McLean Stuart, Brandon Sue, Davies Noel W, Boyle Rebecca, Foley William J, Moore Ben, Pass Georgia J
School of Pharmacy, University of Tasmania, Tasmania 7000, Australia.
J Chem Ecol. 2003 Jun;29(6):1465-77. doi: 10.1023/a:1024273722192.
Glucuronuria is normal in marsupial folivores such as the koala (Phascolarrctos 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 beta-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, 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.
在有袋类食叶动物如树袋熊（Phascolarrctos cinereus）中，葡糖醛酸尿是正常现象，树袋熊每天排泄2 - 3克葡糖醛酸。尽管长期以来这一直被归因于桉树叶萜类化合物的代谢产物，但我们发现这些大多以未结合的形式排泄。我们现在报告树袋熊尿液中占大部分葡糖醛酸的苷元。从六只以头状桉树叶为食的雄性树袋熊（8.8 ± 0.4千克，平均值 ± 标准误）收集24小时尿液。尿液样本通过液相色谱和气相色谱（LC和GC）结合质谱（MS）进行分析。通过LC - MS/MS很容易鉴定出葡糖醛酸苷，它在m/z 113和175处产生特征性产物离子。从相应的母体葡糖醛酸苷离子计算出苷元的质量。在用β - 葡糖醛酸酶水解并与标准化合物比较后，通过GC - MS确认身份。定量通过GC进行。主要的非萜类苷元是4 - 甲基邻苯二酚、间苯二酚、水杨醇和两种未鉴定的C7H8O2酚类。检测到少量的苯甲酸、苯甲醇、苔黑酚、对甲酚、苯酚和间苯三酚。我们之前报道过，在以头状桉树叶为食的相同树袋熊中，萜类代谢产物约占尿中葡糖醛酸苷的10%。本研究发现，另外60%的尿中葡糖醛酸与非萜类，主要是酚类苷元结合。这些酚类化合物似乎以糖苷形式存在于树叶中，并且是树袋熊葡糖醛酸尿的主要原因。
