飞蝗CYP408B1和CYP409A1基因的原核表达

【目的】细胞色素P450是分布极其广泛的超家族酶,在昆虫内源及外源化合物代谢中发挥着重要的作用。本文分析了飞蝗Locusta migratoria CYP408B1和CYP409A1基因在不同组织部位的表达差异,并对两种蛋白进行原核表达,为其分子特性和生物学功能的深入研究提供基础资料。【方法】提取飞蝗5龄若虫不同组织部位的总RNA,体外反转录成c DNA,采用Real-time PCR和RT-PCR技术分析飞蝗CYP408B1和CYP409A1在不同组织部位的表达模式,构建表达载体p CW/CYP408B1、p CW/CYP409A1和p AC/CPR,将p CW/CYP408B1和p CW/CYP409A1分别与p AC/CPR在大肠杆菌Escherichia coli BL21(DE3)中进行共表达。【结果】通过PCR检测,发现CYP408B1和CYP409A1在飞蝗5龄若虫触角、脑、视叶、咽下神经节、胸神经节和附腺中均有表达,其中CYP408B1在附腺中表达量较高。原核表达结果显示,CYP409A1和CPR(NADPH细胞色素P450还原酶)均可表达,蛋白分子量分别约为58 ku和77 ku,但均为包涵体,而CYP408B1未能成功表达。【结论】本文揭示了飞蝗CYP408B1和CYP409A1在不同组织部位的表达模式,并对CYP409A1和CPR进行了原核表达,研究结果为深入探讨飞蝗细胞色素P450基因对杀虫剂的代谢解毒作用提供了实验依据和基础资料。     

飞蝗CYP408B1和CYP409A1基因的原核表达

【目的】细胞色素P450是分布极其广泛的超家族酶,在昆虫内源及外源化合物代谢中发挥着重要的作用。本文分析了飞蝗Locusta migratoria CYP408B1和CYP409A1基因在不同组织部位的表达差异,并对两种蛋白进行原核表达,为其分子特性和生物学功能的深入研究提供基础资料。【方法】提取飞蝗5龄若虫不同组织部位的总RNA,体外反转录成c DNA,采用Real-time PCR和RT-PCR技术分析飞蝗CYP408B1和CYP409A1在不同组织部位的表达模式,构建表达载体p CW/CYP408B1、p CW/CYP409A1和p AC/CPR,将p CW/CYP408B1和p CW/CYP409A1分别与p AC/CPR在大肠杆菌Escherichia coli BL21(DE3)中进行共表达。【结果】通过PCR检测,发现CYP408B1和CYP409A1在飞蝗5龄若虫触角、脑、视叶、咽下神经节、胸神经节和附腺中均有表达,其中CYP408B1在附腺中表达量较高。原核表达结果显示,CYP409A1和CPR(NADPH细胞色素P450还原酶)均可表达,蛋白分子量分别约为58 ku和77 ku,但均为包涵体,而CYP408B1未能成功表达。【结论】本文揭示了飞蝗CYP408B1和CYP409A1在不同组织部位的表达模式,并对CYP409A1和CPR进行了原核表达,研究结果为深入探讨飞蝗细胞色素P450基因对杀虫剂的代谢解毒作用提供了实验依据和基础资料。     

Induction of CYP1A by benzo[k]fluoranthene in human hepatocytes: CYP1A1 or CYP1A2?

