Main Protease Enzyme Research Articles

Potential immunomodulatory role of sesamin in combating immune dysregulation associated with COVID-19

The ongoing outbreak of novel coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused an unprecedented global health crisis. Development of a cure for this devastating disease is currently at full speed, with several vaccines against COVID-19 already authorized and administered. Currently, demand for these vaccines far exceeds supply. As such, boosting immunity represents a viable route to halt the rapid spread of SARS-CoV-2 and limit fatalities until vaccines become more readily and widely available. The use of phytochemicals appears to be a promising panacea. Sesamin, a lignan isolated from Sesamum indicum seeds, is known for its potent pharmacological properties, and is therefore hypothesized as a potential candidate in the therapeutic regimen against COVID-19. Herein, we highlight the confirmed therapeutic anti-inflammatory and immune-modulatory potential of sesamin against myriads of respiratory disorders, and tentatively suggest that sesamin may exert similar potent effects against COVID-19. Precisely, we speculate that sesamin may help alleviate COVID-19 via restoring Th1/Th2 balance and preventing inflammation and cytokine storm development. Additionally, we further support the promising role of sesamin against COVID-19 by underscoring the direct evidence, which suggests that sesamin may demonstrate promising inhibitory potential against three important SARS-CoV-2 targets, namely main protease, spike protein, and angiotensin-converting enzyme 2 receptor. Although preliminary, there is ample evidence to propose sesamin as a potential phytotherapeutic and prophylactic candidate against COVID-19. Further in vitro, in vivo, and preclinical studies are required to further substantiate the role of sesamin in the prevention and/or treatment of COVID-19.

Instant determination of the artemisinin from various Artemisia annua L. extracts by LC-ESI-MS/MS and their in-silico modelling and in vitro antiviral activity studies against SARS-CoV-2.

IntroductionNumerous efforts in natural product drug development are reported for the treatment of Coronavirus. Based on the literature, among these natural plants Artemisia annua L. shows some promise for the treatment of SARS‐CoV‐2.ObjectiveThe main objective of our study was to determine artemisinin content by liquid chromatography electrospray ionisation tandem mass spectrometry (LC‐ESI‐MS/MS), to investigate the in vitro biological activity of artemisinin from the A. annua plants grown in Turkey with various extracted methods, to elaborate in silico activity against SARS‐CoV‐2 using molecular modelling.MethodologyTwenty‐one different extractions were applied. Direct and sequential extractions studies were compared with ultrasonic assisted maceration, Soxhlet, and ultra‐rapid determined artemisinin active molecules by LC‐ESI‐MS/MS methods. The inhibition of spike protein and main protease (3CL) enzyme activity of SARS‐CoV‐2 virus was assessed by time resolved fluorescence energy transfer (TR‐FRET) assay.ResultsArtemisinin content in the range 0.062–0.066%. Artemisinin showed significant inhibition of 3CL protease activity but not Spike/ACE‐2 binding. The 50% effective concentration (EC50) of artemisinin against SARS‐CoV‐2 Spike pseudovirus was found greater than 50 μM (EC45) in HEK293T cell line whereas the cell viability was 94% of the control (P < 0.01). The immunosuppressive effects of artemisinin on TNF‐α production on both pseudovirus and lipopolysaccharide (LPS)‐induced THP‐1 cells were found significant in a dose dependent manner.ConclusionFurther studies of these extracts for COVID‐19 treatment will shed light to seek alternative treatment options. Moreover, these natural extracts can be used as an additional treatment option with medicines, as well as prophylactic use can be very beneficial for patients.

