- 期刊
在人體內血漿中與尿中茶多酚之分析
Analysis of Plasma and Urinary Tea Polyphenols in Human Subjects
摘要
在許多動物模型中，已知茶可以抑制化學性誘發之腫瘤形成作用(tumorigenesis)，但飲茶對人類癌症形成作用(carcinogenesis)之抑制尚未得到結論。爲了發展一種飲茶後之生物標記，我們使用HPLC加上Coulochem electrode array檢測系統用來在人類血漿與尿液檢體中茶多酚之分析方法。綠茶中之主成份為EGCG、、EGC、ECG與EC。而大多數之茶多酚成份在血漿與尿液中呈接合體型。檢體與β-glucuronidnse和sulfatase混合培養來產生茶多酚之游離型。加ethylacetate將其萃取之後，在籍由逆向色層分析法(reversed-phase chromatography)加以分離出EGCG、EGC與EC在其滯留時間內與化學electrochemical特性下被鑑識出來。由於此種檢測法模式具有高度選擇性，干擾又少。對於有著大型濃度範圍之茶多酚，可以建立一種良好之定量關係。檢測血液或尿液檢體之EGCG、EGC、ECG與EC之界限由0.5到1.5 ng/ml。在攝取1.2gm溫水沖泡之去咖啡因綠茶DGT (decaffeinated green tea)1個小時後收集4位志願者其血漿檢體，含有EGCG 46~268 ng/ml、EGC 82~206 ng/ml、EC 48~80 ng/ml，但卻檢測不出ECG。而在飲用後3~6小時，小便中之EGC與EC量排泄最高。大部分之EGC與EC在最初9小時可被排泄，而在最初24小時之收集尿液排泄物中有2.8~3.2mg以及EC1.6~2.3mg，在小便檢體中檢測不出EGCG和ECG。人類在攝取茶或飲用茶多酚後，可定量其血液與小使中之EGCG、EGC、EC來作為標記。此資訊在研究飲茶對人類癌症之影響是重要的。
關鍵字
無資料並列摘要
Tea has been shown to inhibit chemically induced tumorigenesis in many animal models, but the effects of tea consumption on human carcinogenesis are not conclusive. In order to develop biomarkers for tea consumption, we developed methods for the analysis of tea polyphenols in human plasma and urine samples using HPLC with the coulochem electrode array detection system. (-)-Epigallocatechin-3-gablate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin-3-gablate (ECG), and (-)-epicatechin (EC) are the major polyphenols in green tea. Most of the tea polyphenols were in their conjugated forms in the plasma and urine. The samples were incubated with a mixture of β-glouronidase and sulfatase to generate the free form of tea polyphenols. After extraction into ethyl acetate and separation by reversed-phase chromatography, EGCG, EGC, and EC were identified on the basis of their retention times and electrochemical characteristics. Due to the high selectivity of the detection mode, interference was minimized. Good quantitative relationships were established for a large concentration range of tea polyphenols. The limits of detection for EGCG, EGC, ECG, and EC were from 0.5 to 1.5 ng/ml of plasma or urine sample. After ingestion of 1.2 g of decaffeinated green tea in warm water, the plasma samples collected at 1 h from 4 human volunteers contained 46-268 ng/ml of EGCG, 82-206 ng/ml of EGC, and 48-80 ng/ml of EC. ECG was not detected in plasma samples. The maximum urinary excretion of EGC and EC occurred at 3-6 h. Most of the EGC and EC were excreted in the first 9 h, and the cumulative urinary excretions in the first 24 h were 2.8-3.2 mg of EGC and 1.6-2.3 mg of EC. EGCG and ECG were not detected in the urine samples. Plasma and urinary bevels of EGC, EC, and EGCG may be useful markers for quantifying human ingestion of tea and exposure to tea polyphenols. This information is important for studying the effects of tea consumption on human cancers.