Phthalic acid esters (PAEs) are widely used as plasticizers and easily release into the environment. Based on its environmental toxicity, a variety of PAEs have been already listed as priority control pollutants by the United States Environmental Protection Agency and China Environmental Monitoring Center. Therefore, the biological toxicology of PAEs is greatly concerned. In this study, calf thymus DNA (ctDNA) was used as the test material to explore the interaction between PAEs and DNA through the spectroscopy technologies. The hyperchromic effect was found at 260 nm in the UV-Vis spectral experiments, which proved that PAEs could disrupte the base-pairs of ctDNA and intercalate into the ctDNA. Fluorescence intensity of EB-ctDNA complex decreased with the increase of PAEs concentration. The fluorescence intensity for dimethyl phthalate (DMP), diethyl phthalate (DEP) and dibu-tyl phthalate ( DBP ) were decreased by 55%, 50% and 36%, respectively. Meanwhile, in the KI fluorescence quenching test, Ksv of KI to DMP, DEP and DBP decreased from 7.992 (R2= 0.9970), 10.27 (R2= 0.9960) and 13.52 (R2= 0.9806) to 6.721 (R2= 0.9963), 7.047 (R2= 0.9599) and 11.03 (R2= 0.9803), respectively, indicating that PAEs were bound to DNA by the intercalative mode. In the salt ion test, the fluorescence intensity of PAEs-ctDNA did not change with the increase of NaCl concentration. The results of the experiments excluded the groove interaction between PAEs and DNA, and determined their binding mode by intercalation. With the increase of PAEs side chain length, the intercalation effect was weakened.%邻苯二甲酸酯(PAEs)作为增塑剂被广泛使用,易渗透到环境中产生环境毒性,多种PAEs已被美国环境保护署和中国环境监测中心列为优先控制污染物,其生态毒理学机制被广泛关注.本试验以小牛胸腺DNA(ctDNA)为供试材料,旨在通过光谱学技术探究PAEs与DNA的相互作用机制.在紫外可见光谱试验中,随着PAEs浓度的增加,DNA紫外光谱出现增色效应,证明DNA的部分碱基对被PAEs破坏,且PAEs与DNA通过嵌插作用结合.荧光光谱试验中,随着PAEs浓度的增加,EB-ctDNA体系荧光强度逐渐降低,邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)和邻苯二甲酸二丁酯(DBP)的最大荧光抑制率分别为55%、50%和36%;KI荧光猝灭试验中,在加入DNA之后KI对DMP、DEP和DBP的荧光猝灭常数Ksv分别从7.992(R2=0.9970)、10.270(R2=0.9960)和13.52(R2=0.9806)降低到6.721(R2=0.9963)、7.047(R2=0.9599)和11.03(R2=0.9803),荧光猝灭常数均降低,实验结果证明PAEs与DNA通过嵌插作用结合.盐离子试验中,随着NaCl浓度的增加,PAEs-ctDNA的荧光强度没有发生变化.试验结果排除了PAEs与DNA分子之间沟槽作用的可能,确定了其结合方式为嵌插作用,随着PAEs侧链的逐渐增长,嵌插作用逐渐减弱.
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