CAFFEINE AS MARKER OF CYTOCHROME P4502E1

咖啡因作为细胞色素 P4502E1 的标记

• 批准号: 2442157
• 负责人: BING-KOU TANG
• 金额: $ 9.18万
• 依托单位: UNIVERSITY OF TORONTO
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-04-01 至 1998-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2442157
• 关键词: alcoholic beverage consumption; alcoholism /alcohol abuse; biomarker; caffeine; clearance rate; clinical research; cytochrome P450; diagnosis design /evaluation; dosage; drug metabolism; ethanol; human subject; longitudinal human study; muscle relaxants; noninvasive diagnosis; urinalysis

Recently, we showed that CYP2E1 (cytochrome P450 2E1), an ethanol- inducible cytochrome, plays an important role in caffeine biotransformation, in addition to CYP1A2, especially in the formation of theophylline and theobromine. There was a concurrent discovery of a significant shift of caffeine metabolite profile in the urine of 22 confirmed alcoholics. These observations prompted this proposal to test the feasibility of using the change of caffeine metabolite pattern as a marker of CYP2E1 activity, analogous to the use of a caffeine metabolite ratio as an index for CYP1A2 activity. CYP2E1 has become the target of numerous investigations because of its inducibility by ethanol consumption and its capacity to bioactivate pre- carcinogens (e.g. nitrosamines). Because there is no reference method for the in vivo estimation of CYP2E1 activity, development of methods for in vivo tests must rely on results from in vitro studies. Using pure cytochromes CYP1A2 and CYP2E1 from Vaccinia CDNA expression, we plan to establish that the pattern of specific caffeine metabolites is associated with the ratio of CYP2E1 to CYP1A2 activity. Results obtained with the pure enzymes will then be verified by using human liver microsomes. An index for CYP2E1 activity was proposed to estimate CYP2E1 activity where it yielded a value 10 times higher for 22 alcoholics compared to 27 controls. We proposed to assess this index using results of metabolite profiling of already collected urine samples from 125 confirmed alcoholics and 125 controls. In addition, metabolite patterns and ratios will be scrutinized to search for other CYP2E1 indices. Since alcoholics are known to have highly induced CYP2E1 activity, parameters that show large differences between alcoholics and controls will be evaluated.

最近，我们发现CYP 2 E1（细胞色素P450 2 E1），一种乙醇- 诱导细胞色素，在咖啡因中起着重要作用 生物转化，除了CYP 1A 2，特别是在形成 茶碱和可可碱。同时发现了一种 22例患者尿液中咖啡因代谢物谱的显著变化 确认酗酒。这些观察促使这一提议得到检验 利用咖啡因代谢模式的变化作为一种 CYP 2 E1活性的标志物，类似于咖啡因代谢物的使用 比值作为CYP 1A 2活性的指标。 CYP 2 E1已成为许多研究的目标，因为它 诱导乙醇消耗和它的能力，以生物活化前 致癌物质（如亚硝胺）。因为没有参考方法， CYP 2 E1活性的体内评估， 体内试验必须依赖于体外研究的结果。使用纯 细胞色素CYP 1A 2和CYP 2 E1从牛痘cDNA表达，我们计划 确定特定咖啡因代谢物的模式与 与CYP 2 E1和CYP 1A 2活性的比值有关。获成果与 然后将通过使用人肝微粒体来验证纯酶。 提出了一种测定CYP 2 E1活性的指标 22名酗酒者的价值是27名的10倍 对照我们建议使用代谢产物的结果来评估该指标 从125名确诊酗酒者中收集的尿样分析 125个控制器 此外，代谢物模式和比例将 仔细检查以寻找其他CYP 2 E1指标。因为酗酒者 具有高度诱导的CYP 2 E1活性，参数显示大 将评估酗酒者和对照组之间的差异。