While fresh human hepatocyte cultures are widely used to model hepatic cytochrome P450 (CYP) regulation and activity, their CYP1A subfamily composition induced by, e.g., polycyclic aromatic hydrocarbons is ambiguous. CYP1A1, CYP1A2, or both have been reported to be expressed, and their varied roles in chemical carcinogenesis makes resolution of which CYPs are expressed essential. We have used an immunoblot system with Bis-Tris-HCl-buffered polyacrylamide gel, which clearly resolves human CYP1A1 and CYP1A2, and polyclonal goat anti-human CYP1A1/CYP1A2 and rabbit anti-human CYP1A2 antibodies to probe the expressed CYP1A1 and CYP1A2 composition of seven individual human hepatocyte cultures induced with 5 microM benzo[k]fluoranthene (BKF) for 24 h. In six of the cultures only CYP1A1 was detected, and in the seventh both CYPs were detected. In most vehicle-treated hepatocyte cultures, neither CYP1A1 nor CYP1A2 was detected. In three additional hepatocyte cultures treated individually with BKF and 2,3,7,8,-tetrachlorodibenzo-p-dioxin (TCDD), the resultant induced CYP1A1/1A2 profiles were essentially not influenced by the nature of the inducing agents. To develop an activity-based assay to differentiate between CYP1A1 and CYP1A2 expression in human hepatocytes, our previously published R warfarin assay (Drug Metab. Disp. (1995) 23, 1339-1345) was applied to TCDD (10 nM)-treated hepatocyte culture. The low concentration of TCDD did not produce inhibition of the warfarin metabolism-such inhibition could confound the results. Based on the ratios of 6- to 8-hydroxywarfarin formed in two cultures, the ratios of CYP1A1/CYP1A2 expressed in these cultures were determined and they agreed with the ratios determined by immunoblot analysis. Thus each individual human hepatocyte culture must be characterized for induced CYP1A1 and CYP1A2 expression in studies of CYP1A activity. The warfarin assay provides a means of characterizing the cultures.     

DEHP对中国林蛙精巢中StAR、CYP17和CYP19基因表达的影响

为探讨邻苯二甲酸二(2-乙基己基)酯(di-2-ethylhexyl phthalate,DEHP)对两栖动物精巢类固醇激素合成的影响,将中国林蛙(Rana chensinensis)雄性成体分别暴露于浓度为10-7、10-6、10-5、10-4mol·L-1DEHP的水体,分别在暴露20、30和40d取其精巢,提取精巢总RNA,逆转录合成cDNA,通过荧光实时定量PCR检测StAR、CYP17和CYP19mRNA表达相对值。结果表明:与对照组相比,DEHP处理组StAR和CYP19基因表达均上调,CYP17基因表达下调;比较不同DEHP浓度和不同暴露时间对StAR、CYP17和CYP19mRNA表达相对值的影响,显示DEHP浓度变化对3个基因表达影响的规律性不强,而DEHP暴露时间的累积效应较明显;提示DEHP可通过干扰中国林蛙精巢中StAR、CYP17和CYP19基因表达,影响其相应关键酶的表达,从而干扰类固醇激素的合成,产生雌激素效应。     

紫杉醇对食蟹猴和人CYP1A2、CYP3A4及CYP2A6酶代谢的影响

目的探讨紫杉醇对食蟹猴和人肝微粒体CYP1A2、CYP2A6和CYP3A4酶活性的影响。方法采用食蟹猴和人肝脏微粒体,分别以非那西汀、睾丸酮和香豆素分别作为CYP1A2、CYP2A6、CYP3A4的底物,建立CYP1A2、CYP2A6和CYP3A4体外代谢体系。采用不同浓度的紫杉醇分别与上述3种底物共同孵育于肝微粒体代谢体系中。用HPLC法分别测定各底物的代谢产物扑热息痛、6β-羟基睾丸酮、7-羟基香豆素的产生量,计算IC50值,以评估紫杉醇对CYP1A2、CYP2A6和CYP3A4代谢的影响。结果紫杉醇对食蟹猴肝微粒体3种酶的IC50值分别为570±5.9μmol/L、140±2.9μmol/L和无影响;紫杉醇对人肝微粒体3种酶的IC50值分别为193±6.6μmol/L、253±3.6μmol/L和24±1.6μmol/L。结论紫杉醇对食蟹猴肝微粒体CYP1A2和CYP3A4活性具有一定的抑制作用,但对CYP2A6酶的活性几乎没有影响。紫杉醇对人肝微粒体CYP1A2和CYP3A4活性的抑制作用较弱,但对CYP2A6酶的活性抑制作用较强,提示临床上紫杉醇与作为上述酶底物的药物联合用药时应慎重,以避免因中西药物相互作用所导致的不良反应发生。     

