Effect of Crude Extract of Eugenia jambolana Lam. on Human Cytochrome P450 Enzymes

The fruit of Eugenia jambolana Lam. is very popular for its anti‐diabetic property. Previous studies on the crude extract of E. jambolana (EJE) have successfully explored the scientific basis for some of its traditional medicinal uses. Considering its wide use and consumption as a seasonal fruit, the present study investigates the ability of E. jambolana to interact with cytochrome P450 enzymes. The standardized EJE was incubated with pooled human liver microsomes to assess the CYP2C9‐, CYP2D6‐, and CYP3A4‐mediated metabolism of diclofenac, dextromethorphan, and testosterone, respectively. The metabolites formed after the enzymatic reactions were quantified by high performance liquid chromatography. EJE showed differential effect on cytochrome P450 activities with an order of inhibitory potential as CYP2C9 > CYP3A4 > CYP2D6 having IC₅₀ of 76.69, 359.02, and 493.05 µg/mL, respectively. The selectivity of EJE for CYP2C9 rather than CYP3A4 and CYP2D6 led to perform the enzyme kinetics to explicate the mechanism underlying the inhibition of CYP2C9‐mediated diclofenac 4′‐hydroxylation. EJE was notably potent in inhibiting the reaction in a non‐competitive manner with K_i of 84.85 ± 5.27 µg/mL. The results revealed the CYP2C9 inhibitory potential of EJE with lower K_i value suggesting that EJE should be examined for its potential pharmacokinetic and pharmacodynamic interactions when concomitantly administered with other drugs. Copyright © 2014 John Wiley & Sons, Ltd.     

Inhibition of Magnolol and Honokiol on Cytochrome P450 Enzymes in Rat and Human Liver Microsomes

Objective The purpose of this work is to evaluate the in vitro inhibitory effect of magnolol(MN) and honokiol(HN) on rat / human cytochrome P450(CYP) enzymes(1A2/1A2, 2D/2D6, 3A/3A4, 2E1/2E1, and 2C/2C9). Methods Rat liver microsomes(RLM) and human liver microsomes(HLM) were used as the enzyme sources. After the probe substrate of each CYP isoforms was co-incubated individually with MN or HN in RLM or HLM, the metabolite production of each probe substrate in RLM and HLM incubation medium was determined and used to evaluate the activity of corresponding CYP isoforms. Results MN inhibited rat CYP1A2 and human CYP3A4 with the IC50 values of 10.0 and 56.2 μmol/L, respectively. HN inhibited rat CYP1A2 and CYP2E1, human CYP1A2 and CYP3A4 with the IC50 values of 12.1, 12.6, 17.8, and 43.9 μmol/L, respectively. Conclusion HN is a moderate or weak inhibitor of human CYP1A2. Both MN and HN are weak or non inhibitors of the other tested human CYP isoforms. The results suggest that no significant metabolic interaction seems likely to occur when the substrate drugs of CYP isoforms tested in the present work are co-administered with MN and HN.     

Inhibition of Cytochrome P450 by Nomilin and Obacunone and Potential Mechanism in Human Liver Microsomes

Objective Nomilin and obacunone are two important limonoids that are well known for their anticancer effect. Previous studies showed that limonoids had inhibitory effect on cytochrome P450 3A4(CYP3A4). However these effects are inconclusive with regards to prediction of potential drug interactions. Methods Nomilin or obacunone was pre-incubated with HLMs for 30 min. Following 10-fold dilution from the pre-incubation concentration, a second incubation was performed in the presence of NADPH and cytochrome P450 substrates for 15 min. The reaction was quenched and the supernatants were analyzed by chromatography/mass spectrometry. Results In this study, nomilin and obacunone showed potent inhibitory effect on CYP3A4 with the IC_(50) values of 3.50 and 6.08 μmol/L, respectively. The inhibition of CYP3A4 was in a time-, concentration-and NADPH-dependent manner with Ki values of 2.92 and 1.25 μmol/L and Kinact values of 0.033 and 0.078 min~(-1) for nomilin and obacunone respectively. These results elucidated that they were time-dependent inhibitors for CYP3A4. Conclusion Concomitant use of limonoids and other drugs may call for extra caution for purposes of clinical safety.     

