The binding mode of pyrazolone derived copper(II), cobalt(II), nickel(II) and zinc(II) Schiff base coordination compounds with Calf-Thymus DNA
Keywords:Pyrazolone derivatives, octahedral geometry, non-electrolytic nature, intercalation mode
Transition metal complexes with Schiff base ligands possess remarkable biomedical activities that could be used to develop new metal-based anticancer agents. Anticancer metal complexes have attracted considerable interest since the successful application of platinum based anti-cancer drugs. Pyrazolone derivatives have been extensively studied and have shown a wide range of pharmacological activities and anticancer activities. A new class of mononuclear copper (II), cobalt(II), nickel(II) and zinc(II) complexes were synthesized using pyrazolone precursor Schiff base, obtained by the condensation of 4–aminoantipyrine with salicylaldehyde and respective metal(II) chloride. They have been characterized by elemental analysis, magnetic susceptibility, molar conductance measurements, UV-Vis., FT-IR, 1H NMR spectra and EPR studies. Their magnetic susceptibility values of the complexes at room temperature are consistent with octahedral geometry around the central metal ions. These complexes show lower conductance values, supporting their non-electrolytic nature. The data show that the complexes have composition of [ML2] type. In vitro DNA binding profiles of all complexes have been explored by absorption titrations, cyclic voltammetry technique and viscosity measurements. The corroborative results of above experiments suggest that these complexes are efficient metallo intercalators and can interact with CT-DNA. The binding constant values (Kb) clearly signify that the complexes bind to DNA through intercalation mode. The binding affinity of these complexes with CT DNA is found to be in the order, Cu(II)>Zn(II)>Co(II)>Ni(II), among them copper complex displaying a higher binding propensity as compared to other complexes.