银杏叶片对人药物代谢酶CYP2A6、XO和NAT2活性的影响

目的探讨银杏叶片对人肝脏药物代谢酶CYP2A6、XO和NAT2活性的影响,预测银杏叶片与常用药物的相互作用,指导临床合理用药.方法以咖啡因作为药物代谢酶CYP2A6、XO和NAT2的探针药物,以反相高效液相梯度洗脱法测定30名受试者服用银杏叶前后人尿液内咖啡因5种主要代谢物的相对含量,采用代谢物的比率分别评价人肝脏药物代谢酶CYP2A6、XO和NAT2活性的变化.结果受试者服药前CYP2A6、XO和NAT2平均活性为0.227±0.076、0.723±0.060和0.447±0.172;服用银杏叶片28d后CYP2A6、XO和NAT2平均活性为0.227±0.072、0.728±0.074和0.391±0.147;服药前后酶CYP2A6、XO的活性无显著性差异,酶NAT2的活性有显著性差异.结论银杏叶片可能不会影响其他经CYP2A6、XO酶代谢的药物临床疗效,但是可以影响与之合用经NAT2代谢的药物临床疗效.     

银杏叶片对人药物代谢酶CYP1A2与NAT2活性的影响

（1. ［摘要］目的探讨银杏叶片对人肝脏药物代谢酶CYP1A2和N 乙酰基转移酶（NAT2）活性的影响,预测银杏叶片与常用药物的相互作用,指导临床合理用药。方法以咖啡因作为药物代谢酶CYP1A2、NAT2的探针药物,以反相高效液相梯度洗脱法测定30例受试者服用银杏叶前后尿液内咖啡因5种主要代谢物的相对含量,采用代谢物的比值分别评价人肝脏药物代谢酶CYP1A2、NAT2活性的变化。结果受试者服药前CYP1A2、NAT2平均活性分别为2.976±1.428,0.447±0.172;服用银杏叶片28 d后CYP1A2、NAT2平均活性分别为3.021±1.318,0.391±0.147;服药前后CYP1A2的活性差异无显著性,NAT2的活性差异有显著性。结论银杏叶片对人药物代谢酶CYP1A2活性无明显影响,但是对NAT2的活性有明显影响;银杏叶片可能不会影响其他经CYP1A2酶代谢的药物临床疗效,但是可以影响与之合用经NAT2代谢的药物临床疗效。     

质子泵抑制剂对药物代谢酶CYP1A2、NAT2的影响分析

目的 以健康人群作为研究对象,从代谢表型探讨质子泵抑制剂与药物代谢酶CYP1A2、NAT2的关系.方法 以咖啡因作为药物代谢酶CYP1A2、NAT2的探针药物,用反相高效液相色谱(RP-HPLC)方法测定尿液中咖啡因代谢物.结果 健康人群CYP1A2酶活性指标呈对数正态分布,NAT2酶活性活性指标呈两态分布.结论 以咖啡因探针法测定正常人肝脏药物代谢酶CYP1A2、NAT2活性的RP-HPLC梯度洗脱直接进样法,为国内深入开展CYP1A2、NAT2代谢酶的研究开拓了一种新方法.     

奥美拉唑、兰索拉唑和泮托拉唑对黄嘌呤氧化酶活性的影响

目的:探讨奥美拉唑、兰索拉唑和泮托拉唑对药物代谢酶黄嘌呤氧化酶(XO)活性的影响,预测奥美拉唑、兰索拉唑和泮托拉唑与常用药物的相互作用,指导临床医师合理用药。方法:以咖啡因作为药物代谢酶XO的探针药物,以高效液相色谱法测定90名受试者分别服用奥美拉唑、兰索拉唑和泮托拉唑前后尿液内咖啡因2种主要代谢产物的相对含量,采用代谢物的比率评价药物代谢酶XO活性的变化。结果:服用奥美拉唑、兰索拉唑和泮托拉唑3种质子泵抑制剂前XO平均活性分别为(0.42±0.11),(0.37±0.13),(0.45±0.06);服药后活性分别为(0.40±0.09),(0.39±0.08),(0.43±0.08),服药前后药物代谢酶XO活性差异无显著性(P>0.05)。结论:短期内服用治疗剂量的奥美拉唑、兰索拉唑和泮托拉唑不会影响与之合用的需经XO代谢的药物疗效。     

