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.     

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.     

Evaluation of Inhibitory Effects of Caffeic acid and Quercetin on Human Liver Cytochrome P450 Activities

When herbal drugs and conventional allopathic drugs are used together, they can interact in our body which can lead to the potential for herb–drug interactions. This work was conducted to evaluate the herb–drug interaction potential of caffeic acid and quercetin mediated by cytochrome P450 (CYP) inhibition. Human liver microsomes (HLMs) were added to each selective probe substrates of cytochrome P450 enzymes with or without of caffeic acid and quercetin. IC₅₀, Ki values, and the types of inhibition were determined. Both caffeic acid and quercetin were potent competitive inhibitors of CYP1A2 (Ki = 1.16 and 0.93 μM, respectively) and CYP2C9 (Ki = 0.95 and 1.67 μM, respectively). Caffeic acid was a potent competitive inhibitor of CYP2D6 (Ki = 1.10 μM) and a weak inhibitor of CYP2C19 and CYP3A4 (IC₅₀ > 100 μM). Quercetin was a potent competitive inhibitor of CYP 2C19 and CYP3A4 (Ki = 1.74 and 4.12 μM, respectively) and a moderate competitive inhibitor of CYP2D6 (Ki = 18.72 μM). These findings might be helpful for safe and effective use of polyphenols in clinical practice. Our data indicated that it is necessary to study the in vivo interactions between drugs and pharmaceuticals with dietary polyphenols. Copyright © 2014 John Wiley & Sons, Ltd.     

隐丹参酮对大鼠肝微粒体CYP酶的影响

目的 研究隐丹参酮(CTS)对大鼠肝微粒体CYP酶各亚型的影响.方法 取SD大鼠,按体重随机分为6组,每组3只,隐丹参酮各剂量组分别灌胃给予隐丹参酮20、60、180、540mg/kg,连续10 d;阴性对照组,灌胃给予羟丙基环糊精水溶液10 mL/kg,连续10 d;阳性对照组从实验第7天开始按80 mg/kg腹腔注射B-NF,于第10天最后1次给药后将大鼠断头处死,取肝脏制备肝微粒体,分别用Cocktail体外孵育法、蛋白免疫印记及逆转录聚合酶链反应观察CTS对CYP酶各亚型酶活性、蛋白表达及基因表达的影响.结果 CTS灌胃后对大鼠肝微粒体CYP1A2有明显的诱导作用,并呈剂量依赖性,CTS 20～540 mg/kg剂量组CYP1A2探针代谢物的量、蛋白表达及基因表达分别较阴性对照组提高60%～430%、130%～320%及10%～150%;隐丹参酮对CYP酶其他亚型无明显作用.结论 CTS能显著地诱导大鼠肝微粒体CYP1A2,提示经CYP1A2代谢的药物在临床上与CTS合用时,可能发生药物之间的相互作用.     

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。     

Inhibition of human P450 enzymes by natural extracts used in traditional medicine

Different medicinal plants are widely used in Cuba and Mexico to treat several disorders. This paper reports in vitro inhibitory effects on the P450 system of herbal products commonly used by people in Cuba and Mexico in traditional medicine for decades. Experiments were conducted in human liver microsomes. The catalytic activities of CYP1A1/2, 2D6, and 3A4 were measured using specific probe substrates. The Heliopsis longipes extract exhibited a concentration-dependent inhibition of the three enzymes, and similar effects were produced by affinin (an alkamide isolated from the H. longipes extract) and two catalytically reduced alkamides. Mangifera indica L. and Thalassia testudinum extracts, two natural polyphenol-rich extracts, diminished CYP1A1/2 and 3A4 activities, but not the CYP2D6 activity. These results suggest that these herbs inhibit the major human P450 enzymes involved in drug metabolism and could induce potential herbal-drug interactions.     

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。     

Cocktail探针药物法评价小檗碱对肝微粒体CYP450酶的抑制作用

目的: 研究小檗碱对人肝微粒体CYP活性的影响. 方法: 以苯海拉明为内标,建立LC-MS/MS同时测定5种探针药物:咪达唑仑、非那西丁、右美沙芬、甲苯磺丁脲和氯唑沙宗的含量,采用鸡尾酒(cocktail)法探针药物法评价不同浓度小檗碱对混合人肝微粒体CYP不同亚型活性的影响. 结果: 与对照组相比,咪达唑仑、非那西丁和甲苯磺丁脲的代谢速率基本没有变化,而氯唑沙宗的代谢速率明显变慢,对于右美沙芬,当小檗碱的质量浓度为50 μg·L^-1时,其代谢速率基本没有变化,当小檗碱的质量浓度大于200 μg·L^-1时,其代谢速率明显变慢. 结论: 小檗碱质量浓度在2 000 μg·L^-1以下时对人肝微粒体中CYP3A4,CYP1A2和CYP2C9活性没有明显影响,但对CYP2E1和CYP2D6有明显的浓度依赖性抑制作用.     

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.     

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.     

