DNA binding, nuclease activity and cytotoxicity studies of Cu(ii) complexes of tridentate ligands
作者:Pankaj Kumar、Sukhamoy Gorai、Manas Kumar Santra、Biplab Mondal、Debasis Manna
DOI:10.1039/c2dt30232b
日期:——
Cu(II) complexes of three tridentate ligands, L1, L2 and L3,[ L1, N-((1H-imidazole-2-yl)methyl)-2-(pyridine-2-yl)ethanamine; L2, N-((1-methyl-1H-imidazole-2-yl)methyl)-2-(pyridine-2-yl)ethanamine; L3, 2-(pyridine-2-yl)-N-((pyridine-2-yl)methyl)ethanamine] respectively, were synthesized and characterized. The single crystal X-ray structure of complex 1 reveals the pseudo octahedral coordination geometry around the copper center. Absorption and fluorescence experimental evidence show good DNA binding propensity (in the order of 105 M−1) of the complexes. Thermal denaturation and circular dichroism (CD) analyses reveal minor structural changes of calf thymus (CT) DNA in presence of complexes and groove and/or surface binding of the complexes to CT-DNA. Kinetic DNA cleavage assay shows pseudo-first-order kinetic reaction between the complex and supercoiled (SC) DNA. In addition, mechanistic SC DNA cleavage results show higher DNA cleavage activity in presence of reducing agent, due to the presence of hydroxyl radicals. In vitro cytotoxicity assay of the complexes demonstrate that the complexes have low toxicity for different cancer cell lines and IC50 values were between 37 and 156 μM.
L1,N-((1-甲基-1H-咪唑-2-基)甲基)-2-(吡啶-2-基)乙胺;L2,N-((1-甲基-1H-咪唑-2-基)甲基)-2-(吡啶-2-基)乙胺;L3,2-(吡啶-2-基)-N-((吡啶-2-基)甲基)乙胺]。络合物 1 的单晶 X 射线结构显示出围绕铜中心的假八面体配位几何。吸收和荧光实验证据表明,复合物具有良好的 DNA 结合倾向(约为 105 M-1)。热变性和圆二色性(CD)分析表明,小牛胸腺(CT)DNA 在复合物的存在下发生了微小的结构变化,复合物与 CT-DNA 的沟槽和/或表面结合。动力学 DNA 裂解测定显示,复合物与超卷曲(SC)DNA 之间发生了伪一阶动力学反应。此外,SC DNA 的机理裂解结果表明,在存在还原剂的情况下,由于羟基自由基的存在,DNA 的裂解活性更高。复合物的体外细胞毒性实验表明,复合物对不同的癌细胞株毒性较低,IC50 值介于 37 和 156 μM 之间。