细胞色素P450酶系在药物代谢中的作用

该文从细胞色素P450概述、参与药物代谢的人类细胞色素P450亚型、细胞色素P450与药物的相互作用、细胞色素P450多态性在药物不良反应中的作用及细胞色素P450酶系产生药物不良反应的机制等方面综述细胞色素P450酶系对药物代谢的影响，为指导临床合理用药，避免药物不良反应及个体化用药提供参考。     

炎症过程中细胞色素P450酶活性降低及其机制的研究进展

机体在感染或炎症状态下,肝脏细胞色素P450药物代谢酶mRNA表达和蛋白含量显著降低,酶的催化活性降低。这种变化对人体内药物代谢过程乃至相关药物临床治疗安全性具有显著影响。细胞色素P450异构酶活性降低具有不同的变化过程与模式,反映细胞色素P450酶系具有多种活性调节机制。现有研究表明,细胞色素P450酶活性降低主要发生在基因表达环节,由多种炎症细胞因子介导。阐明炎症对细胞色素P450活性的影响有助于明确细胞色素P450酶活性的调控机制,对指导临床安全合理用药具有重要意义。     

细胞色素P450酶与药物选用

目的了解细胞色素P450酶与药物代谢关系,加强认识有利于临床药物选用。方法通过收集文献了解细胞色素P450酶在药物代谢中的作用。结果与结论正确认识细胞色素P450酶的特点,有利于临床药物选用,提高合理用药的水平。     

中成药对细胞色素P450酶的影响

通过参阅大量近年来国内外有关中成药对药物代谢酶细胞色素P450酶影响的文献,对中成药对细胞色素P450酶的研究的文献进行整理和分析.发现一些中成药对细胞色素P450酶确实存在不同程度的抑制或诱导作用.因此深入研究中成药对细胞色素P450酶活性的影响,既有助于指导中成药在临床上的合理使用以避免因药物相互作用导致的不良反应...     

细胞色素P450氧化酶基因多态性对药物代谢影响的研究进展

细胞色素P450氧化酶是人体内的一种重要代谢酶,它能代谢和/或活化许多种药物、前致癌物、前毒物和致变剂。细胞色素P450氧化酶的基因具有遗传多态性,在人类存在等位基因的突变体。本文从基因结构、底物和影响其活性的因素、遗传多态性的分子机制等方面综述细胞色素P450氧化酶的研究进展。     

探讨细胞色素P450酶系和药物的代谢情况

在药物代谢过程中细胞色素P450酶系具有十分重要的作用。此类酶主要存在于肝微粒当中,在生物转化过程承担了十分重要的功能。其活性与药物代谢速率具有密切的关联性,甚至可对药物清除产生直接作用。基于上述特点学术界将其作药物代谢过程中的第一相酶。本文对细胞色素P450酶系和药物的代谢进行了分析并对细胞色素P450酶系的作用进行了综合性阐述,提出了相应的观点,供以参考。     

细胞色素P450靶向抗肿瘤药物研发进展

细胞色素P450酶能催化各种内源性及外源性化合物的代谢,与多种肿瘤的发生发展有着密切关系,因此细胞色素P450酶靶向药物的研制已成为肿瘤治疗的新的研究方向之一,其中肿瘤特异性表达细胞色素P450酶成为研究热点。综述细胞色素P450酶靶向抗肿瘤药物研发进展,并介绍细胞色素P450 2W1及其靶向药物的研究近况。     

细胞色素P450酶系与药物代谢的相互作用

药物在体内代谢,不论是哪一种方式,都有酶的参与.与药物代谢关系最大的是细胞色素P450酶系,它主要存在于人体肝脏的微粒体中,故也称为肝微粒体酶,细胞色素酶是一种以铁卟啉为辅基的蛋白质(cytochrome protein),属于b族细胞色素,因还原型P450与一氧化碳的复合物P450-CO在450 nm处有一强吸收峰,故而得名细胞色素P450[1].该酶有许多同工酶,故称细胞色素P450酶系,简称为CYP450S.     

Cocktail探针药物法在中药细胞色素P450酶代谢研究中的应用

细胞色素P450酶是人体内最重要的药物代谢酶,中药可抑制或诱导某个或某些细胞色素P450亚酶,从而影响合用药物的代谢,导致药物相互作用发生。中药代谢研究是中药现代化研究的重要方面,可提高中药使用的有效性和安全性,促进临床合理用药。Cocktail探针药物法能全面、真实地反映药物代谢的过程,其优点在于多个代谢途径的信息可在单个实验过程获得,并将个体间影响降至最低,此法省时、经济。Cocktail探针药物法用于中药的代谢研究是一个比较新的研究领域,近几年开始有文献报道。该文介绍了Cocktail法在中药细胞色素P450酶代谢研究中的国内外应用进展,以期系统了解并指导该领域的研究。     

基于细胞色素P450酶的药物相互作用机制探讨

细胞色素P450酶是药物体内代谢的关键酶,药物合用时可能因与同一种代谢酶的相互作用,导致药物在体内的处置过程发生改变.本文旨在探讨常见的细胞色素P450酶相关药物相互作用类型和其机制,为临床联合用药的合理、安全、有效提供依据.     

