黄芪多糖对小鼠MC-3T3-E1成骨细胞维生素D受体mRNA及蛋白表达的影响

目的探讨黄芪多糖对小鼠MC-3T3-E1成骨细胞维生素D受体(VDR)mRNA及蛋白表达的影响。方法采用Real-Time PCR、Western Blot检测黄芪多糖对小鼠MC-3T3-E1成骨细胞维生素D受体(VDR)mRNA及蛋白表达情况。实验分为5组,正常组、维生素D组(10-5mmol·L-1)、10μg·ml-1黄芪多糖组、1μg·ml-1L黄芪多糖组、0.1μg·ml-1黄芪多糖组。结果 Real-Time PCR、Western Blot检测结果显示,与正常组比较,不同剂量的黄芪多糖均可上调小鼠MC-3T3-E1成骨细胞VDR mRNA及蛋白相对表达量,且在黄芪多糖剂量为1μg·ml-1时其表达量显著增高(P0.05)。结论黄芪多糖治疗骨质疏松症重要机制之一可能与上调VDR mRNA及蛋白表达水平有关。     

黄芪含药血清对衰老骨髓间充质干细胞CYP24A1，CYP27B1 mRNA和蛋白的影响

目的:通过探讨不同浓度黄芪含药血清对衰老骨髓间充质干细胞(BMSCs)成骨分化过程中24-羟基化酶(CYP24A1),1α羟化酶(CYP27B1)mRNA及蛋白表达的影响,初步探讨其治疗原发性骨质疏松症作用机制。方法:将SD大鼠随机分为6组,正常组、模型组、黄芪含药血清低、中、高质量分数组(20%,40%,60%),维生素D组。细胞增殖毒性检测(CCK-8)法检测不同浓度黄芪含药血清对衰老BMSCs成骨分化细胞存活率的影响;实时荧光定量聚合酶链式反应(Real-time PCR),蛋白免疫印迹法(Western blot)检测不同浓度黄芪含药血清对衰老BMSCs成骨分化细胞CYP24A1,CYP27B1 mRNA和蛋白的表达情况。结果:CCK-8法显示,与正常组比较,模型组BMSCs成骨分化细胞经D-半乳糖诱导后细胞增殖存活率显著降低(P0.01);与模型组比较,黄芪含药血清中、高质量分数组及维生素D组均可在不同程度上提高衰老BMSCs成骨分化细胞增殖存活率(P0.01);Real-time PCR和Western blot结果显示,与正常组比较,模型组CYP27B1 mRNA和蛋白相对表达量显著降低,CYP24A1 mRNA和蛋白相对表达量显著升高(P0.01);与模型组比较,黄芪高质量分数组均可升高CYP27B1 mRNA和蛋白相对表达量(P0.01),降低CYP24A1 mRNA和蛋白相对表达量(P0.01),呈质量分数依赖性。结论:不同浓度黄芪含药血清可治疗骨质疏松症,其机制可能与调节衰老骨髓间充质干细胞成骨分化过程中CYP24A1,CYP27B1 mRNA及蛋白表达水平有关。     

衰老大鼠肾上腺皮质VDR、CYP24A1、CYP27B1基因mRNA表达变化以及淫羊藿苷的干预作用

目的:探讨淫羊藿苷对D-半乳糖致衰老大鼠肾上腺皮质VDR、CYP24A1、CYP27B1基因mRNA表达的影响。方法:将雄性SD大鼠随机分为6组:对照组,衰老模型组,淫羊藿苷低、中、高剂量组,维生素D组。ELISA法观察大鼠血清25(OH)D_3,1,25(OH)_2D_3水平,Real-Time QPCR法观察大鼠肾上腺皮质VDR、CYP24A1、CYP27B1基因mRNA表达。结果:ELISA结果显示模型组的血清25(OH)D_3与1,25(OH)_2D_3水平均相对对照组降低(P0.05),维生素D组与部分淫羊藿苷不同剂量组的血清25(OH)D_3与1,25(OH)_2D_3水平相对衰老模型组上升(P0.05)。Real-Time QPCR结果显示相比对照组,模型组大鼠肾上腺皮质CYP27B1与VDR表达下降(P0.05),CYP24A1表达上升(P0.05);相比模型组,维生素D组与淫羊藿苷不同剂量组的大鼠肾上腺皮质CYP27B1与VDR基因相对模型组表达上升(P0.05),CYP24A1则相对下降(P0.05)。结论:淫羊藿苷可以通过影响相关基因表达上调衰老大鼠肾上腺皮质的维生素D活化水平。     

