肝体外代谢在中药活性成分研究中的应用进展

药物代谢系指药物进入体内后,在机体作用下发生的化学结构转化,即生物转化(Drug Biotransformation).转化在体内酶的作用下进行,能把外源性的物质进行化学处理,从而引起药物的药理活性和毒理活性的改变.近年来,模拟体内代谢过程的体外代谢研究方法迅速发展,通过离体器官、细胞或酶系统进行体外代谢研究[1].中药是一个复杂的体系,其有效成分或单体也作用于药物代谢酶系统,中药的体外代谢研究可以在短时间内得到大量的代谢产物,推断药物可能的代谢途径及参与代谢的酶,计算体内药物代谢的清除率,研究药物的相互作用[2],更好解释中药有效成分的作用机理,同时增强临床用药安全,为新药研究提供基础.     

体外代谢体系中中药及其成分对肝脏CYP450代谢酶抑制作用的研究进展

细胞色素P450 (CYP450)是肝微粒体中参与体内I相代谢反应的酶,临床上90%以上的药物都经CYP450氧化代谢,其被诱导或抑制是引起药物相互作用的主要机制。通过离体器官、细胞或酶系统进行的体外代谢研究以其精准、简化等特点近年来发展迅速。中药的体外代谢研究可推断药物可能的代谢途径和参与代谢的CYP450酶,研究药物的相互作用,更好地解释中药及其成分的作用机制,促进临床合理用药。本文就中药、中药成分、中药提取物在不同种属肝微粒体中对CYP450代谢酶活性的抑制作用进行综述,以期为中药-中药、中药-化学药物之间相互作用研究提供借鉴与参考。     

体外代谢技术在毒品检验中的应用进展

体外代谢技术是借助体外模型模拟研究药物体内代谢和转化途径基础上,确定代谢物,阐明药物作用机理的技术。与体内代谢方法相比,该技术排除了生物体内干扰因素和个体差异的影响,具有成本低、操作简单、重复性好等特点。本文在简要介绍体外代谢研究技术方法的基础上,着重对其在法庭科学毒品物证检验中的应用研究进行综述,以期为涉毒案件物证鉴定提供新的技术方法,进而为案件侦破和诉讼提供科学依据与证据支持。     

中药化学成分体内代谢产物的制备方法

传统中药多为口服用药,其在体内发挥药效的物质可能是中药中的化学成分,还可能是中药成分在体内的代谢产物,中药产生毒副作用和不良反应的原因也可能与中药成分的体内代谢产物有关。而迄今中药成分代谢产物的研究多局限在分析和结构推测鉴定水平,仅对少数可通过简单方法间接获取的代谢产物进行了较深入的生物学研究。因此,代谢产物的获取是深入研究其生物活性,进而明确中药药效和毒效的关键物质基础。本文结合本课题组近几年来的研究成果,对目前中药活性成分体内代谢产物的制备方法进行了总结和综述,希望能够为中药成分的体内代谢研究提供借鉴。     

土荆皮乙酸的代谢产物和代谢途径

综合运用体内实验和多种体外实验模型,分析了土荆皮乙酸(pseudolaric acid B,PB)的代谢情况。在口服和静脉注射给药实验中,使用HPLC和HPLC-ESI/MSn方法在大鼠血、尿、粪和胆汁样品中都检测到去甲基土荆皮乙酸(土荆皮丙2酸,pseudolaric acid C2,PC2),各种样品中几乎都检测不到原形药物,PC2是PB特异性的代谢产物。PB在肠内菌抑制大鼠模型中的代谢情况与正常组一致,说明其代谢与肠内菌无关。在人工胃、肠液中分别孵育48 h均无明显变化,说明胃蛋白酶和胰蛋白酶都不是主导PB代谢的因素,在胃肠道的pH环境下PB也是稳定的。在体外大鼠肝微粒体孵育模型中,PB仅有极少部分被代谢成为脱甲氧基或脱甲氧基脱羧基的产物,说明其代谢也不是由肝微粒体酶主导的。在体外全血孵育模型中,PB在1 h内被逐渐代谢成PC2,并表现出了与孵育时间相关的动力学特点。由此推测土荆皮乙酸一进入血液就被迅速代谢成PC2,以致于在各种样品中都几乎检测不到原形药。这种快速的代谢应该是通过血浆酯酶对PB的C-19酯键的迅速水解而实现的。本文首次初步阐明了PB在体内的代谢途径,对于明确中药土荆皮的有效物质基础、体内...     

