EGCG对DNA辐射损伤的保护作用

利用荧光探针溴化乙啶（ＥＢ）研究了茶儿茶素ＥＧＣＧ与小牛胸腺ＤＮＡ的相互作用，结果表明，ＥＧＣＧ─ＤＮＡ的荧光光谱基本不随时间而变化，但随ＥＧＣＧ浓度增强，λ２峰（５８８．８ｎｍ）强度下降，偏振度增加，这可能与ＥＧＣＧ插入ＤＮＡ碱基对平面，双链有序度增加有关。γ辐照使小牛胸腺ＤＮＡ发生断裂等损伤，剂量越大，损伤越严重，但加入ＥＧＣＧ后，对ＤＮＡ损伤有一定保护作用，这可能与ＥＧＣＧ清除γ辐照间接效应产生的自由基有关。

Protection of EGCG on DNA From Radiative Damage

An in vitro investigation on the interaction between catechin(epigallocatechin gallate, EGCG)and calfthymus DNA was carried out by the fluorescence probe. The fluorescent spectra of the EGCG─DNA didn′tvary with the period of time. The fluorescent intensity of the λ2 peak(588.8 nm)decreased but the polariza-tion increased with the increasing of EGCG concentration, resulting from the inserting of EGCG in the planestructure of DNA base and the increasing of the double─strand ordering conformation. After being radiated byλ─ray, the calf thymus DNA was damaged and the greater was the radiative dosage,the more serious was thedamage. The DNA was protected from the damage by treating the thymus with EGCG before radiation. Theprotection was correlated with the EGCG′s function of scavenging the free radicals resulting from the radia-tion.