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Despite the fast development of vaccines, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) still circulates through variants of concern (VoC) and escape the humoral immune response. SARS-CoV-2 has provoked over 200,000 deaths/months since its emergence and only a few antiviral drugs showed clinical benefit up to this moment. Thus, chemical structures endowed with anti-SARS-CoV-2 activity are important for continuous antiviral development and natural products represent a fruitful source of substances with biological activity. In the present study, agathisflavone (AGT), a biflavonoid from Anacardium occidentale was investigated as a candidate anti-SARS-CoV-2 compound. In silico and enzymatic analysis indicated that AGT may target mainly the viral main protease (M

Ligand-based drug design methods are thought to require large experimental datasets to become useful for virtual screening. In this work, we propose a computational strategy to design novel inhibitors of coronavirus main protease, Mpro. The pipeline integrates publicly available screening and binding affinity data in a two-stage machine-learning model using the recent MACAW embeddings. Once trained, the model can be deployed to rapidly screen large libraries of molecules in silico. Several hundred thousand compounds were virtually screened and 10 of them were selected for experimental testing. From these 10 compounds, 8 showed a clear inhibitory effect on recombinant Mpro, with half-maximal inhibitory concentration values (IC50) in the range 0.18–18.82 μM. Cellular assays were also conducted to evaluate cytotoxic, haemolytic, and antiviral properties. A promising lead compound against coronavirus Mpro was identified with dose-dependent inhibition of virus infectivity and minimal toxicity on human MRC-5 cells.

The coronavirus disease 2019 (COVID-19) pandemic has necessitated the development of antiviral agents against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). 3C-like protease (3CL

Heba Abdel-Halim,1,*,† Malak Hajar1,†, Luma Hasouneh1,†, Suzanne MA Abdelmalek2,† 1Department of Medicinal Chemistry, Faculty of Pharmacy and Medical Sciences, University of Petra, Amman, Jordan; 2Department of Pharmacology and Biomedical Sciences, Faculty of Pharmacy and Medical Sciences, University of Petra, Amman, Jordan†Dr Abdel-Halim passed away on July 14, 2022*These authors contributed equally to this workCorrespondence: Suzanne MA Abdelmalek, Department of Pharmacology and Biomedical Sciences, Faculty of Pharmacy and Medical Sciences, University of Petra, P.O. Box 961343, Amman, 11196, Jordan, Tel +962-6-5799555 Ext. (8310), Fax +962-65715570, Email sabdelmalek@uop.edu.joPurpose: The development of effective treatments for coronavirus infectious disease 19 (COVID-19) caused by SARS-Coronavirus-2 was hindered by the little data available about this virus at the start of the pandemic. Drug repurposing provides a good strategy to explore approved drugs’ possible SARS-CoV-2 antiviral activity. Moreover, drug synergism is essential in antiviral treatment due to improved efficacy and reduced toxicity. In this work, we studied the effect of approved and investigational drugs on one of SARS-CoV-2 essential proteins, the main protease (Mpro), in search of antiviral treatments and/or drug combinations.Methods: Different possible druggable sites of Mpro were identified and screened against an in-house library of more than 4000 chemical compounds. Molecular dynamics simulations were carried out to explore conformational changes induced by different ligands’ binding. Subsequently, the inhibitory effect of the identified compounds and the suggested drug combinations on the Mpro were established using a 3CL protease (SARS-CoV-2) assay kit.Results: Three potential inhibitors in three different binding sites were identified; favipiravir, cefixime, and carvedilol. Molecular dynamics simulations predicted the synergistic effect of two drug combinations: favipiravir/cefixime, and favipiravir/carvedilol. The in vitro inhibitory effect of the predicted drug combinations was established on this enzyme.Conclusion: In this work, we could study one of the promising SARS-CoV-2 viral protein targets in searching for treatments for COVID-19. The inhibitory effect of several drugs on Mpro was established in silico and in vitro assays. Molecular dynamics simulations showed promising results in predicting the synergistic effect of drug combinations.Keywords: molecular dynamics simulations, ligand docking, multiple binding sites, drug synergy, SARS-CoV-2

The global emergence of coronavirus disease 2019 (COVID-19) has caused substantial human casualties. Clinical manifestations of this disease vary from asymptomatic to lethal, and the symptomatic form can be associated with cytokine storm and hyperinflammation. In face of the urgent demand for effective drugs to treat COVID-19, we have searched for candidate compounds using in silico approach followed by experimental validation. Here we identified celastrol, a pentacyclic triterpene isolated from Tripterygium wilfordii Hook F, as one of the best compounds out of 39 drug candidates. Celastrol reverted the gene expression signature from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected cells and irreversibly inhibited the recombinant forms of the viral and human cysteine proteases involved in virus invasion, such as M