黄芪多糖离体条件下对H295R细胞维生素D系统相关蛋白表达及睾酮分泌的影响

目的:探讨黄芪多糖对人肾上腺皮质细胞(H295R细胞)维生素D系统及睾酮表达的影响。方法:随机分为空白对照组、维生素D组、黄芪多糖25μg/mL、50μg/mL、100μg/mL组,四唑盐(MTT)法检测不同浓度的黄芪多糖和维生素D对H295R细胞增殖率的影响,ELISA法检测睾酮分泌水平,实时荧光定量PCR(RT-qPCR)检测维生素D受体(VDR)、25-羟基维生素D3-1α-羟化酶(CYP27B)、维生素D3-24-羟化酶(CYP24A)、17β-羟类固醇脱氢酶(17β-HSD)、19α-羟化酶(CYP19A1)mRNA表达,Western blot法检测VDR、CYP27B、CYP24A蛋白表达。结果:黄芪多糖12.5μg/mL浓度,维生素D在0.25×10~(-11) mol/L和0.5×10~(-11) mol/L浓度,对H295R细胞增殖无显著影响。黄芪多糖200μg/mL,维生素D在2×10~(-11) mol/L和4×10~(-11) mol/L浓度时对H295R细胞增殖存在一定抑制作用。与空白对照组比较,维生素D组与黄芪多糖100μg/mL组睾酮分泌水平显著升高,VDR、CYP24A、17β-HSD mRNA表达显著上调,CYP27B蛋白及mRNA、CYP19A1 mRNA表达明显下调(P<0.05或P<0.01)。结论:离体条件下,黄芪多糖可能通过调节H295R细胞维生素D系统促进睾酮合成分泌。     

黄芪多糖对LPS诱导H295R细胞损伤的维生素D系统关键酶表达及皮质酮分泌的影响

目的 研究黄芪多糖对脂多糖(LPS)诱导H295R细胞损伤的维生素D系统关键酶(CYP27B、CYP24A)及皮质酮表达的影响.方法 用LPS溶液建立H295R细胞损伤模型.MTT法检测不同浓度的黄芪多糖对H295R细胞增值率的影响.分组:对照组,模型组,模型+黄芪多糖低、中、高剂量组,模型+维生素D组.ELISA法检...     

龟甲水提液调控NF-κB炎症微环境对MC3T3-E1成骨分化的影响

目的:探讨龟甲水提液调控核转录因子-κB(NF-κB)炎症微环境促小鼠前成骨细胞系(MC3T3-E1)成骨分化的作用及机制。方法:体外培养MC3T3-E1细胞,并进行成骨诱导,龟甲水提液干预。实验分为空白组、成骨诱导组、龟甲水提液(20 mg·L~(-1))联合成骨诱导组。细胞增殖毒性检测试剂盒(CCK-8)法检测MC3T3-E1增殖能力,并确定最佳干预浓度;碱性磷酸酶(ALP)染色和茜素红(ARS)染色检测MC3T3-E1成骨分化能力;实时荧光定量PCR(Real-time PCR)检测NF-κB p65,NF-κB p105,白细胞介素-6 (IL-6),ALP和Ⅰ型胶原(COL-Ⅰ) mRNA的表达。结果:CCK-8结果显示,随着时间的增长,MC3T3-E1增殖虽无统计学差异,但呈上升趋势,而在20 mg·L~(-1)质量浓度时增殖较其他组明显; ALP和ARS染色结果显示,成骨诱导组和龟甲水提液联合成骨诱导组染色阳性率较空白组明显升高; Real-time PCR结果显示,龟甲干预第7天,与空白组比较,龟甲水提液联合成骨诱导组NF-κB p105和IL-6 mRNA的表达明显降低(P 0. 01),ALP和COL-ⅠmRNA的表达明显升高(P 0. 05);龟甲干预第14天,与空白组比较,龟甲水提液联合成骨诱导组NF-κB p65,NF-κB p105和IL-6 mRNA的表达明显降低(P 0. 01),ALP和COL-ⅠmRNA的表达明显升高(P 0. 05,P 0. 01)。结论:龟甲水提液能够促进MC3T3-E1成骨分化,其机制可能与抑制NF-κB炎性微环境有关。     

