New copper(ii) complexes of the anti-inflammatory drug mefenamic acid: a concerted study including synthesis, physicochemical characterization and their biological evaluation

Abstract

Reaction of hydrated copper(II) mefenamate in the presence of diverse N-donor ligands such as N,N,N′,N′-tetramethylethylenediamine (temed), ethylenediamine (en), β-picoline (β-pic) in a methanol : water mixture (4 : 1, v/v) yielded crystalline monomeric copper(II) complexes [Cu(temed) (mefenamato)₂], 1, [Cu(en)₂(H₂O)₂](mefenamato)₂, 2 and [Cu(β-pic)₂(mefenamato)₂]·H₂O, 3. The newly synthesized complexes have been characterized by elemental analysis, spectroscopic methods (FT-IR, UV-Vis and EPR), thermogravimetric analyses and single-crystal X-ray structure determination in the case of complexes 2 and 3. The ground-state geometry optimization of complex 1 was performed by DFT calculations. In order to verify the complexes capability to get bound and possibly transported by the albumin towards their biological targets (cells and/or tissues), the interaction with bovine (BSA) and human serum albumin (HSA) was studied by fluorescence emission spectroscopy. The interaction of complexes 1–3 with calf-thymus DNA (CT DNA) was monitored by UV-Vis spectroscopy, cyclic voltammetry, viscosity measurements and via the ethidium bromide (EB) displacement from the EB–DNA conjugate performed by fluorescence emission spectroscopy, as a preliminary approach to evaluate their potential biological activity.