黄芩苷对大鼠和人肝微粒体CYP450酶的抑制作用

目的:观察黄芩苷对大鼠/人肝微粒体细胞色素P450(CYP450)酶活性的抑制作用,比较种属差异性,评价其发生药物相互作用的可能性。方法:通过采用体外肝微粒体温孵体系结合特异性探针底物的方法,结合应用LC-MS/MS检测各探针底物的代谢物的生成量,质谱检测条件为电喷雾离子化(ESI)源,选择性反应监测(SRM)扫描方式,色谱分离条件为ZORBAX Eclipse-plus C₁₈色谱柱(2.1 mm×100 mm,3.5 μm),流动相甲醇-0.1%甲酸水溶液梯度洗脱,流速0.2 mL·min^-1,计算半抑制浓度(IC₅₀)。结果:黄芩苷对大鼠肝微粒体CYP450酶7种亚型均无抑制作用,而对人肝微粒体CYP1A2,CYP2C19和CYP2E1有较弱的抑制作用,IC₅₀分别为39.72,40.91,32.83 μmol·L^-1。结论:黄芩苷对CYP450酶的抑制作用存在种属差异性,是人CYP1A2,CYP2C19,CYP2E1的弱抑制剂,临床静脉用药时,应注意可能因CYP450酶抑制引起的药物相互作用。     

Inhibitory effects of curcumenol on human liver cytochrome P450 enzymes

Curcumenol, one of the major components of Zedoary turmeric oil, has been widely used to treat cancer and inflammation. As an antibiotic or anticancer drug, curcumenol is highly likely to be used in combination with various synthetic drugs in most cases, thus it is necessary to evaluate potential pharmacokinetic drug‐drug interactions induced by curcumenol. In this study, the inhibitory effects of curcumenol on seven CYP isoforms were investigated, and the results demonstrated that only CYP3A4 was strongly inhibited (IC₅₀ = 12.6 ± 1.3 μM). Kinetic analysis showed the inhibition type was competitive with K_i value of 10.8 μM. Time‐ and NADPH‐dependent inhibitions were also investigated to show curcumenol is not a mechanism‐based inhibitor. Employing these in vitro data and maximum plasma concentration of curcumenol in human predicted from beagle dog's in vivo pharmacokinetic data, the change in AUC of victim drugs was predicted to be 0.4%, which suggested that curcumenol may be safely used without inducing metabolic drug‐drug interaction through P450 inhibition. Nevertheless, due to the limited pharmacokinetic data available for curcumenol in humans, it is still not possible to evaluate its potential clinical effects on human patients from in vitro data. Thus, the magnitude of drug‐drug interaction (DDI) induced by curcumenol warrants further investigation. Copyright © 2010 John Wiley & Sons, Ltd.     

参芎葡萄糖注射液对小鼠肝细胞色素P450酶活性及表达的影响

目的:研究参芎葡萄糖注射液(Shenxiong glucose injection,SGI)对小鼠肝脏细胞色素P450 2_(E1)(CYP2_(E1)),2_(A11)(CYP2_(A11)),1_(A2)(CYP1_(A2))和2_(D22)(CYP2_(D22))酶活性以及mRNA表达水平的影响。方法:将昆明小鼠随机分为正常组,苯巴比妥组(0.70 g·kg~(-1)),以及SGI低、中、高剂量组(13.0,19.5,26.0 g·kg~(-1))。各组小鼠每天尾静脉注射药物1次,连续注射7 d后处死。取其肝脏制备肝微粒体进行体外代谢实验,测定CYP2_(E1),CYP2_(D22),CYP1_(A2)和CYP3A的酶活性。并用实时荧光定量聚合酶链式反应q PCR技术定量分析小鼠肝组织中CYP2_(E1),CYP2_(D22),CYP1_(A2)和CYP2_(A11)的mRNA表达水平。结果:与正常组比较,各给药组小鼠肝指数没有显著差异。体外代谢实验表明,相较正常组,高剂量SGI能下调CYP2_(E1)酶活性0.45倍(P0.05);中剂量和高剂量的SGI可上调CYP1_(A2)酶活性1.2~1.23倍(P0.05);而SGI对CYP3A和CYP2_(D22)的活性无显著影响。q PCR分析发现,相较正常组,高剂量SGI组CYP2_(E1)mRNA的表达下调了0.6倍(P0.01);SGI中剂量和高剂量组的CYP1_(A2)mRNA的表达分别上调了1.7倍和2.6倍(P0.05)。SGI组和正常组之间的CYP2_(A11)和CYP2_(D22)mRNA表达量无显著性差异。结论:中高剂量的SGI能上调小鼠肝CYP1_(A2)的表达,并诱导小鼠肝CYP1_(A2)的酶活性。而高剂量的SGI能下调小鼠肝CYP2_(E1)的表达,并抑制小鼠肝CYP2_(E1)的酶活性。     