Existing tools to detect and visualize severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) suffer from low selectivity, poor cell permeability, and high cytotoxicity. Here we report a novel self-immolative fluorescent probe (MP590) for the highly selective and sensitive detection of the SARS-CoV-2 main protease (Mpro). This fluorescent probe was prepared by connecting a Mpro-cleavable peptide (N-acetyl-Abu-Tle-Leu-Gln) with a fluorophore (i.e., resorufin) via a self-immolative aromatic linker. Fluorescent titration results show that MP590 can detect Mpro with a limit of detection (LoD) of 35 nM and is selective over interferents such as hemoglobin, bovine serum albumin (BSA), thrombin, amylase, SARS-CoV-2 papain-like protease (PLpro), and trypsin. The cell imaging data indicate that this probe can report Mpro in HEK 293T cells transfected with a Mpro expression plasmid as well as in TMPRSS2-VeroE6 cells infected with SARS-CoV-2. Our results suggest that MP590 can both measure and monitor Mpro activity and quantitatively evaluate Mpro inhibition in infected cells, making it an important tool for diagnostic and therapeutic research on SARS-CoV-2.

The current pandemic caused by the COVID-19 disease has reached everywhere in the world and has affected every aspect of our lives. As of the current data, the World Health Organization (WHO) has reported more than 300 million confirmed COVID-19 cases worldwide and more than 5 million deaths. M

The SARS-CoV-2 main protease (Mpro) is a medicinal chemistry target for COVID-19 treatment. Given the clinical efficacy of β-lactams as inhibitors of bacterial nucleophilic enzymes, they are of interest as inhibitors of viral nucleophilic serine and cysteine proteases. We describe the synthesis of penicillin derivatives which are potent Mproinhibitors and investigate their mechanism of inhibition using mass spectrometric and crystallographic analyses. The results suggest that β-lactams have considerable potential as Mproinhibitors via a mechanism involving reaction with the nucleophilic cysteine to form a stable acyl–enzyme complex as shown by crystallographic analysis. The results highlight the potential for inhibition of viral proteases employing nucleophilic catalysis by β-lactams and related acylating agents.

Vortioxetine an anti-depressant FDA-drug recently reported showing better in vitro efficacy against SARS-CoV-2.In this study, we have synthesized ten new derivatives having alkenes, alkynes, benzyl, aryl, and mixed carbamate at the N-terminal of vortioxetine. Then the binding energy and interactions with the crucial amino acid residues in the binding pocket of main protease (MBased on the docking scores predicted by ADV and AD, most vortioxetine derivatives showed better binding efficiency towards MThis study shows that some vortioxetine derivatives can be developed into promising drugs for COVID-19 treatment.

The outbreak of coronavirus disease 2019 (COVID-19) at the end of 2019 affected global health. Its infection agent was called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Wearing a mask, maintaining social distance, and vaccination are effective ways to prevent infection of SARS-CoV-2, but none of them help infected people. Targeting the enzymes of SARS-CoV-2 is an effective way to stop the replication of the virus in infected people and treat COVID-19 patients. SARS-CoV-2 main protease is a therapeutic target which the inhibition of its enzymatic activity prevents from the replication of SARS-CoV-2. A large database of molecules has been searched to identify new inhibitors for SARS-CoV-2 main protease enzyme. At the first step, ligand screening based on similarity search was used to select similar compounds to known SARS-CoV-2 main protease inhibitors. Then molecules with better predicted pharmacokinetic properties were selected. Structure-based virtual screening based on the application of molecular docking and molecular dynamics simulation methods was used to select more effective inhibitors among selected molecules in previous step. Finally two compounds were considered as SARS-CoV-2 main protease inhibitors.

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in millions of deaths and seriously threatened public health and safety. Despite COVID-19 vaccines being readily popularized worldwide, targeted therapeutic agents for the treatment of this disease remain very limited. Here, we studied the inhibitory activity of the scutellarein and its methylated derivatives against SARS-CoV-2 main protease (M

The challenge continues globally triggered by the absence of an approved antiviral drug against COVID-19 virus infection necessitating global concerted efforts of scientists. Nature still provides a renewable source for drugs used to solve many health problems. The aim of this work is to provide new candidates from natural origin to overcome COVID-19 pandemic. A virtual screening of the natural compounds database (47,645 compounds) using structure-based pharmacophore model and molecular docking simulations reported eight hits from natural origin against SARS-CoV-2 main proteinase (Mpro) enzyme. The successful candidates were of terpenoidal nature including taxusabietane, Isoadenolin AC, Xerophilusin B, Excisanin H, Macrocalin B and ponicidin, phytoconstituents isolated from family Lamiaceae and sharing a common ent-kaurane nucleus, were found to be the most successful candidates. This study suggested that the diterpene nucleus has a clear positive contribution which can represent a new opportunity in the development of SARS-CoV-2 main protease inhibitors.

