A step-ladder manganese(iii) metallacrown hosting mefenamic acid and a manganese(ii)–mefanamato complex: synthesis, characterization and cytotoxic activity

Abstract

The interaction of Mn(II) with the non-steroidal anti-inflammatory drug mefenamic acid (Hmef) in the presence or absence of salicylaldoxime (H₂sao) leads to the formation of the hexanuclear Mn(III) cluster [Mn₆(O)₂(mef)₂(sao)₆(CH₃OH)₄] 1, characterized as stepladder inverse-9-metallacrown-3 accommodating mefenamato ligands, or the mononuclear Mn(II) complex [Mn(mef)₂(CH₃OH)₄], 2, respectively. Both complexes were characterized by physicochemical and spectroscopic techniques and the structure of complex 1 was characterized by X-ray crystallography. The overall magnetic behavior of compound 1 is antiferromagnetic with a high-spin well-isolated ground state S = 4. The in vitro cytotoxic effects of the complexes were evaluated against three cancer cell lines (HeLa, MCF-7 and A549 cells) as well as their combinatory activity with the well-known chemotherapeutic drugs cisplatin and 5-fluorouracil. Furthermore, in silico predictive tools have been employed to study the properties and acute rat toxicity and cell line cytotoxicity of the most active complex.