CYP21和CYP21P基因启动子序列对绿色荧光蛋白基因表达的影响

特异性扩增CYP21基因和CYP21P基因启动子区域－770bp--1bp片段,去除pEGFP-N1载体中的CMV启动子,构建含CYP21基因启动子的pEGFP-N1载体（pCYP21)和CYP21P基因启动子的pEGFP-N1载体（pCYP21P),分别将上述两种构建载体、野生型pEGFP-N1(阳性对照）质粒及阴性对照转染入肾上腺皮质来源的Y1细胞系中,用倒置荧光显微镜,以及激光共聚焦显微镜等方法观测绿色荧光蛋白的表达。转染后,在荧光倒置显微镜下首次发现Y1细胞中出现绿色荧光蛋白的时间阳性对照为3小时,pCYP21为7小时,pCYP21P与阳性对照（未转染任何载体的Y1细胞）始终未观测到绿色荧光蛋白。阳性对照和pCYP21的绿色荧光蛋白表达强于pCYP21,pCYP21P与阴性对照始终未观测到绿色荧光蛋白。阳性对照和pCYP21的绿色荧光蛋白在胞核中的荧光强度高于胞浆。上述结果进一步表明,含有CYP21和CYP21P两种基因启动子的GFP质粒在Y1细胞中表达存在显著差异。     

CYP1B1基因与青光眼

遗传性青光眼包括两种主要的类型,原发性开角型青光眼(primary open angle glaucoma,POAG)和原发性先天型青光眼(primary congenital glaucoma,PCG).眼前节发育不良(anterior segment dysgenesis,ASD)是眼发育异常的遗传异质性病,与增长的眼内压和青光眼有关,包括Peter's异常、Rieger's异常、无虹膜和虹膜发育不全.CYPIB1基因是PCG的致病基因,也有少数报道是POAG的修饰基因,或是POAG和ASD的致病基因.本文就CYP1B1基因突变与遗传性青光眼和ASD发育不全的关系及其遗传特点作一综述.     

“内异消”对子宫内膜异位症大鼠CYP1A2、CYP2E1、CYP3A4活性的影响

本文主要考察"内异消"对子宫内膜异位症大鼠肝微粒体CYP1A2、CYP2E1、CYP3A4活性的影响。将16只SD大鼠随机分为空白对照组、正常给药组,16只模型SD大鼠随机分为模型对照组和模型给药组。正常给药组和模型给药组每天灌胃给予"内异消",空白对照组和模型对照组灌胃给予羧甲基纤维素钠溶液,均连续给药7 d,于第8 d给予"Cocktail"探针药物咖啡因、氯唑沙宗和硝苯地平药物,通过HPLC检测Cocktail探针药物的代谢率评价各组CYP450及CYP1A2、CYP2E1、CYP3A4活性。结果表明,与正常组比较,模型对照组和模型给药组咖啡因、氯唑沙宗的t1/2减小,硝苯地平的t1/2延长,均无显著性差异(P0.05);与正常组比较,模型对照组和模型给药组咖啡因、氯唑沙宗的AUC(0-t)显著升高(P0.05),硝苯地平的AUC(0-t)的增加无显著性。说明"内异消"对子宫内膜异位症大鼠CYP1A2、CYP2E1、CYP3A4的活性不存在显著的相互作用。     

昆虫CYP6家族多样性与进化

了解昆虫CYP6家族的多样性与进化 ,对认识昆虫细胞色素P45 0参与抗药性发生、发展的分子生物学机制具有重要的意义。作者就昆虫CYP6家族多样性的各种表现形式及其形成原因、自然进化史、内部进化关系及进化的分子机制作一综述     