Inhibition of multiple SARS-CoV-2 proteins by an antiviral biomolecule, seselin from Aegle marmelos deciphered using molecular docking analysis

Our earlier experimental and computational report produced evidence on the antiviral nature of the compound seselin purified from the leaf extracts of Aegle marmelos against Bombyx mori Nuclear Polyhedrosis Virus (BmNPV). In the pandemic situation of COVID-19 caused by the SARS-COV-2 virus, an in silico effort to evaluate the potentiality of the seselin was made to test its efficacy against multiple targets of SARS-COV-2 such as spike protein S2, COVID-19 main protease and free enzyme of the SARS-CoV-2 (2019-nCoV) main protease. The ligand seselin showed the best interaction with receptors, spike protein S2, COVID-19 main protease and free enzyme of the SARS-CoV-2 (2019-nCoV) main protease with a binding energy of −6.3 kcal/mol, −6.9 kcal/mol and −6.7 kcal/mol, respectively. Docking analysis with three different receptors identified that all the computationally predicted lowest energy complexes were stabilized by intermolecular hydrogen bonds and stacking interactions. The amino acid residues involved in interactions were ASP1184, GLU1182, ARG1185 and SER943 for spike protein, SER1003, ALA958 and THR961 for COVID-19 main protease, and for SARS-CoV-2 (2019-nCoV) main protease, it was THR111, GLN110 and THR292. The MD simulation and MM/PBSA analysis showed that the compound seselin could effectively bind with the target receptors. The outcome of pharmacokinetic analysis suggested that the compound had favourable drugability properties. The results suggested that the seselin had inhibitory potential over multiple SARS-COV-2 targets and hold a high potential to work effectively as a novel drug for COVID-19 if evaluated in experimental setups in the foreseeable future. Communicated by Ramaswamy H. Sarma

Comparative studies on the interaction of ascorbic acid with gastric enzyme using multispectroscopic and docking methods

Pepsin is the main digestive protease enzyme, is released by the gastric chief cells in the stomach. Ascorbic acid is an essential nutrient that is one of the most prevalent antioxidant nutrients. In this study, experimental and computational methods were used to investigate noncovalent interactions of ascorbic acid and pepsin. UV–vis spectra of results suggested that ascorbic acid–pepsin complexes were formed. The results of fluorescence spectroscopy show that the quenching mechanism was static. Further, the thermodynamic parameters revealed that the binding process of ascorbic acid to pepsin was spontaneous. The negative signs for enthalpy (ΔH°) and entropy (ΔS°) from the interaction of the ascorbic acid–pepsin complex shows that the major driving forces are the van der Waals interactions and hydrogen bond which is agreed with the molecular docking observations.Based on far-CD spectra of pepsin, the α-helix content decreased, followed by an increase in β-sheet compositions. The result of the RMSF value shows that the residues involved in the complex are less flexible. From MD simulation we observed that an average RMSD in complex (1.16 nm) lower than of the free pepsin system(1.44 nm) which agreed with the research of thermal stability (increase in Tm). Kinetic studies showed that by adding ascorbic acid, an increase in enzyme activity happened.

Virtual Screening, Molecular Docking and In silico ADME-Tox Analysis for Identification of Potential Main Protease (Mpro) Enzyme Inhibitors

Objective: Recent pandemic caused by the SARS-CoV-2, first described in Wuhan city of China in December 2019, spread widely in almost all the countries of the world. Coronavirus (COVID-19) led to the unexpected death of many people and caused a severe economic loss in a number of countries. Virtual screening based on molecular docking, drug-likeness prediction, and in silico ADMET studies are some of the effective tools for the identification of small molecules as novel antiviral drugs to treat diseases. Methods: In the current study, virtual screening was performed through molecular docking for identifying potent inhibitors against Mpro enzyme from the ZINC library for the possible treatment of the COVID-19 pandemic. Interestingly, some compounds have been identified as possible anti-covid-19 agents for future research. A total of 350 compounds were screened based on their similarity score with reference compound X77 from ZINC data bank and were subjected to docking with crystal structure available of Mpro enzyme. These compounds were then filtered by their in silico ADME-Tox and drug-likeness prediction values. Result: Out of these 350 screened compounds, 10 compounds were selected based on their docking score and best-docked pose in comparison to the reference compound X77. In silico ADME-Tox and drug likeliness predictions of the top compounds were performed and showed excellent results. All the 10 screened compounds showed a significant binding pose with the target main protease (Mpro) enzyme and satisfactory pharmacokinetic and toxicological properties. Conclusion: Based on these results, it is suggested that the identified compounds may be considered for therapeutic development against the COVID-19 virus and can further be evaluated for in vitro activity, preclinical, clinical studies, and formulated in a suitable dosage form to maximize their bioavailability.