HPLC直接进样测定咖啡因代谢物评价三种药物代谢酶活性

目的：建立测定尿中咖啡因的5种主要代谢物：5-乙酰氨基-6-甲酰氨基-3-甲基尿酸（AFMU）、1-甲基尿酸（1U）、1-甲基黄嘌呤（1X）、1，7-二甲基尿酸（17U）和1，7-二甲基黄嘌呤（17X）的高效液相色谱法，以评价N-乙酰基转移酶（NAT2）、细胞色素P450酶1A2（CYP1A2）和黄嘌呤氧化酶（XO）三种药物代谢酶的活性。方法：采用反相高效液相梯度洗脱法直接进样测定尿液内咖啡因代谢产物AFMU、1U、1X、17U和17X的相对含量，计算AFMU／（AFMU＋1X＋1U）、（AFMU＋1X＋1U）／17U和1U／（1X＋1U），绘制概率分布直方图，分别反映NAT2、CYP1A2和XO的活性。结果：NAT2活性呈两态分布，快、慢乙酰化代谢表型的临界点为0．26，CYP1A2和XO酶活性呈近似正态分布。结论：本方法简便、准确、快速，适合于尿中咖啡因代谢物的测定及NAT2、CYP1A2和XO等药物代谢酶活性的研究。     

藏药佐太对大鼠CYP1A2和NAT2活性的影响

目的:研究藏药佐太对大鼠细胞色素氧化酶(CYP1A2)、药物代谢酶N-乙酰基转移酶2(NAT2)活性的影响。方法:将70只SD大鼠随机均分为正常对照(生理盐水)组和佐太低、中、高剂量(1.2、3.8、12 mg/kg)单次给药组和多次给药组(每天1次,连续12 d),分别ig给药。正常对照组、佐太单次给药组于第2天,佐太多次给药组于第13天分别ig给予咖啡因(25 mg/kg),5 h后采集尿液,按10 mg/ml加入维生素C。采用高效液相色谱法测定大鼠尿液中咖啡因代谢物5-乙酰氨基-6-甲酰氨基-3-甲基尿酸(AFMU)、1-甲基黄嘌呤(1X)、1-甲基尿酸(1U)、1,7-二甲基尿酸(17U)的含量,以(AFMU+1X+1U)/17U、AFMU/(AFMU+1X+1U)比值来反映CYP1A2和NAT2活性。结果:与正常对照组比较,佐太中剂量单次给药组及多次给药组、高剂量多次给药组大鼠(AFMU+1X+1U)/17U、AFMU/(AFMU+1X+1U)比值降低,即CYP1A2和NAT2活性降低,差异有统计学意义(P<0.05)。结论:佐太对大鼠CYP1A2和NAT2活性有明显抑制作用。     

复方丹参滴丸对药物代谢酶CYP1A2，NAT2和XO活性影响的研究

目的 探讨复方丹参滴丸对CYP1A2,NAT2和XO活性的影响,指导临床医师合理用药。     

复方丹参滴丸对人肝脏药物代谢酶CYP1A2活性的影响

目的:研究复方丹参滴丸对人肝脏药物代谢酶CYP1A2活性的影响,指导临床合理用药。方法:采用反相高效液相色谱法测定服用复方丹参滴丸前、后人尿液内咖啡因4种主要代谢产物的相对含量;采用(AFMU+1X+1U)/17U比率法评价人肝脏药物代谢酶CYP1A2活性的变化。结果:受试者用药前CYP1A2的平均活性为4·20±1·54,服用复方丹参滴丸14d后CYP1A2的平均活性为4·26±1·95,用药28d后CYP1A2的平均活性为4·35±1·26,二者分别比用药前升高1·42%和3·57%,但无统计学差异。结论:服用治疗剂量的复方丹参滴丸对人肝脏药物代谢酶CYP1A2的活性无明显影响,不会影响与之合用的需经CYP1A2代谢药物的疗效。     

咖啡因探针法测定正常人肝脏药物代谢酶CYP1A2活性

目的:建立咖啡因4种主要代谢物含量的测定方法,探讨咖啡因代谢物在药物代谢酶CYP1A2活性评价中的意义。方法:采用反相高效液相梯度洗脱法测定尿液内咖啡因代谢产物5—乙酰氨基—6—甲酰氨基—3—甲基尿酸(AFMU)、1—甲基尿酸(1U)、1—甲基黄嘌呤(1X)和1,7—二甲基尿酸(17U)的相对含量,计算代谢物比率(AFMU+1X+1U)/17U,绘制频数分布直方图,评价CYP1A2活性。结果:受试者代谢物比率平均值为4.27,呈正态分布。结论:本方法简便、准确、快速,适合于尿液中咖啡因代谢物的测定及CYP1A2活性的研究。     

