三七总皂苷主要成分对人肝微粒体CYP3A4酶的抑制作用研究

目的：研究三七总皂苷主要成分人参皂苷Rg1、人参皂苷Rb1和三七皂苷R1对人肝微粒体CYP3A4酶的体外抑制作用.方法：采用人肝微粒体体外孵育法,在孵育体系中分别加入不同浓度的人参皂苷Rg1、人参皂苷Rb1和三七皂苷R1与探针底物睾酮共孵育,用LC-MS /MS 法测定代谢产物6β-羟基睾酮的生成量反映CYP3A4酶活性的影响.结果：人参皂苷Rg1在2～1 000 μmol·L-1的测试浓度范围内对CYP3A4未见剂量相关的抑制作用;人参皂苷Rb1在2～200 μmol·L-1的测试浓度范围内对CYP3A4未见剂量相关的抑制作用,在1 000 μmol·L-1的测试浓度下对CYP3A4具有轻微抑制作用;三七皂苷R1在2～1 000 μmol·L-1的测试浓度范围内对CYP3A4的IC50为126 μmol·L-1（＞100 μmol·L-1）.结论：三七总皂苷3个主要有效成分单体对CYP3A4酶的体外抑制作用不同,人参皂苷Rg1无抑制作用,人参皂苷Rb1高浓度下有轻微抑制作用,三七皂苷R1有弱抑制作用,三七总皂苷制剂与CYP3A4酶代谢相关的药物之间产生相互作用的可能性低.     

灯盏细辛注射液对大鼠肝微粒体CYP3A的抑制作用

目的：研究灯盏细辛注射液对大鼠肝微粒体CYP3A酶活性的抑制作用。方法：在体外大鼠肝微粒体孵育体系中加入底物睾酮和不同体积的灯盏细辛注射液,用高效液相色谱法测定睾酮的羟化代谢产物6β-羟基睾酮的生成量反映CYP3A酶的活性。酮康唑用作阳性对照药。结果：在体外孵育体系中,灯盏细辛注射液对大鼠肝微粒体CYP3A酶活性有抑制作用,IC50和Ki值分别为0.40%和0.24%（V/V）。结论：体外给药灯盏细辛注射液对大鼠肝微粒体CYP3A酶活性有抑制作用,符合混合型抑制模型。     

高效液相色谱法检测人肝微粒体CYP3A活性

目的：测定普罗帕酮和N 去丙基普罗帕酮的比值以表达人肝微粒体中CYP3A的活性。方法：以1 mg·mL 1微粒体蛋白浓度37℃孵育普罗帕酮1 h，以HPLC测定普罗帕酮和N 去丙基普罗帕酮的含量。结果： 普罗帕酮和N 去丙基普罗帕酮的线性方程分别为Y＝0.452 0X＋0.003 029(r＝0.999 7)；Y＝1.137 3X＋0.012 740(r＝0.998 5)。结论：N 去丙基普罗帕酮与普罗帕酮的最大比值为1.54，CYP3A具有饱和性。     

重组肝CYP3A4与CYP3A29细胞微粒体药物代谢动力学比较

目的 比较巴马小型猪CYP3A29和人CYP3 A4稳定表达重组肝癌细胞株微粒体的药物代谢特征,在分子水平为巴马小型猪作为临床前药物代谢实验动物提供科学依据.方法 以CYP3A特异性代谢底物硝苯地平、睾酮及其抑制药酮康唑为探针药物,将探针药物与重组CYP3A4、CYP3A29细胞微粒体在优化的微粒体浓度、药物浓度、孵育时间等条件下进行体外孵育,高效液相色谱法检测其药物代谢(抑制)动力学参数,并将二者进行比较分析.结果 巴马小型猪CYP3A29与CYP3A4在硝苯地平和睾酮代谢差异无统计学意义(P＞0.05).酮康唑的抑制活性为:当代谢底物为硝苯地平时,酮康唑对CYP3A29和CYP3A4的半数抑制浓度分别为0.090,0.132 μmol·L-1(P＜0.05);当代谢底物为睾酮时,酮康唑对CYP3A29和CYP3A4的半数抑制浓度分别为0.056,0.032 μmol·L-1(P＜0.05).结论 重组CYP3A29与CYP3 A4细胞微粒体对硝苯地平和睾酮活性差异不显著;酮康唑对重组CYP3A29与CYP3A4细胞微粒体硝苯地平和睾酮代谢活性有差异.     

