Predicted antiviral drugs Darunavir, Amprenavir, Rimantadine and Saquinavir can potentially bind to neutralize SARS-CoV-2 conserved proteins

The recent coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has offered a unique challenge for human survival. However, there is no available known prophylaxis, therapeutic intervention, and vaccine candidate against SARS-CoV-2 to date. We aimed towards identifying novel phytoligands from widely available botanical resources which could serve as potential inhibitors against SARS-CoV-2. Based on literature review, database search, ADMET, and drug-likeness, 55 phytoligands and 8 synthetic repurposing drugs were screened and tested against SARS-CoV-2 spike glycoprotein, main protease, papain-like protease, and RNA-dependent RNA polymerase using molecular docking and protein-ligand interaction. All phytoligands and repurposing drugs showed binding affinity based inhibitory potential against the viral proteins. The highest binding affinities of phytoligands towards antiviral targets were exhibited by colchicine and oleic acid, and that of repurposing drugs was shown by saquinavir and nelfinavir. Capsaicin, oleic acid, azithromycin, nelfinavir, remdesivir, and saquinavir were acted as plausible broad-spectrum inhibitors. Hydrogen bonds and hydrophobic interactions of amino acids were varied significantly within the conserved domain along with glutamic acid richness. Further investigation should be carried out to obtain the synergistic effect using cell-based assays, animal models, and clinical trials to discover novel phytomedicine against SARS-CoV-2.

Proteases and RNA-Dependent RNA polymerase, major enzymes which are essential targets involved in the life and replication of SARS-CoV-2. This study aims at in silico examination of the potential ability of coumarins and their derivatives to inhibit the replication of SARS-Cov-2 through multiple targets, including the main protease, papain-like protease and RNA-Dependent RNA polymerase. Several coumarins as biologically active compounds were studied, including coumarin antibiotics and some naturally reported antiviral coumarins. Aminocoumarin antibiotics, especially coumermycin, showed a high potential to bind to the enzymes’ active site, causing possible inhibition and termination of viral life. They demonstrate the ability to bind to residues essential for triggering the crucial cascades within the viral cell. Molecular dynamics simulations for 50 ns supported these data pointing out the formation of rigid, stable Coumermycin/enzyme complexes. These findings strongly suggest the possible use of Coumermycin, Clorobiocin or Novobiocin in the fight against COVID-19, but biological evidence is still required to support such suggestions.

Here’s what we know about FDA-authorized COVID-19 antivirals

Potent and biostable inhibitors of the main protease of SARS-CoV-2

Since the COVID-19 outbreak in early 2020, researchers and studies are continuing to find drugs and/or vaccines against the disease. As shown before, medicinal plants can be very good sources against viruses because of their secondary compounds which may cure diseases and help in survival of patients. There is a growing trend in the filed patents in this field. In the present study, we test and suggest the inhibitory potential of five herbal based extracts including 7α-acetoxyroyleanone, Curzerene, Incensole, Harmaline, and Cannabidiol with antivirus activity on the models of the significant antiviral targets for COVID-19 like spike glycoprotein, Papain-like protease (PLpro), non-structural protein 15 (NSP15), RNA-dependent RNA polymerase and core protease by molecular docking study. The Salvia rythida root was extracted, dried, and pulverized by a milling machine. The aqueous phase and the dichloromethane phase of the root extractive were separated by two-phase extraction using a separatory funnel. The separation was performed using the column chromatography method. The model of the important antivirus drug target of COVID-19 was obtained from the Protein Data Bank (PDB) and modified. TO study the binding difference between the studied molecules, the docking study was performed. These herbal compounds are extracted from Salvia rhytidea, Curcuma zeodaria, Frankincense, Peganum harmala, and Cannabis herbs, respectively. The binding energies of all compounds on COVID-19 main targets are located in the limited area of 2.22-5.30 kcal/mol. This range of binding energies can support our hypothesis for the presence of the inhibitory effects of the secondary metabolites of mentioned structures on COVID-19. Generally, among the investigated herbal structures, Cannabidiol and 7α- acetoxyroyleanone compounds with the highest binding energy have the most inhibitory potential. The least inhibitory effects are related to the Curzerene and Incensole structures by the lowest binding affinity. The general arrangement of the basis of the potential barrier of binding energies is in the order below: Cannabidiol > 7α-acetoxyroyleanone > Harmaline> Incensole > Curzerene. Finally, the range of docking scores for investigated herbal compounds on the mentioned targets indicates that the probably inhibitory effects on these targets obey the following order: main protease> RNA-dependent RNA polymerase> PLpro> NSP15> spike glycoprotein.