柴竭抑肝纤对大鼠肝星状细胞增殖和TGF-β1/Smad信号通路的影响

目的:研究保肝护肝中药复方柴竭抑肝纤(CJYGX)通过肝星状细胞治疗肝纤维化的作用机制。方法:培养肝星状细胞T6(hepatic stellate cell T6,HSC-T6),设空白组、秋水仙碱1.0 mg·L~(-1)组和200,100,50,25,12.5,6.25 mg·L~(-1)质量CJYGX组,作用24 h后通过细胞计数试剂(cell counting kit-8,CCK-8)检测HSC-T6细胞的增殖情况,筛选合适的CJYGX药物浓度;实时荧光定量聚合酶链式反应(Real-time PCR)检测CJYGX(200,100,50 mg·L~(-1))作用HSC-T6细胞24 h后转化生长因子-β1(TGF-β1),信号转导蛋白Smad2,Smad3,Smad4,Smad7 mRNA表达变化;蛋白免疫印迹法(Western blot)检测CJYGX(200,100,50 mg·L~(-1))作用HSC-T6细胞24 h后TGF-β1,α-平滑肌肌动蛋白(α-SMA)表达变化。结果:(1)与空白组比较,200,100,50 mg·L~(-1)CJYGX对HSC-T6细胞具有显著的抑制增殖作用(P0.05)。(2)200,100,50 mg·L~(-1)CJYGX显著下调TGF-β1,Smad2,Smad3 mRNA的表达(P0.05);200,100 mg·L~(-1)CJYGX显著下调Smad4 mRNA表达,并显著上调Smad7 mRNA表达(P0.05)。(3)200,100 mg·L~(-1)CJYGX显著下调HSC-T6细胞TGF-β1和α-SMA蛋白表达(P0.05)。结论:CJYGX能抑制HSC-T6细胞的增殖,其作用机制与TGF-β1/Smad通路有关。     

淫羊藿苷对衰老大鼠肾上腺皮质CYP24A1、CYP27B1、CYP19A1、CYP17A1基因mRNA表达影响

目的探讨淫羊藿苷对D-半乳糖致衰老大鼠肾上腺皮质CYP24A1、CYP27B1、CYP19A1、CYP17A1基因mRNA表达的影响。方法将雄性SD大鼠随机分为6组:正常组,衰老模型组,淫羊藿苷低、中、高剂量组,维生素D组。Elisa法观察大鼠血清25(OH)D3水平,高效液相检测大鼠血清DHEA、睾酮水平,Real-TimeQPCR法观察大鼠肾上腺皮质CYP24A1、CYP27B1、CYP19A1、CYP17A1基因mRNA表达。结果 Elisa结果显示模型组大鼠血清25(OH)D3水平相对于正常组降低(P0.05),淫羊藿苷不同剂量组以及维生素D组相对于模型组升高(P0.05)。高效液相显示模型组的血清DHEA、睾酮水平均相对正常组降低(P0.05),维生素D组与部分淫羊藿苷不同剂量组的血清DHEA、睾酮水平相对衰老模型组上升(P0.05)。Real-TimeQPCR结果显示相比正常组,模型组大鼠肾上腺皮质CYP27B1、CYP19A1、CYP17A1表达下降(P0.05),CYP24A1表达上升(P0.05);相比模型组,维生素D组与淫羊藿苷不同剂量组的大鼠肾上腺皮质CYP27B1、CYP19A1、CYP17A1基因相对模型组表达上升(P0.05),CYP24A1则相对下降(P0.05)。结论衰老大鼠体内肾上腺皮质性激素相关基因表达水平下调同时衰老大鼠肾上腺皮质维生素D活化与作用降低,淫羊藿苷可以提高衰老大鼠肾上腺皮质维生素D活化与作用水平同时增加衰老大鼠肾上腺皮质性激素相关基因表达与生成。     

