Lee M J, Wang Z Y, Li H, Chen L, Sun Y, Gobbo S, Balentine D A, Yang C S
Laboratory for Cancer Research, College of Pharmacy, Rutgers University, Piscataway, New Jersey 08854, USA.
Cancer Epidemiol Biomarkers Prev. 1995 Jun;4(4):393-9.
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-gallate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin-3-gallate (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 beta-glucuronidase 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.(ABSTRACT TRUNCATED AT 250 WORDS)
在许多动物模型中，茶已被证明能抑制化学诱导的肿瘤发生，但饮茶对人类致癌作用的影响尚无定论。为了开发饮茶的生物标志物，我们开发了使用配备库仑电化学电极阵列检测系统的高效液相色谱法分析人血浆和尿液样本中茶多酚的方法。（-）-表没食子儿茶素-3-没食子酸酯（EGCG）、（-）-表没食子儿茶素（EGC）、（-）-表儿茶素-3-没食子酸酯（ECG）和（-）-表儿茶素（EC）是绿茶中的主要多酚类物质。大多数茶多酚在血浆和尿液中以共轭形式存在。样本与β-葡萄糖醛酸酶和硫酸酯酶的混合物孵育以生成游离形式的茶多酚。用乙酸乙酯萃取并通过反相色谱分离后，根据EGCG、EGC和EC的保留时间和电化学特性对其进行鉴定。由于检测模式的高选择性，干扰被降至最低。在很大的茶多酚浓度范围内建立了良好的定量关系。EGCG、EGC、ECG和EC在血浆或尿液样本中的检测限为0.5至1.5 ng/ml。4名人类志愿者在温水中摄入1.2 g脱咖啡因绿茶后，1小时采集的血浆样本中含有46 - 268 ng/ml的EGCG、82 - 206 ng/ml的EGC和48 - 80 ng/ml的EC。血浆样本中未检测到ECG。EGC和EC的最大尿排泄量出现在3 - 6小时。（摘要截断于250字）