Prediction of In Vivo Interaction Between Triazolam and Erythromycin Based on In Vitro Studies Using Human Liver Microsomes and Recombinant Human CYP3A4

Purpose. To quantitatively predict the in vivo interaction betweentriazolam and erythromycin, which involves mechanism-basedinhibition of CYP3A4, from in vitro studies using human liver microsomes(HLM) and recombinant human CYP3A4 (REC). Methods. HLM or REC was preincubated with erythromycin in thepresence of NADPH and then triazolam was added. - and 4-hydroxy(OH) triazolam were quantified after a 3 min incubation and the kineticparameters for enzyme inactivation (k_inact and K _app) were obtained.Drug-drug interaction in vivo was predicted based on aphysiologically-based pharmacokinetic (PBPK) model, using triazolam anderythromycin pharmacokinetic parameters obtained from the literature and kineticparameters for the enzyme inactivation obtained in the in vitro studies. Results. Whichever enzyme was used, triazolam metabolism was notinhibited without preincubation, even if the erythromycin concentrationwas increased. The degree of inhibition depended on preincubationtime and erythromycin concentration. The values obtained for k_inactand K _app were 0.062 min^–1 and 15.9 M (-OH, HLM), 0.055 min^–1and 17.4 M (4-OH, HLM), 0.173 min^–1 and 19.1 M (-OH, REC),and 0.097 min^–1 and 18.9 M (4-OH, REC). Based on the kineticparameters obtained using HLM and REC, the AUCpo of triazolamwas predicted to increase 2.0- and 2.6-fold, respectively, followingoral administration of erythromycin (333 mg t.i.d. for 3 days), whichagreed well with the reported data. Conclusions. In vivo interaction between triazolam and erythromycinwas successfully predicted from in vitro data based on a PBPK modelinvolving a mechanism-based inhibition of CYP3A4.     

Human PXR-mediated transcriptional activation of CYP3A4 by ‘Fuzi’ extracts

Objective: This study focused on determining whether the ‘Fuzi’ (FZ) extracts from different extraction methods are related to pregnane X receptor (PXR) and cytochrome P450 3A4 (CYP3A4), and explore the mechanism.

Methods: FZ was extracted under various conditions, and the components were identified by Ultra Performance Liquid Chromatography/Quad Time of Flight Mass Spectrometry (UPLC/Q-TOF-MS). Annexin V-FITC and propidium iodide staining assays were used to measure the cell cytotoxicity of these extracts. Real-time PCR, western blot analysis and reporter gene assay were used to detect the expression changes of PXR and CYP3A4.

Results: FZ extracts were found to contain high levels of monoester-diterpene alkaloids (MDAs) and diester-diterpene alkaloids (DDAs). FZ extracts were cytotoxic. Interestingly, we found that FZ extracts and DDAs can induce the expressions of PXR and CYP3A4. And the MDAs can inhibit the expressions of PXR and CYP3A4.

Conclusion: Different extracts of FZ can induce the expressions of PXR and CYP3A4 in different degrees. This may be related to the drug-drug interactions.     