Immunochemical analysis of cytochrome P450 variability in human leukapheresed samples and its consequences for the risk assessment process

Xenobiotic metabolizing cytochrome P450 (P450) enzymes were investigated in leukapheresed samples from 50 human individuals. It was the aim of the study (a). to get insight into the extent of extrahepatic P450 variability, (b). to investigate whether and to which extent P450 expression and variability as it is seen in the liver corresponds to P450 expression at extrahepatic sites, and (c). to contribute to the replacement of traditionally used default factors (usually 10 for interindividual variability) by data-derived factors in the risk assessment process. P450 enzymes were determined by Western Blotting. Immunoquantification was performed for P450 1A, 1B1, 2C, 2D6, 2E1, and 3A which were-with the exception of the polymorphically expressed CYP2D6-detectable in all samples investigated. Amounts of P450 enzymes in leukapheresed samples were (except CYP1B1) lower compared to those reported for the liver. The P450 variabilities were expressed by the ratios between the 95th and the 5th percentiles. They displayed 7-(CYP1A), 4-(CYP1B1), 6-(CYP2C), 30-(CYP2D6), 3-(CYP2E1), and 4-(CYP3A) fold variability in specific protein content. The results show (a). qualitative and quantitative differences in the expression of P450 proteins in leukapheresed samples from 50 individuals compared to liver, (b). a different extent of variability depending on the P450 enzyme, and (c). in cases where polymorphically distributed P450 enzymes are involved, the traditionally used factor of 10 might be too low to account for interindividual variability in both toxicokinetics and toxicodynamics.     

Cocktail法研究CYP450酶活性影响因素的探讨

细胞色素P450酶(cytochrome P450, CYP450)是药物代谢的重要酶系,研究CYP450对阐明药物代谢通路、相互作用、代谢多态性、指导临床合理用药等方面具有重要意义.混合探针底物法(Cocktail法)在研究CYP450亚型酶活性应用广泛,具有高效、准确、灵敏、高通量的特点.但CYP450亚型酶存在种属差异、性别差异、探针药物的特异性等方面的问题.查阅国内外相关文献,探讨Cocktail法研究CYP450酶活性的影响因素.     

Developmental Expression of Cytochrome P450 Enzymes in Human Liver

Abstract: Drug–metabolizing cytochrome P450 enzymes, the major phase I enzymes, are active in human liver already at very early stages of intrauterine development, although presumably at fairly low concentrations and in low numbers. During maturation, these enzymes go through various developmental programmes towards adulthood. The major increase both in abundance as well as in number of different enzymes takes place after birth, probably during the first year of life. Detailed information concerning these developmental changes is still limited. The major drug–metabolizing P450 enzymes appear to be primarily members of the CYP3A subfamily in all stages of development. The balance between different members of this subfamily, however, undergoes significant switches from the foetal predominant CYP3A7 to the major adult form CYP3A4. The ontogeny of the other cytochrome P450 enzymes is less well characterized, but the major switchon appears to occur mainly after birth. Developmental expression of P450 enzymes is one of the key factors determining the pharmacokinetic status of developing individuals both pre– and postnatally.     

非典型抗精神病的药物代谢及药物相互作用

对非典型抗精神病药物氯氮平（clozapine)，利培酮（risperidone), 奥氮平（olanzapine)，奎硫平（quetiapine)，齐派思酮（ziprasidone)，舍吲哚（sertindole)的相互作用进行综述。非典型抗精神病药的代谢主要由细胞色素P450催化，影响药物代谢酶活性的各种因素均可能导致非典型抗精神病药物代谢的改变，从而升高或者降低血药浓度，导致药理作用和毒性的增加或减少，预报药物相互作用时不仅要考虑联用药对酶的抑制作用，同时要考虑药物代谢的途径，对于多途径多酶催化代谢药物如：奎硫平、奥氮平等，尽管发生药物相互作用，但是多数相互作用无临床意义。对氯氮平、利培酮、齐派思酮，舍吲哚等由于代谢途径较少或者催化酶较为单一，则可能发生明显的具有临床意义的药物相互作用。     