A Systematically Combined Genotype and Functional Combination Analysis of CYP2E1, CYP2D6, CYP2C9, CYP2C19 in Different Geographic Areas of Mainland China – A Basis for Personalized Therapy

The cytochrome P450 is the major enzyme involved in drug metabolism. Single CYP genotypes and metabolic phenotypes have been widely studied, but no combination analysis has been conducted in the context of specific populations and geographical areas. This study is the first to systematically analyze the combined genotypes and functional combinations of 400 samples of major CYP genes—CYP2E1, CYP2D6, CYP2C9, and CYP2C19 in four geographical areas of mainland China. 167 different genotype combinations were identified, of which 25 had a greater than 1% frequency in the Chinese Han population. In addition, phenotypes of the four genes for each sample were in line with the predictions of previous studies of the four geographical areas. On the basis of the genotype classification, we were able to produce a systemic functional combinations analysis for the population. 25 of the combinations detected had at least two non-wild phenotypes and four showed a frequency above 1%. A bioinformatics analysis of the relationship between particular drugs and multi-genes was conducted. This is the first systematic study to analyze genotype combinations and functional combinations across whole Chinese population and could make a significant contribution in the field of personalized medicine and therapy.     

棉铃虫P450基因CYP6AE12和CYP9A18的克隆与mRNA表达水平

采用RT-PCR和RACE技术克隆到2个新的棉铃虫细胞色素P450基因：CYP6AE12和CYP9A18。CYP6AE12的cDNA编码区长1 569 bp,编码523个氨基酸;CYP9A18的cDNA编码区长1 590 bp,编码530个氨基酸。用实时定量PCR技术分析了这2个基因在棉铃虫YS敏感品系和YS-FP抗性品系(由氰戊菊酯加辛硫磷混剂筛选YS品系而得) 6龄幼虫脂肪体和中肠中mRNA的表达水平。结果表明：CYP6AE12和CYP9A18的mRNA表达具有组织特异性,CYP6AE12在脂肪体中表达量较高,而CYP9A18在中肠中的表达量较高。与相对敏感品系YS相比,CYP6AE12在YS-FP抗性品系中肠和脂肪体中的mRNA表达量分别为YS品系的3.6倍和1.3倍;CYP9A18在YS-FP品系中肠和脂肪体的mRNA表达量分别为YS品系的0.3倍和1.0倍。CYP6AE12的过量表达与YS-FP品系棉铃虫的抗药性可能有一定关系。     

Substrate analog studies of the ω-regiospecificity of Mycobacterium tuberculosis cholesterol metabolizing cytochrome P450 enzymes CYP124A1, CYP125A1 and CYP142A1

We report the synthesis and evaluation of a series of cholesterol side-chain analogs as mechanistic probes of three important Mycobacterium tuberculosis cytochrome P450 enzymes that selectively oxidize the ω-position of the methyl-branched cholesterol side-chain. To probe the structural requirements for the thermodynamically disfavored ω-regiospecificity we compared the binding of these substrate analogs to each P450, determined the turnover rates, and characterized the enzymatic products. The results are discussed in the context of the structure-activity relationships of the enzymes and how their active sites enforce ω-oxidation.     