In vitro Metabolism of Strychnine by Human Cytochrome P450 and Its Interaction with Glycyrrhetic Acid

Objective To investigate the metabolism of strychnine(STN)and the metabolic interaction between STN and glycyrrhetic acid(GA)in vitro.Methods Human liver microsomes(HLM)and human recombinant cytochrome P450(CYP)isoforms were employed to study the metabolism of STN and the metabolic interaction of STN with GA in vitro.Results In HLM,the Km,Vmax,and clearance of STN were 88.50μmol/L,0.88 nmol/(mg·min),and 9.93 mL/(mg·min),respectively.STN was metabolized mainly by CYP3A4.However,STN noncompetitively inhibited CYP3A4-catalyzed testosterone 6β-hydroxylation with IC50 value of 5.9μmol/L and Ki value of 5.5 μmol/L.Moreover,GA competitively inhibited STN metabolism with IC50 value of 10.6μmol/L and Ki value of 17.7μmol/L.Conclusion Although STN is mainly metabolized by CYP3A4 in vitro,STN has noncompetitive inhibition on CYP3A4-catalyzed testosterone 6β-hydroxylation.Moreover,GA could competitively inhibit STN metabolism.The present work is helpful to elucidate the metabolic interaction between STN and GA.     

Inhibitory Activities of Thai Medicinal Plants with Promising Activities Against Malaria and Cholangiocarcinoma on Human Cytochrome P450

Malaria and cholangiocarcinoma remain important public health problems in tropical countries including Southeast Asian nations. Newly developed chemotherapeutic and plant‐derived drugs are urgently required for the control of both diseases. The aim of the present study was to investigate the propensity to inhibit cytochrome P450‐mediated hepatic metabolism (CYP1A2, CYP2C19, CYP2D6 and CYP3A4) of the crude ethanolic extract of eight Thai medicinal plants with promising activities against malaria and cholangiocarcinoma, using human liver microsomes in vitro. Piper chaba Linn. (PC) and Atractylodes lancea (thung.) DC. (AL) exhibited the most potent inhibitory activities on CYP1A2‐mediated phenacetin O‐deethylation with mean IC₅₀ of 0.04 and 0.36 µg/mL, respectively. Plumbago indica Linn. (PI) and Dioscorea membranacea Pierre. (DM) potently inhibited CYP2C19‐mediated omeprazole 5‐hydroxylation (mean IC₅₀ 4.71 and 6.92 µg/mL, respectively). DM, Dracaena loureiri Gagnep. (DL) and PI showed the highest inhibitory activities on dextromethorphan O‐demethylation (mean IC₅₀ 2.93–9.57 µg/mL). PC, DM, DL and PI exhibited the most potent inhibitory activities on CYP3A4‐mediated nifedipine oxidation (mean IC₅₀ 1.54–6.43 µg/mL). Clinical relevance of the inhibitory potential of DM, PC and PI is of concern for the further development of these plants for the treatment of malaria and/or cholangiocarcinoma. Copyright © 2015 John Wiley & Sons, Ltd.     

热毒宁注射液对大鼠肝微粒体CYP450酶的诱导作用研究

目的：研究热毒宁注射液（RDN）对大鼠肝微粒体CYP450酶的诱导作用。方法：将SD大鼠随机分为空白溶剂组、阳性对照组和热毒宁注射液低、中、高剂量组（1、2、4 mL·kg^-1·d^-1）,分别于连续给药7天后处死,取肝组织称重并制备肝微粒体。计算大鼠肝脏的脏器系数,以BCA法测定微粒体的蛋白含量,以“cocktail”法测定大鼠肝微粒体中5种重要的CYP450酶亚型CYP1A2、CYP2C9、CYP2C19、CYP2D6和CYP3A1/2的活性。结果：与空白溶剂组比较,阳性对照组大鼠的肝脏脏器系数、微粒体得率及各CYP450酶亚型的活性均明显增加（P<0.01）。热毒宁注射液低、中剂量组的脏器系数、微粒体得率和蛋白含量无显著性差异,但高剂量组的脏器系数和微粒体得率有显著性差异（P<0.05）。对酶活性的影响方面,热毒宁注射液能显著诱导大鼠CYP1A2的活性,且呈剂量依赖性;中、高剂量组对CYP2C9和CYP2C19均有一定的诱导作用;对CYP3A1/2和CYP2D6的作用不明显。结论：阳性对照组对大鼠肝微粒体CYP450酶有明显的诱导作用,所建立的实验体系可用于诱导作用的评价;热毒宁注射液对大鼠CYP1A2、CYP2C9和CYP2C19亚型有一定的诱导作用,对CYP3A1/2和CYP2D6无明显作用。     

