Screening of Clinically Approved and Investigation Drugs as Potential Inhibitors of COVID-19 Main Protease: A Virtual Drug Repurposing Study

There is an urgent need for a new drug against COVID-19. Since designing a new drug and testing its pharmacokinetics and pharmacodynamics properties may take years, here we used a physics-driven high throughput virtual screening drug re-purposing approach to identify new compounds against COVID-19. As the molecules considered in repurposing studies passed through several stages and have well-defined profiles, they would not require prolonged preclinical studies and hence, they would be excellent candidates in the cases of disease emergencies or outbreaks. While the spike protein is the key for the virus to enter the cell though the interaction with ACE2, enzymes such as main protease are crucial for the life cycle of the virus. This protein is one of the most attractive targets for the development of new drugs against
COVID-19 due to its pivotal role in the replication and transcription of the virus. We used 7922 FDA approved small molecule drugs as well as compounds in clinical investigation from NIH Chemical Genomics Center (NCGC) Pharmaceutical Collection (NPC) database in our drug repurposing study. Both apo and holo forms of target protein COVID-19 main proteases were used in virtual screening. Target proteins were retrieved from protein data bank (PDB IDs, 6M03 and 6LU7). Standard Precision (SP) protocol of Glide docking program of Maestro was used in docking. Compounds were then ranked based on their docking scores that represents binding energies. Top-30 compounds from each docking simulations were considered initially in short (10-ns) molecular dynamics (MD) simulations and their average binding energies using collected 1000 trajectories throughout the MD simulations were calculated by Molecular Mechanics Generalized Born Surface Area (MM/GBSA) method. Selected promising hit compounds based on average MM/GBSA scores were then used in long (100-ns) MD simulations. These numerical calculations showed that the following 6 compounds can be considered as COVID-19 Main Protease inhibitors: Lasinavir, Brecanavir, Telinavir, Rotigaptide, 1,3-Bis-(2-ethoxycarbonylchromon-5-yloxy)-2-(lysyloxy)propane and Pimelautide.