In vitro metabolism of chloroquine:: Identification of CYP2C8, CYP3A4, and CYP2D6 as the main isoforms catalyzing N-desethylchloroquine formation
In vitro metabolism of chloroquine:: Identification of CYP2C8, CYP3A4, and CYP2D6 as the main isoforms catalyzing N-desethylchloroquine formation
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DOI：
10.1124/dmd.31.6.748
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发表时间：
2003-06-01
影响因子：
3.9
通讯作者：
Ducharme, J
中科院分区：
文献类型：
--
作者：
Projean, D;Baune, B;Ducharme, J
在人类中，抗疟药物氯喹（CQ）被代谢成一种主要代谢物，N-脱乙基氯喹（DCQ）。使用人肝微粒体（HLM）和重组人细胞色素P450（P450），我们进行了研究，以确定参与CQ N-脱乙基化的P450亚型。在与CQ孵育的HLM中，只能检测到DCQ。表观K-m和V-max值（平均值+/- S.D.）代谢产物形成的浓度分别为444 ± 121 μ M和617 ± 128 pmol/min/mg蛋白质。在一组16个人类肝脏的微粒体中，10种不同的P450亚型的表型，DCQ形成与睾酮6 β-羟基化（r = 0.80; p < 0.001），CYP 3A介导的反应和CYP 2C 8介导的紫杉醇α-羟基化（r = 0.82; p < 0.001）高度相关。当与槲皮素（20-40%抑制）、酮康唑或三乙酰竹桃霉素（20-30%抑制）共孵育时，CQ N-脱乙基作用减弱，并被酮康唑和槲皮素联合强烈抑制（80%抑制），这进一步证实了CYP 2C 8和CYP 3A的作用。在检测的10种cDNA表达的人P450中，仅CYP 1A 1、CYP 2D 6、CYP 3A 4和CYP 2C 8产生DCQ。CYP 2C 8和CYP 3A 4构成低亲和力/高容量系统，而CYP 2D 6与较高亲和力但显著较低容量相关。这一特性可以解释CQ在体外和体内抑制CYP 2D 6介导的代谢的能力。在治疗相关浓度下（类似于肝脏中的100 μ M CQ），CYP 2C 8、CYP 3A 4和（在更小程度上）CYP 2D 6预期解释大部分CQ N-脱乙基化。
In humans, the antimalarial drug chloroquine (CQ) is metabolized into one major metabolite, N-desethylchloroquine (DCQ). Using human liver microsomes (HLM) and recombinant human cytochrome P450 (P450), we performed studies to identify the P450 isoform(s) involved in the N-desethylation of CQ. In HLM incubated with CQ, only DCQ could be detected. Apparent K-m and V-max values (mean +/- S.D.) for metabolite formation were 444 +/- 121 muM and 617 +/- 128 pmol/min/mg protein, respectively. In microsomes from a panel of 16 human livers phenotyped for 10 different P450 isoforms, DCQ formation was highly correlated with testosterone 6beta-hydroxylation (r = 0.80; p < 0.001), a CYP3A-mediated reaction, and CYP2C8-mediated paclitaxel alpha-hydroxylation (r = 0.82; p < 0.001). CQ N-desethylation was diminished when coincubated with quercetin (20-40% inhibition), ketoconazole, or troleandomycin (20-30% inhibition) and was strongly inhibited (80% inhibition) by a combination of ketoconazole and quercetin, which further corroborates the contribution of CYP2C8 and CYP3As. Of 10 cDNA-expressed human P450s examined, only CYP1A1, CYP2D6, CYP3A4, and CYP2C8 produced DCQ. CYP2C8 and CYP3A4 constituted low-affinity/high-capacity systems, whereas CYP2D6 was associated with higher affinity but a significantly lower capacity. This property may explain the ability of CQ to inhibit CYP2D6-mediated metabolism in vitro and in vivo. At therapeutically relevant concentrations (similar to100 muM CQ in the liver), CYP2C8, CYP3A4, and, to a much lesser extent, CYP2D6 are expected to account for most of the CQ N-desethylation.