Nickel(II) complexes with niflumic acid, piroxicam, and isoxicam: structural characterization and biological activity

Three mononuclear nickel(II) complexes with the non-steroidal anti-inflammatory drugs niflumic acid, piroxicam, and isoxicam have been synthesized and characterized with diverse techniques. The molecular structure of complex [Ni(niflumato-O)2(MeOH)4] was determined with single-crystal X–ray crystallography. The antioxidant activity of the compounds was evaluated via their ability to scavenge 1,1–diphenyl–picrylhydrazyl and 2,2΄–azinobis–(3–ethylbenzothiazoline–6–sulfonic acid) radicals. The interaction of the drugs and their complexes with calf-thymus DNA was studied with diverse techniques revealing their potency to intercalate tightly to DNA. The interaction of the compounds for bovine serum albumin was studied with fluorescence emission spectroscopy and revealed their tight and reversible binding to the albumin.