Exploring the SARS-CoV-2 main protease (Mpro) and RdRp targets by updating current structure-based drug design utilizing co-crystals to combat COVID-19

Structure-Based Virtual Screening for Methyltransferase Inhibitors of SARS-CoV-2 nsp14 and nsp16

The ongoing COVID-19 pandemic still threatens human health around the world. The methyltransferases (MTases) of SARS-CoV-2, specifically nsp14 and nsp16, play crucial roles in the methylation of the N7 and 2'-O positions of viral RNA, making them promising targets for the development of antiviral drugs. In this work, we performed structure-based virtual screening for nsp14 and nsp16 using the screening workflow (HTVS, SP, XP) of Schrödinger 2019 software, and we carried out biochemical assays and molecular dynamics simulation for the identification of potential MTase inhibitors. For nsp14, we screened 239,000 molecules, leading to the identification of three hits A1-A3 showing N7-MTase inhibition rates greater than 60% under a concentration of 50 µM. For the SAM binding and nsp10-16 interface sites of nsp16, the screening of 210,000 and 237,000 molecules, respectively, from ZINC15 led to the discovery of three hit compounds B1-B3 exhibiting more than 45% of 2'-O-MTase inhibition under 50 µM. These six compounds with moderate MTase inhibitory activities could be used as novel candidates for the further development of anti-SARS-CoV-2 drugs.

Identification of Promising Sulfonamide Chalcones as Inhibitors of SARS-CoV-2 3CLpro through Structure-Based Virtual Screening and Experimental Approaches

3CLpro is a viable target for developing antiviral therapies against the coronavirus. With the urgent need to find new possible inhibitors, a structure-based virtual screening approach was developed. This study recognized 75 pharmacologically bioactive compounds from our in-house library of 1052 natural product-based compounds that satisfied drug-likeness criteria and exhibited good bioavailability and membrane permeability. Among these compounds, three promising sulfonamide chalcones were identified by combined theoretical and experimental approaches, with SWC423 being the most suitable representative compound due to its competitive inhibition and low cytotoxicity in Vero E6 cells (EC50 = 0.89 ± 0.32 μM; CC50 = 25.54 ± 1.38 μM; SI = 28.70). The binding and stability of SWC423 in the 3CLpro active site were investigated through all-atom molecular dynamics simulation and fragment molecular orbital calculation, indicating its potential as a 3CLpro inhibitor for further SARS-CoV-2 therapeutic research. These findings suggested that inhibiting 3CLpro with a sulfonamide chalcone such as SWC423 may pave the effective way for developing COVID-19 treatments.

The efficacy of Paxlovid against COVID-19 is the result of the tight molecular docking between Mpro and antiviral drugs (nirmatrelvir and ritonavir)

Purpose

Currently, a number of medications for coronavirus disease 2019 (COVID-19) treatment are tested in clinical trials; however, credible clinical studies are becoming increasingly difficult to come by. Paxlovid is a ritonavir-boosted nirmatrelvir drug that the U.S. Food and Drug Administration (FDA) authorized for the treatment of COVID-19.

This study aimed to demonstrate the interaction of nirmatrelvir and ritonavir on the active site of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease (M^pro).

Materials and methods

To locate the optimal docking between M^pro and antiviral drugs, and to conduct dynamic simulations between atoms in the fusion areas, various bioinformatics and mathematical equations were applied.

Results

According to the docking data, nirmatrelvir has a stronger interaction with M^pro than ritonavir, which has more multiple bonds. Molecular docking of antiviral drugs such as Paxlovid has a significant impact on the treatment of COVID-19 virus.

Conclusions

According to this study, Paxlovid may work on new strains, including Omicron, because the M^pro mutation P132H in the Omicron variant has no direct effect on the protein.