Antioxidant activity of tea polyphenols in vivo: Evidence from animal studies
Antioxidant activity of tea polyphenols in vivo: Evidence from animal studies
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DOI：
10.1093/jn/133.10.3275s
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发表时间：
2003-10-01
影响因子：
4.2
通讯作者：
Higdon, JV
中科院分区：
文献类型：
--
作者：
Frei, B;Higdon, JV
茶中富含多酚类物质，包括儿茶素、茶黄素和茶红素，这些物质被认为对茶的健康益处有贡献。茶多酚在体外通过清除活性氧和氮物质以及螯合具有氧化还原活性的过渡金属离子而起到抗氧化剂的作用。它们也可能通过以下方式间接起到抗氧化剂的作用：1）抑制对氧化还原敏感的转录因子，即核因子 - κB和激活蛋白 - 1；2）抑制“促氧化”酶，如诱导型一氧化氮合酶、脂氧合酶、环氧合酶和黄嘌呤氧化酶；3）诱导Ⅱ相酶和抗氧化酶，如谷胱甘肽S - 转移酶和超氧化物歧化酶。儿茶素被快速且广泛代谢这一事实强调了在体内证明其抗氧化活性的重要性。动物研究为评估茶和茶多酚的抗氧化特性对在不同氧化应激模型中给予茶的生理效应的贡献提供了独特的机会。最有希望的是在皮肤、肺、结肠、肝脏和胰腺癌的动物模型中一致的发现，即给予茶和茶多酚抑制了致癌物诱导的氧化DNA碱基8 - 羟基 - 2'- 脱氧鸟苷的增加。在动脉粥样硬化的动物模型中，给予绿茶和红茶导致脂蛋白对体外氧化的抵抗力有适度提高，尽管有限的数据表明绿茶或绿茶儿茶素抑制动脉粥样硬化的形成。为了确定茶多酚在体内是否作为有效的抗氧化剂起作用，未来在动物和人类中的研究应采用对脂质、蛋白质和DNA氧化损伤敏感且特异的生物标志物。
Tea is particularly rich in polyphenols, including catechins, theaflavins and thearubigins, which are thought to contribute to the health benefits of tea. Tea polyphenols act as antioxidants in vitro by scavenging reactive oxygen and nitrogen species and chelating redox-active transition metal ions. They may also function indirectly as antioxidants through 1) inhibition of the redox-sensitive transcription factors, nuclear factor-kappaB and activator protein-1; 2) inhibition of "pro-oxidant" enzymes, such as inducible nitric oxide synthase, lipoxygenases, cyclooxygenases and xanthine oxidase; and 3) induction of phase II and antioxidant enzymes, such as glutathione S-transferases and superoxide dismutases. The fact that catechins are rapidly and extensively metabolized emphasizes the importance of demonstrating their antioxidant activity in vivo. Animal studies offer a unique opportunity to assess the contribution of the antioxidant properties of tea and tea polyphenols to the physiological effects of tea administration in different models of oxidative stress. Most promising are the consistent findings in animal models of skin, lung, colon, liver and pancreatic cancer that tea and tea polyphenol administration inhibit carcinogen-induced increases in the oxidized DNA base, 8-hydroxy-2'-deoxyguanosine. In animal models of atherosclerosis, green and black tea administration has resulted in modest improvements in the resistance of lipoproteins to ex vivo oxidation, although limited data suggest that green tea or green tea catechins inhibit atherogenesis. To determine whether tea polyphenols act as effective antioxidants in vivo, future studies in animals and humans should employ sensitive and specific biomarkers of oxidative damage to lipids, proteins and DNA.