PXR受体调控的CYP3A诱导及其在药物代谢中的重要意义

机体每日都要接触大量外源性化合物（xenobiotics），包括环境、饮食、药物中的各种成分，其中亲脂性化合物如果不能被及时代谢为极性化合物，就会在肝脏蓄积并影响机体正常生理功能，产生毒性甚至致癌。细胞色素P450（CYPS）属于血红素蛋白基因超家族，编码一系列代谢酶系统，参与各类不同结构亲脂性化合物的生物转化，增强代谢物水溶性，利于排出体外，     

大鼠肝微粒体法测定3种中药对CYP3A4 亚型的作用

［摘要］目的建立肝微粒体测定法,观察中药制剂对CYP3A4 亚型的作用。方法取大鼠肝脏,制备肝微粒体,分别优化肝微粒体体外温孵系统的反应时间、蛋白浓度及探针药物咪达唑仑的浓度;高效液相色谱 质谱联用（HPLC MS MS）法测定大鼠肝微粒体中咪达唑仑的浓度,计算咪达唑仑的活性;在肝微粒体体外温孵系统中分别加入不同浓度的血脂康胶囊、通心络胶囊、枣仁安神胶囊内容物及对照药物酮康唑,测定其半数抑制浓度（IC50）及抑制常数（Ki）。结果肝微粒体体外温孵系统的反应条件为0.4 g&;#8226;L 1大鼠肝微粒体,4 μmol&;#8226;L 1咪达唑仑溶液,37 ℃温育5 min。酮康唑、血脂康胶囊、通心络胶囊的IC50分别为（3.4±0.2）,（25.1±0.3）,（56.2±0.3） mg&;#8226;L 1,枣仁安神胶囊的IC50﹥150 mg&;#8226;L 1;酮康唑、血脂康胶囊、通心络胶囊的Ki分别为（1.7±0.1）,（25.0±0.2）,（50.0±0.3） mg&;#8226;L 1。结论建立了中药制剂对CYP3A4亚型作用的大鼠肝微粒体研究模型。血脂康胶囊和通心络胶囊对大鼠CYP3A4亚型有较弱的抑制作用。     

Roles of Different CYP Enzymes in the Formation of Specific Fluvastatin Metabolites by Human Liver Microsomes

Abstract: Fluvastatin has been considered to be metabolised to 5‐hydroxy fluvastatin (M‐2), 6‐hydroxy fluvastatin (M‐3) and N‐desisopropyl fluvastatin (M‐5) in human liver microsomes by primarily CYP2C9. To elucidate the contribution of different CYP enzymes on fluvastatin metabolism, we examined the effect of CYP inhibitors and CYP2C‐specific monoclonal antibodies on the formation of fluvastatin metabolites in human liver microsomes. Human liver microsomes were incubated with fluvastatin with or without pre‐treatment with CYP inhibitors or monoclonal antibodies. Selective inhibitors of CYP2C9 (sulfaphenazole), CYP3A (ketoconazole) and CYP2C8 (quercetin) were employed and monoclonal antibodies were against CYP2C8, CYP2C9, CYP2C19 and CYP2C8/9/18/19. According to the amount of fluvastatin metabolites produced, the formation of M‐3 was found to be major pathway of fluvastatin metabolism (the relative contribution was calculated to be more than 80%). Sulfaphenazole inhibited the formation of M‐2 largely, but had little effect on the formation of M‐3. It also inhibited the formation of M‐5. Ketoconazole markedly inhibited the formation of M‐3, but did not inhibit the formation of M‐2 and M‐5. Quercetin had a moderate inhibitory effect on the formation of all three fluvastatin metabolites. Monoclonal antibodies against CYP2C9 and CYP2C8/9/18/19 markedly inhibited the formation of M‐2 and M‐5. None of monoclonal antibodies showed clear inhibition on the formation of M‐3. In contrast to previous published work, our results suggest that M‐2 and M‐5 are formed preferentially by CYP2C9, and that M‐3 is mainly formed by CYP3A. In summary, the results contribute to a better understanding of the drug‐drug interaction potential for fluvastatin in vivo.     

