Manganese(ii) complexes with the non-steroidal anti-inflammatory drugs naproxen and mefenamic acid: synthesis, structure, antioxidant capacity, and interaction with albumins and DNA

The interaction of the non-steroidal anti-inflammatory drugs naproxen or mefenamic acid with MnCl2 in the presence of the nitrogen-donor ligands 2,2-bipyridine, 1,10-phenanthroline, 2,2-bipyridylamine or pyridine resulted in the formation of one dinuclear and four mononuclear Mn(ii) complexes. The complexes were characterized by diverse physicochemical and spectroscopic techniques and single-crystal X-ray crystallography. The biological activity of the complexes was evaluated in regard to their ability to scavenge the free radicals of 1,1-diphenyl-2-picrylhydrazyl, 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and hydroxyl and their binding affinity towards calf-thymus (CT) DNA and serum albumins. The complexes exhibit noteworthy scavenging activity towards ABTS and hydroxyl radicals; they can bind tightly to CT DNA via intercalation and can bind to bovine or human serum albumins tightly and reversibly.