Nongallated compared with gallated flavan-3-ols in green and black tea are more bioavailable.
Nongallated compared with gallated flavan-3-ols in green and black tea are more bioavailable.
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DOI：
10.1093/jn/138.8.1529s
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发表时间：
2008-08
期刊：
影响因子：
--
通讯作者：
Heber D
中科院分区：
文献类型：
--
作者：
Henning SM;Choo JJ;Heber D
绿色茶和红茶（BT）含有没食子酸化[（−）-表没食子儿茶素-3-没食子酸酯（EGCG）、（−）-表儿茶素-3-没食子酸酯]和非没食子酸化[（−）-表儿茶素、（−）-表没食子儿茶素（EGC）]茶多酚（PP）。在BT生产过程中，PP经历氧化并形成较大的聚合物，如茶黄素（THE）和茶红素，这有助于BT的健康益处。本文概述了茶叶PP的化学特性和内源性代谢的作用及其在人体中的生物利用度，并描述了提高其生物利用度的尝试。在接近中性的pH下，EGCG和EGC形成均二聚体和异二聚体，产生过氧化氢。为了确认细胞培养基中EGCG、EGC和THE的pH不稳定性，在存在和不存在过氧化氢酶的情况下测定它们的抗增殖活性。当在EGCG、EGC和THE处理之前与过氧化氢酶孵育时，LNCaP前列腺癌细胞中的抗增殖活性降低。此外，新的研究结果表明，甲基-EGC的形成增加了在中性pH下的稳定性相比，EGC。综述了提高黄烷-3-醇生物利用度的方法，包括茶与果汁联合给药、与胡椒碱联合给药以及EGCG的全乙酰化。未来的干预研究不仅需要关注绿色茶和BT PP的生物活性，还需要关注其代谢产物和生物转化产物的生物活性。
Green tea and black tea (BT) contain gallated [(−)-epigallocatechin-3-gallate (EGCG), (−)-epicatechin-3-gallate] and nongallated [(−)-epicatechin, (−)-epigallocatechin (EGC)] tea polyphenols (PP). During BT production, PP undergo oxidation and form larger polymers such as theaflavins (THE) and thearubigins, which contribute to the health benefit of BT. This article gives an overview of the role of chemical characteristics and endogenous metabolism of tea PP and their bioavailability in humans and describes attempts to increase their bioavailability. At pH close to neutral, EGCG and EGC form homo- and heterodimers generating hydrogen peroxide. To confirm the pH instability of EGCG, EGC, and THE in cell culture medium, their anti-proliferative activity was determined in the presence and absence of catalase. The antiproliferative activity in LNCaP prostate cancer cells was decreased when incubated with catalase prior to EGCG, EGC, and THE treatment. In addition, new findings demonstrated that the formation of methyl-EGC increased the stability at neutral pH compared with EGC. Approaches to increase the bioavailability of flavan-3-ols are reviewed, which include the administration of tea in combination with fruit juices, coadministration with piperine, and peracetylation of EGCG. Future intervention studies will need to focus on the bioactivity not only of green tea and BT PP but also of their metabolites and biotransformation products.