Diagnostic testing continues to be an integral component of the strategy to contain the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) global pandemic, the causative agent of Coronavirus Disease 2019 (COVID-19). The SARS-CoV-2 genome encodes the 3C-like protease (3CLpro) which is essential for coronavirus replication. This study adapts an in vitro colorimetric gold nanoparticle (AuNP) based protease assay to specifically detect the activity of SARS-CoV-2 3CLpro as a purified recombinant protein and as a cellular protein exogenously expressed in HEK293T human cells. We also demonstrate that the specific sensitivity of the assay for SARS-CoV-2 3CLpro can be improved by use of an optimised peptide substrate and through hybrid dimerisation with inactive 3CLpro mutant monomers. These findings highlight the potential for further development of the AuNP protease assay to detect SARS-CoV-2 3CLpro activity as a novel, accessible and cost-effective diagnostic test for SARS-CoV-2 infection at the point-of-care. Importantly, this versatile assay could also be easily adapted to detect specific protease activity associated with other viruses or diseases conditions.

The emergence of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) with the most contagious variants, alpha (B.1.1.7), beta (B.1.351), delta (B.1.617.2), and Omicron (B.1.1.529) has continuously added a higher number of morbidity and mortality, globally. The present integrated bioinformatics-cheminformatics approach was employed to locate potent antiviral marine alkaloids that could be used against SARS-CoV-2. Initially, 57 antiviral marine alkaloids and two repurposing drugs were selected from an extensive literature review. Then, the putative target enzyme SARS-CoV-2 main protease (SARS-CoV-2-Mpro) was retrieved from the protein data bank and carried out a virtual screening-cum-molecular docking study with all candidates using PyRx 0.8 and AutoDock 4.2 software. Further, the molecular dynamics (MD) simulation of the two most potential alkaloids and a drug docking complex at 100 ns (with two ligand topology files from PRODRG and ATB server, separately), the molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA) free energy, and contributions of entropy were investigated. Then, the physicochemical-toxicity-pharmacokinetics-drug-likeness profiles, the frontier molecular orbitals energies (highest occupied molecular orbital, lowest unoccupied molecular orbital, and ΔE), and structural-activity relationship were assessed and analyzed. Based on binding energy, 8-hydroxymanzamine (-10.5 kcal/mol) and manzamine A (-10.1 kcal/mol) from all alkaloids with darunavir (-7.9 kcal/mol) and lopinavir (-7.4 kcal/mol) against SARS-CoV-2-Mpro were recorded. The MD simulation (RMSD, RMSF, Rg, H-bond, MM/PBSA binding energy) illustrated that the 8-hydroxymanzamine exhibits a static thermodynamic feature than the other two complexes. The predicted physicochemical, toxicity, pharmacokinetics, and drug-likeness profiles also revealed that the 8-hydroxymanzamine could be used as a potential lead candidate individually and/or synergistically with darunavir or lopinavir to combat SARS-CoV-2 infection after some pharmacological validation.

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) currently poses a threat to human health. 3C-like proteinase (3CLpro) plays an important role in the viral life cycle. Hence, it is considered an attractive antiviral target protein. Whole-genome sequencing showed that the sequence homology between SARS-CoV-2 3CLpro and SARS-CoV 3CLpro is 96.08%, with high similarity in the substrate-binding region. Thus, assessing peptidomimetic inhibitors of SARS-CoV 3CLpro could accelerate the development of peptidomimetic inhibitors for SARS-CoV-2 3CLpro. Accordingly, we herein discuss progress on SARS-CoV-2 3CLpro peptidomimetic inhibitors. Inflammation plays a major role in the pathophysiological process of COVID-19. Small-molecule compounds targeting 3CLpro with both antiviral and anti-inflammatory effects are also briefly discussed in this paper.

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in millions of deaths and threatens public health and safety. Despite the rapid global spread of COVID-19 vaccines, effective oral antiviral drugs are urgently needed. Here, we describe the discovery of S-217622, the first oral non-covalent, non-peptidic SARS-CoV-2 3CL protease inhibitor clinical candidate. S-217622 was discovered via virtual screening followed by biological screening of an in-house compound library, and optimization of the hit compound using a structure-based drug-design strategy. S-217622 exhibited antiviral activity in vitro against current outbreaking SARS-CoV-2 variants and showed favorable pharmacokinetic profiles in vivo for once-daily oral dosing. Furthermore, S-217622 dose-dependently inhibited intrapulmonary replication of SARS-CoV-2 in mice, indicating that this novel non-covalent inhibitor could be a potential oral agent for treating COVID-19.