延胡索乙素对映体对人肝微粒体细胞色素P450酶抑制作用机制研究

目的考察延胡索乙素(tetrahydropalmatine,THP)对映体对人肝微粒体中主要细胞色素P450酶(cytochrome P450,CYP450)的抑制作用及其机制。方法采用Cocktail探针药物法分别考察左旋延胡索乙素[(-)-tetrahydropalmatine,(-)-THP]和右旋延胡索乙素[(+)-tetrahydropalmatine,(+)-THP]对人肝微粒体中主要I相药物代谢酶CYP1A2、CYP2C9、CYP2C19、CYP3A4、CYP2E1和CYP2D6活性的影响;采用两步孵育法考察(-)-THP对人肝微粒体中CYP2D6的底物右美沙芬脱甲基活性的影响,研究其对CYP2D6的抑制机制;采用时间依赖性实验考察(-)-THP对CYP2D6的酶动力学参数。结果 (+)-THP对CYP450各亚型无明显抑制作用,而(-)-THP对CYP2D6的抑制作用强(IC50=0.46μmol/L);在加或不加NADPH[(+)NADPH/(-)NADPH]预孵育体系中,(-)-THP对CYP2D6的IC50值分别为2.40、0.46μmol/L,即IC50(-)NADPH/IC50(+)NADPH=5.22;(-)-THP对CYP2D6的酶动力学参数Ki和Kinact分别为0.690μmol/L和0.084 6 min-1。结论 (-)-THP对CYP2D6的抑制作用强,抑制类型为基于机制抑制(MBI),提示在临床应用中需注意(-)-THP可能引起显著的代谢性药物相互作用。     

中草药代谢与细胞色素P450的关系研究进展

目的:阐述中草药代谢与细胞色素P450酶(CYP450)的关系。方法:查阅近年来国内外相关文献100余篇,从CYP450概述、CYP450研究方法、代谢性相互作用以及中草药-药物相互作用与CYP450之间关系等方面进行文献归纳。结果:CYP450研究方法主要包括体外细胞、亚细胞水平研究及体内研究,CYP450酶活性改变是代谢性相互作用的主要原因,中草药复杂成分对CYP450酶活性影响较大。结论:CYP450在药物代谢中起重要作用,由中草药引起药物相互作用屡的原因大多缘于中草药影响了机体CYP450活性或机体CYP450蛋白表达,导致由CYP450参与代谢的其它药物在机体内代谢特征的改变,引发不良药物反应。     

Inhibitory and inductive effects of Corydalis saxicola Bunting total alkaloids (CSBTA) on cytochrome P450s in rats

Corydalis saxicola Bunting, a well‐known traditional Chinese medicine in south China, has been widely used for the treatment of various hepatic diseases. Its active ingredients are Corydalis saxicola Bunting total alkaloids (CSBTA), which primarily include dehydrocavidine, palmatine, and berberine. These representative alkaloids could be metabolized by hepatic CYP450s. Hence, it is necessary to investigate the potential influences of CSBTA on CYP450s to explore the possibility of herb–drug interactions. In present study, in vitro inhibition and in vivo induction studies were performed to evaluate the potential effects of CSBTA extract on CYP450s in rats. Inhibition assay illustrated that CSBTA exerted inhibitory effects on CYP1A2 (IC₅₀, 38.08 μg/ml; K_i, 14.3 μg/ml), CYP2D1 (IC₅₀, 20.89 μg/ml; K_i, 9.34 μg/ml), CYP2C6/11 (IC₅₀ for diclofenac and S‐mephenytoin, 56.98 and 31.59 μg/ml; K_i, 39.0 and 23.8 μg/ml), and CYP2B1 (IC₅₀, 48.49 μg/ml; K_i, 36.3 μg/ml) in a noncompetitive manner. Induction study showed CSBTA had obvious inhibitory rather than inductive effects on CYP1A2 and CYP2C6/11. Interestingly, neither inhibition nor induction on CYP3A was observed for CSBTA. In conclusion, CSBTA–drug interactions might occur through CYP450s inhibition, particularly CYP1A and CYP2D. Further studies are still needed to elucidate the underlying mechanisms of inhibition.     