Green synthesis of silver nanoformulation of Scindapsus officinalis as potent anticancer and predicted anticovid alternative: Exploration via experimental and computational methods

The current study was focused on the investigation of anticancer activity of Scindapsus Officinalis fruit extract embedded silver nanoparticles (So-AgNPs) followed by anticovid activity prognosis of major phytocompounds, which participate in nanoformulation synthesis. The synthesis process involved the addition of AgNO3 solution (1 mM) and color change of the extract from light brown to dark, confirmed the formation of silver nanoparticles. Further, the characterization of synthesized So-AgNPs were done using different spectroscopical and microscopical techniques. FTIR spectra of So-AgNPs indicated vibrational peaks of polyphenolic hydroxyl groups, which are responsible for the stabilization of nanoformulation. Others microscopy methods such as SEM, TEM, XRD, and EDX illustrated that the synthesized So-AgNPs consist irregular size, spherical shape and thoroughly dispersed above the plane. Anticancer evaluation illustrated that the So-AgNPs have dose dependent anti-breast and anti-hepatic cancer activity (range of 97.72 ± 0.42–54.86 ± 0.46% cell viability), which were noticed more effective than raw fruit extract of Scindapsus Officinalis. The computational anticovid prediction of major phyto-compound of the extract [which designate as inhibitor 1: ((2R,3S,4S, 5R)-2-(hydroxymethyl)-6-(((1S, 5S)-1-methyl-5-(2-methylprop-1-en-1-yl)cyclopent-2-en-1-yl)oxy)tetrahydro-2H-pyran-3,4,5-triol)] illustrated moderate tendency to interact with corona main protease enzyme (expected pIC > 6 μM). However, the molecular docking and dynamics studies showed that selected compounds have moderate tendency to interact human dihydrofolate reductase and topoisomerase 1 enzyme. The accomplished approach shows that So-AgNPs with adsorbed phytocompounds on its surface consist valuable experimentally proved anticancer potency and computationally predicted anticovid effect. Thus, the formulation can be used as an alternative to the covid infected cancer population.

In vitro inhibition and molecular docking of a new ciprofloxacin-chalcone against SARS-CoV-2 main protease.

Background/AimSARS‐CoV‐2 is one of the coronavirus families that emerged at the end of 2019. It infected the respiratory system and caused a pandemic worldwide. Fluoroquinolones (FQs) have been safely used as antibacterial agents for decades. The antiviral activity of FQs was observed. Moreover, substitution on the C‐7 position of ciprofloxacin enhanced its antiviral activity. Therefore, this study aims to investigate the antiviral activity of 7‐(4‐(N‐substituted‐carbamoyl‐methyl)piperazin‐1yl)‐chalcone in comparison with ciprofloxacin against SARS‐CoV‐2 main protease (Mpro).Materials and methodsVero cells were infected with SARS‐CoV‐2. After treatment with ciprofloxacin and the chalcone at the concentrations of 1.6, 16, 160 nmol/L for 48 h, SARS‐CoV‐2 viral load was detected using real‐time qPCR, SARS‐CoV‐2 infectivity was determined using plaque assay, and the main protease enzyme activity was detected using in vitro 3CL‐protease inhibition assay. The activity of the chalcone was justified through molecular docking within SARS‐CoV‐2 Mpro, in comparison with ciprofloxacin.ResultsThe new chalcone significantly inhibited viral load replication where the EC50 was 3.93 nmol/L, the plaque formation ability of the virus was inhibited to 86.8% ± 2.47. The chalcone exhibited a significant inhibitory effect against SARS‐CoV‐2 Mpro in vitro in a dose‐dependent manner. The docking study into SARS‐CoV‐2 Mpro active site justified the importance of adding a substitution to the parent drug. Additionally, the assessment of the drug‐likeness properties indicated that the chalcone might have acceptable ADMET properties.ConclusionThe new chalcone might be useful and has new insights for the inhibition of SARS‐CoV‐2 Mpro.

