Synthesis, enzyme inhibitory and antioxidant activities, and molecular docking studies of metal complexes of a Schiff base ligand bearing pyridine moiety

Abstract

In the present study, Ni(II) and Co(II) complexes of a Schiff base (L) containing pyridine were synthesized and characterized using various physicochemical and spectroscopic techniques (FT-IR, UV-Visible, mass spectra, TGA, microanalysis, molar conductivity, and magnetic susceptibility measurements). The analytical and spectroscopic analysis showed that the L-Ni(II) and L-Co(II) complexes assumed octahedral structures. Thermal analysis was used to determine water molecules' presence, number, and positions. Moreover, newly synthesized L-Ni(II) and L-Co(II) complexes of the Schiff base, as well as previously synthesized L-Ru(II) and L-Pd(II) complexes of the same ligand were tested for their antioxidant and enzyme inhibitory activities. The antioxidant activities of the metal(II) complexes of the Schiff base towards radical solutions were determined by ABTS and DPPH spectrophotometric methods. The results of this study revealed that the L-Ru(II) and L-Pd(II) complexes emerged as potent radical scavengers as compared to the standard antioxidants. Still, the L-Co(II) and L-Ni(II) complexes had low antioxidant effects. The pancreatic lipase inhibitory activities of these synthesized metal complexes were investigated to see their possible effects on obesity treatments. All metal complexes were found to have effective pancreatic lipase inhibitions compared to the standard orlistat compound. Finally, in silico molecular docking studies were performed in support of experimental results.