DNA binding studies of new valine derived chiral complexes of tin(IV) and zirconium(IV)

Abstract

Valine derived chiral complexes of SnCl 4 ( 1) and ZrCl 4 ( 2) were designed as potent antitumor agents. These complexes were characterized by elemental analysis, IR, 1H NMR, 119Sn NMR and ESI mass spectroscopy. In vitro binding studies of complexes 1 and 2 under physiological conditions at room temperature with CT-DNA were carried out employing UV–vis absorption titration, fluorescence studies and viscosity measurements. The extent of binding was quantified by K b values of complexes 1 and 2 which were found to be 1.97 × 10 4 and 1.17 × 10 3 M −1, respectively, suggesting that complex 1 has significantly greater DNA binding propensity in contrast to the complex 2. The mode of action at the molecular level was ascertained by the interaction of complex 1 with 5′GMP and 5′TMP which revealed that complex 1 binds via electrostatic mode with the oxygen of the negatively charged surface phosphate group of the DNA helix. The supercoiled pBR322 plasmid DNA cleavage activity of complex 1 was ascertained by gel electrophoresis assay.