Computer-assisted comparison of the nonstructural polyprotein of hepatitis E virus (HEV) with proteins of other positive-strand RNA viruses allowed the identification of the following putative functional domains: (i) RNA-dependent RNA polymerase, (ii) RNA helicase, (iii) methyltransferase, (iv) a domain of unknown function ("X" domain) flanking the papain-like protease domains in the polyproteins of animal positive-strand RNA viruses, and (v) papain-like cysteine protease domain distantly related to the putative papain-like protease of rubella virus (RubV). Comparative analysis of the polymerase and helicase sequences of positive-strand RNA viruses belonging to the so-called "alpha-like" supergroup revealed grouping between HEV, RubV, and beet necrotic yellow vein virus (BNYVV), a plant furovirus. Two additional domains have been identified: one showed significant conservation between HEV, RubV, and BNYVV, and the other showed conservation specifically between HEV and RubV. The large nonstructural proteins of HEV, RubV, and BNYVV retained similar domain organization, with the exceptions of relocation of the putative protease domain in HEV as compared to RubV and the absence of the protease and X domains in BNYVV. These observations show that HEV, RubV, and BNYVV encompass partially conserved arrays of distinctive putative functional domains, suggesting that these viruses constitute a distinct monophyletic group within the alpha-like supergroup of positive-strand RNA viruses.

The pandemic caused by the coronavirus SARS-CoV-2 led to a global crisis in the world healthcare system. Despite some progress in the creation of antiviral vaccines and mass vaccination of the population, the number of patients continues to grow because of the spread of new SARS-CoV-2 mutations. There is an urgent need for direct-acting drugs capable of suppressing or stopping the main mechanisms of reproduction of the coronavirus SARS-CoV-2. Several studies have shown that the successful replication of the virus in the cell requires proteolytic cleavage of the protein structures of the virus. Two proteases are crucial in replicating SARS-CoV-2 and other coronaviruses: the main protease (Mpro) and the papain-like protease (PLpro). In this review, we summarize the essential viral proteins of SARS-CoV-2 required for its viral life cycle as targets for chemotherapy of coronavirus infection and provide a critical summary of the development of drugs against COVID-19 from the drug repurposing strategy up to the molecular design of novel covalent and non-covalent agents capable of inhibiting virus replication. We overview the main antiviral strategy and the choice of SARS-CoV-2 Mpro and PLpro proteases as promising targets for pharmacological impact on the coronavirus life cycle.

The ongoing COVID-19 pandemic has resulted in a global panic because of its continual evolution and recurring spikes. This serious malignancy is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Since the outbreak, millions of people have been affected from December 2019 till now, which has led to a great surge in finding treatments. Despite trying to handle the pandemic with the repurposing of some drugs, such as chloroquine, hydroxychloroquine, remdesivir, lopinavir, ivermectin, etc., against COVID-19, the SARS-CoV-2 virus continues its out-of-control spread. There is a dire need to identify a new regimen of natural products to combat the deadly viral disease. This article deals with the literature reports to date of natural products showing inhibitory activity towards SARS-CoV-2 through different approaches, such as in vivo, in vitro, and in silico studies. Natural compounds targeting the proteins of SARS-CoV-2—the main protease (Mpro), papain-like protease (PLpro), spike proteins, RNA-dependent RNA polymerase (RdRp), endoribonuclease, exoribonuclease, helicase, nucleocapsid, methyltransferase, adeno diphosphate (ADP) phosphatase, other nonstructural proteins, and envelope proteins—were extracted mainly from plants, and some were isolated from bacteria, algae, fungi, and a few marine organisms.

