INSPIRED RESEARCH ON THE DNA BINDING AND CLEAVAGE ABILITY: DESIGN, SYNTHESIS, CHARACTERIZATION AND PROPERTIES OF THEIR DINUCLEAR METAL (II) COMPLEXES

Metal complexes of Cu(II), Ni(II) and VO(II) with a tetradentate NNOS donor Schiff base ligand (H2L), synthesized by condensation of 3, 3′-dihydroxybenzidine, 2, 3- pentanedione and 2-aminothiophenol were prepared and characterized by elemental analyses, IR, electronic, ESR, NMR studies, as well as conductance measurements. Squareplanar geometry for the Cu (II), Ni(II) and square pyramidal for VO(II) complexes have been assigned to the prepared complexes. Absorption studies revealed that the complexes are an avid binder of calf thymus DNA. 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 the complexes was carried out on double stranded pUC18DNA by using a gel electrophoresis experiment in the presence and absence of oxidant (H2O2). All the metal complexes cleaved supercoiled DNA by hydrolytic paths. The antibacterial activities of the synthesized compounds were tested in vitro against the sensitive organisms Staphylococcus aureus, Bacillus subtilis as Gram positive bacteria, Escherichia coli and Klebsilla pneumonia as Gram negative bacteria, and the results are discussed. We found that the antioxidant activity of the complexes on DPPH is concentration dependent and higher than that of the free ligand L.