Neutral and cationic manganese(II)–diclofenac complexes: structure and biological evaluation

<div><p>The interaction of MnCl₂ with the non-steroidal anti-inflammatory drug sodium diclofenac in the presence of 2,2′-bipyridine and pyridine resulted in the formation of cationic and neutral mononuclear complexes [Mn(diclofenac)(2,2′-bipyridine)(H₂O)₂] (diclofenac) (<b>1</b>) and [Mn(diclofenac)₂(pyridine)₂(H₂O)₂] (<b>2</b>), respectively. The structure of <b>1</b> was characterized by X-ray crystallography. In a preliminary attempt to evaluate the biological properties and possible application, the interaction of the complexes with calf-thymus DNA and human or bovine serum albumins was monitored. Additionally, the ability of the compounds to scavenge radicals such as 1,1-diphenyl-picrylhydrazyl, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), and hydroxyl radicals was evaluated; the complexes were more potent scavengers than free sodium diclofenac.</p></div

Manganese(II) Complexes with the Non-steroidal Anti-Inflammatory Drug Tolfenamic Acid: Structure and Biological Perspectives

Manganese­(II) complexes with the non-steroidal anti-inflammatory drug tolfenamic acid (Htolf) with the nitrogen-donor heterocyclic ligands 1,10-phenanthroline (phen), pyridine (py), or 2,2′-bipyridylamine (bipyam) and/or the oxygen-donor ligands H₂O or <i>N</i>,<i>N</i>-dimethylformamide (DMF) have been synthesized and characterized. The crystal structures of complexes [Mn­(tolf-O)­(tolf-O,O′)­(phen)­(H₂O)], [Mn₂(μ₂-tolf-O,O′)₂(tolf-O,O′)₂(bipyam)₂], [Mn₂(μ₂-H₂O)­(μ₂-tolf-O,O′)₂(tolf-O)₂(py)₄]·1.5MeOH·py, and [Mn­(μ₂-tolf-O,O′)₂(DMF)₂]_<i>n</i> have been determined by X-ray crystallography. The interaction of the complexes with serum albumin proteins was investigated, and relative high binding constant values were calculated. The ability of the compounds to scavenge 1,1-diphenyl-picrylhydrazyl, 2,2′-azinobis­(3-ethylbenzothiazoline-6-sulfonic acid), and hydroxyl radicals was evaluated, and [Mn­(tolf)₂(phen)­(H₂O)] was the most active scavenger among the compounds. The compounds have also exhibited noteworthy <i>in vitro</i> inhibitory activity against soybean lipoxygenase. UV titration studies of the interaction of the complexes with calf-thymus (CT) DNA have proved the binding to CT DNA with [Mn­(μ₂-tolf)₂(DMF)₂]_<i>n</i> exhibiting the highest DNA-binding constant (<i>K</i>_b = 5.21 (±0.35) × 10⁵ M^–1). The complexes bind to CT DNA probably via intercalation as suggested by DNA-viscosity measurements and competitive studies with ethidium bromide (EB), which revealed the ability of the complexes to displace the DNA-bound EB