Molecular Docking Study of Several Seconder Metabolites from Medicinal Plants as Potential Inhibitors of COVID-19 Main Protease

Objectives: Coronaviruses (CoVs) cause infections that affect the respiratory tract, liver, central nervous, and the digestive systems in humans and animals. This study focused on the main protease (M-pro) in CoVs (PDB ID: 6LU7) that is used as a potential drug target to combat 2019-CoV. In this study, a total of 35 secondary metabolites from medical plants was selected and docked into the active site of 6LU7 by molecular docking studies to find a potential inhibitory compound that may be used to inhibit Coronavirus Disease-2019 (COVID-19) infection pathway. Materials and Methods: The chemical structures of the ligands were obtained from the Drug Bank (https://www.drugbank.ca/). AutoDockTools (ADT ver. 1.5.6) was used for molecular docking studies. The docking results were evaluated using BIOVIA Discovery Studio Visualizer and PyMOL (ver. 2.3.3, Schrodinger, LLC). Results: Pycnamine, tetrahydrocannabinol, oleuropein, quercetin, primulic acid, kaempferol, dicannabidiol, lobelin, colchicine, piperidine, medicagenic acid, and narcotine is found to be potential inhibitors of the COVID-19 M-pro. Among these compounds, pycnamine, which was evaluated against COVID-19 for the first time, showed a high affinity to the COVID-19 M-pro compared with other seconder metabolites and reference drugs. Conclusion: Our results obtained from docking studies suggest that pycnamine should be examined in vitro to combat 2019-CoV. Moreover, pycnamine might be a promising lead compound for anti-CoV drugs.