Quintus Joachim, Kovar Karl-Artur, Link Peter, Hamacher Harald
Pharmazeutisches Institut, Eberhard-Karls-Universität Tübingen, Tübingen, Germany.
Planta Med. 2005 Feb;71(2):147-52. doi: 10.1055/s-2005-837782.
An HPLC assay with fluorimetric detection of the arbutin metabolites hydroquinone glucuronide (2) and hydroquinone sulphate (6) in urine was developed and validated. Methylarbutin (4) and 6 were synthesised as reference substances. Compound 2 was prepared enzymatically from hydroquinone and uridine 5'-diphosphoglucuronic acid using the glucosyltransferase system of rat liver microsomes and enriched by two liquid-liquid and an additional solid phase extraction. Compound 2 as the main component of this purified product was identified by UV and fluorescence spectroscopy, by HPLC-MS, and by enzymatic hydrolysis to hydroquinone (5). The assay yields precise and accurate urine levels of 2, 5 and 6 in the concentration range expected after oral administration of recommended therapeutic doses of bearberry leaf extract. In a preliminary pharmacokinetic study on 3 volunteers the time-dependent renal excretion of arbutin metabolites 2, 5 and 6 was investigated after ingestion of an aqueous bearberry leaf extract containing an arbutin dose recommended by the German Kommission E. More than half of the administered dose of arbutin was excreted within 4 hours mainly in form of the metabolites 2 and 6 and more than 75 % of the total applied arbutin was excreted within 24 h. The elimination of 5 was negligible in 2 out of 3 volunteers. The excretion of this metabolite in the third test person reached 5.6 % of the total administered arbutin dose. The preliminary pharmacokinetic results confirm that renal elimination of toxicologically critical concentrations of the metabolite 5 will not be expected.
建立并验证了一种采用高效液相色谱法结合荧光检测尿中熊果苷代谢物对苯二酚葡糖苷酸（2）和对苯二酚硫酸盐（6）的方法。合成了甲基熊果苷（4）和6作为参考物质。使用大鼠肝微粒体的葡糖基转移酶系统，由对苯二酚和尿苷5'-二磷酸葡糖醛酸酶法制备化合物2，并通过两次液-液萃取和一次额外的固相萃取进行富集。通过紫外光谱和荧光光谱、高效液相色谱-质谱联用以及酶水解为对苯二酚（5），鉴定出该纯化产物中的主要成分化合物2。该分析方法能够精确且准确地测定口服推荐治疗剂量的熊果叶提取物后预期浓度范围内的尿中2、5和6的含量。在一项对3名志愿者的初步药代动力学研究中，摄入德国委员会E推荐剂量的熊果叶水提取物后，研究了熊果苷代谢物2、5和6随时间的肾脏排泄情况。超过一半的给药熊果苷剂量在4小时内排出，主要以代谢物2和6的形式，超过75%的总给药熊果苷在24小时内排出。3名志愿者中有2名对5的消除可忽略不计。第三名受试者中该代谢物的排泄量达到总给药熊果苷剂量的5.6%。初步药代动力学结果证实，预计不会出现对毒理学关键浓度的代谢物5进行肾脏消除的情况。
