Role of biologically important imidazole moiety on the antimicrobial and anticancer activity of Fe(III) and Mn(II) complexes

Currently, most pathogens influencing a number of epidemics outline a notable warning to human health. It has pushed researchers to design new antimicrobial drugs using transition metals that are studied in proceeding fewer years for their antimicrobial properties. Henceforth, in this work, two mononuclear complexes [Imz-H][Fe(pda)₂]⋅1⋅3H₂O (1) and [Mn(Imz)₆]⋅2Cl^-⋅2H₂O (2) [Imz = imidazole and H₂pda = 2,6 pyridine dicarboxylic acid] are isolated and characterized systematically by various spectral and single-crystal XRD studies. The antimicrobial activity of the present hexadentate complexes of Fe(III) and Mn(II) against Gram-positive as well as Gram-negative bacteria is also assessed. Augmented activity against standard isolates of Staphylococcus aureus with a minimum inhibitory concentration (MIC) is observed. Similar activity was also observed toward Escherichia coli, Klebsiella pneumoniae and Listeria monocytogenes. 1 and 2 have excellent bactericidal activity, and no resistant mutant for S. aureus was seen. The compound also unveiled antibiofilm activity and was capable to disrupt significantly the pre-formed biofilms and this property was confirmed by XTT assay experiment. The MTT assay data indicate that 1 and 2 can be used as anticancer agents toward the RAW 64.7 (human macrophage/monocyte) cell line. Further, the molecular docking study reveals that the role of imidazole is very important in the biological activity of these complexes. Moreover, our results suggest that 1 and 2 with its effective anti-microbial, anti-biofilm and cytotoxicity activity can be used to treat bacterial and fungal infections and could be appraised clinically for further applications.

Communicated by Ramaswamy H. Sarma