (13) except man, Old World monkeys and the pigeon. The three species of New World monkeys formed both the glutamine and glycine conjugates.

Taurine conjugation of indolylacetic acid was studied in the green monkey, the squirrel monkey, the capuchin monkey, the ferret and pigeon. Indolylacetyltaurine was a substantial metabolite in these species and in the pigeon it was the only conjugate of indolylacetic acid found.

Synthesis of indolylacetylglutamine and indolylacetyltaurine is described.