Steele V E, Kelloff G J, Balentine D, Boone C W, Mehta R, Bagheri D, Sigman C C, Zhu S, Sharma S
Chemoprevention Branch, Division of Cancer Prevention, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
Carcinogenesis. 2000 Jan;21(1):63-7. doi: 10.1093/carcin/21.1.63.
Black tea extracts (hot aqueous, polyphenols and theaflavins) and green tea extracts (hot aqueous, polyphenols, epicatechin, epicatechin gallate, epigallocatechin and epigallocatechin gallate) were tested in nine standardized cell culture assays for comparative cancer chemopreventive properties. Most black and green tea extracts strongly inhibited neoplastic transformation in mouse mammary organ cultures, rat tracheal epithelial cells and human lung tumor epithelial cells. Nearly all tea fractions strongly inhibited benzo[a]pyrene adduct formation with human DNA. Induction of phase II enzymes, glutathione-S-transferase and quinone reductase, were enhanced by nearly all tea fractions, while glutathione was induced by only a few fractions. Ornithine decarboxylase activity was inhibited by nearly all the green tea fractions, but none of the black tea fractions. 12-O-tetradecanoylphorbol-13-acetate-induced free radicals were inhibited by most tea fractions. These results provide strong evidence of both anti-mutagenic, anti-proliferative and anti-neoplastic activities for both black and green tea extracts. Such anticancer mechanisms may well be responsible for the cancer preventive efficacies seen in both experimental and human studies.
对红茶提取物(热的水性提取物、多酚和茶黄素)和绿茶提取物(热的水性提取物、多酚、表儿茶素、表儿茶素没食子酸酯、表没食子儿茶素和表没食子儿茶素没食子酸酯)进行了九种标准化细胞培养试验,以比较其癌症化学预防特性。大多数红茶和绿茶提取物在小鼠乳腺器官培养、大鼠气管上皮细胞和人肺肿瘤上皮细胞中强烈抑制肿瘤转化。几乎所有的茶提取物组分都强烈抑制苯并[a]芘与人DNA的加合物形成。几乎所有的茶提取物组分都能增强II期酶、谷胱甘肽-S-转移酶和醌还原酶的诱导作用,而只有少数组分能诱导谷胱甘肽。几乎所有的绿茶提取物组分都能抑制鸟氨酸脱羧酶活性,但红茶提取物组分均无此作用。大多数茶提取物组分能抑制12-O-十四烷酰佛波醇-13-乙酸酯诱导的自由基。这些结果为红茶和绿茶提取物的抗诱变、抗增殖和抗肿瘤活性提供了有力证据。这种抗癌机制很可能是实验研究和人体研究中所观察到的癌症预防效果的原因。