基于分子对接的方法探讨桑根酮C对MC3T3-E1细胞的作用

目的:观察桑根酮C(SanC)对地塞米松(DEX)作用下小鼠MC3T3-E1成骨细胞增殖与分化的影响,并探讨其作用机制。方法:将SanC与同源建模所得的Runt-相关转录因子2(Runx2)蛋白结构进行分子对接。不同浓度SanC(8,16,32μmol·L^-1)和1μmol·L^-1DEX共同作用MC3T3-E1细胞,而后采用细胞增殖-毒性检测试剂盒(CCK-8)法检测SanC对MC3T3-E1成骨细胞增殖影响。试剂盒测定MC3T3-E1成骨细胞碱性磷酸酶(ALP)活性和茜素红染色检测骨矿化结节的形成。采用实时荧光定量聚合酶链反应(Real-time PCR)检测Runt-相关转录因子2(Runx2),ALP,和锌指结构转录因子(Osterix)mRNA的表达水平。蛋白免疫印迹法(Western blot)检测Runx2蛋白表达。结果:SanC与Runx2对接打分为-9.78。与正常组比较,DEX组显著降低细胞存活率(P<0.01),其中7 d存活率差异达到最大;与DEX组比较,SanC能显著促进MC3T3-E1的细胞增值(P<0.01),其中32μmol·L^-1SanC作用细胞7 d增殖率差异达到最大。与正常组比较,DEX组Runx2,ALP和Osterix mRNA的表达均有一定程度升高(P<0.05);与DEX组比较,不同浓度SanC组依赖性上调Runx2,ALP和Osterix mRNA的表达(P<0.01)。与正常组比较,DEX组Runx2蛋白表达明显下降(P<0.05);与DEX组比较,SanC干预下细胞Runx2蛋白表达显著升高(P<0.01)。结论:桑根酮C能促进MC3T3-E1成骨细胞增殖、分化和矿化,其机制可能与上调Runx2表达有关。     

18β-甘草酸和18α-甘草酸对大鼠原代肝细胞 CYP3A酶表达的影响

目的:研究甘草中的2种成分18β-甘草酸和18α-甘草酸对原代培养大鼠肝细胞中细胞色素P450 3A(CYP3A)在mRNA及蛋白水平表达的影响,并探讨其剂量.效应关系.方法:原位两步胶原酶灌流法分离大鼠肝细胞并采用"胶原蛋白凝胶三明治"培养原代肝细胞,无血清条件下培养细胞,并用不同剂量的18β-甘草酸和18α-甘草酸处理细胞,RT-PCR法测定CYP3A mRNA表达水平,Western-blot法测定CYP3A蛋白表达.结果:实验条件下对照组、18β-甘草酸、18α-甘草酸处理组CYP3A基因及蛋白均可被检测,18βv甘草酸浓度依赖性诱导CYP3A mRNA(25～100 μmol·L~(-1))及蛋白表达(50～400μmol·L~(-1)),而18α-甘草酸浓度依赖性抑制CYP3A mRNA(25～100 μmol·L~(-1))及蛋白表达(25～100 μmol·L~(-1))表达.结论:18β-甘草酸和18αv甘草酸在转录水平上分别上调和下调大鼠肝细胞CYP3A的表达.     

