Comprehensive Study on the Binding of Iron Schiff Base Complex with DNA and Determining the Binding Mode
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ORIGINAL PAPER
Comprehensive Study on the Binding of Iron Schiff Base Complex with DNA and Determining the Binding Mode Maryam Nejat Dehkordi & Per Lincoln
Received: 28 September 2012 / Accepted: 24 February 2013 # Springer Science+Business Media New York 2013
Abstract The iron (III) [N, N′ Bis (5-(triphenyl phosphonium methyl) salicylidene)-1, 2 ethanediamine] chloride [Fe Salen] Cl, has been synthesized and characterized as described previously. The interaction of iron complex with calf thymus (CT) DNA has been studied extensively by experimental techniques. Absorption spectra showed both hypochromism and hyperchromism. Thermal denaturation study of DNA with complex revealed the ΔTm of 5 °C. Competitive binding study shows that the enhanced emission intensity of ethidium bromide (EB) in the presence of DNA was quenched by adding of the iron complex indicating that it displaces EB from its binding site in DNA and the apparent binding constant has been estimated to be 5×106 μM−1. Fluorescence Scatchard plot revealed type B behavior for interaction of complex to DNA. Circular dichroism (CD) spectra measurements showed that the complex interacts with DNA via surface and groove bindings. Linear dichroism (LD) measurements confirmed the bending of DNA in the presence of complex. Furthermore, Isothermal titration calorimetry (ITC) experiments approved that the binding of complex is based on both electrostatic and hydrophobic interactions. More, ITC profile exhibits the existence of two binding phases for the complex. Keywords Schiff base . ct-DNA . Fluorescence . Circular dichroism (CD) . Linear dichroism (LD) . Isothermal titration calorimetry (ITC) M. Nejat Dehkordi (*) Department of Chemistry, Faculty of Science, Islamic Azad University, Shahrekord branch, Shahrekord, Iran e-mail: [email protected] M. Nejat Dehkordi e-mail: [email protected] P. Lincoln Department of Chemical and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
Introduction Among the organic compounds, Schiff bases possess excellent properties such as, structural similarities with natural biological substances, simple preparation procedures, flexibility in synthesis, wide applications, and diverse structure modification [1, 2]. Schiff bases have been reported to show a variety of biological actions by virtue of the azomethine linkage, which is responsible for various antibacterial, antifungal, herbicidal, clinical and analytical activities [3–6]. Schiff base complexes have been widely studied due to the numerous applications. They serve as models for biologically important species and find applications in biomimetic catalytic reactions. Chelating ligands containing N, S and O donor atoms show broad biological activity and they are of special interest due to the variety of ways in which they are bonded to metal ions. It is known that the existence of metal ions bonded to biologically active compounds may enhance their activities [7–12]. Schiff bases have potential for anticancer drugs. The anticancer act
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