Biologically vital metal-based antimicrobial active mixed ligand complexes: synthesis, characterization, DNA binding and cleavage studies

Abstract

Few novel cobalt(II) and copper(II) complexes [M(fmp)3]Cl2, [M(fmp)(bpy)2]Cl2,<br />[M(fmp)(phen)2]Cl2 and [M(fmp)(phen)(bpy)]Cl2 (fmp = 3-furan-2-ylmethylene-pentane-2,4-<br />dione, phen = 1,10-phenanthroline, bpy = 2,2'-bipyridine) have been synthesized and<br />characterized by elemental analyses, molar conductance, magnetic susceptibility measurements,<br />IR, electronic, EPR, mass spectra and cyclic voltammetric studies. The synthesized complexes<br />are found to be monomeric and electrolytic nature. The UV-Vis., magnetic susceptibility and<br />EPR spectral data of the complexes suggest a distorted octahedral geometry for Cu(II)<br />complexes and octahedral geometry for Co(II) complexes around the central metal ion. The CV<br />profile of the complexes shows a quasi-reversible peak which indicates that the metal-ligand<br />linkage is more covalent in nature. Spectroscopic and viscosity measurements prove that the<br />[M(fmp)(phen)2]Cl2 complexes bind more efficiently with DNA than other complexes through<br />intercalative mode. The difference of peak potential and electrochemical parameters between<br />free and DNA-bound complexes shows the formation of an electrochemical active complex<br />between synthesized complexes and DNA. All the complexes cleave the Supercoiled pUC19<br />DNA in vitro under the presence of reducing agent (3-mercaptopropionic acid). The in vitro<br />antimicrobial activities of the compounds have been tested against the bacterial and fungal<br />strains using the disc diffusion method. The minimum inhibitory concentration (MIC) values<br />against the growth of microorganisms are much larger for metal chelates than the individual<br />ligands.