Blood and urine levels of tea catechins after ingestion of different amounts of green tea by human volunteers.
Blood and urine levels of tea catechins after ingestion of different amounts of green tea by human volunteers.
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发表时间：
1998-04
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通讯作者：
Chung S. Yang;Laishun Chen;Mao-jung Lee;D. Balentine;May-Chen Kuo;S. Schantz
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作者：
Chung S. Yang;Laishun Chen;Mao-jung Lee;D. Balentine;May-Chen Kuo;S. Schantz
茶对肿瘤发生的抑制活性已在许多动物模型中得到证实，并已由一些流行病学研究提出。这种活性通常归因于茶儿茶素。为了了解茶儿茶素在人体中的生物利用度，我们给18个人不同数量的绿色茶，并测量茶儿茶素的时间依赖性血浆浓度和尿排泄。在服用1.5、3.0和4.5 g脱咖啡因的绿色茶固体（溶于500 ml水中）后，（-）-表没食子儿茶素-3-没食子酸酯（EGCG）的最大血浆浓度（Cmax）为326 ng/ml，（-）-表没食子儿茶素（EGC）的Cmax为550 ng/ml，（-）-表儿茶素（EC）的Cmax为190 ng/ml。这些Cmax值在摄入茶制剂后1.4 - 2.4小时观察到。当剂量从1.5 g增加至3.0 g时，Cmax值增加2.7 - 3.4倍，但剂量增加至4.5 g并未显著增加Cmax值，这表明存在饱和现象。EGCG的半衰期（5.0 - 5.5 h）似乎高于EGC或EC的半衰期（2.5 - 3.4 h）。EGC和EC，但不是EGCG，经尿液排泄。尿EGC和EC的90%以上在8 h内排出。随着茶叶剂量的增加，EGC和EC的排泄量似乎增加，但没有观察到明显的剂量-反应关系。本研究提供了绿色茶儿茶素在人体内的基本药代动力学参数，这些参数可用于估计这些化合物在喝茶后的水平。
The inhibitory activity of tea against tumorigenesis has been demonstrated in many animal models and has been suggested by some epidemiological studies. Such activity has generally been attributed to tea catechins. To understand the bioavailability of tea catechins in humans, we gave 18 individuals different amounts of green tea and measured the time-dependent plasma concentrations and urinary excretion of tea catechins. After taking 1.5, 3.0, and 4.5 g of decaffeinated green tea solids (dissolved in 500 ml of water), the maximum plasma concentration (Cmax) of (-)-epigallocatechin-3-gallate (EGCG) was 326 ng/ml, the Cmax of (-)-epigallocatechin (EGC) was 550 ng/ml, and the Cmax of (-)-epicatechin (EC) was 190 ng/ml. These Cmax values were observed at 1.4-2.4 h after ingestion of the tea preparation. When the dosage was increased from 1.5 to 3.0 g, the Cmax values increased 2.7-3.4-fold, but increasing the dose to 4.5 g did not increase the Cmax values significantly, which suggested a saturation phenomenon. The half-life of EGCG (5.0-5.5 h) seemed to be higher than the half-life of EGC or EC (2.5-3.4 h). EGC and EC, but not EGCG, were excreted in the urine. Over 90% of the total urinary EGC and EC was excreted within 8 h. When the tea dosage was increased, the amount of EGC and EC excretion seemed to increase, but a clear dose-response relationship was not observed. The present study provides basic pharmacokinetic parameters of green tea catechins in humans; these parameters may be used to estimate the levels of these compounds after drinking tea.