[The experiment of tumor-inhibiting effect of green tea extract in animal and human body].

Green tea extract (GTE) inhibits obviously gastrointestinal malignant tumors in rats induced by N-methyl-N'-nitro-n-nitrosoguanidine (MNNG). The incidence of tumor was 93.3% in the MNNG positive control group, whereas 53.3% in the MNNG plus GTE group (P < 0.01). The percentage of inhibiting tumor growth was 88% (P < 0.001). N-nitrosoproline blockage test in 3 groups of 45 cases of patients from the highly prone to (gastric cancer people), examined with gastroscope and classified pathologically, revealed that GTE can block N-nitroso-proline synthesis in vivo, with blockage rate of 91% in superficial chronic gastritis (P < 0.001), 94% in intestinal metaplasia (P < 0.001) and 93% in atypical hyperplasia and gastric cancer (P < 0.001). Chemical analysis demonstrated that the main ingredients in GTE are catechols (with the content of 50%), vitamins and trace elements. The mechanism of GTE's cancer-inhibiting and cancer-preventing function might be that catechols combine with N-nitroso-compounds or resolve them, and reduce their carcinogenic activity. These results will be of great significance in preventing gastrointestinal cancer.