Identification of Food Compounds as inhibitors of SARS-CoV-2 main protease using molecular docking and molecular dynamics simulations

SARS-CoV-2 has rapidly emerged as a global pandemic with high infection rate. At present, there is no drug available for this deadly disease. Recently, Mpro (Main Protease) enzyme has been identified as essential proteins for the survival of this virus. In the present work, Lipinski's rules and molecular docking have been performed to identify plausible inhibitors of Mpro using food compounds. For virtual screening, a database of food compounds was downloaded and then filtered using Lipinski's rule of five. Then, molecular docking was accomplished to identify hits using Mpro protein as the target enzyme. This led to identification of a Spermidine derivative as a hit. In the next step, Spermidine derivatives were collected from PubMed and screened for their binding with Mpro protein. In addition, molecular dynamic simulations (200 ns) were executed to get additional information. Some of the compounds are found to have strong affinity for Mpro, therefore these hits could be used to develop a therapeutic agent for SARS-CoV-2.

Virtual screenings of the bioactive constituents of tea, prickly chaff, catechu, lemon, black pepper, and synthetic compounds with the main protease (Mpro) and human angiotensin-converting enzyme 2 (ACE 2) of SARS-CoV-2

BackgroundCOVID-19 has mutation capability, and there are no specific drug therapies that are available to fight or inhibit the proteins of this virus. The present study aims to investigate the binding affinity of the bioactive and synthetic compounds with the main protease (Mpro) enzymes and angiotensin-converting enzyme 2 (ACE 2) by computational approach. PASS prediction, pharmacokinetics, and toxicological properties prediction studies were performed through the Google PASS prediction and Swiss ADME/T website. Besides, molecular docking studies were accomplished by BIOVIA Discovery Studio 2020, UCSF Chimera, and PyRx autodock vina.ResultsThe docking scores were inferred and the selected compounds showed results varying from −3.2 to −9.8 (kcal/mol). Theaflavin scored the highest docking score to the 5REB, 6VW1, and 1R42 enzymes and showed the binding affinity as −6.3 kcal/mol, −9.8 kcal/mol, and −8.6 kcal/mol, respectively. Again, kaempferol showed the best binding affinity to the 7BQY (−7.1 kcal/mol) and 6Y2FB (−6.6 kcal/mol) enzymes. All the chemical constituents showed better probability in action in pass prediction analysis. Besides, no ligands (except theaflavin) have any conflict with Lipinski’s rules of five, which authorized the drug probability of these ligands.ConclusionTherefore, the selected compounds could be considered a potential herbal treatment source against SARS-CoV-2.

Phytoconstituents from ten natural herbs as potent inhibitors of main protease enzyme of SARS-COV-2: In silico study