Screening of Eleven Commonly Used Traditional Chinese Medicines for Inhibitory Effects on Human Cytochrome P450 Enzymes

Objective Traditional Chinese medicines(TCMs) as natural therapeutic agents have been widely used and received great attention over the world.However,the information on them to cause herb-drug interactions mediated by cytochrome P450(CYP) enzymes is limited.The present study aims to evaluate the inhibitory effects of 11 commonly used TCMs,including Nelumbinis Folium,Ginseng Radix et Rhizoma,Ziziphi Spinosae Semen,Chrysanthemi Flos,Lonicera Japonica Flos,Lycii Fructus,Cassiae Semen,Poria,Crataegi Fructus,Schisandrae Chinensis Fructus,and Polygonati Rhizoma,on the five human major CYP isoenzymes 2C19,2D6,3A4,2E1,and 2C9.Methods An in vitro cocktail method was used.Results The aqueous extracts of all tested TCMs were found no significant inhibitory effect,with IC_(50) values higher than 100 μg/mL while,the ethanolic extracts of some herbs showed more potent inhibition.These herbs include Nelumbinis Folium with IC_(50) values of 1 2.05 and 61.43 μg/mL on CYP2D6 and CYP2E1,Schisandrae Chinensis Fructus with IC_(50) values of 64.42 and 47.24 μg/mL on CYP2C1 9and CYP3A4,and Chrysanthemi Flos with IC_(50) values of 45.25 μg/mL on CYP2C9,respectively.Conclusion Co-administration of these TCMs and their products with conventional medicines should be paid much attention to,and their potential inhibitory effects on CYP enzyme activities need to be further investigated.     

Inhibition of cytochrome P450 enzymes by rhein in rat liver microsomes

Rhein, an active ingredient extensively found in plants such as Aloe, Cassitora L., rhubarb and so on, has been used for a long time in China. Pharmacological tests revealed that rhein not only had a strong antibacterial action, but also may be useful in cancer chemotherapy as a biochemical modulator. Its therapeutic action and toxicity is still the subject of considerable research. With microsome incubation assays in vitro and HPLC methods, the inhibition of rat liver CYP1A2, CYP2C9, CYP2D6, CYP2E1 and CYP3A enzymes by rhein were studied kinetically. The results showed the most inhibition of CYP2E1 by rhein (K(i) = 10 microm, mixed); CYP3A and CYP2C9 were also inhibited by rhein, K(i) = 30 microm (mixed) and K(i) = 38 microm (mixed), respectively; rhein revealed some inhibition of CYP1A2 (K(i) = 62 microm, uncompetitive) and CYP2D6 (K(i) = 74 microm, mixed). Drug-drug interactions, especially cytochrome P450 (CYP)-mediated interactions, cause an enhancement or attenuation in the efficacy of co-administered drugs. Inhibition of the five major CYP enzymes observed for rhein suggested that changes in pharmacokinetics of co-administered drugs were likely to occur. Therefore, caution should be paid to the possible drug interaction of medicinal plants containing rhein and CYP substrates.     

Investigation of the in Vitro Metabolism of Evodiamine: Characterization of Metabolites and Involved Cytochrome P450 Isoforms

