Studies in detoxication. 65. The metabolism of quinoline. New metabolites of quinoline, with observations on the metabolism of 3-, 5- and 6-hydroxyquinoline and 2:4-dihydroxyquinoline

Abstract

3-Hydroxy-, 2:6- and 5:6-dihydroxy-quinolines were isolated in small amounts from the urine of rabbits dosed with quinoline. The 5:6-dihydroxyquinoline occurs in the urine as 6-hydroxyquinolyl-5-sulfuric acid, which was isolated. This ethereal sulfate was synthesized by an Elbs persulfate oxidation of 6-hydroxy-quinoline. About 3-4% of quinoline (250 mg/kg) was excreted as 5:6-dihydroxyquinoline and 10% excreted as a labile compound which yields quinoline on heating with acid. 6-Hydroxyquino-line is converted to a very small extent into 2:6- and 5:6-dihydroxy-quinoline by the rabbit. 5-Hydroxyquinoline is not oxidized to the 5:6-dihydroxy derivative. 3-Hydroxyquinoline yields very small amounts of 2:3-dihydroxyquinoline. 3-, 5- and 6-Hydroxyquinolines are mainly metabolized by direct conjugation. 2:4-Dihydroxyquinoline does not yield an ethereal sulfate in the rabbit but is conjugated (20-40%) with glucuronic acid. The glucuronide was proved to be 2-quinolonyl-4-glucosiduronic acid.