BackgroundLack of treatment of novel Coronavirus disease led to the search of specific antivirals that are capable to inhibit the replication of the virus. The plant kingdom has demonstrated to be an important source of new molecules with antiviral potential. PurposeThe present study aims to utilize various computational tools to identify the most eligible drug candidate that have capabilities to halt the replication of SARS-COV-2 virus by inhibiting Main protease (Mpro) enzyme MethodsWe have selected plants whose extracts have inhibitory potential against previously discovered coronaviruses. Their phytoconstituents were surveyed and a library of 100 molecules was prepared. Then, computational tools such as molecular docking, ADMET and molecular dynamic simulations were utilized to screen the compounds and evaluate them against Mpro enzyme. ResultsAll the phytoconstituents showed good binding affinities towards Mpro enzyme. Among them laurolitsine possesses the highest binding affinity i.e. -294.1533 kcal/mol. On ADMET analysis of best three ligands were simulated for 1.2 ns, then the stable ligand among them was further simulated for 20 ns. Results revealed that no conformational changes were observed in the laurolitsine w.r.t. protein residues and low RMSD value suggested that the Laurolitsine-protein complex was stable for 20 ns. ConclusionLaurolitsine, an active constituent of roots of Lindera aggregata, was found to be having good ADMET profile and have capabilities to halt the activity of the enzyme. Therefore, this makes laurolitsine a good drug candidate for the treatment of COVID-19.

Appraisals of the Bangladeshi Medicinal Plant Calotropis gigantea Used by Folk Medicine Practitioners in the Management of COVID-19: A Biochemical and Computational Approach.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first recognized in Wuhan in late 2019 and, since then, had spread globally, eventually culminating in the ongoing pandemic. As there is a lack of targeted therapeutics, there is certain opportunity for the scientific community to develop new drugs or vaccines against COVID-19 and so many synthetic bioactive compounds are undergoing clinical trials. In most of the countries, due to the broad therapeutic spectrum and minimal side effects, medicinal plants have been used widely throughout history as traditional healing remedy. Because of the unavailability of synthetic bioactive antiviral drugs, hence all possible efforts have been focused on the search for new drugs and alternative medicines from different herbal formulations. In recent times, it has been assured that the Mpro, also called 3CLpro, is the SARS-CoV-2 main protease enzyme responsible for viral reproduction and thereby impeding the host’s immune response. As such, Mpro represents a highly specified target for drugs capable of inhibitory action against coronavirus disease 2019 (COVID-19). As there continue to be no clear options for the treatment of COVID-19, the identification of potential candidates has become a necessity. The present investigation focuses on the in silico pharmacological activity of Calotropis gigantea, a large shrub, as a potential option for COVID-19 Mpro inhibition and includes an ADME/T profile analysis of that ligand. For this study, with the help of gas chromatography–mass spectrometry analysis of C. gigantea methanolic leaf extract, a total of 30 bioactive compounds were selected. Our analyses unveiled the top four options that might turn out to be prospective anti–SARS-CoV-2 lead molecules; these warrant further exploration as well as possible application in processes of drug development to combat COVID-19.

DFT, molecular docking and molecular dynamics simulation studies on some newly introduced natural products for their potential use against SARS-CoV-2

Throughout the history, natural products always give new paths to develop new drugs. As with many other diseases, natural compounds can be helpful in the treatment of COVID-19. SARS-CoV-2 main protease enzyme has an important role in viral replication and transcription. Therefore, inhibiting this enzyme may be helpful in the treatment of COVID-19. In this study, it is aimed to investigate eight natural compounds which have recently entered the literature, computationally for their potential use against SARS-CoV-2. For this purpose, first, density functional theory (DFT) calculations were performed on the investigated compounds, and energy minimizations, geometry optimizations, vibrational analyses, molecular electrostatic potential map calculations were carried out. After DFT calculations, geometry optimized structures were subjected to molecular docking calculations with the use of SARS-CoV-2 main protease (pdb id: 5r80) and top-scoring ligand-receptor complexes were obtained. In the next part of the study, molecular dynamics (MD) simulations were performed on the top-scoring ligand-receptor complexes to investigate the stability of the ligand-receptor complexes and the interactions between ligands and receptor in more detail. Additionally, in this part of the study, binding free energies are calculated with the use of molecular mechanics with Poisson-Boltzmann surface area (MM-PBSA) method. Results showed that, all ligand-receptor complexes remain stable during the MD simulations and most of the investigated compounds but especially two of them showed considerably high binding affinity to SARS-CoV-2 main protease. Finally, in the study, ADME (adsorption, desorption, metabolism, excretion) predictions and drug-likeness analyses were performed on the investigated compounds.

