Enzyme kinetics for the formation of 3-hydroxyquinine and three new metabolites of quinine in vitro;: 3-hydroxylation by CYP3A4 is indeed the major metabolic pathway
Enzyme kinetics for the formation of 3-hydroxyquinine and three new metabolites of quinine in vitro;: 3-hydroxylation by CYP3A4 is indeed the major metabolic pathway
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DOI：
10.1124/dmd.30.12.1368
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发表时间：
2002-12-01
影响因子：
3.9
通讯作者：
Ericsson, Ö
中科院分区：
文献类型：
--
作者：
Mirghani, RA;Yasar, Ü;Ericsson, Ö
在人肝微粒体和人重组表达的CYP 3A 4中研究了3-羟基奎宁、2 '-奎宁酮、（10 S）-11-二羟基二氢奎宁和（10 R）-11-二羟基二氢奎宁的形成动力学。通过使用不同浓度的酮康唑、三乙酰竹桃霉素和氟伏沙明来研究抑制概况。此外，代谢产物的形成率与20个人肝脏微粒体中CYP 1A 2、CYP 2C 9、CYP 2C 19、CYP 2D 6和CYP 3A 4的不同酶探针活性相关。3-羟基奎宁的形成在人肝微粒体中具有最高的固有清除率（平均值+/-S.D.）11.0 +/- 4.6穆尔/min/mg。测定到2 ′-奎宁酮、（10 R）-11-二羟基二氢奎宁和（10 S）-11-二羟基二氢奎宁的固有清除率明显较低，分别为1.4 +/- 0.7、0.5 +/- 0.1和1.1 +/- 0.2穆尔/min/mg。与2 '-奎宁酮形成相比，与人重组CYP 3A 4孵育导致3-羟基奎宁的固有清除率高20倍，而未检测到其他代谢产物。酮康唑（1 μ M）和三乙酰竹桃霉素（80 μ M）可完全抑制3-羟基奎宁的形成。这两种抑制剂对2 ′-奎宁酮的形成有强烈的抑制作用，而对（10 S）-11-二羟基二氢奎宁的形成有部分抑制作用。未观察到对（10 R）-11-二羟基二氢奎宁形成的抑制。奎宁代谢物的形成速率与CYP 3A 4选择的标记探针的活性之间存在显著相关性。这项体外研究表明，3-羟基奎宁是奎宁的主要代谢产物，CYP 3A 4是参与该代谢途径的主要酶。
The formation kinetics of 3-hydroxyquinine, 2'-quininone, (10S)-11-dihydroxydihydroquinine, and (10R)-11-dihydroxydihydroquinine were investigated in human liver microsomes and in human recommbinant-expressed expressed CYP3A4. The inhibition profile was studied by the use of different concentrations of ketoconazole, troleandomycin, and fluvoxamine. In addition, formation rates of the metabolites were correlated to different enzyme probe activities of CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 in microsomes from 20 human livers. Formation of 3-hydroxyquinine had the highest intrinsic clearance in human liver microsomes ( mean +/-S.D.) of 11.0 +/- 4.6 mul/min/mg. A markedly lower intrinsic clearance, 1.4 +/- 0.7, 0.5 +/- 0.1, and 1.1 +/- 0.2 mul/min/mg was measured for 2'-quininone, (10R)-11-dihydroxydihydroquinine and (10S)-11-dihydroxydihydroquinine, respectively. Incubation with human recombinant CYP3A4 resulted in a 20-fold higher intrinsic clearance for 3-hydroxyquinine compared with 2'-quininone formation whereas no other metabolites were detected. The formation rate of 3-hydroxyquinine was completely inhibited by ketoconazole (1 muM) and troleandomycin (80 muM). Strong inhibition was observed on the formation of 2'-quininone whereas the formation of (10S)-11-dihydroxydihydroquinine was partly inhibited by these two inhibitors. No inhibition on the formation of (10R)-11-dihydroxydihydroquinine was observed. There was a significant correlation between the formation rates of quinine metabolites and activities of the CYP3A4 selected marker probes. This in vitro study demonstrates that 3-hydroxyquinine is the principal metabolite of quinine and CYP3A4 is the major enzyme involved in this metabolic pathway.