Pogostone inhibits the activity of CYP3A4, 2C9, and 2E1 in vitro

ContextPogostone possesses various pharmacological activities, which makes it widely used in the clinic. Its effect on the activity of cytochrome P450 enzymes (CYP450s) could guide its clinical combination.ObjectiveTo investigate the effect of pogostone on the activity of human CYP450s.Materials and methodsThe effect of pogostone on the activity of CYP450s was evaluated in human liver microsomes (HLMs) compared with blank HLMs (negative control) and specific inhibitors (positive control). The corresponding parameters were obtained with 0–100 μM pogostone and various concentrations of substrates.ResultsPogostone was found to inhibit the activity of CYP3A4, 2C9, and 2E1 with the IC₅₀ values of 11.41, 12.11, and 14.90 μM, respectively. The inhibition of CYP3A4 by pogostone was revealed to be performed in a non-competitive and time-dependent manner with the K_i value of 5.69 μM and the KI/K_inact value of 5.86/0.056/(μM/min). For the inhibition of CYP2C9 and 2E1, pogostone acted as a competitive inhibitor with the K_i value of 6.46 and 7.67 μM and was not affected by the incubation time.Discussion and conclusionsThe inhibitory effect of pogostone on the activity of CYP3A4, 2C9, and 2E1 has been disclosed in this study, implying the potential risk during the co-administration of pogostone and drugs metabolized by these CYP450s. The study design provides a reference for further in vivo investigations to validate the potential interaction.     

Comparative analysis of substrate and inhibitor interactions with CYP3A4 and CYP3A5

To evaluate the role that cytochrome (CYP) 3A5 plays in hepatic drug metabolism, the substrate selectivity and inhibitory potential of over 60 compounds towards CYP3A4 and CYP3A5 were assessed using Escherichia coli recombinant cell lines. CYP3A4-mediated metabolism predominated for many of the compounds studied. However, a number of drugs gave similar CL_int estimates using CYP3A5 compared with CYP3A4 including midazolam (CL_int?=?3.4 versus 3.3?µl?min^–1?pmol^–1). Significant CYP3A5-mediated metabolism was also observed for several drugs including mifepristone (CL_int?=?10.3 versus 2.4?µl?min^–1?pmol^–1), and ritonavir (CL_int?=?0.76 versus 0.47?µl?min^–1?pmol^–1). The majority of compounds studied showed a greater inhibitory potential (IC₅₀) towards CYP3A4 compared with CYP3A5 (eightfold lower on average). A greater degree of time-dependent inhibition was also observed with CYP3A4 compared with CYP3A5. The range of compounds investigated in the present study extends significantly previous work and suggests that CYP3A5 may have a significant role in drug metabolism particularly in populations expressing high levels of CYP3A5 and/or on co-medications known to inhibit CYP3A4.     

蛇葡萄素在大鼠肝微粒体中的代谢动力学及药用辅料对其抑制作用的研究

目的 研究蛇葡萄素在大鼠肝微粒体的代谢规律及药用辅料对其代谢的影响。方法 建立UPLC-MS/MS方法学体系,通过检测代谢反应体系的蛇葡萄素剩余浓度进行体外代谢反应条件的筛选和代谢规律的评价。结果 反应体系的孵育时间、肝微粒体浓度及蛇葡萄素浓度均对代谢产生影响,大鼠肝细胞色素P450亚酶CYP3A、CYP1A1/2和CYP2E1对蛇葡萄素代谢起主要作用。药用辅料对蛇葡萄素代谢的抑制作用呈剂量依赖性,其中聚氧乙烯氢化蓖麻油40、吐温80、聚维酮K30、羟丙基β环糊精、普朗尼克F68以混合竞争模式显著抑制蛇葡萄素的代谢。结论 这些药用辅料有望通过抑制代谢作用来提高蛇葡萄素的口服生物利用度。     