CYP2C19遗传多态性的研究进展

S-美芬妥英羟化代谢多态性不仅存在个体差异,而且存在种族差异。CYP2C19基因是决定S-美芬妥英羟化代谢的决定基因,该基因的突变是导致S-美芬妥英羟化代谢多态性的分子机制。近年来对CYN50s基因型和表型相关性的研究越来越受到重视,人们希望利用基因型分析来了解个体中该药物代谢酶的活性,期望既能提高药物治疗水平同时又降低不良反应的发生。有关CYP2C19的研究在此方面已树立了一个成功的典范。     

CYP3A4基础与临床研究进展

细胞色素P4503A4(CYP3A4)是存在人类肝脏及肠道中的一种主要的细胞色素CYP450酶,约占成人肝脏CYP450酶总量的25%左右。临床中约有50%的药物是通过其代谢,并且其基因位点突变也与其多种疾病相关,知晓CYP3A4的表达水平和不同功能的遗传学基础,无论是对疾病的发病基础、临床药物的应用,会带来前所未有的启发,在药物应用过程中,通过对基因组学的认识,从而可以在基因层面了解个体代谢差异产生的原因,调整药物用量,提高疗效,最终使药物副作用降到最低限。目前对CYP3A4的研究渐趋于成熟,已逐渐阐明了其药物间相互作用的机制,它能够被多种药物竞争性抑制或者诱导,并受到某些蛋白受体的调控影响,可改变药物的药代动力学,增强或降低药效,造成个体用药差异,这也是造成药物间相互作用的重要原因。然而CYP3A4基因多态性与基因导向治疗关系,还有待进一步深入研究。该文对CYP3A4基因多态性、分布以及与临床疾病及用药的研究现状作一综述。     

Cocktail探针药物法评价傣药"雅解沙把" 对大鼠肝药酶P450亚型 CYP1A2、CYP2C19、CYP2E1、CYP3A4 活性的影响

目的:采用cocktail探针药物法研究傣药"雅解沙把"对肝细胞色素P450亚型CYP1A2、CYP2C19、CYP2E1、CYP3A4的影响。方法:将SD大鼠随机分为空白对照组、苯巴比妥钠组(10.8 mg/kg)、"雅解沙把"低剂量组(0.27 g生药/kg)和"雅解沙把"高剂量组(2.43 g生药/kg),按上述剂量灌胃给药,空白对照组灌胃蒸馏水。连续灌胃7天后处死动物,取肝脏制备肝微粒体,以甲硝唑为内标,建立HPLC方法检测Cocktail探针药物奥美拉唑、氯唑沙宗、咖啡因、氨苯砜的代谢情况。结果:与空白对照组比较,"雅解沙把"低剂量组和高剂量组氯唑沙宗的代谢明显升高,氯唑沙宗的含量显著降低(P0.01),"雅解沙把"高剂量组奥美拉唑和氨苯砜的代谢明显升高,奥美拉唑和氨苯砜的含量明显降低(P0.05)。"雅解沙把"低剂量组和高剂量组虽咖啡因代谢较与空白对照组有上升的趋势,但差异无统计学意义(P0.05)。结论:傣药"雅解沙把"能促进肝药酶CYP3A4、CYP2C19、CYP2E1的活性,加速药物代谢,这可能是其解药物毒的作用机制之一。     

氯吡格雷对大鼠肝药物酶CYP3A4 和CYP1A2 表达的影响

目的：氯吡格雷主要由CYP3A4 催化使其激活,CYP1A2 也参与氯吡格雷活化。关于氯吡格雷对肝微粒体酶的影响国内外 文献报道不多,因此本实验通过检测肝细胞色素氧化酶CYP3A4 和CYP1A2 的表达,探讨氯吡格雷对大鼠肝药物酶的影 响。方法：生理盐水为对照组,氯吡格雷设高、中、低三个剂量组（27,13.5,6.75mg/kg/d）,雄性健康大鼠连续灌胃给药7天,脱臼处 死,取肝组织,通过western blot法检测大鼠肝脏CYP3A4 和CYP1A2 蛋白表达情况。结果：1）、氯吡格雷抑制大鼠CYP3A4 蛋白 表达,氯吡格雷高中低剂量组分别比生理盐水组大鼠CYP3A4 蛋白表达量降低（P<0.05）;氯吡格雷低中高剂量组间进行比较,大 鼠CYP3A4 蛋白表达量呈梯度减少（P<0.05）;2）、氯吡格雷抑制大鼠CYP1A2 蛋白表达,氯吡格雷高中低剂量组分别比生理盐水 组大鼠CYP1A2 蛋白表达量降低（P<0.05）,氯吡格雷低中高剂量组间进行比较,大鼠CYP1A2 蛋白表达量呈梯度减少（P<0.05）。 结论：氯吡格雷使肝细胞色素氧化酶CYP3A4 和CYP1A2 的表达量减少,因此氯吡格雷高、中、低3 个剂量组均不同程度的抑制 大鼠肝脏CYP3A4 和CYP1A2 的表达,提示当氯吡格雷与某些主要经CYP3A4 和CYP1A2 代谢的药物合用时,发生代谢性相关 作用的可能性大。     

