Glucuronic Acid-conjugated Dihydroxy Fatty Acids in the Urine of Patients with Generalized Peroxisomal Disorders

Abstract Urine extracts from children diagnosed with generalized peroxisomal disorders were screened by continuous flow-negative ion fast atom bombardment-mass spectrometry. In 45 of 60 children with generalized peroxisomal disorders, we observed one or more intense ions (m/z 489, 505, 461, and others) that are infrequently found in children with cholestatic liver disease or normal children. Compounds giving rise to these ions were isolated using reverse phase and anion exchange chromatography. After appropriate derivatization and/or methanolysis the compounds were analyzed using capillary gas chromatography-mass spectrometry. The major compounds were found to be 12,13-dihydroxy-9-octadecenoic acid and 9,10-dihydroxy-12-octadecenoic acid, with one of the hydroxyl groups in glycosidic linkage with glucuronic acid. Minor compounds were glucuronic acid conjugates of 9,10-dihydroxy-octadecanoic acid, and 12,13-dihydroxy-6,9-, 15,16-dihydroxy-9,12-, and 9,10-dihydroxy-12,15-octadecadienoic acids. A series of hexadecanoic, hexadecenoic, and hexadecadienoic acid glucuronides which appear to be β-oxidation products of the C18 fatty acids were also observed, with the major species being 10,11-dihydroxy-7-hexadecenoic acid glucuronide. In all, 16 C16 and C18 dihydroxy fatty acids were identified by gas chromatography-mass spectrometry. A series of at least 11 trihydroxy fatty acids was also observed but not fully characterized. Measurement of these compounds may prove to be useful in the diagnosis of some peroxisomal disorders.