用凝胶电泳法研究羟基肉桂酸衍生物对DNA的辐射保护效应

GEL ELECTROPHORESIS STUDY OF RADIOPROTECTIVE EFFECT OF HYDROXY CINNAMIC ACID DERIVATIVES ON DNA

用凝胶电泳法研究了DNA在γ射线作用下链断裂和链交联及保护剂对它的保护效应。DNA样品经电泳、荧光染色、紫外灯下照相后对底片进行光密度分析,最后经计算机数据处理,可以得到其辐照前后的分子量分布变化,并由此得出DNA的链断裂和链交联的定量数据。以此研究了冰冻干燥二元体系中羟基肉桂酸衍生物,在室温下对小牛胸腺DNA的辐射保护效应。测量了DNA与咖啡酸及芥子碱在不同摩尔比下时DNA的链交联和链断裂G值,发现两者对DNA均有明显的辐射保护效应,但咖啡酸的辐射保护效应强于芥子碱。对照对它们的ESR研究,并分析它们的结构异同,初步探讨了两者辐射保护效应强弱的原因。

ABSTRACT The radioprotective effect exerted by hydroxy cinnamic acid derivati-ves on the radiation damage of DNA, such as double-strand break (DSB). intermole-cular crosslinking (CL), has been studied by gel electrophoresis. The molecular lengthdistribution of DNA can be measured by this method, and by comparing average mo-lecular length of DNA before and after irradiation, the frequency of DSB and CL canbe determined quantitatively, The radioprotective effect of caffeic acid and sinapine oncalf thymus DNA in binary system at room temperature have been determined. Bothcaffeic acid and sinapine reveal apparent protective effects and the former is strongerthan the latter. The mechanism of radioprotection at room temperature has been discus-sed. Based. on this finding, combined with the previous ESR study and an analysis ofthe molecular structure about these two protectors, it is suggested that the target isprotected as a result of hydrogen atom transfering from protector to target.