GLUCURONIC ACID-CONJUGATED DIHYDROXY FATTY-ACIDS IN THE URINE OF PATIENTS WITH GENERALIZED PEROXISOMAL DISORDERS

Urine extracts from children diagnosed with generalized peroxisomal di sorders were screened by continuous flow-negative ion fast atom bombar dment-mass spectrometry. In 45 of 60 children with generalized peroxis omal disorders, we observed one or more intense ions (m/z 489, 505, 46 1, and others) that are infrequently found in children with cholestati c liver disease or normal children. Compounds giving rise to these ion s were isolated using reverse phase and anion exchange chromatography. After appropriate derivatization and/or methanolysis the compounds we re analyzed using capillary gas chromatography-mass spectrometry. The major compounds were found to be 12,13-dihydroxy-9-octadecenoic acid a nd 9,10-dihydroxy-12-octadecenoic acid, with one of the hydroxyl group s in glycosidic linkage with glucuronic acid. Minor compounds were glu curonic acid conjugates of 9,10-dihydroxy-octadecanoic acid, and 12, 1 3-dihydroxy-6,9-, 15, 16-dihydroxy-9,12-, and 9,10-dihydroxy-12,15-oct adecadienoic acids. A series of hexadecanoic, hexadecanoic, and hexade cadienoic acid glucuronides which appear to be beta-oxidation products of the C18 fatty acids were also observed, with the major species bei ng 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 m ay prove to be useful in the diagnosis of some peroxisomal disorders.