苹果蠹蛾细胞色素P450基因CYP332A19和CYP337B19的克隆及表达分析

【目的】本研究旨在通过克隆苹果蠹蛾Cydia pomonella细胞色素P450基因CYP332A19和CYP337B19,并对其进行序列和表达分析,以更好地了解这两个P450基因在植物次生物质解毒方面的作用,为进一步的功能研究提供依据。【方法】采用本地BLAST搜索苹果蠹蛾转录组数据库获得细胞色素P450基因cDNA序列,采用RT-PCR技术克隆目的基因的编码区。利用生物信息学软件分析目的基因的序列特征及与其他近缘物种的P450基因的系统进化关系。采用RT-qPCR技术测定目的基因在苹果蠹蛾不同发育阶段(卵、1-5龄幼虫、蛹和成虫)、4龄幼虫不同组织(头部、表皮、脂肪体、中肠和马氏管)以及4龄幼虫分别取食添加0.1%香豆素和0.5%槲皮素的人工饲料2 d后的表达水平。【结果】克隆获得苹果蠹蛾细胞色素P450基因CYP332A19(GenBank登录号: MF574708)和CYP337B19(GenBank登录号: MF574697)的全长cDNA序列,开放阅读框(ORF)分别长1 518和1 491 bp,分别编码505和496个氨基酸,其蛋白质分子量分别为58.586和57.734 kD,理论等电点分别为8.99和7.61。结构域分析显示,CYP332A19和CYP337B19中均包含包括血色素结合区在内的5个保守的细胞色素P450结构域。系统发育树显示,苹果蠹蛾CYP332A19与苹淡褐卷蛾Epighyas postvittana CYP332A9等CYP332A基因聚在一枝,而CYP337B19与稻纵卷叶螟Cnaphalocrocis medinalis CYP337B12和六星灯蛾Zygaena filipendulae CYP337B11等CYP337B基因聚在另一枝。RT-qPCR分析结果表明,CYP332A19和CYP337B19在苹果蠹蛾幼虫期的表达水平高于卵期的,分别在4龄幼虫脂肪体和中肠中的表达量最高。取食分别含0.1%香豆素和0.5%槲皮素的人工饲料2 d后,4龄幼虫体内的CYP332A19和CYP337B19相对表达量显著高于对照组(取食含2%DMSO的人工饲料)。【结论】CYP332A19和CYP332B19分别在苹果蠹蛾幼虫脂肪体和中肠中高表达,且在取食含香豆素和槲皮素的人工饲料的苹果蠹蛾幼虫体内表达量升高,说明这两个基因可能参与苹果蠹蛾对外源物质的解毒代谢过程。本研究的结果有助于我们了解苹果蠹蛾对寄主次生物质解毒代谢机理,为苹果蠹蛾防治提供新思路。     