大鼠肝微粒体中CYP2C9酶的活性及动力学研究

目的 以双氯芬酸为探针药,建立HPLC测定大鼠肝微粒体CYP2C9酶活性的方法,并对其进行动力学考察。方法 采用Agilent ZORBAX SB-C18色谱柱;流动相为乙腈-水-0.1%三氟乙酸,梯度洗脱;流速为1 mL·min^-1;柱温30 ℃;检测波长为278 nm。大鼠肝微粒体加入双氯芬酸钠孵育30 min后,用盐酸和乙酸乙酯终止反应,加入内标地西泮,涡旋后高速离心,取上层有机相吹干复溶进样检测;以Lineweaver-Burk作图计算Km和Vmax。结果 双氯芬酸、4-羟基双氯芬酸和内标分离良好且无内源性干扰。4-羟基双氯芬酸浓度在0.05-10 μmol·L^-1内线性关系良好（r=0.999 8）,定量下限为0.05 μmol·L^-1;日内、日间精密度均〈10%,回收率〉75%。动力学考察表明选择盐酸和乙酸乙酯作为终止试剂效果良好,测得大鼠肝微粒体中双氯芬酸羟化反应的Km为26.87 μmol·L^-1,Vmax为2.359 nmol·min^-1·mg^-1 pro。结论 该方法稳定,结果能准确反映CYP2C9酶的活性,可用于相关动力学研究。     

In vivo inhibition of CYP3A-mediated midazolam metabolism by anchusan in rats

Cytochrome P450 (CYP)-mediated drug interactions caused by Kampo medicine have not been investigated sufficiently. The current study was conducted to reveal the effect of anchusan, a commonly used Kampo formula for gastrointestinal disease, on CYP3A-mediated drug metabolism in rats. The pharmacokinetics of midazolam (MDZ) was investigated after the single or one-week administration of anchusan (500 mg/kg) to evaluate its inhibitory and inducible effect on CYP3A, respectively. MDZ was administrated 16 h after the last anchsan treatment in the multiple dose study, while their intervals were 2 or 16 h in the single dose study. Unexpectedly, the multiple-pretreatment of anchusan increased the AUC of MDZ by 2.4-fold rather than decreasing it, and the CYP3A contents and activities were unchanged in hepatic and intestinal microsomes of these rats. In contrast, no significant inhibitory effects on MDZ metabolism were observed by the single anchusan pretreatment. In vitro study showed that the preincubation of anchusan and some of its component extracts with rat liver microsomes reduced CYP3A activity in a time- and NADPH-dependent manner. These results suggested that anchusan increased the serum MDZ concentration in rats, at least in part, by the time-dependent inhibition of CYP3A.     

Stereoselective Metabolism of Bupropion by Cytochrome P4502B6 (CYP2B6) and Human Liver Microsomes

Purpose Hydroxylation of the antidepressant and smoking deterrent drug bupropion is a clinically important bioactivation and elimination pathway. Bupropion hydroxylation is catalyzed selectively by cytochrome P4502B6 (CYP2B6). CYP2B6-catalyzed bupropion hydroxylation has been used as an in vitro and in vivo phenotypic probe for CYP2B6 activity and CYP2B6 drug interactions. Bupropion is chiral, used clinically as a racemate, and disposition is stereoselective. Nevertheless, it is unknown whether CYP2B6-catalyzed bupropion hydroxylation is stereoselective. Methods Hydroxylation of racemic bupropion by recombinant CYP2B6 and human liver microsomes was evaluated using a stereoselective assay. Results At therapeutic concentrations, hydroxylation of (S)-bupropion was threefold and 1.5-greater than (R)-bupropion, respectively, by recombinant CYP2B6 and human liver microsomes. In vitro intrinsic clearances were likewise different for bupropion enantiomers. Conclusions Stereoselective bupropion hydroxylation may have implications for the therapeutic efficacy of bupropion as an antidepressant or smoking cessation therapy, and for the use of bupropion as an in vivo phenotypic probe for CYP2B6 activity.     

Substrate-dependent modulation of the catalytic activity of CYP3A by erlotinib

Aim:

To ascertain the effects of erlotinib on CYP3A, to investigate the amplitude and kinetics of erlotinib-mediated inhibition of seven major CYP isoforms in human liver microsomes (HLMs) for evaluating the magnitude of erlotinib in drug-drug interaction in vivo.

