Spectroscopic, electrochemical, DNA binding and antioxidant biomimetic catalytic activities of metformin-based copper(II) complexes

Abstract

Interaction of copper(II) perchorate hexahydrate with metformin as a primary ligand and amino acids as secondary ligands lead to the formation of three mixed ligand complexes, viz., [Cu(Met)(AA)(ClO4)(H2O)] (Met=metformin, AA=glycine (1), L-glutamine (2), and L-arginine (3)). Their structures and properties were characterized by elemental analysis, IR, UV–Vis, and ESR spectroscopy, electrochemical measurements including cyclic voltammetry, electrical molar conductivity and magnetic moment measurements. An octahedral geometry is proposed for the three compounds in monomeric structures. The redox behavior of complexes was investigated by cyclic voltammetry. Also, the interaction of copper complexes with calf thymus double-stranded DNA (CT-DNA) was studied electrochemically by using CV. The binding constants of complexes (2) and (3) with DNA were determined through the changes on the redox peak currents. The binding constants were evaluated to be 4.6×104 and 2.8×104M−1 for complexes (2) and (3), respectively. Additionally, the antioxidant (superoxide dismutase and catalase) biomimetic catalytic activities of the obtained complexes (1–3) have been assessed for their efficiency of O2− scavenging with and complete reactive oxygen species (ROS) detoxification with respect to peroxides.