药物肠代谢研究方法与中药肠代谢的研究进展

［摘要］介绍药物肠代谢研究方法以及中药肠代谢的研究进展。小肠在药物的首关代谢中日益受到重视,其研究的方法学也在不断改进,主要有体外法和在体法。体外法中重点介绍了肠微粒体法、完整组织系统法、Caco 2细胞模型法及肠组织切片法,从肠道内的Ⅰ相、Ⅱ相代谢酶对中药的作用提出肠道代谢的重要性。     

中药药动学研究进展

中药药动学是近10余年才迅速发展起来的药学新领域,主要研究中药单体、单方、复方在体内过程动态变化的规律,并将研究结果用数学方程和相关药动学参数来表达,反映了药物在体内的吸收、分布、代谢和排泄过程,具有整体、综合、动态和定量的特点。影响其特征的主要因素包括个体差异、年龄、疾病和生理等方面。其研究对阐明中药的药效物质基础、组方原理、作用机制,指导中药新制剂的研究和促进临床合理用药等方面都具有重要意义。目前,中药药动学研究方法主要有体内药物浓度法和生物效应法两大类。体内药物浓度法主要适用于有效成分明确的中药;…     

浅谈中药成分体内代谢研究

传统中药多为口服用药,这决定了中药成分在体内发挥药效的形式具有多样性。中药在体内发挥药效的物质可能是中药中的化学成分,还可能是中药成分在体内的代谢产物。尽管中药化学成分研究在过去的30年里取得了令人瞩目的成就,但中药成分的体内代谢研究一直进展缓慢。本文针对目前研究现状提出加快该领域研究的一些建议和想法,并通过一些研究实例揭示中药成分体内代谢研究在阐明中药药效物质等方面的作用。     

肝细胞代谢模型及色谱技术在药物代谢研究中的应用

药物代谢即药物的生物转化过程,研究药物代谢对于了解药物在体内的变化过程至关重要。药物代谢研究的方法主要分为体内和体外两种。体内代谢法因药物在生物体内的分布较广,加上代谢转化的器官和酶系的多样性,使药物及其代谢产物在体内的浓度比较低,代谢产物的检测具有一定的困难。体外代谢法在短时间内可以得到大量的代谢产物,且代谢条件可控,代谢体系比较“干净”,代谢物易于分离、提取,有利于代谢途径研究及代谢产物结构的确定等,因而,体外代谢法具有突出的优越性。     

抗肿瘤药LS-177在大鼠和人肝微粒体中的代谢产物研究

目的：推测LS-177在大鼠和人肝微粒体中代谢产物的结构及其可能的体外代谢途径。方法：体外孵育大鼠和人肝微粒体代谢模型,采用超高效液相质谱联用（LC-MSⁿ）法,推测LS-177的体外代谢产物的结构。结果：通过质谱数据、保留时间和碎片离子,在肝微粒体中共检测到5个代谢产物,初步推测LS-1177在肝微粒体中可能的代谢途径。结论：建立LC-MSⁿ方法,初步推测LS-177在大鼠和人肝微粒体中代谢产物的结构,为其体内外代谢的进一步研究以及化学结构类似物的体外代谢研究提供一定的参考依据。     

An assessment of human liver-derived in vitro systems to predict the in vivo metabolism and clearance of almokalant.

The ability of various human derived in vitro systems to predict various aspects of the in vivo metabolism and kinetics of almokalant have been investigated in a multicenter collaborative study. Although almokalant has been withdrawn from further clinical development, its metabolic and pharmacokinetic properties have been well characterized. Studies with precision-cut liver slices, primary hepatocyte cultures, and hepatic microsomal fractions fortified with UDP-glucuronic acid all suggested that almokalant is mainly glucuronidated to the stereoisomers M18a and M18b, which is in good agreement with the results in vivo. Both in vivo and in vitro studies indicate that the formation of M18b dominates over that of M18a, although the difference is more pronounced with the in vitro systems. Molecular modeling, cDNA-expressed enzyme analysis, correlation analysis, and inhibition studies did not clearly indicate which P450 enzymes catalyze the oxidative pathways, which may indicate a problem in identifying responsible enzymes for minor metabolic routes by in vitro methods. All of the in vitro systems underpredicted the metabolic clearance of almokalant, which has previously been reported to be a general problem for drugs that are cleared by P450-dependent metabolism. Although few studies on in vivo prediction of primarily glucuronidated drugs have appeared, in vitro models may consistently underpredict in vivo metabolic clearance. We conclude that in vitro systems, which monitor phase II metabolism, would be beneficial for prediction of the in vivo metabolism, although all of the candidate liver-derived systems studied here, within their intrinsic limitations, provided useful information for predicting metabolic routes and rates.     