Isolation and In Silico Anti-COVID-19 Main Protease (Mpro) Activities of Flavonoids and a Sesquiterpene Lactone from Artemisia sublessingiana

The emergence of the COVID-19 pandemic declared the huge need of humanity for new and effective antiviral drugs. The reported antimicrobial activities of Artemisia sublessingiana encouraged us to investigate the ethanol extract of its aerial parts which led to the isolation of six flavonoids and a sesquiterpenoid. The structures of the isolated compounds were elucidated by EI-MS, 1D, and 2D NMR spectroscopic methods to be (1) eupatilin, (2) 3′,4′-dimethoxyluteolin, (3) 5,7,3′-trihydroxy-6,4′,5′-trimethoxyflavone, (4) hispidulin, (5) apigenin, (6) velutin, and (7) sesquiterpene lactone 8α,14-dihydroxy-11,13-dihydromelampolide. The isolated compounds were in silico examined against the COVID-19 main protease (Mpro) enzyme. Compounds 1–6 exhibited promising binding modes showing free energies ranging from −6.39 to −6.81 (kcal/mol). The best binding energy was for compound 2. The obtained results give hope of finding a treatment for the COVID-19 pandemic.

Non-competitive interactions between hydroxychloroquine and azithromycin: Systematic density functional, molecular dynamics, and docking calculations

In this study, density functional theory (DFT) and docking calculations were systematically performed to study the non-competitive interaction between Hydroxychloroquine (HCQ) and azithromycin (AZTH). The calculated changes in Gibbs free energy and enthalpy (at 310 K) were positive, indicating the non-spontaneous formation of HCQ-AZTH specifically in water media. Docking calculation confirmed the obtained DFT result as evident from the different binding sites of both drugs to the SARS-CoV-2 main protease and human angiotensin-converting enzyme 2 (ACE2) proteins. The HCQ-AZTH structure revealed enhanced electrochemical properties, suggesting the synergy between HCQ and AZTH without affecting their therapeutic efficacy against SARS-CoV-2.

Molecular Docking study to Identify Potent Fungal Metabolites as Inhibitors against SARS-CoV-2 Main Protease Enzyme

Severe acute respiratory syndrome (SARS) is a viral respiratory disease caused by a SARS-associated coronavirus and SARS-CoV-2 has proven to be a pandemic worldwide. Coronaviruses are a type of enveloped virus. They are basically single-stranded and positive-sense RNA viruses which belongs to the subfamily Coronavirinae. Structure of SARS-CoV-2 is predicted to be the same as SARS-CoV due to high sequence similarity. SARS-CoV-2 is proven to be a major pandemic creator and affected the world at an exponential rate. The genome of COVID19 codes for the main protease 6LU7, is essential for viral replication and multiplication. To get a possible antiviral drug(s), nowadays is the major concern. In our study we screened ten fungal metabolites such as Aspirochlorine, Aflatoxin B1, Alpha-Cyclopiazonic acid, Sporogen, Asperfuran, Aspergillomarasmine A, Maltoryzine, Kojic acid, Aflatrem and Ethyl 3-nitropropionic acid against main protease 6LU7. These molecules were of fungal origin from Aspergillus flavus and Aspergillus oryzae. Aspergillomarasmine A exhibited the docking score of - 6.02 Kcal/mol, almost nearer to presently used drug Chloroquine (-6.29 Kcal/mol). Second highest docking score was found for Asperfuran (-5.5 Kcal/mol), whereas Aflatoxin B1 provided docking score was -5.0 Kcal/mol. We found similar docking score -5.4 Kcal/mol for Asperfuran, Maltoryzine and Kojic acid. Aspirochlorine and Ethyl 3-nitropropionic acid exhibited docking score were -5.3 Kcal/mol and -5.1 Kcal/mol respectively. These natural bioactive compounds could be tested in near future for their ability to inhibit viral growth both in invitro as well as invivo study.