P450 and carcinogenesis

Multiple forms of cytochrome P450 play important roles in metabolic activation of a variety of environmental procarcinogens. Large species differences in substrate specificities between experimental animals and humans are critical factors in evaluation of chemical safety. To study the role of human P450s in genotoxic activation of environmental chemicals, transgenic bacteria expressing both human P450s and P450 reductase have been developed for the mutagenicity test. Mice lacking CYP1A2, and CYP1B1, and CYP2E1 were prepared to investigate the mechanism of procarcinogen activation in vivo. The first human transgenic animals were mice carrying human fetus-specific CYP3A7. Using these transgenic mice, mutagenic activation of a natural mycotoxin, aflatoxin B1, catalyzed by CYP3A7 in vivo was demonstrated. This observation was clear in extrahepatic tissues that did not express mouse CYP3A enzymes. In conclusion, P450s are key factors involved in metabolic activation of environmental procarcinogens for their biological actions.     

Rat cytochrome p450 1A and 3A enzymes involved in bioactivation of tegafur to 5-fluorouracil and autoinduced by tegafur in liver microsomes.

Tegafur, an anticancer prodrug, is reported to be bioactivated to 5-fluorouracil (5-FU) by cytochrome P450 (P450) enzymes. Liver microsomal P450 enzymes involved in the biotransformation of tegafur into 5-FU in rats and the effect of tegafur in vivo on P450 levels in rats were investigated. Of 12 cDNA-expressed rat P450 enzymes tested, CYP1A2, CYP3A1, and CYP2C11 had high 5-FU formation rates from 100 microM and 1.0 mM tegafur concentrations. The contributions of CYP1A, CYP2C, and CYP3A enzymes to 5-FU formation in male rat liver microsomes were supported by immunoinhibition studies. 5-FU formation from tegafur, at substrate concentrations of 100 microM and 1.0 mM, was increased by intraperitoneal treatment of tegafur (50 mg/kg for 5 days) as well as by beta-naphthoflavone, phenobarbital, and dexamethasone. Orally administered tegafur (100 mg/kg daily for 20 days) caused the induction of CYP2B (5-fold) and of CYP1A and CYP3A (approximately 2-fold) and of 5-FU formation (approximately 2-fold) in rat liver microsomes. These results suggest that CYP1A and CYP3A enzymes, autoinduced by tegafur, have important roles in 5-FU formation from tegafur in rat liver microsomes. Coadministration of tegafur and P450-inducing drugs could markedly enhance the biotransformation of tegafur into 5-FU via P450 induction.     

Structure-activity relationship for human cytochrome P450 substrates and inhibitors

Criteria governing the avidity of substrate binding to human hepatic cytochromes P450 (CYP) associated with Phase 1 metabolism of drugs are described. The results of extensive quantitative structure-activity relationship (QSAR) analyses are reported for substrates of human P450s: CYPIA2, CYP2A6, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4, representing the enzymes exhibiting major involvement in the metabolism of drug substrates in Homo sapiens. In particular, it is shown that hydrogen bond properties in each class of enzyme-substrate complex are especially important factors in determining substrate binding affinity towards those human P450s which are involved in drug metabolism.     

Investigating human P450s involved in drug metabolism via homology with high-resolution P450 crystal structures of the CYP2C subfamily

The important role of high-resolution crystal structures of cytochrome P450 (CYP) enzymes for the generation of P450 models by homology is discussed. The main focus is on human P450 enzymes involved in drug metabolism, where the role of homology modelling has been emphasized in the recent literature. Report of the first human P450 crystal structure has provided an opportunity for comparison between those modelled from other crystallographic templates, and the recent substrate-bound rabbit CYP2C5 structure exemplifies the relevance of high-resolution template structures to generating 3-D models of P450s where the homology is relatively high. In particular, the homology models of human CYP1 and CYP2 family enzymes are presented, where good agreement with experiment findings are apparent.     

Porcine cytochrome 2A19 and 2E1

Cytochrome P450 (CYP) is a major group of enzymes, which conduct Phase I metabolism. Among commonly used animal models, the pig has been suggested as the most suitable model for investigating drug metabolism in human beings. Moreover, porcine CYP2A19 and CYP2E1 are responsible for the biotransformation of both endogenous and exogenous compounds such as 3‐methylindole (skatole), sex hormones and food compounds. However, little is known about the regulation of porcine CYP2A19 and CYP2E1. In this MiniReview, we summarise the current knowledge about the regulation of porcine CYP2A19 and CYP2E1 by environmental, biological and dietary factors. Finally, we reflect on the need for further research, to clarify the interaction between active feed components and the porcine CYP system.