Design and development of salen-type Schiff bases as potential antivirus agents: Experimental and theoretical approach

Abstract

Five new salen-type Schiff base compounds (LH₂-L⁴H₂) have been designed and synthesized and their interaction with SARS-CoV-2, HIV virus and DNA polymerase IV have been studied by in silico approaches. The newly synthesized salen-type Schiff base ligands have been derived from the condensation of substituted salicylaldehydes and ethylenediamine in MeOH. ¹H and ¹³C NMR, FT-IR and UV-Vis spectral techniques have been applied in order to confirm the structural elucidation of the desired products. The crystal structure of the compound LH₂ is determined by the single crystal X-ray diffraction. Density functional theory (DFT) calculations have been employed to evaluate the optimized electronic structure, HOMO-LUMO, energy gap, and global parameters. Extensive classical molecular dynamics simulations have been performed to investigate the consequences of docking of the synthesized ligand, LH₂ on a protein moiety (PDB id: 7O46). Molecular docking studies have been performed on compounds (LH₂-L⁴H₂) to predict the binding mode and interactions between the ligands and the main protease of the SARS-CoV-2 (PDB ID: 7O46) for COVID-19 and HIV virus (PDB ID: 1UUI). The molecular docking results show that compounds (LH₂-L⁴H₂) with SARS-CoV-2 and HIV virus exhibit good binding affinity at binding site of receptor protein. As potential drug candidates, Swiss-ADME and target predictions (pharmacokinetics and drug-likeness prediction) analyses have also been studied and the results are compared with Chloroquine (CQ) and Hydroxychloroquine (HCQ) as anti-SARS-CoV-2 drugs. Salen-type ligands have also been docked into the DNA polymerase IV (PDB ID: 5YUX) for surface binding and intercalation. Overall, the present study offers the therapeutic potential for a series of compounds (LH₂-L⁴H₂) for biomedical applications with reference to coronavirus (SARS-CoV-2) and HIV virus.