甲基莲心碱对大鼠肝CYP450酶含量及CYP2D1, CYP3A1,CYP2E1 mRNA的影响

目的 :探讨甲基莲心碱对大鼠微粒体混悬液蛋白中细胞色素P450(CYP450)含量,及其对CYP450亚型CYP3A1,CYP2D1,CYP2E1的mRNA表达水平的影响。 方法 :Wistar大鼠48只,随机分成空白组、肝药酶诱导剂组、肝药酶抑制剂组,甲基莲心碱(Nef)低、中、高剂量组。对照组给予1%羧甲基纤维素钠(CMC-Na),诱导剂组地塞米松100 mg ·kg^-1,抑制剂组酮康唑40 mg ·kg^-1,Nef低、中、高剂量组分别为Nef 10,20, 50 mg ·kg^-1 灌胃给药,1日1次,连续6 d。取大鼠的肝制备肝微粒体,测定肝微粒体中的蛋白浓度,用分光光度计对样品进行比色测定CYP450总酶的含量。并采用实时定量反转录——聚合酶链反应(Quantitive real-time RT-PCR)定量分析了大鼠CYP450亚型CYP3A1,CYP2D1,CYP2E1的mRNA表达水平。 结果 :甲基莲心碱在高剂量组的P450含量与空白组比较有显著性差异(P＜0.01),提示该药在较大剂量时(20~50 mg ·kg^-1)对CYP450有诱导作用。Nef在高剂量时,分别对CYP3A1和CYP2D1有诱导作用,可显著升高二者的活性(分别为空白组的1.92,2.99倍,P＜0.05);中剂量时对CYP2D1具有诱导作用(为空白组的2.40倍,P＜0.05);Nef在3个剂量下对CYP2E1均无诱导作用。 结论 :Nef在20,50 mg ·kg^-1剂量可增加CYP450总酶活性和CYP2D6 mRNA的表达,在50 mg ·kg^-1剂量可增加CYP3A1 mRNA的表达,提示Nef在较高剂量时可诱导肝药酶加速自身代谢。     

Mechanism-based inhibition of CYP3A4 and CYP2D6 by Indonesian medicinal plants

Thirty samples of Indonesian medicinal plants were tested for their mechanism-based inhibition on cytochrome P450 3A4 (CYP3A4) and CYP2D6 via erythromycin N-demethylation and dextromethorphan O-demethylation activities in human liver microsomes. From screening with 0 and 20min preincubation at 0.5mg/ml of methanol extracts, five plants (Cinnamomum burmani bark, Foeniculum vulgare seed, Strychnos ligustrina wood, Tinospora crispa stem, and Zingiber cassumunar rhizome) showed more than 30% increase of CYP3A4 inhibition, while three (Alpinia galanga rhizome, Melaleuca leucadendron leaf, and Piper nigrum fruit) showed more than 30% increase of CYP2D6 inhibition. In these eight plants, Foeniculum vulgare seed, Cinnamomum burmani bark, and Strychnos ligustrina wood showed time-dependent inhibition on CYP3A4 and Piper nigrum fruit and Melaleuca leucadendron leaf on CYP2D6. Among these, four plants other than Melaleuca leucadendron revealed NADPH-dependent inhibition. Thus, Foeniculum vulgare, Cinnamomum burmani, and Strychnos ligustrina should contain mechanism-based inhibitors on CYP3A4 and Piper nigrum contain that on CYP2D6.     