The pandemic of novel coronavirus disease 2019 (COVID-19) has rampaged the world, with more than 58.4 million confirmed cases and over 1.38 million deaths across the world by 23 November 2020. There is an urgent need to identify effective drugs and vaccines to fight against the virus. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) belongs to the family of coronaviruses consisting of four structural and 16 non-structural proteins (NSP). Three non-structural proteins, main protease (Mpro), papain-like protease (PLpro), and RNA-dependent RNA polymerase (RdRp), are believed to have a crucial role in replication of the virus. We applied computational ligand-receptor binding modeling and performed comprehensive virtual screening on FDA-approved drugs against these three SARS-CoV-2 proteins using AutoDock Vina, Glide, and rDock. Our computational studies identified six novel ligands as potential inhibitors against SARS-CoV-2, including antiemetics rolapitant and ondansetron for Mpro; labetalol and levomefolic acid for PLpro; and leucal and antifungal natamycin for RdRp. Molecular dynamics simulation confirmed the stability of the ligand-protein complexes. The results of our analysis with some other suggested drugs indicated that chloroquine and hydroxychloroquine had high binding energy (low inhibitory effect) with all three proteins—Mpro, PLpro, and RdRp. In summary, our computational molecular docking approach and virtual screening identified some promising candidate SARS-CoV-2 inhibitors that may be considered for further clinical studies.

Type: DATASET, Abstract: At the end of 2019, a cluster of pneumonia cases with unknown origin was reported in Wuhan, China. The main symptoms of this disease were fever and coughing but in some cases the disease pattern evolved to severe pneumonia and even death (1). Early 2020, a novel coronavirus was found to be responsible for this outbreak which was designated SARS-CoV-2 (2). The World Health Organization has named the disease caused by the SARS-CoV-2 coronavirus disease 2019 (COVID-19). After SARS-1 (2002-2003) and MERS (2012), SARS-CoV-2 is the third coronavirus that causes significant international concerns in less than two decades. Due to globalization and international travel, SARS-CoV-2 spread around the globe, infected over 125 million people and caused at least 2,7 million people to die by March 2021. SARS-CoV-2, like SARS-1, OC43, HKU and MERS, is a betacoronavirus with a 30kB genome divided into 14 open reading frames (ORFs). The first two ORFs, 1a and 1ab, (67% of the genome) code for 16 non-structural proteins (NSP), while the remaining part of the genome encodes accessory proteins and structural proteins (3). The main viral drug targets in SARS-CoV-2 are the spike protein (structural), the Main protease (Mpro), the Papain-like protease (PLpro), the RNA-dependent RNA polymerase and the exonuclease, although other accessory proteins may prove to be valuable targets in the future. As part of an immediate response strategy to COVID-19, a drug repurposing library consisting of ~5500 FDA-approved drugs and clinical candidates that have passed phase I studies was screened in a stable GFP-expressing VeroE6 cell line infected with SARS-CoV-2. This assay system provides a positive readout: when cells are intact, they express GFP which can be detected with a GFP plate reader or microscope; when cells succumb to CPE caused by the virus (or toxicity), the GFP signal disappears., Authors: Ellen Van Damme

It is well known that vital enzymes in the replication process of the coronavirus are the SARS-CoV-2 PLpro and SARS-CoV-2 3CLpro, both of which are important targets in the search for anti-coronavirus agents. These two enzymes are responsible for cleavage at various polyprotein sites in the SARS-CoV-2 lifecycle. Herein, the dynamics of the polyprotein cleavage sequences for the boundary between non-structural proteins Nsp1 and Nsp2 (CS1) and between Nsp2 and Nsp3 (CS2) in complex with both the papain-like protein PLpro and the main protease 3CLpro were explored using computational methods. The post dynamics analysis reveals that CS1 and CS2 both have greater stability when complexed with PLpro. Of these two, greater stability is observed for the CS1-PLpro complex, while destabilization resulting in loss of CS2 from the PLpro active site is observed for CS2-PLpro, suggesting the rate of exchange by the papain-like protease is faster for CS2 compared to CS1. On the other hand, the 3CLpro main protease also reveals stability for CS1 suggesting that the main protease could also play a potential role in the cleavage at point CS1. However, destabilization occurs early in the simulation for the complex CLpro-CS2 suggesting a poor interaction and non-plausible protease cleavage of the polyprotein at CS2 by the main protease. These findings could be used as a guide in the development and design of potent COVID-19 antiviral inhibitors that mimic the CS1 cleavage site.

