Yoshizawa S
First Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka.
Fukuoka Igaku Zasshi. 1996 Oct;87(10):215-21.
(-)-Epigallocatechin gallate (EGCG), the main constituent of green tea, inhibited a tumor promoting activity of okadaic acid in a two-stage carcinogenesis experiment on mouse skin. The group treated with a single application of 100 micrograms 7, 12-dimethylbenz (a) anthracene followed by repeated applications of 1 microgram okadaic acid resulted in 80% of tumor-bearing mice and 4.7 of average numbers of tumors per mouse in week 20. Repeated applications of 5 mg EGCG, prior to okadaic acid, completely inhibited the tumor formation in mice up to week 20. The inhibitory effects of EGCG with two different doses of each application, 1 mg and 5 mg, were dose-dependent. A topical application of 5 mg EGCG immediately reduced the specific binding of [3H]okadaic acid to a particulate fraction of mouse skin to as low as 30% of control. According to the Scatchard analysis, the reduction of specific [3H]okadaic acid binding was mainly due to the reduction of the binding sites, not due to the change of the affinity. The reduction of the specific binding was closely related to the inhibitory effct of EGCG on tumor promotion of okadaic acid. Since EGCG is a non-toxic compound, ingested in green tea in daily life in Japan, EGCG is one of the candidates for practical cancer chemopreventive agents.
（-）-表没食子儿茶素没食子酸酯（EGCG）是绿茶的主要成分，在小鼠皮肤的两阶段致癌实验中，它抑制了冈田酸的促肿瘤活性。用100微克7,12-二甲基苯并（a）蒽单次处理，随后重复应用1微克冈田酸的组，在第20周时，80%的小鼠出现肿瘤，每只小鼠平均肿瘤数为4.7个。在冈田酸之前重复应用5毫克EGCG，直至第20周完全抑制了小鼠肿瘤的形成。EGCG每次应用1毫克和5毫克这两种不同剂量的抑制作用呈剂量依赖性。局部应用5毫克EGCG可立即将[3H]冈田酸与小鼠皮肤微粒部分的特异性结合降低至对照的30%。根据Scatchard分析，特异性[3H]冈田酸结合的降低主要是由于结合位点的减少，而不是由于亲和力的改变。特异性结合的降低与EGCG对冈田酸肿瘤促进作用的抑制效果密切相关。由于EGCG是一种无毒化合物，在日本人日常生活中可从绿茶中摄取，因此EGCG是实际癌症化学预防剂的候选之一。