Methods:

The activities of 7 major CYP isoforms (CYP1A2, CYP2A6, CYP3A, CYP2C9, CYP2D6, CYP2C8, and CYP2E1) were assessed in HLMs using HPLC or UFLC analysis. A two-step incubation method was used to examine the time-dependent inhibition of erlotinib on CYP3A.

Results:

The activity of CYP2C8 was inhibited with an IC₅₀ value of 6.17±2.0 μmol/L. Erlotinib stimulated the midazolam 1′-hydroxy reaction, but inhibited the formation of 6β-hydroxytestosterone and oxidized nifedipine. Inhibition of CYP3A by erlotinib was substrate-dependent: the IC₅₀ values for inhibiting testosterone 6β-hydroxylation and nifedipine metabolism were 31.3±8.0 and 20.5±5.3 μmol/L, respectively. Erlotinib also exhibited the time-dependent inhibition on CYP3A, regardless of the probe substrate used: the value of K_I and k_inact were 6.3 μmol/L and 0.035 min⁻¹ for midazolam; 9.0 μmol/L and 0.045 min⁻¹ for testosterone; and 10.1 μmol/L and 0.058 min⁻¹ for nifedipine.

Conclusion:

The inhibition of CYP3A by erlotinib was substrate-dependent, while its time-dependent inhibition on CYP3A was substrate-independent. The time-dependent inhibition of CYP3A may be a possible cause of drug-drug interaction, suggesting that attention should be paid to the evaluation of erlotinib''s safety, especially in the context of combination therapy.     

Cocktail-substrate assay system for mechanism-based inhibition of CYP2C9, CYP2D6, and CYP3A using human liver microsomes at an early stage of drug development

1. We established a mechanism-based inhibition cocktail-substrate assay system using human liver microsomes and drug–probe substrates that enabled simultaneous estimation of the inactivation of main cytochrome P450 (CYP) enzymes, CYP2C9, CYP2D6, and CYP3A, in drug metabolism.

2. The inactivation kinetic parameters of typical mechanism-based inhibitors, tienilic acid, paroxetine, and erythromycin, for each enzyme in the cocktail-substrate assay were almost in agreement with the values obtained in the single-substrate assay.

3. Using this system, we confirmed that multiple CYP inactivation caused by mechanism-based inhibitors such as isoniazid and amiodarone could be detected simultaneously.

4. Mechanism-based inhibition potency can be estimated by the determination of the observed inactivation rate constants (k_obs) at a single concentration of test compounds because the k_obs of eleven CYP3A inactivators at 10?μM in the assay system nearly corresponded to k_inact/K_I values, an indicator of a compound’s propensity to alter the activity of a CYP in vivo (R²?=?0.97).

5. Therefore, this cocktail-substrate assay is considered to be a powerful tool for evaluating mechanism-based inhibition at an early stage of drug development.

     

磷酸哌喹有关物质的检测研究

目的建立高效液相色谱法测定磷酸哌喹中的有关物质,考察磷酸哌喹对光的稳定性。方法采用Agilent C18柱,以0.04mol.L-1磷酸二氢钾-乙腈-三乙胺（90∶10∶0.2,用磷酸调节pH至2.5）为流动相,流速：0.5mL.min-1,检测波长：230nm,柱温：25℃。结果磷酸哌喹有关物质含量为0.21%~0.39%,强光照射10d后有明显增加。结论本法准确可靠,简便快捷,适用于磷酸哌喹的质量控制。     

CYP3A4高表达细胞模型及其应用于药物代谢研究进展

细胞色素P450酶3A4(cytochrome P450 3A4,CYP3A4)属于细胞色素P450酶家族,参与多种化合物代谢及相互作用,是药物(尤其是口服药物)筛选和代谢研究的重要对象。该文按年代顺序对国外文献中CYP3A4高表达细胞模型的建立及在药物代谢中的应用进行综述,旨在将这一有价值的模型引入到新药研究中。