Evodiamine is the main active alkaloid of Evodia rutaecarpa (E. rutaecarpa) and has been demonstrated to exhibit many pharmacological activities including vasorelaxation, uterotonic action, anoxia and control of body temperature. The present study focused on the metabolism of evodiamine. Human and phenobarbital‐induced rat liver microsomal incubation of evodiamine in the presence of NADPH resulted in the formation of five major metabolites (M‐1, M‐2, M‐3, M‐4, M‐5). Four metabolites (M‐1, M‐2, M‐3 and M‐5) were identified to mono‐hydroxylated evodiamine and one metabolite (M‐4) was identified to be N‐demethylated evodiamine. CYP3A4, CYP2C9 and CYP1A2 were identified to be the main CYP isoforms involved in the metabolism of evodiamine in human liver microsomes. Finding new metabolites can help us decipher novel substance basis of efficiency and toxicity. Elucidation of drug metabolizing enzymes will facilitate explaining the individual difference for response to the same drugs or herbs and the potential drug–drug interaction or herb–drug interaction. Taken together, these results are of significance for better understanding the pharmacokinetic behaviour of evodiamine and helpful for clinical application of evodiamine and E. rutaecarpa. Copyright © 2012 John Wiley & Sons, Ltd.     

In vitro inhibition of Huanglian [Rhizoma coptidis (L.)] and its six active alkaloids on six cytochrome P450 isoforms in human liver microsomes

Huanglian (Rhizoma Coptidis) as a popular herb has been used for the treatment of various diseases such as diarrhea, eye inflammation and women's abdominal ailments. Alkaloids are considered to be responsible for its pharmacological effects. In this investigation, Huanglian and its six alkaloids (coptisine, epiberberine, berberine, jateorrhizine, palmatine and magnoflorine) were systematically evaluated for their inhibition of six cytochrome P450 isoforms (CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6 and CYP3A4) in human liver microsomes by the LC‐MS/MS method. Huanglian showed the strongest inhibition of CYP2D6, followed by CYP1A2 and CYP3A4_T. The IC₅₀ values were 5.8 µg/mL, 36.8 µg/mL and 59.2 µg/mL, respectively. Of the constituents tested, coptisine and epiberberine showed strong inhibition of CYP2D6 with IC₅₀ values of 4.4 µm and 7.7 µm ; berberine, jateorrhizine and palmatine showed weak inhibition of CYP2D6 with IC₅₀ values of 45.5 µm , 49.4 µm and 92.6 µm , respectively; jateorrhizine showed moderate inhibition of CYP3A4_T with an IC₅₀ value of 13.3 µm ; coptisine showed weak inhibition of CYP1A2 with an IC₅₀ value of 37.3 µm . In addition, activation was observed in coptisine/CYP2C9 and palmatine/CYP2C9/CYP2C19. Other CYP450 isoforms were not affected markedly by the six alkaloids. In conclusion, Huanglian showed in vitro inhibition of CYP2D6, the inhibition might be contributed mostly by protoberberine alkaloids, especially coptisine and epiberberine. Herb–drug interactions may occur through the CYP2D6 inhibition. Copyright © 2011 John Wiley & Sons, Ltd.     

肉桂酸的代谢与CYP450酶的相关性研究

 目的通过离体肝匀浆实验法来研究肉桂酸的代谢转化过程,探讨参与肉桂酸代谢的CYP450亚酶,为临床上合理用药提供科学依据。方法应用高效液相色谱法检测大鼠肝匀浆温孵液中剩余肉桂酸的含量,分析各诱导和抑制剂对肉桂酸代谢的影响。结果特异性CYP1A诱导剂β-NF组中肉桂酸代谢速率明显高于对照组,而主要诱导CYP2B的PB组和CYP3A的DEX组与对照组比较无明显区别;特异的CYP1A抑制剂α-NF则显著抑制肉桂酸的代谢。结论CYP1A是介导肉桂酸代谢转化的主要酶系,肉桂酸与抑制或诱导CYP1A酶的药物合用可能存在相互作用。     

Effects of Vernonia cinerea Compounds on Drug‐metabolizing Cytochrome P450s in Human Liver Microsomes

Vernonia cinerea has been widely used in traditional medicines for various diseases and shown to aid in smoking abstinence and has anticancer properties. V. cinerea bioactive compounds, including flavonoids and hirsutinolide‐type sesquiterpene lactones, have shown an inhibition effect on the nicotine‐metabolizing cytochrome P450 2A6 (CYP2A6) enzyme and hirsutinolides reported suppressing cancer growth. In this study, V. cinerea ethanol extract and its bioactive compounds, including four flavonoids and four hirsutinolides, were investigated for an inhibitory effect on human liver microsomal CYPs 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4 using cocktail inhibition assays combined with LC‐MS/MS analysis. Among tested flavonoids, chrysoeriol was more potent in inhibition on CYP2A6 and CYP1A2 than other liver CYPs, with better binding efficiency toward CYP2A6 than CYP1A2 (K_i values in competitive mode of 1.93 ± 0.05 versus 3.39 ± 0.21 μM, respectively). Hirsutinolides were prominent inhibitors of CYP2A6 and CYP2D6, with IC₅₀ values of 12–23 and 15–41 μM, respectively. These hirsutinolides demonstrated time‐dependent inhibition, an indication of mechanism‐based inactivation, toward CYP2A6. Quantitative prediction of microsomal metabolism of these flavonoids and hirsutinolides, including half‐lives and hepatic clearance rate, was examined. These findings may have implications for further in vivo studies of V. cinerea. Copyright © 2017 John Wiley & Sons, Ltd.     