氯吡格雷对大鼠肝药物酶CYP3A4和CYP1A2表达的影响

目的：氯吡格雷主要由CYP3A4催化使其激活,CYPlA2也参与氯吡格雷活化。关于氯吡格雷对肝微粒体酶的影响国内外文献报道不多,因此本实验通过检测肝细胞色素氧化酶CYP3A4和CYPlA2的表达,探讨氯吡格雷对大鼠肝药物酶的影响。方法：生理盐水为对照组,氯吡格雷设高、中、低三个剂量组（27,13．5,6．75mg／kg／d）,雄性健康大鼠连续灌胃给药7天,脱臼处死,取肝组织,通过westernblot法检测大鼠肝脏CYP3A4和CYPlA2蛋白表达情况。结果：1）、氯吡格雷抑制大鼠CYP3A4蛋白表达,氯吡格雷高中低剂量组分别比生理盐水组大鼠CYP3A4蛋白表达量降低（P〈0．05）;氯吡格雷低中高剂量组间进行比较,大鼠CYP3A4蛋白表达量呈梯度减少（P〈0．05）;2）、氯吡格雷抑制大鼠CYPlA2蛋白表达,氯吡格雷高中低剂量组分别比生理盐水组大鼠CYPlA2蛋白表达量降低（P〈0．05）,氯吡格雷低中高剂量组间进行比较,大鼠CYPlA2蛋白表达量呈梯度减少（P〈0．05）。结论：氯吡格雷使肝细胞色素氧化酶CYP3A4和CYPlA2的表达量减少,因此氯吡格雷高、中、低3个剂量组均不同程度的抑制大鼠肝脏CYP3A4和CYPlA2的表达,提示当氯吡格雷与某些主要经CYP3A4和CYPlA2代谢的药物合用时,发生代谢性相关作用的可能性大。     

草地贪夜蛾CYP4G15和CYP4L4的时空表达及其对高低温胁迫的响应

[目的]为明确草地贪夜蛾Spodoptera frugiperda在高低温胁迫条件下CYP4G15和CYP4L4是否参与调控.[方法]本研究采用RT-PCR方法检测CYP4G15和CYP4L4在草地贪夜蛾各发育阶段和不同组织以及在36℃高温和4℃低温条件下的表达情况.[结果]CYP4G15和CYP4L4基因均在草地贪夜蛾低龄时表达量最高;CYP4G15在表皮组织中表达量最高;CYP4L4在前肠组织中表达量最高;在高温和低温胁迫条件下,两个基因均存在差异表达.[结论]CYP4G15和CYP4L4可能参与草地贪夜蛾体内.多种内源物质合成以及受高温、低温胁迫的代谢过程.     

Inhibition of CYP3A4 and CYP2C9 by podophyllotoxin: Implication for clinical drug–drug interactions

Podophyllotoxin (PPT) and its derivatives exert significant anti-cancer activities, and one derivative etoposide is often utilized to treat various cancers in the clinic. The aim of the present study is to investigate the inhibitory effects of PPT on major cytochrome P450 (CYP) isoforms in human livers. Inhibition of CYP3A4, CYP2C9, CYP2C8, CYP2D6, CYP2E1 and CYP2A6 by PPT was investigated in the human liver microsomal system. Time-dependent inhibition of CYP3A4 by PPT was also evaluated. The results showed that PPT strongly exhibited inhibitory effects on CYP3A4 and CYP2C9 in a concentration-dependent manner. Half inhibition concentration (IC₅₀) was 1.1 ± 0.3 and 4.6 ± 0.3 μM for CYP3A4 and CYP2C9, respectively. Inhibition kinetic analysis showed that PPT exhibited competitive inhibition towards CYP3A4 and CYP2C9 with K_i of 1.6 and 2.0 μM, respectively. Additionally, PPT exerted time-dependent inhibition towards CYP3A4 and the kinetic parameters were 4.4 ± 2.1 μM and 0.06 ± 0.01 min^–1 for K_I and k_inact, respectively. Our experimental data indicate that potential drug–drug interaction (DDI) might exist when PPT is co-administered with the substrates which mainly undergo CYP3A4- or CYP2C9-mediated metabolism.