Molecular dynamics and in silico mutagenesis on the reversible inhibitor-bound SARS-CoV-2 main protease complexes reveal the role of lateral pocket in enhancing the ligand affinity

The 2019 novel coronavirus pandemic caused by SARS-CoV-2 remains a serious health threat to humans and there is an urgent need to develop therapeutics against this deadly virus. Recent scientific evidences have suggested that the main protease (Mpro) enzyme in SARS-CoV-2 can be an ideal drug target due to its crucial role in the viral replication and transcription processes. Therefore, there are ongoing research efforts to identify drug candidates against SARS-CoV-2 Mpro that resulted in hundreds of X-ray crystal structures of ligand-bound Mpro complexes in the Protein Data Bank (PDB) describing the interactions of different fragment chemotypes within different sites of the Mpro. In this work, we performed rigorous molecular dynamics (MD) simulation of 62 reversible ligand–Mpro complexes in the PDB to gain mechanistic insights about their interactions at the atomic level. Using a total of over 3 µs long MD trajectories, we characterized different pockets in the apo Mpro structure, and analyzed the dynamic interactions and binding affinity of ligands within those pockets. Our results identified the key residues that stabilize the ligands in the catalytic sites and other pockets of Mpro. Our analyses unraveled the role of a lateral pocket in the catalytic site in Mpro that is critical for enhancing the ligand binding to the enzyme. We also highlighted the important contribution from HIS163 in the lateral pocket towards ligand binding and affinity against Mpro through computational mutation analyses. Further, we revealed the effects of explicit water molecules and Mpro dimerization in the ligand association with the target. Thus, comprehensive molecular-level insights gained from this work can be useful to identify or design potent small molecule inhibitors against SARS-CoV-2 Mpro.

Novel inhibitors of the main protease enzyme of SARS-CoV-2 identified via molecular dynamics simulation-guided in vitro assay

For the COVID-19 pandemic caused by SARS-CoV-2, there are currently no effective drugs or vaccines to treat this coronavirus infection. In this study, we focus on the main protease enzyme of SARS-CoV-2, 3CLpro, which is critical for viral replication. We employ explicit solvent molecular dynamics simulations of about 150 compounds docked into 3CLpro’s binding site and that had emerged as good main protease ligands from our previous in silico screening of over 1.2 million compounds. By incoporating protein dynamics and applying a range of structural descriptors, such as the ability to form specific contacts with the catalytic dyad residues of 3CLpro and the structural fluctuations of the ligands in the binding site, we are able to further refine our compound selection. Fourteen compounds including estradiol shown to be the most promising based on our calculations were procured and screened against recombinant 3CLpro in a fluorescence assay. Eight of these compounds have significant activity in inhibiting the SARS-CoV-2 main protease. Among these are corilagin, a gallotannin, and lurasidone, an antipsychotic drug, which emerged as the most promising natural product and drug, respectively, and might thus be candidates for drug repurposing for the treatment of COVID-19. In addition, we also tested the inhibitory activity of testosterone, and our results reveal testosterone as possessing moderate inhibitory potency against the 3CLpro enzyme, which may thus provide an explanation why older men are more severely affected by COVID-19.