Covalent inhibitors targeting the main protease (Mpro, or 3CLpro) of SARS-CoV-2 have shown promise in preclinical investigations. Herein, we report the discovery of two new series of molecules that irreversibly bind to SARS-CoV-2 Mpro. These acrylamide containing molecules were discovered using our covalent DNA-encoded library (DEL) screening platform. Following selection against SARS-CoV-2 Mpro, off-DNA compounds were synthesized and investigated to determine their inhibitory effects, the nature of their binding, and to generate preliminary structure-activity relationships. LC-MS analysis indicates a 1:1 (covalent) binding stoichiometry between our hit molecules and SARS-CoV-2 Mpro. Fluorescent staining assay for covalent binding in the presence of cell lysate suggests reasonable selectivity for SARS-CoV-2 Mpro. And lastly, inhibition of enzymatic activity was also observed against a panel of 3CLpro enzymes from different coronavirus strains, with IC50 values ranging from inactive to single digit micromolar. Our results indicate that DEL selection is a useful approach for identifying covalent inhibitors of cysteine proteases.

Aim: The prevailing crisis caused by the COVID-19 pandemic demands the development of effective therapeutic agents that can be implemented with minimal to zero adverse effects. Background: Vitex negundo L. (VNL) is a medicinal plant with reported efficacy against respiratory diseases and some of the COVID-19 symptoms. Funded by the Department of Science and Technology (DOST), the University of the Philippines – Philippine General Hospital (UP-PGH) is currently conducting clinical trials of VNL and other medicinal plants as adjuvant therapeutic agents against mild cases of COVID-19. The basis for the clinical trials is primarily the pharmacological efficacy of the medicinal plants against respiratory disorders and associated COVID-19 symptoms. Objective: This study assessed the in silico potential of VNL components against SARS-CoV-2 main protease (Mpro), an enzyme that plays an important role in COVID-19, the disease caused by the SARS-CoV-2. Objective: This study assessed the in silico potential of VNL components against SARS-CoV-2 main protease (Mpro), an enzyme that plays an important role in COVID-19, the disease caused by the SARS-CoV-2. Method: Phytochemical mining of VNL components from the literature was conducted. A database consisting of 250 known compounds from different parts of VNL was created and screened against SARS-CoV-2 Mpro using the PyRx virtual screening tool. The most promising components were further subjected to in silico absorption, distribution, metabolism, excretion, and toxicity (ADMET) analyses using the SwissADME web server and Toxtree software. Results: Virtual screening revealed that 102 VNL components in the database had comparable to or better binding affinities toward SARS-COV-2 Mpro than known chemical inhibitors (e.g. N3 and carmofur). It was determined that the active site of SARS-CoV-2 Mpro receptor consists of multiple H-donor and acceptor sites; hence, the most stable receptor-ligand complexes are generally formed by VNL ligands that establish effective H-bonding with the SARS-CoV-2 Mpro. The promising components, representing a “cocktail” of potential inhibitors also revealed interesting ADMET properties. Conclusion: This in silico study identified VNL as a potential single source of a cocktail of SARS-CoV-2 Mpro inhibitors and a promising adjuvant therapeutic agent against COVID-19 or its symptoms. Furthermore, the study offers a rationale on phytochemical mining from medicinal plants as a means that can be implemented in the early stage of a drug discovery and development program.

In this study, we target the main protease (M(pro)) of the SARS-CoV-2 virus as it is a crucial enzyme for viral replication. Herein, we report three plausible allosteric sites on M(pro) that can expand structure-based drug discovery efforts for new M(pro) inhibitors. To find these sites, we used mixed-solvent molecular dynamics (MixMD) simulations, an efficient computational protocol that finds binding hotspots through mapping the surface of unbound proteins with 5% cosolvents in water. We have used normal mode analysis to support our claim of allosteric control for these sites. Further, we have performed virtual screening against the sites with 361 hits from M(pro) screenings available through the National Center for Advancing Translational Sciences (NCATS). We have identified the NCATS inhibitors that bind to the remote sites better than the active site of M(pro), and we propose these molecules may be allosteric regulators of the system. After identifying our sites, new X-ray crystal structures were released that show fragment molecules in the sites we found, supporting the notion that these sites are accurate and druggable.