糖脂代谢体外模型研究进展

糖代谢和脂代谢作为机体的两大基础代谢，二者的动态平衡对于维持机体稳态至关重要。目前糖尿病、超重和肥胖等糖脂代谢紊乱性疾病正严重危害公共卫生安全，由于发病机制复杂，相关药物研发亟需合适的糖脂代谢模型。此外，肿瘤细胞在适宜环境下表现出的无限增殖特性，主要是通过糖酵解和氧化磷酸化（OXPHOS）过程的相互转换实现的，因此糖脂代谢模型研究对于肿瘤治疗也有重要意义。体外3D模型可模拟细胞与细胞、细胞与细胞外基质相互作用，相较于2D模型而言更加接近体内环境，并可通过多细胞共培养进一步提高其体内相似性。细胞球样体和器官芯片是目前糖脂代谢体外研究的两种主要3D模型，对于糖脂代谢机制研究和药物筛选有重要作用，但这两种模型的糖脂代谢能力与生理水平相比仍有一定差距。     

Use of embryo culture to study normal development and developmental mechanisms.

Mammalian embryo culture techniques have been used to study many aspects of embryonic development. The advantages and limitations of such studies as models for in vivo development are discussed by reference to the following specific examples: development of the paraxial mesoderm, regulation of growth, protein uptake and metabolism, and carbohydrate metabolism. Embryo culture techniques are useful for the study of morphogenesis and growth because the embryo is made accessible for manipulation and observation. Development in vivo and in vitro over equivalent periods can be compared. The limitations of the system have important implications for the interpretation of studies of embryonic metabolism. In vitro metabolic activity can be assessed by assays of the culture media and embryonic tissue at intervals throughout the culture. However, the sensitivity of the metabolic pathways to explantation remains unknown because of the technical difficulties involved in studying embryonic metabolism in vivo.     

Metabolism of minaprine in human and animal hepatocytes and liver microsomes--prediction of metabolism in vivo

1. The metabolism of minaprine and its major metabolite p-hydroxyminaprine were studied using hepatocytes and liver microsomes from different species. Metabolism of this drug in vitro was then compared with in vivo data already published. 2. Our results showed that the major metabolic route (4-hydroxylation of the aromatic ring) is the same in the two experimental systems. Other in vivo biotransformation pathways (i.e. N-oxidation, reductive ring cleavage, N-dealkylation, oxidation) were also confirmed in hepatocytes. 3. Similar inter-species variability was observed both in vitro and in vivo. The present study has led to the same conclusion as previous in vivo metabolic investigations, namely, that metabolism in the dog quantitatively differs from that observed in other animal species. 4. These results clearly demonstrate that in vitro models (i.e. isolated hepatocytes and liver microsomes) are powerful tools in predicting the metabolic pathways of a drug in man and animal species.     

In vitro metabolism of methylene chloride in human and animal tissues: use in physiologically based pharmacokinetic models

Physiologically based pharmacokinetic (PB-PK) models describe the dynamic behavior of chemicals and their metabolites in individual tissues of living animals. Because PB-PK models contain specific parameters related to the physiological and biochemical properties of different species as well as the physical chemical characteristics of individual chemicals, they are useful tools for performing high dose/low dose, dose route, and interspecies extrapolations in hazard evaluations. An example of such extrapolation has been presented by M. E. Andersen, H. J. Clewell III, M. L. Gargas, F. A. Smith, and R. H. Reitz (Toxicol. Appl. Pharmacol. 87, 185-205, 1987), who employed a PB-PK model for methylene chloride (CH2Cl2) to estimate the chronic toxicity of this material. However, one limitation of this PB-PK model was that the metabolic rate constants for the glutathione-S-transferase (GST) pathway in humans were estimated by allometric scaling rather than from experimental data. In this paper we report studies designed to estimate the in vivo rates of metabolism of CH2Cl2 from in vitro incubations of lung and liver tissues from B6C3F1 mice, F344 rats, Syrian Golden hamsters, and humans. A procedure for calculating in vivo metabolic rate constants from the in vitro studies is presented. This procedure was validated by making extrapolations with mixed function oxidase enzymes (MFO) acting on CH2Cl2, where both in vitro and in vivo rates of metabolism are known. The in vitro rate constants for the two enzyme systems are consistent with the hypothesis presented by Andersen et al. that metabolism of CH2Cl2 occurs in vivo by two competing pathways: a high-affinity saturable pathway (identified as MFO) and a low-affinity first-order pathway (identified as GST). The metabolic rate constants for GST obtained from these studies are also consistent with the hypothesis of Andersen et al. that production of large quantities of glutathione/CH2Cl2 conjugates in vivo may increase the frequency with which lung and liver tumors develop in some species of animals (e.g., B6C3F1 mouse). When in vivo studies in humans are unavailable, in vitro enzyme assays provide a reasonable method for estimating metabolic rate constants.     

