DNA binding/cleavage, antioxidant and cytotoxic activities of water soluble cobalt(II) and copper(II) antipyrine complexes

Two transition metal complexes have been synthesized by reacting antipyrine (AP) with CoCl2·6H2O or CuCl2·2H2O. The structures of the complexes have been determined by single crystal X-ray diffraction studies. The interaction of cobalt(II) and copper(II) complexes with calf thymus DNA (CT-DNA) was investigated by electronic absorption spectroscopic technique. The experimental evidences indicated that the two water-soluble metal(II) complexes could strongly bind to CT-DNA via intercalation mechanism. A gel electrophoresis assay demonstrated the ability of the complexes to cleave the pBR322 plasmid DNA via oxidative pathway. Investigation of the antioxidative properties showed that the two water soluble metal(II) complexes have a significant radical scavenging potency against DPPH, OH and ABTS radicals. Further, the cytotoxic effect of the compounds examined on cancerous cell lines, viz., HeLa, HEp-2 and MCF-7, showed that the complexes exhibited substantial cytotoxic specificity on HeLa over the other two cell lines.