Zn(II) complexes with mefenamic acid: Synthesis, characterization, and anticancer activity

In this study, three Zn(II) complexes were synthesized by reacting Zn(CH3COO)2. 2H2O or Zn(ClO4)2. 6H2O with mefenamic acid in the presence of imidazole and pyridine-based co-ligands. The resulting complexes were [Zn (mef)2(imi)2]; (1), [Zn(mef)(py)3]. (ClO4); (2), and [Zn3(mef)6(apy)2]; (3), where mef represents deprotonated mefenamic acid/mefenamato, imi represents imidazole, py represents pyridine and apy represents 2-aminopyridine. Elemental analysis, spectroscopic techniques (FTIR, UV-Vis, 1H and 13C NMR, fluorescence), PXRD (1) and (3), thermal analysis (TG-DSC) (1) and (3), and single crystal X-ray crystallography were employed to characterize the complexes. The Zn(II) in (1) and (2) are in a distorted tetrahedral coordination environment. In (1), the Zn(II) is coordinated by two mefenamato ligands, each coordinating via a monodentate carboxylate oxygen atom and two nitrogens of the imidazole ligands. In (2), the Zn(II) is coordinated by one mefenamato and three pyridine ligands. Complex (3) is a trinuclear zinc complex in which the central Zn(II) is coordinated by six oxygen atoms from six bridging carboxylate groups of the mefenamato ligands. Three mefenamato ligands and a monodentate 2-aminopyridine ligand also coordinate to two terminal Zn(II) ions in a tetrahedral coordination environment in (3). The cytotoxicity of the complexes was evaluated using an MTT assay against MCF-7 (human breast cancer cell line). The complexes demonstrated dependent cell cytotoxicity, with (2) showing the highest anticancer activity.