The Metabolism of Quinaldylglycylglycine, a Urinary Metabolite of Quinaldic Acid in the Cat.

Quinaldic acid, which was found to be a metabolite of kynurenic acid (l), was not conjugated by the rabbit (2), but was excreted by the rat both free and as the glycine conjugate (3). When quinaldic acid was administered orally or parenterally to the cat, the urine contained little, if any, quinaldic acid or quinaldylglycine, but about two-thirds of the compound was accounted for as quinaldylglycyltaurine (4). A minor conjugate of quinaldic acid in the urine of the cat was always eluted from Dowex 2-acetate columns between quinaldic acid and quinaldylglycine. This conjugate has now been isolated, characterized, and proved by synthesis to be quinaldylglycylglycine. When the glycylglycine conjugate of quinaldic acid was fed to the cat, it was excreted in part in the feces, along with quinaldic acid, and in part in the urine, with the glycyltaurine conjugate.