Glucuronuria in the Koala

Date

2003

Authors

McLean, Stuart
Brandon, Sue
Davies, Noel
Boyle, Rebecca
Foley, William
Moore, Ben
Pass, Georgia

Journal Title

Journal ISSN

Volume Title

Publisher

Plenum Publishing Corporation

Abstract

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 β-glucuronidase and comparison with standard compounds. Quantitation was by GC. The major non-terpene aglycones were 4-methylcatechol, resorcinol, salicyl alcohol, and two unidentified C7H8O2 phenols. Smaller amounts of benzoic acid, benzyl alcohol, orcinol, pcresol, 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.

Description

Keywords

Keywords: 4 methylcatechol; benzoic acid derivative; beta glucuronidase; glucuronic acid; phenol derivative; resorcinol; saligenin; terpene; chemical ecology; marsupial; urine; article; bear; detoxification; Eucalyptus; excretion; foliage; gas chromatography; hydro Detoxification; Eucalyptus; Glucuronic acid; Koala; Phascolarctos cinereus; Phenolics; Terpenes

Citation

Source

Journal of Chemical Ecology

Type

Journal article

Book Title

Entity type

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2037-12-31
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The Australian National University acknowledges, celebrates and pays our respects to the Ngunnawal and Ngambri people of the Canberra region and to all First Nations Australians on whose traditional lands we meet and work, and whose cultures are among the oldest continuing cultures in human history.


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