人類志願者攝食不同劑量之綠茶後其血液與尿液中之兒茶素濃度

Blood and Urine Levels of Tea Catechins after Ingestion of Different Amounts of Green Tea by Human Volunteers

劉紹毅 ； Chung S. Yang ； Lai-Shun Chen ； Mao-Jung Lee ； Douglas Balentine ； May Chen Kuo ； Stimson P. Schantz

《中華民國血液淨化醫學會雜誌》 14卷3-4期 (2009/12) Pp. 66-67

https://doi.org/10.30024/JFBPS.200912.0011

摘要

茶對抗腫瘤形成作用之抑制活性已在許多之動物模型以及流行病學中被證明。此種抑制作用一般均來自茶中之兒茶素成份(catechins)。爲了要了解在人體內之生物利用性，我們給18位志願者不同量之綠茶，並按時間檢測其在血漿與小使中排泄之濃度。在分別給予1.5、3.0、4.5 gm之去咖啡因綠茶（將之溶於500c.c.之水中）之後，其在血漿中之最大濃度(Cmax)，EGCG為326 ng/ml、EGC為550 ng/ml和EC為190 ng/ml。此Cmax是在攝食綠茶製劑1.4~2.44小時之後所觀察到的。當劑量由1.5gm個增加到3.0gm時，Cmax值會增加2.7~3.4倍，可是當劑量增加到4.5gm時，Cmax值就不會再有明顯之上升，此表示已達到飽和狀態。EGCG之半衰期（5.0~5.5小時）似乎比EGC或EC（2.5~3.4小時）為高。EGC與EC，但非EGCG，是由小便中排除。超過90%之EGC與EC，在8小時內均由校小便中排除。當茶之劑量增加，EGC與EC之尿中排除似乎會增加，但並未觀察到一個很明確的劑量－反應關係。本研究提供了綠茶兒茶素(green tea catechins)在人體內之基本藥物動力學之參數；這些參數可能可以用來在飲茶之後來評估此種化合物之濃度之用。

並列摘要

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. Tounderstand 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 (C(subscript max)) of (-)-epigallocatechin-3-galbate (EGCG) was 326 ng/ml, the C(subscript max) of (-)-epigallocatechin (EGC) was 550 ng/ml, and the C(subscript max) of (-)-epicatechin (EC) was 190 ng/ml. These C(subscript max) 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 C(subscript max) values increased 2.7-3.4-fold, but increasing the dose to 4.5 g did not increase the C(subscript max) values significantly, which suggested a saturation phenomenon. The half-life of EGCG (5.0-5.5h) 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.