建立一种测定细胞色素P450 3A4活性的方法

 目的建立一种细胞色素P450 3A4(cytochrome P450 3A4,CYP3A4)活性定量的新方法。方法将CYP3A4底物硝苯地平与人肝微粒体进行体外温孵,以高效液相色谱法测定硝苯地平及其氧化产物,以甲醇-水(64∶36)为流动相,流速为0.5 mL·min^-1,检测波长为254 nm。结果在所建立的HPLC条件下,硝苯地平及其氧化产物的出峰时间分别在8.44和6.15 min,能够完全分离,且无其他生物基质峰干扰;氧化硝苯地平在人肝微粒体的最低检测限为25μg·L^-1(S/N=3),线性范围是0.25～32 mg·L^-1(r=0.999 4),符合检测要求;在0.5,4.0,20.0 mg·L^-1时的萃取率分别为(67.05±3.49)%,(66.63±3.60)%,(67.08±2.78)%(n=5);方法回收率分别为(100.17±6.97)%,(91.96±3.71)%,(96.55±3.98)%(n=5);日内及日间RSD均小于7%。结论本实验所建立的HPLC能够准确、快速检测出硝苯地平及其在人肝微粒体中的氧化产物,能够对CYP 3A4活性进行快速评价,适合于体外药物代谢动力学研究和第三代多药抗药性逆转剂的筛选。     

齐墩果酸对健康人体CYP1A2,CYP2E1及CYP3A4抑制作用的研究

 目的在人体内研究齐墩果酸对CYP1A2,CYP2E1及CYP3A4酶活性的影响,以预测齐墩果酸与常用临床药物的相互作用。方法分别以咖啡因、氯唑沙宗和咪哒唑仑作为CYP1A2,CYP2E1及CYP3A4的探药,采用随机、开放、双周期交叉设计,12名健康男性受试者在服用7d齐墩果酸前后均服用100mg咖啡因、400mg氯唑沙宗和7.5mg咪哒唑仑,服探药后采血测定探药及相应代谢产物的浓度,并计算相关参数。探药和代谢物的浓度分别用RP-HPLC和HPLC-MS测定。结果服用齐墩果酸7d后,咖啡因的代谢受到显著的抑制,其达峰时间、消除半衰期及药-时曲线下面积显著增加;氯唑沙宗的代谢受到轻微抑制,达峰浓度、达峰时间、消除半衰期及药-时曲线下面积均有升高趋势,但无显著性差异;咪哒唑仑的代谢未受影响。结论服用7d齐墩果酸对CYP1A2体内活性有显著抑制作用,对CYP2E1体内活性有轻微抑制作用,而对CYP3A4酶活性无影响。     

CYP1A2、CYP2E1和CYP3A4探针间的药动学相互作用

目的 研究茶碱、氯唑沙宗和氨苯砜在大鼠体内的药动学相互作用,以评价3药作为Cocktail探针的可行性.方法 21只大鼠随机均分成3组,分别单独灌胃给予茶碱(30 mg·kg-1)、氯唑沙宗(50 mg·kg-1)和氨苯砜(20mg·kg-1),用HPLC测定各组大鼠的血药浓度;经过14d的清洗期和恢复期后,以相同的给药剂量,3组大鼠均同时灌胃给予3个探针药物,用HPLC法同时测定大鼠体内3个探针底物的血药浓度,DAS2.0软件计算药动学参数.结果 大鼠单独和同时给予茶碱、氯唑沙宗和氨苯砜后,各探针的t1/2、AUC、CL和Cmax等药动学参数在统计学上均无显著性差异(P>0.05).结论 茶碱、氯唑沙宗和氨苯砜在同时给药时,彼此之间不会发生药动学上的相互作用,可作为Cocktail探针分别用于评价药物对CYP1A2、CYP2E1和CYP3A4活性的影响.     

