Yamane T, Nakatani H, Kikuoka N, Matsumoto H, Iwata Y, Kitao Y, Oya K, Takahashi T
First Department of Surgery, Kyoto Prefectural University of Medicine, Japan.
Cancer. 1996 Apr 15;77(8 Suppl):1662-7. doi: 10.1002/(SICI)1097-0142(19960415)77:8<1662::AID-CNCR36>3.0.CO;2-W.
Recently, and epidemiologic study showed a lower risk of gastrointestinal carcinogenesis in green tea drinkers. An experiment on two-stage skin carcinogenesis in mice showed that (-)-epigallocatechin gallate (EGCG), one of the main constituents of green tea, inhibited tumor formation.
The inhibitory effects of EGCG and green tea extract (GTE) on N-ethyl-N'-nitro-N-nitroguanidine (ENNG)-induced duodenal carcinogenesis in the mouse, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced carcinogenesis of the glandular stomach in the rat, and azoxymethane-induced colon carcinogenesis in the rat were examined. The toxicity of GTE was assessed experimentally and GTE was applied clinically in normal volunteers to determine the effective dose and to assess its harmful effects.
EGCG and GRE inhibited chemical carcinogenesis of the gastrointestinal tract in rodents. Judging from the epidemiologic and experimental findings, it was determined that 1 g per day of GTE might be an effective dose. GTE was not toxic and no harmful effect was found during its clinical use.
These findings suggest that EGCG and GTE are useful in preventing gastrointestinal carcinogenesis, and the clinical usefulness of GTE, which has no harmful effects and is inexpensive, should be studied further.
最近，一项流行病学研究表明，饮用绿茶者发生胃肠道癌变的风险较低。一项针对小鼠两阶段皮肤致癌作用的实验表明，绿茶的主要成分之一（-）-表没食子儿茶素没食子酸酯（EGCG）可抑制肿瘤形成。
研究了EGCG和绿茶提取物（GTE）对N-乙基-N'-硝基-N-亚硝基胍（ENNG）诱导的小鼠十二指肠癌变、N-甲基-N'-硝基-N-亚硝基胍（MNNG）诱导的大鼠腺胃癌变以及偶氮甲烷诱导的大鼠结肠癌变的抑制作用。通过实验评估了GTE的毒性，并在正常志愿者中对GTE进行了临床应用，以确定有效剂量并评估其有害影响。
EGCG和GTE可抑制啮齿动物胃肠道的化学致癌作用。根据流行病学和实验结果判断，每天1克GTE可能是有效剂量。GTE无毒，临床应用期间未发现有害影响。
这些发现表明，EGCG和GTE对预防胃肠道癌变有用，GTE无害且价格低廉，其临床实用性应进一步研究。
