Synthesis, DFT calculations and molecular docking study of mixed ligand metal complexes containing 4,4′-dimethyl-2,2′-bipyridyl as α-glucosidase inhibitors

Abstract Novel mixed ligand metal complexes including 4,4′-dimethyl-2,2′-bipyridyl (dmdpy) and 6-methylpyridine-2-carboxylic acid (6-mpaH) {[VO(6-mpa)(dmdpy)]·SO3, (1), [Fe(6-mpa)(dmdpy)(NO3)2]·NO3, (2), Ni(6-mpa)(dmdpy)Cl2, (3), [Zn(6-mpa)(dmdpy)Cl2]·H2O, (4), Cd(6-mpa)2(dmdpy), (5), [Hg(6-mpa)(dmdpy)(NO3)2]·H2O, (6)} were synthesized as potential α-glucosidase inhibitors. Their structural characterizations, vibrational and electronic spectral behaviours were investigated by elemental analysis, LC-MS/MS, FT–IR and UV–Vis spectroscopic techniques. The inhibitory activities of these complexes against α-glucosidase (from Saccharomyces cerevisiae, EC No: 3.2.1.20) were determined. The synthesized complexes 1–6 exhibited α-glucosidase inhibitory activity with the IC50 values ranging from 0.4699 to >600 μM. Besides, density functional theory (DFT) calculations in the mode of hybrid HSEh1PBE method with 6-311G(d,p) and LanL2DZ basis sets for optimal complex geometries were fulfilled to obtain the vibrational frequencies and electronic spectral behaviours as well as substantial contributions to the electronic transitions. Furthermore, the molecular docking study was performed to examine protein-ligand interactions between the synthesized complexes (1–6) and target protein (the template structure S. cerevisiae isomaltase (PDBID: 3A4A )).