In vitro biological activities of novel Ni(II)-2-chloroquinoline derivative complex: Synthesis, characterization and computational studies

Abstract

Quinoline derivative nickel complexes have received considerable attention in biomedical research. Herein, novel nickel(II) complex [Ni(II)(HL)2].2H2O was synthesized from newly synthesised ligand 2-((2-hydroxyethyl)amino)quinoline-3-carbaldehyde (H2L) through bidentate fashion of metal–ligand interaction. The complex was characterized using spectroscopic and physicochemical methods. The formation constant (KNi(II) = 2.36 × 107) of the complex was calculated spectroscopically and thermodynamic parameters (ΔG, ΔH and ΔS) were determined from it. In vitro antibacterial activity analysis of the newly synthesized complex exhibited mean inhibition zones ranging from medium to high (16.55 ± 1.03 mm, 16.69 ± 0.63 and 20.94 ± 2.01 mm) at 600 μg/mL against E. coli, S. aureus and P. aeruginosa, respectively. The complex also showed enhanced antioxidant activities compared with the corresponding free ligand. The energy band gap (1.183 eV) was calculated from the HOMO and LUMO of the most stable structure of the synthesized complex. The DFT calculated results and molecular docking analysis results showed good agreement with the experimental results. The complex showed pronounced biological activities than the free ligand. The in silico binding modes of the complex against E. Coli DNA Gyrase and S. aureus Dihydrofolate reductase (PDB: 2w9h) were found to be in excellent agreement with the in vitro biological studies.