Natural medicinal plant products as an immune-boosters: A possible role to lessen the impact of Covid-19

In the present study, a new category of 1,3,4-thiadiazoles was developed by submitting methyl 2-(4-hydroxy-3-methoxybenzylidene) hydrazine-1-carbodithioate to react with the appropriate hydrazonoyl halides in presence of few drops of diisopropyl ethyl amine. The chemical structures of the newly synthesized derivatives were inferred by means of their micro-analytical and spectral data. Utilizing combined molecular docking and molecular dynamics techniques, the binding affinities and features of the synthesized compounds were evaluated against four SARS-CoV-2 target enzymes, namely, main protease (Mpro), papain-like protease (PLpro), RNA-dependent RNA polymerase (RdRp), and receptor-binding domain (RBD) of the spike protein. Compound 7 demonstrated promising binding affinities with the target enzymes Mpro, PLpro, RdRp, and RBD with docking scores of −11.4, −9.4, −8.2, and −6.8 kcal/mol, respectively. In addition, compound 7 exhibited MM-GBSA//100 ns MD docking score of −35.9 kcal/mol against Mpro. Structural and energetic analyses revealed the stability of the 7-Mpro complex over 100 ns MD simulations. In addition, compound 7 obeyed Lipinski’s rule of five, as it has acceptable absorption, distribution, and oral bioavailability inside the body. Therefore, compound 7 is considered as a promising starting point for designing potential therapeutic agents against Covid-19.

ABSTRACTObjectives:The recent global coronavirus disease 2019 (COVID-19) pandemic, resulting from infection by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), can cause severe and fatal pneumonia along with other life-threatening complications.Materials and Methods:The rare and limited accessibility of approved therapeutic agents or vaccines is of great distress. Swiftly working on designing and identifying inhibitors against all possible viral key protein targets, seven key SARS-CoV-2 viral enzymes were selected as targets, particularly in the action on the virus-entry, viral replication, and immune evasion of COVID-19. Papain-like protease, main protease, RNA-dependent RNA polymerase, endoribonuclease (nsp15), receptor-binding domain-angiotensin-converting enzyme 2, transmembrane serine protease 2 (TMPRSS2), and 2’- O-ribose methyltransferase (2′MTase), which were subjected to an unbiased in silico screening against 22 small molecules originating from Garcinia linii concomitantly with Remdesivir, Nirmatrelvir, and Molnupiravir were approved by Food and Drug Administration as repurposing drugs against SARS-CoV-2 invasion.Results:The in silico results showed that natural bioactive compounds containing α-Tocopheryolquinone, 6β-Hydroxystigmast-4-en-3-one, Squalene, Rutin and Quercetin have a high binding affinity with seven selected viral protein targets concurrently with the preference of absorption, distribution, metabolism, excretion, and toxicity and drug-likeness.Conclusion:This study provides potential phytoactive compounds from G. linii through multi-target screen with molecular dynamic simulation for combating COVID-19 pandemics that need further experimental validation to confirm the prospective efficacy.

Ixodes scapularis is the main vector of Lyme disease in the eastern and central United States. Tick salivary secretion has been shown as important for both blood-meal completion and pathogen transmission. Here we report a duplication event of cystatin genes in its genome that results in a transcription-regulated boost of saliva inhibitory activity against a conserved and relatively limited number of vertebrate papain-like cysteine proteases during blood feeding. We further show that the polypeptide products of the two genes differ in their binding affinity for some enzyme targets, and they display different antigenicity. Moreover, our reverse genetic approach employing RNA interference uncovered a crucial mediation in tick-feeding success. Given the role of the targeted enzymes in vertebrate immunity, we also show that host immunomodulation is implicated in the deleterious phenotype of silenced ticks making I. scapularis cystatins attractive targets for development of anti-tick vaccines.