细胞色素P450同工酶对马兜铃酸所致的细胞毒性的影响

目的：探讨细胞色素P450同工酶(cytochrome P450 isozymes)对马兜铃酸(aristolochic acid，AA)致肾小管上皮细胞毒性的影响。方法：采用体外培养的人类肾小管上皮细胞(HK-2细胞)，AA与α-萘黄酮(CYP450 1A1和1A2的抑制剂)、酮康唑(CYP4503A4的抑制剂)、二乙基二硫代氨基甲酸钠(CYP450 2A6和2E1的抑制剂)、奎尼丁(CYP450 2D的抑制剂)、α-硫辛酸 (NADPH，P450 还原酶的抑制剂)、磺胺苯吡唑(CYP450 2C 的抑制剂)等抑制剂在有或无CYP450存在的条件下进行体外联合用药，采用四甲基偶氮唑(MTT)法测定细胞增殖抑制率以及连续监测法测定乳酸脱氢酶(LDH)释放率。结果：AA可抑制细胞增殖和促进LDH释放，在12.5～100 mg·L^-1呈剂量依赖性，随浓度的升高，细胞毒性更明显。在培养体系中加入S9可使AA的细胞毒性降低，细胞增殖抑制作用减轻，LDH释放减少(加与不加S9相比P<0.05)。在无S9存在时，酮康唑或α-萘黄酮对AA的细胞毒性无明显影响，而在S9存在的条件下，加入酮康唑或α-萘黄酮对AA的细胞毒性作用增强。其他抑制剂所形成的CYP450亚型抑制效应对AA的细胞毒性影响不明显。结论：微粒体混合酶对AA的细胞毒性有影响，能够降低AA细胞毒性，其中CYP450 3A和CYP450 1A可能是影响AA细胞毒性的主要同工酶。     

灯盏细辛和赤芍配伍组方对小鼠部分肝细胞色素P450亚型活性的影响及其机制分析

目的:探讨灯盏细辛和赤芍配伍组方(辛芍组方)对小鼠细胞色素P450酶(CYP450s)主要亚型CYP1a2,CYP2d22,CYP2e1和CYP3a11代谢活性的影响以及相关机制。方法:小鼠分为5组,分别为正常组、苯巴比妥组(70 mg·kg-1)和辛芍组方低、中、高剂量组(0.31,0.62,1.25 g·kg-1)。给药结束后,取各组小鼠肝脏制备微粒体,考察CYP1a2,CYP2d22,CYP2e1和CYP3a11的代谢活性;并提取肝组织总RNA和蛋白,实时荧光定量聚合酶链式反应法(Real-time PCR)和蛋白免疫印迹法(Western blot)考察辛芍组方对CYP1a2,CYP2d22,CYP2e1,CYP3a11和孕烷X受体(PXR)mRNA及蛋白表达的影响;利用报告基因法考察辛芍组方对PXR的激活作用。结果:与正常组比较,辛芍组方可诱导CYP3a11酶活性,上调CYP3a11,PXR mRNA和蛋白水平,并具有PXR激活作用(P0.05,P0.01);与模型组比较,辛芍中、高剂量组方能抑制CYP1a2酶活性(P0.05),但对CYP1a2的mRNA水平和蛋白水平无明显影响;而辛芍组方对CYP2e1,CYP2d22的酶活性,mRNA水平和蛋白水平无明显影响。结论:辛芍组方具有CYP3a11活性诱导作用,该作用很可能与辛芍组方上调PXR表达并激活PXR从而促进CYP3a11表达有关;而其CYP1a2活性抑制作用机制与CYP1a2的表达调控无关,需要进一步研究。