Dysregulation in component 1q (C1q) levels is associated with weak placental development in preeclampsia (PE). Human immunodeficiency virus infection (HIV-1) triggers the C1q complex, resulting in opsonization of healthy host cells, contributing to their removal, and augmented progression of HIV disease. In coronavirus disease 2019 (COVID-19)-infected patients, the deposition of C1q activates the complement. Considering the paucity of data, this review highlights a significant gap in the potential of C1q in the immunocompromised state of preeclamptic HIV-infected women and COVID-19 infection. In PE, C1q is downregulated; while in antiretroviral treatment-treated HIV/COVID-19 infected patients, C1q is upregulated. It is plausible that C1q is augmented in the triad and may exacerbate severity of disease. This thereby provides a foundation for future intended research which involves the investigation of single nucleotide polymorphism expression of the C1q gene, specifically in these diseases.

The paper analyzes a set of equations that adequately predict the IC50 value for SARS-CoV-2 main protease inhibitors. The training set was obtained using filtering by criteria independent of prediction of target value. It included 76 compounds, and the test set included nine compounds. We used the values of energy contributions obtained in the calculation of the change of the free energy of complex by MMGBSA method and a number of characteristics of the physical and chemical properties of the inhibitors as independent variables. It is sufficient to use only seven independent variables without loss of prediction quality (Q² = 0.79; R²prediction = 0.89). The maximum error in this case does not exceed 0.92 lg(IC50) units with a full range of observed values from 1.26 to 4.95.V rabote analiziruetsia nabor uravneniĭ, adekvatno predskazyvaiushchiĭ velichinu IC50 dlia ingibitorov glavnoĭ proteazy SARS-CoV-2. Obuchaiushchaia vyborka poluchena s ispol'zovaniem fil'tratsii po nezavisimym ot predskazaniia tselevoĭ velichiny kriteriev. V ee sostav voshlo 76 soedineniĭ, testovaia vyborka sostavila 9 soedineniĭ. V kachestve nezavisimykh peremennykh ispol'zovali velichiny énergeticheskikh vkladov, poluchennykh pri raschete metodom MMGBSA izmeneniia svobodnoĭ énergii kompleksa, i riad kharakteristik fiziko-khimicheskikh svoĭstv ingibitorov. Dostatochno ispol'zovat' vsego 7 nezavisimykh peremennykh bez poteri kachestva predskazaniia (Q² = 0,79; R²predskazaniia = 0,89). Maksimal'naia oshibka pri étom ne prevyshaet 0,92 edinitsy lg(IC50) pri polnom diapazone nabliudaemykh velichin ot 1,26 do 4,95.

As a highly pathogenic human coronavirus, SARS-CoV-2 has to counteract an intricate network of antiviral host responses to establish infection and spread. The nucleic acid-induced stress response is an essential component of antiviral defense and is closely related to antiviral innate immunity. However, whether SARS-CoV-2 regulates the stress response pathway to achieve immune evasion remains elusive. In this study, SARS-CoV-2 NSP5 and N protein were found to attenuate antiviral stress granule (avSG) formation. Moreover, NSP5 and N suppressed IFN expression induced by infection of Sendai virus or transfection of a synthetic mimic of dsRNA, poly (I:C), inhibiting TBK1 and IRF3 phosphorylation, and restraining the nuclear translocalization of IRF3. Furthermore, HEK293T cells with ectopic expression of NSP5 or N protein were less resistant to vesicular stomatitis virus infection. Mechanistically, NSP5 suppressed avSG formation and disrupted RIG-I–MAVS complex to attenuate the RIG-I–mediated antiviral immunity. In contrast to the multiple targets of NSP5, the N protein specifically targeted cofactors upstream of RIG-I. The N protein interacted with G3BP1 to prevent avSG formation and to keep the cofactors G3BP1 and PACT from activating RIG-I. Additionally, the N protein also affected the recognition of dsRNA by RIG-I. This study revealed the intimate correlation between SARS-CoV-2, the stress response, and innate antiviral immunity, shedding light on the pathogenic mechanism of COVID-19.

The SARS-CoV-2 main protease (Mpro) has a pivotal role in mediating viral genome replication and transcription of the coronavirus, making it a promising target for drugs against the COVID-19 pandemic. Here, a crystal structure is presented in which Mpro adopts an inactive state that has never been observed before, called new-inactive. It is shown that the oxyanion loop, which is involved in substrate recognition and enzymatic activity, adopts a new catalytically incompetent conformation and that many of the key interactions of the active conformation of the enzyme around the active site are lost. Solvation/desolvation energetic contributions play an important role in the transition from the inactive to the active state, with Phe140 moving from an exposed to a buried environment and Asn142 moving from a buried environment to an exposed environment. In new-inactive Mpro a new cavity is present near the S2′ subsite, and the N-terminal and C-terminal tails, as well as the dimeric interface, are perturbed, with partial destabilization of the dimeric assembly. This novel conformation is relevant both for comprehension of the mechanism of action of Mpro within the catalytic cycle and for the successful structure-based drug design of antiviral drugs.

