Design, Synthesis, Theoretical, Spectroscopic and Molecular Docking Studies of Ruthenium and Zinc Complexes and their Antimycobacterial Study

Abstract

The six mononuclear complexes of ruthenium and zinc viz. [Ru(bpy)2(HL1)]Cl (ML1), [Ru(bpy)2(HL2)]Cl (ML2), [Ru(bpy)2(HL3)]Cl (ML3), [ZnCl(H2O)HL1]Cl (ML4), [ZnCl(H2O)HL2]Cl (ML5), [ZnCl(H2O)HL3]Cl (ML6); bpy = 2,2′-bipyridyl, HL = substituted thiosemicarbazone: HL1 = Cl, HL2 = OCH3, HL3 = OCH2Ph) were synthesized and characterized by elemental analysis, IR, 1H and 13C NMR, UV-Vis and ESI-MS spectroscopy techniques. The gas phase geometries of all the complexes have been optimized by density functional theory (DFT). The antimycobacterial activity of all the compounds was performed initially at 100 μM concentration, followed by MIC determination studies with compounds, which showed 90% reduction in fluorescence intensity. In addition, molecular docking analysis was performed to know the interactions between complexes and their probable binding sites in penicillin binding protein (PBP2). The 90% reduction in fluorescence intensity of the mycobacterial cultures were observed with HL2, HL3 and ML3. The MIC determination study showed good inhibition of ML3 and HL3 treated cultures even at 25 μM concentration. The potential activity shown by HL3 and ML3 cultures shows to be promising compounds, which may be further optimized for improved antimycobacterial activity. Electronic properties and various reactivity descriptors have been determined theoretically and an attempt has been perform to establish the correlation between biological activity and these parameters for the concerned metal complexes.