Quinoline and Quinazoline Alkaloids against COVID-19: An In Silico Multitarget Approach

The recent outbreak of the highly contagious coronavirus disease 2019 (COVID-19) caused by the novel coronavirus SARS-CoV-2 has created a global health crisis with socioeconomic impacts. Although, recently, vaccines have been approved for the prevention of COVID-19, there is still an urgent need for the discovery of more efficacious and safer drugs especially from natural sources. In this study, a number of quinoline and quinazoline alkaloids with antiviral and/or antimalarial activity were virtually screened against three potential targets for the development of drugs against COVID-19. Among seventy-one tested compounds, twenty-three were selected for molecular docking based on their pharmacokinetic and toxicity profiles. The results identified a number of potential inhibitors. Three of them, namely, norquinadoline A, deoxytryptoquivaline, and deoxynortryptoquivaline, showed strong binding to the three targets, SARS-CoV-2 main protease, spike glycoprotein, and human angiotensin-converting enzyme 2. These alkaloids therefore have promise for being further investigated as possible multitarget drugs against COVID-19.

In Silico Identification of Flavonoids from Corriandrum sativum Seeds against Coronavirus Covid-19 Main Protease

Molecular docking analysis is routinely used in modern drug research to understand and predict the relationship between a drug molecule and a target protein from a microbe. The entry and replication of pathogens in host cells can be prevented by drugs identified in this way. The coronavirus disease associated with SARS-CoV-2, COVID-19, has become today's most infectious and lethal pandemic disease in the world. Burgeoning in the absence of any particular vaccine or therapeutic agent against SARS-CoV-2.The situation urges the need for appropriate medications to treat patients infected with the virus. Consequently, the study focus on evaluate the therapeutic potential of flavonoids present in Corriandrum sativum seeds that could serve as suitable remedies for COVID19.We analyzed the binding affinity of four flavonoids were screened against Mpro protein of SARS-CoV-2 by PyRx Virtual Screening tool and also results are validated with Lig-Plot Plus. Lopinavir shows binding affinity of -8.3 Kcal/mol and exhibit stable, strong interaction with active site of COVID19 main protease. Besides flavonoids, Rutin found to have the highest binding affinity compared to Lopinavir with the Mpro protease, followed by Chlorogenic acid, Quercetin and Caffeic acid. The present study concludes that Rutin present in the integrant of seeds shows the highest potentiality for acting as in inhibitor of main protease enzyme. Further, characterization of the amino acid residues comprising the viral binding site and the nature of the hydrogen bonding involved in the ligand receptor interaction shows significant findings with Rutin binding to the MPro protein at amino acid. The amino acid acid present in active sites of Mpro protease responsible for virus pathogenicity. The findings of the present study need in vivo experiments to prove the utility of Rutin compounds and further use in making Corriandrum sativum seeds as anti-SARS-CoV-2 product in near future.&#x0D; Keywords: Corriandrum sativum seeds,Novel Coronavirus, SARS-CoV2, COVID-19, Protease, Molecular Docking.

A molecular docking study of potential inhibitors and repurposed drugs against SARS-CoV-2 main protease enzyme

COVID-19 has affected millions of people. Although many drugs are in use to combat disease, there is not any sufficient treatment yet. Having critical role in propagation of the novel coronavirus (SARS-CoV-2) works Main Protease up into a significant drug target. We have performed a molecular docking study to define possible inhibitor candidates against SARS-CoV-2 Main Protease enzyme. Besides docking Remdesivir, Ribavirin, Chloroquine and 28 other antiviral inhibitors (totally 31 inhibitors) to Main Protease enzyme, we have also performed a molecular docking study of 2177 ligands, which are used against Main Protease for the first time by using molecular docking program Autodock4. All ligands were successfully docked into Main Protease enzyme binding site. Among all ligands, EY16 coded ligand which previously used as EBNA1-DNA binding blocker candidate showed the best score for Main Protease with a binding free energy of −10.83 ​kcal/mol which was also lower than re-docking score of N3 ligand (−10.72 ​kcal/mol) contained in crystal structure of Main Protease. After analyzing the docking modes and docking scores we have found that our ligands have better binding free energy values than the inhibitors in use of treatment. We believe that further studies such as molecular dynamics or Molecular Mechanic Poisson Boltzmann Surface Area studies can make contribution that is more exhaustive to the docking results.