The main protease (Mpro) is a validated antiviral drug target of SARS-CoV-2. A number of Mpro inhibitors have now advanced to animal model study and human clinical trials. However, one issue yet to be addressed is the target selectivity over host proteases such as cathepsin L. In this study we describe the rational design of covalent SARS-CoV-2 Mpro inhibitors with novel cysteine reactive warheads including dichloroacetamide, dibromoacetamide, tribromoacetamide, 2-bromo-2,2-dichloroacetamide, and 2-chloro-2,2-dibromoacetamide. The promising lead candidates Jun9-62-2R (dichloroacetamide) and Jun9-88-6R (tribromoacetamide) had not only potent enzymatic inhibition and antiviral activity but also significantly improved target specificity over caplain and cathepsins. Compared to GC-376, these new compounds did not inhibit the host cysteine proteases including calpain I, cathepsin B, cathepsin K, cathepsin L, and caspase-3. To the best of our knowledge, they are among the most selective covalent Mpro inhibitors reported thus far. The cocrystal structures of SARS-CoV-2 Mpro with Jun9-62-2R and Jun9-57-3R reaffirmed our design hypothesis, showing that both compounds form a covalent adduct with the catalytic C145. Overall, these novel compounds represent valuable chemical probes for target validation and drug candidates for further development as SARS-CoV-2 antivirals.

Coronavirus disease 2019 (COVID-19) is a rapidly growing pandemic that requires urgent therapeutic intervention. Finding potential anti COVID-19 drugs aside from approved vaccines is progressively going on. The chemically diverse natural products represent valuable sources for drug leads. In this study, we aimed to find out safe and effective COVID-19 protease inhibitors from a library of natural products which share the main nucleus/skeleton of FDA-approved drugs that were employed in COVID-19 treatment guidelines or repurposed by previous studies. Our library was subjected to virtual screening against SARS-CoV Main protease (Mpro) using Molecular Operating Environment (MOE) software. Twenty-two out of those natural candidates showed higher binding scores compared to their analogues. We repurpose these natural products including alkaloids, glucosinolates, and phenolics as potential platforms for the development of anti-SARS-CoV-2 therapeutics. This study paves the way towards discovering a lead used in the treatment of COVID-19 from natural sources and introduces phytomedicines with dual therapeutic effects against COVID-19 besides their original pharmacological effects. We recommend further in vitro evaluation of their anti-COVID-19 activity and future clinical studies. Supplementary Information The online version contains supplementary material available at 10.1007/s11356-021-17642-9.

The main protease is regarded as an essential drug target for treating Coronavirus Disease 2019. In the present study, 13 marketed drugs were investigated to explore the possible binding mechanism, utilizing molecular docking, molecular dynamics simulation, and MM-PB(GB)SA binding energy calculations. Our results suggest that fusidic acid, polydatin, SEN-1269, AZD6482, and UNC-2327 have high binding affinities of more than 23 kcal mol

A global pandemic caused by the SARS-CoV-2 virus that started in 2020 and has wreaked havoc on humanity still ravages up until now. As a result, the negative impact of travel restrictions and lockdowns has underscored the importance of our preparedness for future pandemics. The main thrust of this work was based on addressing this need by traversing chemical space to design inhibitors that target the SARS-CoV-2 papain-like protease (PLpro). Pathfinder-based retrosynthesis analysis was used to generate analogs of GRL-0617 using commercially available building blocks by replacing the naphthalene moiety. A total of 10 models were built using active learning QSAR, which achieved good statistical results such as an R2 > 0.70, Q2 > 0.64, STD Dev < 0.30, and RMSE < 0.31, on average for all models. A total of 35 ideas were further prioritized for FEP+ calculations. The FEP+ results revealed that compound 45 was the most active compound in this series with a ΔG of −7.28 ± 0.96 kcal/mol. Compound 5 exhibited a ΔG of −6.78 ± 1.30 kcal/mol. The inactive compounds in this series were compound 91 and compound 23 with a ΔG of −5.74 ± 1.06 and −3.11 ± 1.45 kcal/mol. The combined strategy employed here is envisaged to be of great utility in multiparameter lead optimization efforts, to traverse chemical space, maintaining and/or improving the potency as well as the property space of synthetically aware design ideas.