以咖啡因为代谢探针测定细胞色素P450 CYP2A6活性

细胞色素P450CYP2A6（CYP2A6）是体内重要的药物代谢酶之一，主要在肝脏表达，约占肝脏细胞色素P450酶的5％。CYP2A6参与抗肿瘤药（环磷酰胺和异环磷酰胺）、麻醉药（氟烷和甲氧氟烷）、前致癌物（黄曲霉素B1、亚硝胺盐等）、环境化合物（汽油醚）及烟草中尼古丁的代谢。CYP2A6活性与这些物质的疗效或毒性以及一些肿瘤的易感性密切相关，测定CY1Y2A6活性有助于预测药物疗效、预防药物毒副反应及肿瘤病因调查。     

Effect of St John's wort on the activities of CYP1A2, CYP3A4, CYP2D6, N-acetyltransferase 2, and xanthine oxidase in healthy males and females

AIMS: To investigate the influence of St. John's wort (SJW) on CYP3A4, CYP1A2, CYP2D6, N-acetyltransferase 2 (NAT2), and xanthine oxidase (XO) activities in healthy males and females. METHODS: Eight males and eight females were treated with SJW extract (3 x 300 mg day(-1)) for 14 days. Assessment of CYP1A2, NAT2, XO, CYP2D6, and CYP3A4 activities was performed before and at the end of the study period, using caffeine, dextromethorphan, and endogenous cortisol as probes. The corresponding metabolic ratios measured were 17MX/137MX in saliva and (AFMU+1MX+1MU)/17MU in urine for CYP1A2, AFMU/1MX for NAT2, 1MU/1MX for XO, DOR/DMO for CYP2D6, 3MM/DMO and 6OHC/C for CYP3A4, all determined in urine. RESULTS: The ratios of the treatment to baseline values for CYP3A4 using cortisol as the probe were 1.5 [95% confidence interval (CI) 1.3, 1.9] for males, and 1.9 (1.1, 3.0) for females. The corresponding ratios using dextromethorphan as the probe for CYP2D6 were 0.9 (95% CI 0.5, 2.1) for males and 1.9 (1.3, 3.2) for females. For CYP1A2, a significant increase in the metabolic ratios was found only for females (ratio of values 1.2; 95% CI 1.1, 1.4). No influence of SJW on CYP2D6, NAT2, and XO activities was observed. CONCLUSIONS: An induction of CYP3A4 by SJW was confirmed. CYP1A2 appears to be induced by SJW only in females. The activities of CYP2D6, NAT2, and XO were not affected by SJW.     

Xanthine oxidase inhibition by allopurinol affects the reliability of urinary caffeine metabolic ratios as markers for N-acetyltransferase 2 and CYP1A2 activities

Objectives: To evaluate the in vivo effect of xanthine oxidase (XO) inhibition by allopurinol on the determination of polymorphic N-acetyltransferase 2 (NAT2) and cytochrome P450 1A2 (CYP1A2) with urinary caffeine metabolic ratios. Methods: In an open, prospective study involving 21 healthy subjects (eight fast, 13 slow NAT2 acetylators) allopurinol (300 mg perday) was administered orally on trial days 1–8, followed by a wash-out period of 8 days. Urinary caffeine tests (200 mg caffeine p.o.) were performed repetitively. Urine was collected for 8 h and venous blood samples for the determination of allopurinol, oxypurinol and uric acid were drawn. The urinary caffeine metabolites 1-methyluric acid (1MU), 1-methylxanthine (1MX), 1,7-dimethyluric acid (17MU), 1,7-dimethylxanthine (17MX), 5-acetylamino-6-formylamino-3-methyluracil (AFMU), plasma allopurinol and oxypurinol were analysed using high-performance liquid chromatography (HPLC). Results: During XO inhibition by allopurinol, the formation of 1MU from 1MX and therefore the XO ratio 1MU/1MX decreased to 15.9 (1.2)% [mean with (SEM)] of baseline values (P < 0.005). The NAT2 ratio AFMU/1MX decreased likewise to 56.7 (6.3)% (P < 0.005). AFMU/(AFMU + 1MX + 1MU), an alternative NAT2 ratio, remained constant, but the CYP1A2 ratio (AFMU + 1MX + 1MU)/17MU, used to express CYP1A2 activity, transiently increased to 167 (13)% (P < 0.005). The NAT2 phenotype did not influence CYP1A2 and XO ratios or plasma oxypurinol pharmacokinetics. Conclusions: Several caffeine metabolic ratios are commonly used to express the activities of NAT2, CYP1A2 and XO both in healthy volunteers and in polymedicated patients, although their reliability has not been evaluated thoroughly during concurrent drug administration. The findings of this study suggest that NAT2 phenotyping should be performed using the ratio AFMU/(AFMU + 1MX + 1MU) if an XO inhibitor may be present. It also shows that the determination of CYP1A2 activity with caffeine as a metabolic probe is considerably altered under these conditions. Thus, concomitant drug administration may impair the robustness of multiple pathways of the complex caffeine test. This points to the need for alternative probes, designed to assess only the activity of a single enzyme because, in contrast to healthy volunteers, in patients known or unknown drug interactions may often be present. Received: 10 August 1998 / Accepted in revised form: 5 October 1998     

