Synthesis, characterization and biological activities of a novel Mannich base 2-[(3,4-dimethoxyphenyl)(pyrrolidin-1-yl)methyl]cyclopentanone and its complexes with Cu(II), Co(II), Ni(II) and Fe(II) ions

Abstract

One-pot, three-component Mannich reaction was carried out by condensation of 3,4-dimethoxybenzaldehyde, pyrrolidine and cyclopentanone in the presence of calcium chloride using ethanol as a solvent to afford a novel Mannich base (L). The resulting Mannich base (L) was isolated and complexed with Cu(II), Co(II), Ni(II) and Fe(II) ions. The structures of the synthesized scaffolds were confirmed by IR, H-1 NMR, C-13 NMR, mass spectroscopy, TGA and elemental analyses. The metal contents were determined by ICP-OES. All compounds showed poor antibacterial activities. The anti-enzymatic activities of the Mannich base (L) and its metal complexes were checked against jack bean urease. The Mannich base ligand (L), its nickel and iron complexes showed potent antiurease activity with IC50 values of 9.25 +/- 0.002, 1.42 +/- 0.003, 5.41 +/- 0.005 mu M, respectively, and were superior inhibitors than the standard, thiourea (IC50 21.25 +/- 0.15 mu M). The probable binding mode of the most active Ni(II) complex was determined using molecular docking simulations.