Cobalt(II) complexes with the non-steroidal anti-inflammatory drug diclofenac and nitrogen-donor ligands

The interaction of the non-steroidal anti-inflammatory drug sodium diclofenac with CoCl₂ in the absence or presence of the nitrogen-donor ligands 2,2'-bipyridine, 1,10-phenanthroline, 2,2'-bipyridylamine, pyridine or imidazole resulted in the formation of six mononuclear Co(II) complexes. The complexes were characterized by diverse physicochemical and spectroscopic techniques and single-crystal X-ray crystallography revealing a monodentate or a bidentate chelating binding mode of the diclofenac ligands. The scavenging activity of the complexes was evaluated in vitro against the free radicals of 1,1-diphenyl-2-picrylhydrazyl, 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and hydroxyl; the complexes present significant scavenging activity of ABTS and hydroxyl radicals. The interaction of the complexes with calf-thymus (CT) DNA and bovine serum albumin (BSA) was also investigated; the complexes can bind tightly to CT DNA via intercalation and can bind to BSA tightly and reversibly.