苦参对大鼠细胞色素P4501A2体内代谢活性的影响

目的以咖啡因作为探针药物,研究苦参对大鼠细胞色素P450 1A2(CYP1A2)体内代谢活性的影响。方法将Wistar大鼠随机分为4组:空白对照组、苦参组(实验组)、苯巴比妥组(诱导剂阳性对照组)和西咪替丁组(抑制剂阳性对照组)。苦参组,灌胃给予苦参溶液100 mg.kg-1;空白对照组,灌胃给予与苦参组体积相同的生理盐水;苯巴比妥组,腹腔注射苯巴比妥注射液50 mg.kg-1;西咪替丁组,每日腹腔注射西咪替丁注射液50 mg.kg-1,各组均为每日1次,连续5 d。第6 d,各组大鼠均经尾静脉注射咖啡因溶液2.5 mg.kg-1,于给药前及给药后不同时间,眼内眦静脉取血0.8 mL,用高效液相色谱法,测定血浆中咖啡因的浓度。结果给予大鼠苦参5 d后,苦参组的咖啡因AUC、MRT、Cmax明显低于空白对照组和西咪替丁组(P<0.05),明显高于苯巴比妥组(P<0.05);而CL明显高于空白对照组和西咪替丁组(P<0.05)而明显低于苯巴比妥组(P<0.05)。结论苦参可明显诱导大鼠CYP1A2的体内代谢活性;但诱导强度低于苯巴比妥。     

白藜芦醇对小鼠实验性胃黏膜损伤的保护作用

目的研究白藜芦醇对小鼠实验性胃黏膜损伤的保护作用。方法制备小鼠无水乙醇型、阿司匹林型、吲哚美辛型胃黏膜损伤模型,测定胃黏膜损伤面积;测定血清中丙二醛和超氧化物歧化酶含量。结果白藜芦醇（25,50,100mg·kg^-1, ig）可剂量依赖性地抑制小鼠实验性胃黏膜损伤。白藜芦醇可使阿司匹林致小鼠胃黏膜损伤过程中血清中升高的丙二醛含量降低,可使降低的超氧化物歧化酶水平回升。结论白藜芦醇对小鼠实验性胃黏膜损伤具有保护作用,其作用机制可能与抗氧化作用有关。     

细胞色素P4501A2活性与奥氮平代谢的相关性研究

目的 研究奥氮平(抗精神病药)体内代谢与细胞色素P450酶亚型1A2(CYP1A2)活性的相关性.方法 15例男性健康志愿者单次口服咖啡因150mg,第5 h末采血;2天后单次口服奥氮平10 mg,收集血样;用高效液相色谱电化学法测定奥氮平血浆浓度,紫外法测定咖啡因及其代谢产物次黄嘌呤的血浆浓度.结果 次黄嘌呤与咖啡因的比值与奥氮平清除的奥氮平AUC0.96的倒数不相关(γ=0.057,P=0.84).结论 CYP1A2酶活性与奥氮平体内代谢不相关.     

Variability of cytochrome P450 1A2 activity over time in young and elderly healthy volunteers

AIMS: To assess the age-associated changes over time of plasma paraxanthine/caffeine (PAX/CAF) ratios used as a probe for CYP1A2 activity. METHODS: Intraindividual and interindividual variabilities in PAX/CAF ratio were compared by phenotyping with caffeine, 16 young and 16 elderly healthy subjects on five occasions. RESULTS: PAX/CAF ratio variability was comparable regardless of age (intraindividual CV: 17.6 +/- 6% and 16.2 +/- 5.9%, interindividual CV: 48.1 +/- 2.9% and 42.7 +/- 3.6% in young and elderly, respectively). The PAX/CAF ratio was lower in elderly than in young subjects (95% CI for the difference: 0.004, 0.32) but the difference was not significant in nonsmokers compared separately. CONCLUSIONS: The variability over time of the PAX/CAF ratio is not influenced by age.