In Silico and In Vitro Identification of New Eugenol Derivatives as Inhibitors of the Spike SARS-CoV-2 Protein...

Coronavirus Disease-2019 (COVID-19) caused by SARS-CoV-2 remains a serious health concern worldwide. Inhibitors of the protein-protein interaction (iPPI) between the SARS-CoV-2 spike protein (S) and human Angiotensin-Converting Enzyme-2 (ACE2) are promising as potential antiviral agents. This study aimed to identify and evaluate novel compounds as inhibitors of the S receptor-binding domain (RBD) and ACE2 interaction through Eugenol- and Structure-Based virtual screening approaches. The hit compounds were corroborated as protein-protein interaction inhibitors using an ELISA-based enzyme assay. Molecular docking and molecular dynamics (MD) studies of the selected compounds showed that they maintained a molecular interaction and stability (RMSD fluctuations less than 4 Å) with essential residues of the S protein. The best compound, Eu-1 (IC₅₀ = 16 μM), prevented the interaction between the S protein and ACE2 receptor efficiently with an 83.7% inhibition at 50 μM. In addition, Eu-1 had an adequate value of cytotoxicity (CC₅₀ > 200 μM). Therefore, Eu-1 is a candidate compound for further SARS-CoV-2 preclinical experiments.