Exploring Biological Properties of Manganese(II)‐Phenanthroline‐Based Complexes: In Vitro Insights

Manganese is a bioessential element that plays a crucial role in biological systems. Four Mn(II) complexes with different 1,10‐phen skeletons were synthesized, characterized, and their purity was confirmed by elemental analysis. The solid structure of cis ‐[Mn(phenOne) 2 Cl 2 ] ( 3 ) where phenOne is 1,10‐phenanthroline‐5,6‐dione, was determined by x‐ray diffraction. All complexes are stable in aqueous media and interact with human serum albumin, an important behavior for a good pharmacokinetic profile. All complexes were tested against Mycobacterium tuberculosis, Trypanosoma cruzi , and Leishmania amazonensis . Furthermore, their cytotoxicity was investigated on breast (MDA‐MB‐231 and MCF‐10A) and lung (A549 and MRC‐5) human cell lines. The effect of complex 3 , the most promising complex, on the morphology of MDA‐MB‐231 breast cancer cells was further studied at different concentrations. The cytotoxic effect was confirmed by fluorescence microscopy using Hoechst/PI dyes. Viscosity, circular dichroism, fluorescence experiments, and electrophoresis indicated that DNA is not the main target for this compound. Overall, manganese(II)–phenanthroline complexes represent a promising scaffold for medicinal applications.