Antibacterial and superoxide dismutase activity as well as DNA interactions of ciprofloxacin-based ternary copper(II) phenanthroline complexes

摘要

Five neutral mixed-ligand mononuclear square-pyramidal copper(II) complexes of the type [Cu(cpf)(L~n)Cl] (cpf = ciprofloxacin and L~n = phenanthroline derivatives) (1-5) were synthesized and characterized. The complexes were screened for their antibacterial activity and bactericidal activity against two Gram~((+ve)) and three Gram~((-ve)) microorganisms and the results showed that all complexes studied are more potent than the quinolone standard drug ciprofloxacin. Absorption titration, viscosity, and thermal denaturation measurement studies revealed that each of these square-pyramidal complexes moderately interacts with calf thymus DNA. The binding constants for mixed ligand complexes are in order of 1.5 × 10 ~4-3.0 × 10~4 M~(-1). Based on the data obtained in the DNA binding studies an intercalative mode of binding is suggested for these complexes. The nucleolytic cleavage activity of adducts and gyrase inhibition assay were studied on double stranded pUC19 DNA by gel electrophoresis experiments. From the SOD mimic study; the concentration of complexes ranging from 0.45 μM to 1.45 μM are enough to inhibit the reduction rate of NBT by 50 % (IC50) in NADH/PMS system.