Background The coronavirus nonstructural protein 5 (Nsp5) is a cysteine protease required for processing the viral polyprotein and is therefore crucial for viral replication. Nsp5 from several coronaviruses have also been found to cleave host proteins, disrupting molecular pathways involved in innate immunity. Nsp5 from the recently emerged SARS-CoV-2 virus interacts with and can cleave human proteins, which may be relevant to the pathogenesis of COVID-19. Based on the continuing global pandemic, and emerging understanding of coronavirus Nsp5-human protein interactions, we set out to predict what human proteins are cleaved by the coronavirus Nsp5 protease using a bioinformatics approach. Results Using a previously developed neural network trained on coronavirus Nsp5 cleavage sites (NetCorona), we made predictions of Nsp5 cleavage sites in all human proteins. Structures of human proteins in the Protein Data Bank containing a predicted Nsp5 cleavage site were then examined, generating a list of 92 human proteins with a highly predicted and accessible cleavage site. Of those, 48 are expected to be found in the same cellular compartment as Nsp5. Analysis of this targeted list of proteins revealed molecular pathways susceptible to Nsp5 cleavage and therefore relevant to coronavirus infection, including pathways involved in mRNA processing, cytokine response, cytoskeleton organization, and apoptosis. Conclusions This study combines predictions of Nsp5 cleavage sites in human proteins with protein structure information and protein network analysis. We predicted cleavage sites in proteins recently shown to be cleaved in vitro by SARS-CoV-2 Nsp5, and we discuss how other potentially cleaved proteins may be relevant to coronavirus mediated immune dysregulation. The data presented here will assist in the design of more targeted experiments, to determine the role of coronavirus Nsp5 cleavage of host proteins, which is relevant to understanding the molecular pathology of coronavirus infection.

The main protease (M(pro)) plays a crucial role in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication and is highly conserved, rendering it one of the most attractive therapeutic targets for SARS-CoV-2 inhibition. Currently, although two drug candidates targeting SARS-CoV-2 M(pro) designed by Pfizer are under clinical trials, no SARS-CoV-2 medication is approved due to the long period of drug development. Here, we collect a comprehensive list of 817 available SARS-CoV-2 and SARS-CoV M(pro) inhibitors from the literature or databases and analyze their molecular mechanisms of action. The structure–activity relationships (SARs) among each series of inhibitors are discussed. Additionally, we broadly examine available antiviral activity, ADMET (absorption, distribution, metabolism, excretion, and toxicity), and animal tests of these inhibitors. We comment on their druggability or drawbacks that prevent them from becoming drugs. This Perspective sheds light on the future development of M(pro) inhibitors for SARS-CoV-2 and future coronavirus diseases.

Despite the recent availability of vaccines against the acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the search for inhibitory therapeutic agents has assumed importance especially in the context of emerging new viral variants. In this paper, we describe the discovery of a novel noncovalent small-molecule inhibitor, MCULE-5948770040, that binds to and inhibits the SARS-Cov-2 main protease (Mpro) by employing a scalable high-throughput virtual screening (HTVS) framework and a targeted compound library of over 6.5 million molecules that could be readily ordered and purchased. Our HTVS framework leverages the U.S. supercomputing infrastructure achieving nearly 91% resource utilization and nearly 126 million docking calculations per hour. Downstream biochemical assays validate this Mpro inhibitor with an inhibition constant (Ki) of 2.9 μM (95% CI 2.2, 4.0). Furthermore, using room-temperature X-ray crystallography, we show that MCULE-5948770040 binds to a cleft in the primary binding site of Mpro forming stable hydrogen bond and hydrophobic interactions. We then used multiple μs-time scale molecular dynamics (MD) simulations and machine learning (ML) techniques to elucidate how the bound ligand alters the conformational states accessed by Mpro, involving motions both proximal and distal to the binding site. Together, our results demonstrate how MCULE-5948770040 inhibits Mpro and offers a springboard for further therapeutic design.

As per the World Health Organization report, around 226 844 344 confirmed positive cases and 4 666 334 deaths are reported till September 17, 2021 due to the recent viral outbreak. A novel coronavirus (severe acute respiratory syndrome coronavirus 2 [SARS‐CoV‐2]) is responsible for the associated coronavirus disease (COVID‐19), which causes serious or even fatal respiratory tract infection and yet no approved therapeutics or effective treatment is currently available to combat the outbreak. Due to the emergency, the drug repurposing approach is being explored for COVID‐19. In this study, we attempt to understand the potential mechanism and also the effect of the approved antiviral drugs against the SARS‐CoV‐2 main protease (Mpro). To understand the mechanism of inhibition of the malaria drug hydroxychloroquine (HCQ) against SARS‐CoV‐2, we performed molecular interaction studies. The studies revealed that HCQ docked at the active site of the Human ACE2 receptor as a possible way of inhibition. Our in silico analysis revealed that the three drugs Lopinavir, Ritonavir, and Remdesivir showed interaction with the active site residues of Mpro. During molecular dynamics simulation, based on the binding free energy contributions, Lopinavir showed better results than Ritonavir and Remdesivir.

