Studying the Biological Activity of Trans-[Cu (quin)2(EtOH)2] as Potent Antimicrobial Cu(II) Complex through Computational Investigations: DFT, ADMET and Molecular Docking

Abstract

Background: Trans-[Cu (quin)2(EtOH)2], a new copper (II) complex, was characterized using a variety of computational techniques to explore its biological role in pharmacological applications.

Methods: The computational methods included density functional theory (DFT), ADMET and molecular docking.

Results: The optimized geometrical parameters revealed that the plane containing the Cu ion and the Quinaldinate ligands was confirmed to be nearly planar. DFT findings suggest that the complex has a stable structure with a moderate band gap of 3.88 eV. Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) analysis revealed a planar surface intramolecular charge transfer from its donor sites, in the center, to its ends instead of the vertical plane. Two electron-rich regions were observed around the oxygen ions in the molecular electrostatic potential (MEP) map, which were expected to be the sites of molecular bonding and interactions with target proteins. Drug-likeness and pharmacokinetics parameters were determined to provide insight into the safety level of the studied compound. The ADMET (absorption, distribution, metabolism, excretion, and toxicity) results showed favorable pharmacological features, as evidenced by a high oral bioavailability and a low risk of toxicity. A molecular docking study was performed by fitting the copper complex into the active sites of target proteins for Bacillus cereus, Staphylococcus aureus, and Escherichia coli bacteria. The title complex had the strongest antifungal effect within the inhibitory zone of B. cereus with a strong binding affinity of -9.83 kcal/mol. Also, maximum activity was exhibited against S.aureus (-6.65 kcal/mol) compared to the other recently reported Cu complexes within the limits of the screened references. Docking studies implicated modest inhibitory activity against E. coli bacteria.

Conclusions: The findings highlighted the compound's biological activities and identified it as a possible treatment drug for the bacteria B. cereus and S. aureus.

Keywords: ADMET; DFT; HOMO and LUMO; MEP; copper complexes; geometrical structure; molecular docking.