Roy Atanu Singha, Samanta Sintu Kumar, Ghosh Pooja, Tripathy Debi Ranjan, Ghosh Sudip Kumar, Dasgupta Swagata
Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, India.
Department of Biotechnology, Indian Institute of Technology, Kharagpur 721302, India.
Mol Biosyst. 2016 Aug 16;12(9):2818-33. doi: 10.1039/c6mb00344c.
The dietary components, flavonoids, are important for their anti-oxidant properties and the ability to act as metal ion chelators. The characterization of the morin-Cu(ii) complex is executed using elemental analysis, FTIR and mass spectroscopy. DNA cleaving and cell cytotoxicity properties followed by serum albumin binding have been investigated in this report. The morin-Cu(ii) complex was found to cleave plasmid pBR322 DNA via an oxidative pathway as revealed by agarose gel based assay performed in the presence of some scavengers and reactive oxygen species. The breaking of the deoxyribose ring of calf thymus DNA (ct-DNA) was also confirmed by the formation of thiobarbituric acid reacting species (TBARS) between thiobarbituric acid and malonaldehyde. The morin-Cu(ii) complex is able to inhibit the growth of human HeLa cells. Fluorescence studies revealed that the morin-Cu(ii) complex can quench the intrinsic fluorescence of serum albumins (SAs) via a static quenching method. The binding constants were found to be in the order of 10(5) M(-1) and observed to increase with temperature. Both ΔH° and ΔS° are positive for the binding of the morin-Cu(ii) complex with serum albumins which indicated the presence of hydrophobic forces. Site-selectivity studies reveal that the morin-Cu(ii) complex binds to both site 1 (subdomain IIA) and site 2 (subdomain IIIA) of human serum albumin (HSA) and bovine serum albumin (BSA). Circular dichroism (CD) studies showed the structural perturbation of SAs during binding with the morin-Cu(ii) complex. The results from binding studies confirmed that after complexation with the Cu(ii) ion, morin alters its mode of interaction with SAs which could have differential implications on its other biological and pharmaceutical properties.
膳食成分黄酮类化合物因其抗氧化特性以及作为金属离子螯合剂的能力而十分重要。使用元素分析、傅里叶变换红外光谱（FTIR）和质谱对桑色素 - 铜（II）配合物进行表征。本报告研究了其DNA裂解、细胞毒性特性以及随后的血清白蛋白结合情况。如在一些清除剂和活性氧存在下进行的琼脂糖凝胶分析所揭示，桑色素 - 铜（II）配合物通过氧化途径裂解质粒pBR322 DNA。硫代巴比妥酸与丙二醛之间形成硫代巴比妥酸反应物质（TBARS）也证实了小牛胸腺DNA（ct - DNA）脱氧核糖环的断裂。桑色素 - 铜（II）配合物能够抑制人宫颈癌细胞系（HeLa细胞）的生长。荧光研究表明，桑色素 - 铜（II）配合物可通过静态猝灭方法猝灭血清白蛋白（SAs）的固有荧光。发现结合常数约为10⁵ M⁻¹，且随温度升高而增加。桑色素 - 铜（II）配合物与血清白蛋白结合的ΔH°和ΔS°均为正值，这表明存在疏水作用力。位点选择性研究表明，桑色素 - 铜（II）配合物与人血清白蛋白（HSA）和牛血清白蛋白（BSA）的位点1（亚结构域IIA）和位点2（亚结构域IIIA）均结合。圆二色性（CD）研究显示了SAs在与桑色素 - 铜（II）配合物结合过程中的结构扰动。结合研究结果证实，与铜（II）离子络合后，桑色素改变了其与SAs的相互作用模式，这可能对其其他生物学和药学性质产生不同影响。
