Glucuronidation of dihydroartemisinin in vivo and by human liver microsomes and expressed UDP-glucuronosyltransferases
Glucuronidation of dihydroartemisinin in vivo and by human liver microsomes and expressed UDP-glucuronosyltransferases
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DOI：
10.1124/dmd.30.9.1005
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发表时间：
2002-09-01
影响因子：
3.9
通讯作者：
Edwards, G
中科院分区：
文献类型：
--
作者：
Ilett, KF;Ethell, BT;Edwards, G
本研究的目的是阐明青蒿素衍生物青蒿琥酯（ARTS）的活性代谢产物双氢青蒿素（DHA）的代谢途径。从17名患有恶性疟疾的越南成年人收集尿液，这些人接受了120 mg ARTS静脉注射，采用高效液相色谱-质谱联用技术（HPLC-MS）分析代谢产物。将人肝微粒体与[12-H-3]DHA和辅助因子一起孵育，用于葡萄糖醛酸化或细胞色素P450催化氧化。将人肝胞质溶胶与辅因子一起孵育用于硫酸化。通过HPLC-MS和/或HPLC结合放射化学检测法检测代谢物。研究了重组人UDP-葡萄糖醛酸转移酶（UGT）对DHA的代谢。尿液的HPLC-MS分析鉴别出α-DHA-β-葡糖苷酸（α-DHA-G）和一种表征为α-DHA-G的四氢呋喃异构体的产物。DHA仅以非常少量存在。四氢呋喃异构体α-DHA-G的比例变化很大（中位数为0.75;范围为0.09-64）。然而，α-DHA-G通常是患者DHA葡萄糖醛酸化的主要尿液产物。四氢呋喃异构体似乎至少部分是尿液中发生的非酶反应的产物，并且很容易通过铁介导的异构化由α-DHA-G形成。在人肝微粒体孵育中，DHA-G（非对映体未指明）是唯一发现的代谢物（V-max 177 +/- 47 pmol min（-1）mg（-1），K-m 90 +/- 16 μ M）。在DHA与表达的UGT 1A 9（K-m 32 μ M，V-max 8.9 pmol min（-1）mg（-1））或UGT 2B 7（K-m 438 μ M，V-max 10.9 pmol mg（-1）min（-1））孵育中形成α-DHA-G，但与UGT 1A 1或UGT 1A 6孵育中不形成。有没有显着的代谢DHA的细胞色素P450氧化或细胞溶质磺基转移酶。我们的结论是，α-DHA-G是人体中DHA的重要代谢产物，其形成由UGT 1A 9和UGT 2B 7催化。
The aim of this study was to elucidate the metabolic pathways for dihydroartemisinin (DHA), the active metabolite of the artemisinin derivative artesunate (ARTS). Urine was collected from 17 Vietnamese adults with falciparum malaria who had received 120 mg of ARTS i.v., and metabolites were analyzed by high-performance liquid chromatography-mass spectrometry (HPLC-MS). Human liver microsomes were incubated with [12-H-3]DHA and cofactors for either glucuronidation or cytochrome P450-catalyzed oxidation. Human liver cytosol was incubated with cofactor for sulfation. Metabolites were detected by HPLC-MS and/or HPLC with radiochemical detection. Metabolism of DHA by recombinant human UDP-glucuronosyltransferases (UGTs) was studied. HPLC-MS analysis of urine identified alpha-DHA-beta-glucuronide (alpha-DHA-G) and a product characterized as the tetrahydrofuran isomer of alpha-DHA-G. DHA was present only in very small amounts. The ratio of the tetrahydrofuran isomer, alpha-DHA-G, was highly variable (median 0.75; range 0.09-64). Nevertheless, alpha-DHA-G was generally the major urinary product of DHA glucuronidation in patients. The tetrahydrofuran isomer appeared to be at least partly a product of nonenzymic reactions occurring in urine and was readily formed from alpha-DHA-G by iron-mediated isomerization. In human liver microsomal incubations, DHA-G (diastereomer unspecified) was the only metabolite found (V-max 177 +/- 47 pmol min(-1) mg(-1), K-m 90 +/- 16 muM). alpha-DHA-G was formed in incubations of DHA with expressed UGT1A9 (K-m 32 muM, V-max 8.9 pmol min(-1) mg(-1)) or UGT2B7 (K-m 438 muM, V-max 10.9 pmol mg(-1) min(-1)) but not with UGT1A1 or UGT1A6. There was no significant metabolism of DHA by cytochrome-P450 oxidation or by cytosolic sulfotransferases. We conclude that alpha-DHA-G is an important metabolite of DHA in humans and that its formation is catalyzed by UGT1A9 and UGT2B7.