The Natural Products Withaferin A and Withanone from the Medicinal HerbWithania somniferaAre Covalent Inhibitors of the SARS-CoV-2 Main Protease

Abstract

The current COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) created a global health crisis. The ability of vaccines to protect immunocompromised individuals and from emerging new strains are major concerns. Hence antiviral drugs against SARS-CoV-2 are essential. The SARS-CoV-2 main protease M pro is vital for replication and an important target for antivirals. Using CMap analysis and docking studies, withaferin A (wifA) and withanone (win), two natural products from the medicinal herb Withania somnifera (ashwagandha), were identified as promising candidates that can covalently inhibit the viral protease M pro . Cell culture, enzymatic, LC-MS/MS, computational, and equilibrium dialysis based assays were performed. DFT calculations indicated that wifA and win can form stable adducts with thiols. The cytotoxicity of M pro was significantly reduced by wifA and win. Both wifA and win were found to irreversibly inhibit 0.5 μM M pro with IC 50 values of 0.54 and 1.8 μM, respectively. LC-MS/MS analysis revealed covalent adduct formation with wifA at cysteines 145 and 300 of M pro . The natural products wifA and win can irreversibly inhibit the SARS-CoV-2 main protease M pro . Based on the work presented here we propose that both wifA and win have the potential to be safely used as preventative and therapeutic interventions for COVID-19.

The immunomodulatory role of withania somnifera (L.) dunal in inflammatory diseases

“…ACE2 receptor is considered the main receptor of entry for SARS-COV-2 into cells and is expressed in many tissues including the heart, kidneys, and lung tissues (Beyerstedt et al, 2021). In addition, certain w. Somnifera constituents are believed to suppress the main protease of SARS-CoV-2 which is very important for viral replication (Tripathi et al, 2021;Chakraborty et al, 2022;Shree et al, 2022). Withanoside V is one of the natural constituents of w. Somnifera that inhibit the main protease of SARS-CoV-2 (Tripathi et al, 2021).…”

Structure-Based Discovery of the SARS-CoV-2 Main Protease Noncovalent Inhibitors from Traditional Chinese Medicine

“…More recently, Selvaraj et al performed microsecond molecular dynamics (MD) simulation and multiple-conformation virtual screening over 20,000 compounds from TCW databased@Taiwan, and five compounds were unraveled to satisfy their filtering criteria . In addition, alkaloids, flavonoids, and terpenoids were found to present inhibitory activities with SARS-CoV-2 Mpro using the virtual screening approach. − These reported studies provide much valuable guidance for the discovery of SARS-CoV-2 Mpro inhibitors.…”

Unraveling antiviral efficacy of multifunctional immunomodulatory triterpenoids against SARS‐COV‐2 targeting main protease and papain‐like protease

“…However, former predictions were based solely on computational analysis, and the efficacy data from their clinical trials against SARS-CoV-2 is missing. [47][48][49][50] The present study investigates the antiviral and anti-inflammatory potential of identified triterpenoids in terms of Mpro and PLpro inhibition and cell-culture-based SARS-CoV-2 inhibition studies. The experimentally validated lead triterpenoids identified in this study present a dual-targeting virus-directed and host-directed strategy to avenge the pandemic of COVID-19.…”

“…Several in silico drug repurposing studies also predicted these triterpenoids to target Mpro and PLpro of SARS‐CoV‐2. However, former predictions were based solely on computational analysis, and the efficacy data from their clinical trials against SARS‐CoV‐2 is missing 47–50 . The present study investigates the antiviral and anti‐inflammatory potential of identified triterpenoids in terms of Mpro and PLpro inhibition and cell‐culture‐based SARS‐CoV‐2 inhibition studies.…”