Antibacterial, nuclease, and SOD-mimic behaviors of copper(II) complexes of norfloxacin and phenanthrolines

Square-pyramidal complexes [Cu(NFL)(An)Cl] center dot 5H2O (An = phenanthroline derivatives and NFL = deprotonated norfloxacin) have been synthesized and characterized. Interactions with Herring Sperm DNA and pUC19 DNA have been investigated. Mode and extent of interaction was measured by the perturbation in absorbance of complexes in the absence and presence of DNA. Hydrodynamic volume change and gel electrophoretic results were also kept under consideration. Synthesized complexes bind to DNA via intercalation with binding constant 0.875-1.446 x 104 (mol L-1)-1 based on bathochromism and hypochromism observed. Intercalative binding of complexes with DNA was further supported by relative viscosity, where 5 intercalates more strongly with most increase in relative viscosity, and Kb value of 1.446 x 104 (mol L-1)-1. Evaluation of electrophoretic separation of plasmid on agarose gel reveals that 5 cleaves more efficiently. Square-pyramidal geometry at the metal center supports superoxide-dismutase (SOD)-mimic behavior in addition to an electron-withdrawing group on the ancillary ligand stabilizing Cu-O bonding.