Identification and determination of urinary metabolites of 2-isopropylnaphthalene in rabbits

Four unconjugated metabolites, which were produced through the oxidation of the isopropyl chain of 2-isopropylnaphthalene (2-IPN), were isolated from the urine of rabbits receiving 2-IPN orally and identified: 2-(2-naphthyl)propionic acid, 2-(2-naphthyl)-2-propanol, 2-(2-naphthyl)-1,2-propanediol, and 2-(2-naphthyl)-2-hydroxypropionic acid, together with a small amount of the unchanged compound. Further, the unconjugated metabolites, which were produced through the oxidation of the naphthalene ring, were isolated and identified: 2-isopropylnaphthols and 2-isopropyl-5,6 (or 7,8)-dihydronaphthalene-5,6 (or 7,8)-diol. The identification of these metabolites was made by means of TLC, GLC, MS, IR, GC/MS, and FT-NMR. The presence of glucuronides of metabolites B, C, D, F, and H was also suggested by TLC and GLC of the extract obtained after hydrolysis by beta-glucuronidase. In addition, quantitative determination of the metabolites indicated that the total urinary excretion of the metabolites except 2-isopropylnaphthols in 24 hr after administration was about 29% of the dose.