乳香没药对细胞色素P450活性的影响

目的:考察乳香没药对细胞色素P450活性的影响。方法:56只小鼠分为对照组和乳香+没药3.15,2.10,1.05 g.kg-1剂量组,连续ig给药7 d;48只小鼠分为对照组和乳香、没药、乳香+没药组,ig给药3.15 g.kg-11次。所有小鼠末次药后30 min ip给予戊巴比妥钠,观察乳香没药对P450的影响。40只大鼠分为对照组、乳香组、没药组、乳香+没药组,以3.00 g.kg-1连续ig给药14 d,取肝脏制备各组动物肝微粒体,并用cocktail探针法考察乳香没药对大鼠CYP1A2,CYP2E1,CYP3A4的影响。结果:乳香+没药3.15,2.10,1.05 g.kg-1剂量连续给药7 d均可使戊巴比妥钠诱导的小鼠睡眠率降低(P<0.05,P<0.01),而单次给药3.15g.kg-1有使戊巴比妥钠诱导的小鼠睡眠率升高的趋势。乳香、没药及乳香+没药混合物组大鼠肝微粒体体外对非那西丁、氯唑沙宗代谢率显著高于对照组,而氨苯砜无明显差异。结论:乳香、没药连续用药均使CYP1A2,CYP2E1活性增强,而对CYP3A4则无显著影响。     

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.     

Scutellarin inhibits cytochrome P450 isoenzyme 1A2 (CYP1A2) in rats

Scutellarin is the most important flavone glycoside in the herbal drug Erigeron breviscapus (Vant.) Hand.‐Mazz. It is used frequently in the clinic to treat ischemic vascular diseases in China. However, the direct relationship between scutellarin and cytochrome P450 (CYP450) is unclear. The present study investigated the in vitro and in vivo effects of scutellarin on cytochrome P450 1A2 (CYP 1A2) metabolism. According to in vitro experiments, scutellarin (10–250 µ m ) decreased the formation of 4‐acetamidophenol in a concentration‐dependent manner, with an IC₅₀ value of 108.20 ± 0.657 µ m . Furthermore, scutellarin exhibited a weak mixed‐type inhibition against the activity of CYP1A2 in rat liver microsomes, with a K_i value of 95.2 µ m . Whereas in whole animal studies, scutellarin treatment for 7 days (at 5, 15, 30 mg/kg, i.p.) decreased the clearance (CL), and increased the T_1/2 (at 15, 30 mg/kg, i.p.), it did not affect the V_d of phenacetin. Scutellarin treatment (at 5, 15, 30 mg/kg, i.p.) increased the AUC_0‐∞ by 14.3%, 67.3% and 159.2%, respectively. Scutellarin at 30 mg/kg also weakly inhibited CYP1A2 activity, in accordance with our in vitro study. Thus, the results indicate that CYP1A2 is inhibited directly, but weakly, by scutellarin in vivo, and provide useful information on the safe and effective use of scutellarin in clinical practice. Copyright © 2012 John Wiley & Sons, Ltd.     

LC-MS/MS研究人体及人肝微粒体内盐酸非洛普代谢产物

 目的 通过在体及离体实验阐明盐酸非洛普代谢情况。方法 健康志愿者口服盐酸非洛普60 mg,收集系列时间点血样,采用液相色谱串联质谱法检测志愿者血浆中的代谢产物并推测其可能结构;在建立人肝微粒体孵育体系中加入盐酸非洛普,常规温孵,采用液质联用仪分析孵育体系中的代谢产物,与在体实验进行对比。结果 在志愿者血浆中,除原型外检测到1个代谢产物,代谢物的m/z为212.1,推测其结构可能为盐酸非洛普分子中间断裂产物;在人肝微粒体孵育体系中,除原型外共检测到 6个代谢产物,m/z分别为360.1、342.2、415.1、281.4和330.2,推测其分别为盐酸非洛普氧化、脱氢、甲基化并结合甘氨酸、失掉相对分子质量62.6片段以及脱甲基的产物。结论 盐酸非洛普在志愿者体内及体外人肝微粒体孵育体系中的主要代谢产物不同。盐酸非洛普在人体内可能存在肝脏以外的其他代谢途径,并起主要作用。
     

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.     

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.     

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。     

桂枝汤对大鼠肝微粒体细胞色素P450酶活性的影响

目的:研究桂枝汤对大鼠肝微粒体细胞色素P450酶CYP1A2、CYP2D6和CYP3A4活性的影响。方法:18只大鼠被随机分成3组,每组6只。以生理盐水为空白对照,大鼠每日灌胃给予桂枝汤10 g/kg,连续7 d,测定其肝微粒体CYP1A2、CYP2D6和CYP3A4活性。结果:与对照组相比,桂枝汤对大鼠CYP1A2、CYP2D6和CYP3A4的活性无明显差异(P>0.05)。结论:桂枝汤对大鼠CYP1A2、CYP2D6和CYP3A4活性无影响。     

丹皮酚对大鼠肝微粒体细胞色素P450酶含量及活性的影响

目的:考察丹皮酚对大鼠肝微粒体的蛋白含量、CYP450酶总量和主要CYP450酶亚型(CYP1A2、CYP2D6、CYP3A4和CYP2C19)活性的影响。方法:大鼠灌胃给予丹皮酚(100 mg/(kg·d)-1,连续7 d,测定其肝微粒体蛋白含量、CYP450蛋白含量以及CYP1A2、CYP2D6、CYP3A4及CYP2C19活性。结果与空白对照组相比,丹皮酚给药组大鼠肝微粒体蛋白含量及肝微粒体CYP450含量无明显差异(P>0.05)。丹皮酚给药后,给药组大鼠的平均CYP2D6活性是对照组的2倍;而二两组之间CYP1A2、CYP3A4和CYP2C19的活性相当。结论丹皮酚对大鼠CYP2D6活性有一定诱导作用,对CYP1A2、CYP3A4和CYP2C19的活性没有影响。     

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。