药物代谢清除率体外预测模型研究进展与问题分析

本文介绍了药物代谢清除率临床前预测的相关理论和数学模型，从而将所得的体外代谢清除率数据用于肝清除率的推算，并根据国内外学者对该预测方法准确度评估及体内体外相关性考察，指出该研究领域中出现的难点和可能的改进方案；以期使体内代谢行为的预测更加准确，并对尽早确定创新药物在人体内药物代谢动力学行为是否适合进行进一步研究开发具有重要的指导意义，并为今后创新药物的研发提供新的思路。     

Emerging role of drug interaction studies in drug development: the good,the bad,and the unknown

Significant scientific advancements in the last decade have armed researchers with tools to assess drug metabolism and the effects of drugs on metabolic pathways; however, most of this research has focused on cytochrome P450 isozymes. Early delineation of this information aids in the prediction of potential drug-drug interactions, which may ultimately determine whether a compound is pursued in the drug development process. The recent withdrawals of medications such as terfenadine, astemizole, cisapride, and mibefradil from the market demonstrate the relevance of this a priori approach--the risk of drug interactions was largely unrecognized prior to their approval by the Food and Drug Administration (FDA). Drug interaction studies for new drug applications (NDAs) field between 1987 and 1991 were largely in vivo studies with potential coadministered drugs, whereas for NDAs field between 1992 and 1997, the majority of studies involved metabolic mechanisms and in vitro methodology. Despite current limitations in the extrapolation of in vitro drug metabolism data to the in vivo environment, in vitro studies remain the mainstay of initial evaluations in this area primarily because of the high throughput nature of these investigations and the reduced cost compared with in vivo studies. The FDA has published several guidance documents in the area of drug metabolism and drug interaction studies in drug development with suggestions for in vitro as well as in vivo approaches to these investigations. Current and future research will likely focus on in vitro models for cytochrome P450 induction, Phase II metabolism, and drug transporters, and include validation and extrapolation of these approaches in vivo.     

FDA evaluations using in vitro metabolism to predict and interpret in vivo metabolic drug-drug interactions: impact on labeling.

Recent advances in in vitro metabolism methods have led to an improved ability to predict clinically relevant metabolic drug-drug interactions. To address the relationships of in vitro metabolism data and in vivo metabolism outcomes, the Office of Clinical Pharmacology and Biopharmaceutics in the Center for Drug Evaluation and Research, Food and Drug Administration, evaluated a number of recently approved new drug applications. The goal of these evaluations was to determine the contribution of in vitro metabolism data in (1) predicting in vivo drug-drug interactions, (2) determining the need to conduct an in vivo drug-drug interaction study, and (3) incorporating findings into drug product labeling. Ten cases are presented in this article. They fall into two major groups: (1) in vitro data were predictive of in vivo results, and (2) in vitro data were not predictive of in vivo results. Discussion of these cases highlights factors limiting predictability of in vivo metabolic interactions from in vitro metabolism data. The integration of these findings into drug product labeling is also discussed.     

Innovation for hepatotoxicity in vitro research models: A review

Many categories of drugs can induce hepatotoxicity, so improving the prediction of toxic drugs is important. In vitro models using human hepatocytes are more accurate than in vivo animal models. Good in vitro models require an abundance of metabolic enzyme activities and normal cellular polarity. However, none of the in vitro models can completely simulate hepatocytes in the human body. There are two ways to overcome this limitation: enhancing the metabolic function of hepatocytes and changing the cultural environment. In this review, we summarize the current state of research, including the main characteristics of in vitro models and their limitations, as well as improved technology and developmental prospects. We hope that this review provides some new ideas for hepatotoxicity research.     

用体外代谢数据预测临床上药物体内代谢性相互作用

用体外代谢数据可以预测临床上药物体内代谢的相互作用。本文介绍其中一些重要概念、预测模型、方法及影响预测准确性的因素。