绿茶及混合茶抑制二乙基亚硝胺诱发大鼠肝癌前期病变的抗氧化机理研究

用二乙基亚硝胺（ＤＥＮ）诱发Ｗｉｓｔａｒ大鼠肝癌前期病变（Ｓｏｌｔ－Ｆａｒｂｅｒ模型）。实验前６周给大鼠饮用２％绿茶水及０．５％混合茶水，于实验第８周末宰杀动物。结果发现，绿茶组及混合茶组肝ｒ－ＧＴ异常病灶数均明显低于阳性对照组（Ｐ＜０．０１）。经ＨＰＬＣ法分离肝微粒体脂质过氧化产物丙二醛（ＭＤＡ）、乙醛（ＡＣＴ）、戊醛（ＰＰ）、丙酮（ＡＣＯＮ），与阳性对照组相比，绿茶组和混合茶组的各种脂质过氧化产物均有不同程度的降低。此外，对多种抗氧化酶和Ⅱ相代谢酶活性进行检测，其中绿茶组ＳＯＤ、ＧＳＴ、ＱＲ活性明显高于阳性对照组；混合茶组ＣＡＴ、ＳＯＤ、ＧＳＴ、ＱＲ活性明显高于阳性对照组。结果表明，绿茶和混合茶对ＤＥＮ诱发大鼠肝癌的发生均有显著的预防作用。其作用机理可能和诱导抗氧化酶及某些Ⅱ相代谢酶活性，以及抑制脂质过氧化作用有关。

Inhibitory Effects of Tea and Tea Mixture on Diethylni trosamine Induced Precancerous Hepatic Lesions in Rats and its Antioxidative Mechanisms

The inhibitory effects and antioxidative mechanisms of green tea and tea mixture on N nitrosodiethylamine(DEN) initiated carcinogenesis were studied in a rats model treated with multiple small doses of DEN.The results showed that oral administration of 2% green tea and 0 5% tea mixture as drinking water both resulted in significant reduction of DEN induced glutamyl transpeptidaose positive foci in the rat liver and peroxidation products(MDA,ACT,ACON,PP)formed in the rat liver microsome( P <0 01).On the other hand,it was found that drinking green tea increased the activities of superoxide dismutase(SOD),quinone reductase(QR) and glutatione S transferase (GST) in rat liver( P <0 01).Whereas the activities of catalase(CAT),SOD,QR,GOT were increased in tea mixture group( P <0 01).The above results showed that both green tea and tea mixture inhibited DEN induced precancerous hepatic lesions in rats.The mechanisms of such effects may involve the enhancement of the activity of antioxidative enzyme and phase Ⅱ enzyme systems and the suppression of lipid peroxidation in liver.