中国汉族和蒙古族健康人药物代谢酶CYP3A4、CYP2C9、CYP2C19、CYP2D6基因多态性分析

 目的 用基因分型技术对中国汉族、蒙古族健康人CYP3A4、CYP2C9、CYP2C19、CYP2D6进行基因多态性分析,并对汉族人和蒙古族人基因表型和基因频率进行比较。方法 聚合酶链反应-限制性片段长度多态性(PCR-RFLP)对CYP3A4、CYP2C9、CYP2C19、CYP2D6进行分型。结果 汉族、蒙古族健康人CYP3A4*5等位基因频率为0, CYP3A4*18等位基因频率分别为0.183 8、0.202 5,CYP2C9*2等位基因频率分别为0.011 0、0.025 3, CYP2C9*13等位基因频率分别为0、0.00 32,CYP2C19*2等位基因频率分别为0.386 0、0.4146, CYP2C19*3等位基因频率分别为0.051 5、0.044 3,CYP2D6*10等位基因频率分别为0.573 5、0.465 2。结论 汉族、蒙古族健康人群CYP3A4*18、CYP2C19*2、CYP2C19*3、CYP2D6*10等位基因频率均没有显著性差异;本试验在汉族、蒙古族健康人中未发现CYP3A4*5等位基因;仅在蒙古族健康受试人群中发现1人为CYP2C9*1/*13基因型;蒙古族CYP2C9*2等位基因频率远小于汉族（P=0.023）。     

Inhibitory effects of cytochrome P450 enzymes CYP2C8, CYP2C9, CYP2C19 and CYP3A4 by Labisia pumila extracts

Ethnopharmacological relevance

Labisa pumila (LP), popularly known with its local name, Kacip Fatimah, is a well known herb grown in Indochina and Southeast Asia and is traditionally used to regain energy after giving birth in women. The propensity of LP to cause drug–herb interaction via cytochrome P450 (CYP) enzyme system has not been investigated.

Aim of the study

To evaluate the in vitro inhibitory effects of various LP extracts (aqueous, ethanol, dichloromethane (DCM) and hexane) on cytochrome P450 2C8 (CYP2C8), CYP2C9, CYP2C19 and CYP3A4 activities.

Materials and methods

Probe substrate-based high performance liquid chromatography (HPLC) methods were established for CYP2C9, CYP2C19 and CYP3A4 whereas a fluorescence-based enzyme assay was established for CYP2C8. The metabolite formations were examined after incubation of probe substrate with respective CYP isoform in the present or absent of LP extracts. The inhibitory effect of LP was characterized with kinetic parameters IC₅₀ and K_i values.

Results

LP extracts showed differential effect of CYP activities with the order of inhibitory potency as follows: dichloromethane>hexane>ethanol>aqueous. This differential effect was only observed in CYP2C isoforms but not CYP3A4. Both the hexane and DCM extracts exhibited moderate to potent inhibition towards CYP2C activities in different modes including non-competitive, competive and mixed-type. The DCM effect was notably strong for CYP2C8 and CYP2C9 showing K_i values of below 1 μg/ml. The selectivity of LP for CYP2C isoforms rather than CYP3A4 may be attributed to the presence of relatively small, lipophilic yet slightly polar compounds within the LP extracts.

Conclusions

The results of our study revealed that phytoconstituents contained in LP, particularly in hexane and dichloromethane extracts, were able to selectively inhibit CYP2C isoforms. The inactivation was characterized by low K_i values, in particular, in CYP2C8 and CYP2C9. These in vitro data indicate that LB preparations contain constituents that can potently inhibit CYP2C activities and suggest that this herb should be examined for potential pharmacokinetic drug interactions in vivo.     

Effects of Panax notoginseng saponins on the activities of CYP1A2, CYP2C9, CYP2D6 and CYP3A4 in rats in vivo

