Withaferin A for COVID-19

Abstract The main protease (MPro) of SARS-CoV-2 plays a crucial role in viral replication and is a prime target for therapeutic interventions. Phytochemicals, known for their antiviral properties, have been previously identified as potential MPro inhibitors in several in silico studies. However, the efficacy of these remains in question owing to the inherent flexibility of the MPro binding site, posing challenges in selecting suitable protein structures for virtual screening. In this study, we conducted an extensive analysis of the MPro binding pocket, utilizing molecular dynamics (MD) simulations to explore its conformational diversity. Based on pocket volume and shape-based clustering, five representative protein conformations were selected for virtual screening. Virtual screening of a library of ~ 48,000 phytochemicals suggested 39 phytochemicals as potential MPro inhibitors. Based on subsequent MM-GBSA binding energy calculations and ADMET property predictions, five compounds were advanced to cell-based viral replication inhibition assays, with three compounds (demethoxycurcumin, shikonin, and withaferin A) exhibiting significant (EC50 < 10 uM) inhibition of SARS-CoV-2 replication. Our study provides an understanding of the binding interactions between these phytochemicals and MPro, contributing significantly to the identification of promising MPro inhibitors. Furthermore, beyond its impact on therapeutic development against SARS-CoV-2, this research highlights a crucial role of proper nutrition in the fight against viral infections.

Background: The recent COVID-19 (coronavirus disease 2019) pandemic triggered research on the development of new vaccines/drugs, repurposing of clinically approved drugs, and assessment of natural anti-COVID-19 compounds. Based on the gender difference in the severity of the disease, such as a higher number of men hospitalized and in intense care units, variations in sex hormones have been predicted to play a role in disease susceptibility. Cell surface receptors (Angiotensin-Converting Enzyme 2; ACE2 and a connected transmembrane protease serine 2- TMPSS2) are upregulated by androgens. Conversely, androgen antagonists have also been shown to lower ACE2 levels, implying their usefulness in COVID-19 management. Objective: In this study, we performed computational and cell-based assays to investigate the anti-- COVID-19 potential of Withaferin-A and Caffeic acid phenethyl ester, natural compounds from Withania somnifera and honeybee propolis, respectively. Methods: Structure-based computational approach was adopted to predict binding stability, interactions, and dynamics of the two test compounds to three target proteins (androgen receptor, ACE2, and TMPRSS2). Further, in vitro, cell-based experimental approaches were used to investigate the effect of compounds on target protein expression and SARS-CoV-2 replication. Results: Computation and experimental analyses revealed that (i) CAPE, but not Wi-A, can act as androgen antagonist and hence inhibit the transcriptional activation function of androgen receptor, (ii) while both Wi-A and CAPE could interact with ACE2 and TMPRSS2, Wi-A showed higher binding affinity, and (iii) combination of Wi-A and CAPE (Wi-ACAPE) caused strong downregulation of ACE2 and TMPRSS2 expression and inhibition of virus infection. Conclusion: Wi-A and CAPE possess multimodal anti-COVID-19 potential, and their combination (Wi-ACAPE) is expected to provide better activity and hence warrant further attention in the laboratory and clinic.

COVID-19 pandemic caused by the novel SARS-CoV-2 has impacted human livelihood globally. Strenuous efforts have been employed for its control and prevention; however, with recent reports on mutated strains with much higher infectivity, transmissibility, and ability to evade immunity developed from previous SARS-CoV-2 infections, prevention alternatives must be prepared beforehand in case. We have perused over 128 recent works (found on Google Scholar, PubMed, and ScienceDirect as of February 2023) on medicinal plants and their compounds for anti-SARS-CoV-2 activity and eventually reviewed 102 of them. The clinical application and the curative effect were reported high in China and in India. Accordingly, this review highlights the unprecedented opportunities offered by medicinal plants and their compounds, candidates as the therapeutic agent, against COVID-19 by acting as viral protein inhibitors and immunomodulator in (32 clinical trials and hundreds of in silico experiments) conjecture with modern science. Moreover, the associated foreseeable challenges for their viral outbreak management were discussed in comparison to synthetic drugs.

Coronavirus disease (COVID-19) has killed millions of people since first reported in Wuhan, China, in December 2019. Intriguingly, Withania somnifera (WS) has shown promising antiviral effects against numerous viral infections, including SARS-CoV and SARS-CoV-2, which are contributed by its phytochemicals. This review focused on the updated testing of therapeutic efficacy and associated molecular mechanisms of WS extracts and their phytochemicals against SARS-CoV-2 infection in preclinical and clinical studies with the aim to develop a long-term solution against COVID-19. It also deciphered the current use of the in silico molecular docking approach in developing potential inhibitors from WS targeting SARS-CoV-2 and host cell receptors that may aid the development of targeted therapy against SARS-CoV-2 ranging from prior to viral entry until acute respiratory distress syndrome (ARDS). This review also discussed nanoformulations or nanocarriers in achieving effective WS delivery to enhance its bioavailability and therapeutic efficacy, consequently preventing the emergence of drug resistance, and eventually therapeutic failure.

The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had a profound impact on the world’s health and economy. Although the end of the pandemic may come in 2023, it is generally believed that the virus will not be completely eradicated. Most likely, the disease will become an endemicity. The rapid development of vaccines of different types (mRNA, subunit protein, inactivated virus, etc.) and some other antiviral drugs (Remdesivir, Olumiant, Paxlovid, etc.) has provided effectiveness in reducing COVID-19’s impact worldwide. However, the circulating SARS-CoV-2 virus has been constantly mutating with the emergence of multiple variants, which makes control of COVID-19 difficult. There is still a pressing need for developing more effective antiviral drugs to fight against the disease. Plants have provided a promising production platform for both bioactive chemical compounds (small molecules) and recombinant therapeutics (big molecules). Plants naturally produce a diverse range of bioactive compounds as secondary metabolites, such as alkaloids, terpenoids/terpenes and polyphenols, which are a rich source of countless antiviral compounds. Plants can also be genetically engineered to produce valuable recombinant therapeutics. This molecular farming in plants has an unprecedented opportunity for developing vaccines, antibodies, and other biologics for pandemic diseases because of its potential advantages, such as low cost, safety, and high production volume. This review summarizes the latest advancements in plant-derived drugs used to combat COVID-19 and discusses the prospects and challenges of the plant-based production platform for antiviral agents.

Because of the present pandemic researchers are seeking for phytocandidates that can inhibit or stop SARS-CoV-2. The main protease (Mpro) of SARS-CoV-2 and spike glycoprotein (S) are both suppressed by bioactive compounds found in plants that work by docking them together. The Mpro proteins 6LU7 (complex with an inhibitor N3) and 5C3N (space group C2221) were employed in docking research. PyRx and AutoDock Vina software were used as docking engine. 22 identified phytoconstituents were selected from IMPPAT, a manually curated database, on the basis of their antiviral effects. Docking studies showed that phytoconstituents β-amyrin (-8.4 kcal/mol), withaferin A (-8.3 kcal/mol), oleanolic acid (-7.8 kcal/mol), and patentiflorin A (-8.1 kcal/mol) had the best results against 5C3N Mpro protein whereas kuwanon L (-7.1 kcal/mol), β-amyrin (-6.9 kcal/mol), oleanolic acid (-6.8 kcal/mol), cucurbitacin D (-6.5 kcal/mol), and quercetin (-6.5 kcal/mol) against 6LU7 Mpro protein. All the compounds were examined for their ADMET characteristics using SwissDock. Present research reports that the phytoconstituents along with docking score will be helpful for future drug development against Covid-19.