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绿茶抑制大鼠体内杂环胺 |
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林东昕1 肖颖2 谭文1 Fred F. Kadlubar3 陈君石4
【摘要】 目的 食物中的致突变物2-氨基-1-甲基-6-苯基咪唑并［4,5-b］吡啶(PhIP)可诱发大鼠结肠和乳腺肿瘤，而且与人类癌症特别是结肠和直肠癌有密切关系。本研究以致癌物-DNA加合物为生物标记物，观察绿茶对PhIP致癌作用的预防效果及机理。方法 雄性SD大鼠分别饮水或饮茶(3%)10天后，经口摄入PhIP(10 mg/kg)。以32P-后标记方法测定动物心、肝、肺和结肠PhIP-DNA加合物，同时以1-氯-2,4-二硝基苯为底物测定肝、肺和结肠粘膜细胞液谷胱甘肽硫转移酶(GST)活性。结果 大鼠摄入PhIP后上述器官中均有PhIP-DNA加合物形成，含量(加合物/108核苷)以结肠粘膜最高(53±9)，其次为心(41±14)和肺(22±5)，而肝中含量很低(5±3)。动物饮茶10天后给予致癌物，各器官中的PhIP-DNA加合物含量显著低于对照组，抑制率达59%～66% (P<0.01)。饮茶不影响上述组织中GST活性水平，提示饮茶抑制PhIP-DNA加合物形成与总GST活性无关。结论 饮茶可有效抑制大鼠体内PhIP-DNA加合物形成。因为致癌物-DNA加合物形成是化学致癌过程所必需的起始事件，所以饮茶可预防PhIP潜在的致癌作用。
【关键词】 茶 2-氨基-1-甲基-6-苯基咪唑并［4，5-b］吡啶 DNA加合物
Chemoprotection by Green Tea Against the Formation of Food-borne Carcinogen 2-amino-1-methyl-6-phenylimidazo ［4,5-b］ pyridine (PhIP)-DNA Adducts in Rats
Lin Dongxin*, Xiao Ying, Tan Wen, et al. *Cancer Institute (Hospital), Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100021
【Abstract】 Objective The food-borne mutagen 2-amino-1-methyl-6-phenylimidazo ［4,5-b］ pyridine (PhIP) induces colon and mammary gland tumors in rats and has been implicated in the etiology of human cancer, particularly colorcctal cancer. This study was conducted to examine the potential chemopreventive effect of Chinese green tea against PhIP-DNA adduct formation in rats and its possible mechanisms. Methods Sprague-Dawley rats were maintained on freshly prepared aqueous extract of Chinese green tea (3%) or tap water as the sole source of drinking fluid for 10 days prior to administration with a single dose of PhIP (10 mg/kg body wt) by oral gavage. Rats were sacrificed at 20 h after PhIP treatment and PhIP-DNA adducts in the colon, heart, lung, and liver were analyzed using 32P-postlabeling technique. The activity of cytosolic glutathione S-transferases (GSTs) in the liver, lung and colon mucosa was also determined using CDNB as substrate. Results The levels o[1] [2] [3] 下一页
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