The aim of this study was to assess the influence of the Panax notoginseng saponins (PNS) on the activities of the drug‐metabolizing enzymes cytochrome P450 (CYP450) 1A2, 2 C9, 2D6 and 3A4 in rats. The activities of CYP1A2, 2 C9, 2D6 and 3A4 were measured using specific probe drugs. After pretreatment for 1 week with PNS or physiological saline (control group), probe drugs caffeine (10 mg/kg; CYP1A2 activity), tolbutamide (15 mg/kg; CYP2C9 activity), metoprolol (20 mg/kg; CYP2D6 activity) and dapsone (10 mg/kg; CYP3A4 activity) were administered to rats by intraperitoneal injection. The blood was then collected at different times for ultra performance liquid chromatography/tandem mass spectrometry (UPLC‐MS/MS) analysis. The data showed that PNS exhibited an induction effect on CYP1A2 by decreasing caffeine C_max (36.3%, p < 0.01) and AUC_0‐∞ (22.77%, p < 0.05) and increasing CL/F (27.03%, p < 0.05) compared with those of the control group. Western blot analysis was used to detect the effect of PNS on the protein level of CYP1A2, and the results showed that PNS could upregulate the protein expression of CYP1A2. However, no significant changes in CYP2C9, 2D6 or 3A4 activities were observed. In conclusion, the results indicate that PNS could induce CYP1A2, which may affect the disposition of medicines primarily dependent on the CYP1A2 pathway. Our work may be the basis of related herb–drug interactions in the clinic. Copyright © 2011 John Wiley & Sons, Ltd.     

Potent CYP3A4 inhibitory constituents of Piper cubeba

The EtOAc-soluble fraction of the water extract of Piper cubeba, having shown potent inhibitory activity on the metabolism mediated by CYP3A4, was subjected to activity-guided isolation to yield two new lignans, (8R,8'R)-4-hydroxycubebinone (1) and (8R,8'R,9'S)-5-methoxyclusin (2), and two new sesquiterpenes, (5 alpha,8 alpha)-2-oxo-1(10),3,7(11)-guaiatrien-12,8-olide (3) and (1 alpha,2 beta,5 alpha,8 alpha 10 alpha)-1,10-epoxy-2-hydroxy-3,7(11)-guaiadien-12,8-olide (4), along with 16 known compounds (5-20). The structures of the isolated compounds were elucidated on the basis of spectroscopic and chemical analyses. The isolated compounds were tested for their inhibitory activity on the metabolism mediated by CYP3A4 or CYP2D6 using [N-methyl-(14)C]erythromycin or [O-methyl-(14)C]dextromethorphan as a substrate, respectively. The compounds (8R,8'R,9'S)-5-methoxyclusin (2), (-)-clusin (10), (-)-yatein (13), ethoxyclusin (15), and (-)-dihydroclusin (17), having one methylenedioxyphenyl moiety in their structures, showed very potent and selective inhibitory activity against CYP3A4 with IC(50) values (0.44-1.0 microM) identical to that of the positive control, ketoconazole (IC(50), 0.72 microM).     

The in vitro inhibition of human CYP1A2, CYP2D6 and CYP3A4 by tetrahydropalmatine, neferine and berberine

The purpose of this study was to investigate the in vitro inhibition potential of the three purified herbal constituents tetrahydropalmatine (Tet), neferine (Nef) and berberine (Ber) towards recombinant human CYP1A2, CYP2D6 and CYP3A4 metabolic activities. In vitro incubations were performed with phenacetin, dextromethorphan and testosterone, respectively, as CYP substrates and their metabolites were determined by validated HPLC methods. Positive control inhibitors were run for each CYP in all incubation series. Inhibition was expressed by IC₅₀ values. All herbal constituents demonstrated some, but variable, inhibition potencies towards the investigated CYP enzymes. CYP2D6 was the most sensitive for inhibition and then mainly by Tet and Ber with IC₅₀ values of 3.04 ± 0.26 µm and 7.40 ± 0.36 µm , respectively. CYP3A4 and especially CYP1A2 were inhibited to a much smaller extent by all constituents. Neferine showed the lowest overall interaction potential towards the CYP enzymes investigated. The CYP inhibition potential for the purified constituents could be related to their chemical structures. No clinical significant metabolic interaction seems likely to occur between the CYP enzymes and herbal constituents tested, with a possible exception for the CYP2D6 inhibition by Tet and Ber. Copyright © 2011 John Wiley & Sons, Ltd.