We present the results of classical and QM/MM simulations for the inhibition of SARS‐CoV‐2 3CL protease by a hydroxymethylketone inhibitor, PF‐00835231. In the noncovalent complex the carbonyl oxygen atom of the warhead is placed in the oxyanion hole formed by residues 143 to 145, while P1–P3 groups are accommodated in the active site with interactions similar to those observed for the peptide substrate. According to alchemical free energy calculations, the P1′ hydroxymethyl group also contributes to the binding free energy. Covalent inhibition of the enzyme is triggered by the proton transfer from Cys145 to His41. This step is followed by the nucleophilic attack of the Sγ atom on the carbonyl carbon atom of the inhibitor and a proton transfer from His41 to the carbonyl oxygen atom mediated by the P1′ hydroxyl group. Computational simulations show that the addition of a chloromethyl substituent to the P1′ group may lower the activation free energy for covalent inhibition, Multiscale simulations unveil the binding and reaction mechanism of the SARS‐CoV‐2 main protease inhibitor, PF‐00835231 inhibitor. This compound contains a hydroxymethyl group that plays a relevant role in the formation of the noncovalent and covalent complexes. In silico modifications show a possible strategy for the design of new inhibitors.

COVID-19, an acute viral pneumonia, has emerged as a devastating pandemic. Drug repurposing allows researchers to find different indications of FDA-approved or investigational drugs. In this current study, a sequence of pharmacophore and molecular modeling-based screening against COVID-19 Mpro (PDB: 6LU7) suggested a subset of drugs, from the Drug Bank database, which may have antiviral activity. A total of 44 out of 8823 of the most promising virtual hits from the Drug Bank were subjected to molecular dynamics simulation experiments to explore the strength of their interactions with the SARS-CoV-2 Mpro active site. MD findings point toward three drugs (DB04020, DB12411, and DB11779) with very low relative free energies for SARS-CoV-2 Mpro with interactions at His41 and Met49. MD simulations identified an additional interaction with Glu166, which enhanced the binding affinity significantly. Therefore, Glu166 could be an interesting target for structure-based drug design. Quantitative structural–activity relationship analysis was performed on the 44 most promising hits from molecular docking-based virtual screening. Partial least square regression accurately predicted the values of independent drug candidates’ binding energy with impressively high accuracy. Finally, the EC50 and CC50 of 10 drug candidates were measured against SARS-CoV-2 in cell culture. Nilotinib and bemcentinib had EC50 values of 2.6 and 1.1 μM, respectively. In summary, the results of our computer-aided drug design provide a roadmap for rational drug design of Mpro inhibitors and the discovery of certified medications as COVID-19 antiviral therapeutics.

Novel SARS-CoV-2, an etiological factor of Coronavirus disease 2019 (COVID-19), poses a great challenge to the public health care system. Among other druggable targets of SARS-Cov-2, the main protease (Mpro) is regarded as a prominent enzyme target for drug developments owing to its crucial role in virus replication and transcription. We pursued a computational investigation to identify Mpro inhibitors from a compiled library of natural compounds with proven antiviral activities using a hierarchical workflow of molecular docking, ADMET assessment, dynamic simulations and binding free-energy calculations. Five natural compounds, Withanosides V and VI, Racemosides A and B, and Shatavarin IX, obtained better binding affinity and attained stable interactions with Mpro key pocket residues. These intermolecular key interactions were also retained profoundly in the simulation trajectory of 100 ns time scale indicating tight receptor binding. Free energy calculations prioritized Withanosides V and VI as the top candidates that can act as effective SARS-CoV-2 Mpro inhibitors.

SARS-CoV-2 represents the causative agent of the current pandemic (COVID-19). The drug repurposing technique is used to search for possible drugs that can bind to SARS-CoV-2 proteins and inhibit viral replication. In this study, the FDA-approved antiplatelets are tested against the main protease and spike proteins of SARS-CoV-2 using in silico methods. Molecular docking and molecular dynamics simulation are used in the current study. The results suggest the effectiveness of vorapaxar, ticagrelor, cilostazol, cangrelor, and prasugrel in binding the main protease (Mpro) of SARS-CoV-2. At the same time, vorapaxar, ticagrelor, and cilostazol are the best binders of the spike protein. Therefore, these compounds could be successful candidates against COVID-19 that need to be tested experimentally. Supplementary Information The online version contains supplementary material available at 10.1007/s11239-021-02558-5.