Synthesis, characterization, computational analyses, in silico ADMET studies, and inhibitory action against SARS-CoV-2 main protease (Mpro) of a Schiff base

COVID-19 disease caused by the severe acute respiratory syndrome coronavirus (SARS-CoV-2) has struck the whole world and raised severe health, economic, and social problems. Many scientists struggled to find a vaccine or an antiviral drug. Eventually, both vaccines and recommended drugs, repurposed drugs, or drug combinations were found, but new strains of SARS-CoV-2 continue to threaten human life and health. As part of the fight against COVID-19 disease, this study involves an in silico molecular docking analysis on the main protease (Mpro) of SARS-CoV-2. To this aim, a Schiff base compound was synthesized and characterized using spectroscopic techniques, including X-ray, FTIR, and UV-Vis. Surface analysis and electronic properties of this molecule were investigated using the DFT method. The drug-likeness parameters of the title compound were studied according to the rules of Lipinski, Veber, Ghose, Egan, and Muegge and were found in agreement with these rules. In silico toxicity analyses revealed that the new compound is a potentially mutagenic and carcinogenic chemical. The title compound was predicted to be an inhibitor of cytochrome P450 enzymes (5 CYPs). This inhibitory effect indicates a weak metabolism of the molecule in the liver. In addition, this compound was displayed good intestinal absorption and blood-brain barrier penetration. The druggability properties of the title compound were investigated, and Swiss Target Prediction predicted it to be a protease inhibitor. In this context, the SARS-CoV-2 main protease was selected as a biological target in molecular docking studies. Docking results were compared with the known native ligand N3 inhibitor. The value of binding energy between the Schiff base compound and the binding pocket of the main protease is higher than that of the reference ligand N3. The calculated free energies of binding of the Schiff base compound and the reference ligand N3 are -8.10 and -7.11 kcal/mol, respectively.