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Glucuronuria is normal in marsupial folivores such as the koala (Phascolarctos cinereus), which excretes 2–3 g glucuronic acid daily. Although this has long been attributed to the metabolites of Eucalyptus terpenes, we have found that these are mostly excreted in the unconjugated form. We now report on the aglycones that account for most of the glucuronic acid in koala urine. Urine (24 hr) was collected from six male koalas (8.8 ± 0.4 kg, mean ± SE) that were maintained on E. cephalocarpa foliage. Urine samples were analyzed by liquid and gas chromatography (LC and GC) coupled with mass spectrometry (MS). Glucuronides were readily identified by LC-MS/MS, which generated characteristic product ions at m/z 113 and 175. From the corresponding parent glucuronide ions, the masses of the aglycones were calculated. Confirmation of identity was by GC-MS after hydrolysis with -glucuronidase and comparison with standard compounds. Quantitation was by GC. The major non-terpene aglycones were 4-methylcatechol, resorcinol, salicyl alcohol, and two unidentified C7H8 O 2 phenols. Smaller amounts of benzoic acid, benzyl alcohol, orcinol, p-cresol, phenol, and phloroglucinol were detected. We have previously reported that terpene metabolites account for about 10% urinary glucuronides in the same koalas fed E. cephalocarpa. The present study found that an additional 60% urinary glucuronic acid is conjugated with non-terpene, mainly phenolic, aglycones. It seems likely that these phenolic compounds are present in leaves as glycosides and are chiefly responsible for the glucuronuria in koalas.

Item Type:	Refereed Article
Keywords:	Glucuronic acid - Phascolarctos cinereus - koala - phenolics - Eucalyptus - terpenes - detoxification
Research Division:	Medical and Health Sciences
Research Group:	Pharmacology and Pharmaceutical Sciences
Research Field:	Basic Pharmacology
Objective Division:	Environment
Objective Group:	Flora, Fauna and Biodiversity
Objective Field:	Forest and Woodlands Flora, Fauna and Biodiversity
UTAS Author:	McLean, SR (Professor Stuart McLean)
UTAS Author:	Brandon, S (Mrs Susan Brandon)
UTAS Author:	Davies, NW (Associate Professor Noel Davies)
UTAS Author:	Boyle, RR (Dr Rebecca Boyle)
UTAS Author:	Pass, GJ (Ms Georgia Jane Pass)
ID Code:	28448
Year Published:	2003
Web of Science® Times Cited:	9
Deposited By:	Pharmacy
Deposited On:	2003-08-01
Last Modified:	2011-05-25
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