Black tea polyphenols, theaflavins, prevent cellular DNA damage by inhibiting oxidative stress and suppressing cytochrome P450 1A1 in cell cultures
Black tea polyphenols, theaflavins, prevent cellular DNA damage by inhibiting oxidative stress and suppressing cytochrome P450 1A1 in cell cultures
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DOI：
10.1021/jf010875c
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发表时间：
2002-01-02
影响因子：
6.1
通讯作者：
Osawa, T
中科院分区：
文献类型：
--
作者：
Feng, Q;Torii, Y;Osawa, T
在许多实验模型中，茶多酚已被证明是化学预防剂。然而，与绿茶相比，人们对红茶的化学预防机制知之甚少。对茶黄素（红茶多酚）的一些有益特性进行了研究。茶黄素对大鼠正常肝上皮细胞RL-34细胞系中H2O2-和叔丁基过氧化氢（tBuOOH）诱导的细胞毒性（通过溴化四氮唑还原评价）、细胞氧化应激（通过2′，7′-二氯荧光素氧化检测）和DNA损伤（通过8-OHdG量和彗星测定）具有抑制作用。此外，茶黄素还能抑制奥美拉唑诱导的人肝癌HepG2细胞系细胞色素P450 1A1。此外，当HepG2细胞用奥美拉唑预处理以诱导CYP1A1，然后暴露于苯并[a]芘（B[a]P）时，使用彗星法观察DNA损伤。然而，茶黄素可以抑制这种DNA损伤。这些结果表明，茶黄素可以通过抑制细胞氧化应激和抑制细胞色素P450 1A1来预防细胞DNA损伤。
Tea polyphenols have been demonstrated as chemopreventive agents in a number of experimental models. However, less is known about the mechanism of chemoprevention by black tea compared with that of green tea. Some beneficial properties of theaflavins, the black tea polyphenols, were investigated in the present study. Theaflavins showed inhibitory effects on H2O2- and tert-butyl hydroperoxide (tBuOOH)-induced cytotoxicity (evaluated by tetrazolium bromide reduction), cellular oxidative stress (detected by oxidation of 2', 7'-dichlorofluorescin), and DNA damage (measured by amount of 8-OHdG and comet assay) in rat normal liver epithelium cell RL-34 cell lines. In addition, theaflavins also exhibited suppression of cytochrome P450 1A1 induced by omeprazole in the human hepatoma HepG2 cell line. Furthermore, when HepG2 cells were pretreated with omeprazole to induce CYP1A1, then exposed to benzo[a]pyrene (B[a]P), DNA damage was observed using the comet assay. However, theaflavins could inhibit this DNA damage. These results indicated that theaflavins could prevent cellular DNA damage by inhibiting oxidative stress and suppressing cytochrome P450 1A1 in cell cultures.