Molecular Insights of Marine Algal Polycyclic Aromatic Compounds as Promising Anti-Viral Agents for Targeting SARS-CoV-2 Proteins–an in Silico Validation

In this study, in silico SARS-CoV-2 inhibitory potential of 19 marine algal polycyclic aromatic compounds plus three commercial anti-viral drug were validated comparatively against three target proteins. Among 19 marine algal compounds apigenin-7-O-neohesperidoside,dieckol, luteolin-7-rutinoside, oxoglyantrypine, hydroxypentafuhalol A, and pseudopentafuhalol B exhibited good binding affinity of toward all three screened targets (Mpro, RdRp, and spike protein) of SARS-CoV-2 shortlisted for further In silico virtual screening analysis. Complete docking interaction analysis indicates that apigenin-7-O-neohesperidoside, dieckol, luteolin-7-rutinoside compounds display very excellent binding and inhibitory potential against the all three screened targets of SAR-CoV-2 among 19 screened marine algal compounds than standard anti-viral drugs. DFT analysis affirms the essential Homo-Lumo orbital energies of apigenin-7-O-neohesperidoside to inhibit targets of SARS-CoV-2. Further in silico analysis confirmed three chosen marine algal compounds are showing their excellent pharmacokinetic and molecular electrostatic potentials (MEPs) toward targets of SARS-CoV-2. MD simulation analysis of three chosen marine algal compounds possesses best simulation trajectories toward the binding pocket of target proteins essential to inhibit SARS-CoV-2 multiplication comparatively standard anti-viral drugs possess lesser binding affinity. However, further human clinical trials are necessary to justify their clinical pertinence. © 2023 Taylor & Francis Group, LLC.

Research Article Molecular Docking and Drug Likeness Prediction of New Potent Sars Cov-2 Main Protease Inhibitors

The novel corona virus whose outbreak took place in December 2019 continues to spread at a rapid rate worldwide. The Main protease (Mpro) plays critical role in the SARS-CoV-2 life cycle through virus replication and transcription process making it as an attractive drug target. Herein, molecular docking study followed by drug-Likeness prediction, were performed in order to identify new potent Mpro inhibitors. Indeed, molecular docking of 1880 compounds into the Mpro active site reveals compounds S1 and S2 as promising inhibitors of this enzyme with binding energy of -39,22 KJ/mol, -36.27 KJ/mol respectively. These two compounds were also predicted to have satisfying drug likeness properties, indicating that they might be promising lead compounds for further anti-SARS CoV-2 drug research.Copyright © KESS All rights reserved.

Structure-based virtual identification of natural inhibitors of SARS-CoV-2 and its Delta and Omicron variant proteins

Plain language summaryMutant strains of SARS-CoV-2 called 'variants of concern' (VOCs) are linked to a good ability to infect, re-infect and spread among people. They are also linked to poor ability to fight the disease and reduced effectiveness of vaccines. Delta and Omicron are important VOCs because they are difficult to control and treat. Specific resistance to some drugs used to treat COVID-19 poses a further challenge. Therefore, discovering natural or plant-derived drugs with no known resistance would be valuable to the treatment of COVID-19. In this study, we screen and identify seven plant-derived compounds that may be useful to treating COVID-19 - we identify Quercetin-3-acetyl-glucoside, Rutin, Kaempferol, Catechin, Orientin, Obetrioside and Neridienone A as potential candidates. Orientin, Obetrioside, Catechin and Neridienone A are identified as candidates against Delta and Omicron for the first time. Aim: Structure-based identification of natural compounds against SARS-CoV-2, Delta and Omicron target proteins. Materials & methods: Several known antiviral natural compounds were subjected to molecular docking and MD simulation against SARS-CoV-2 Mpro, Helicase and Spike, including Delta and Omicron Spikes. Results: Of the docked ligands, 20 selected for each complex exhibited overall good binding affinities (-7.79 to -5.06 kcal/mol) with acceptable physiochemistry following Lipinski's rule. Finally, two best ligands from each complex upon simulation showed structural stability and compactness. Conclusion: Quercetin-3-acetyl-glucoside, Rutin, Kaempferol, Catechin, Orientin, Obetrioside and Neridienone A were identified as potential inhibitors of SARS-CoV-2 Mpro, Helicase and Spike, while Orientin and Obetrioside also showed good binding-affinities with Omicron Spike. Catechin and Neridienone A formed stable complexes with Delta Spike. Tweetable We report structure-based identification of natural compounds viz., Quercetin-3-acetyl-glucoside, Rutin, Kaempferol, Catechin, Orientin, Obetrioside and Neridienone A against SARS-CoV-2 Mpro, Helicase and Spike as well as Delta and Omicron Spike proteins.

In silico assessment of diterpenes as potential inhibitors of SARS-COV-2 main protease

Aim: We aimed to investigate the potential inhibitory effects of diterpenes on SARS-CoV-2 main protease (Mpro). Materials & methods: We performed a virtual screening of diterpenoids against Mpro using molecular docking, molecular dynamics simulation and absorption, distribution, metabolism and excretion) analysis. Results: Some tested compounds followed Lipinski's rule and showed drug-like properties. Some diterpenoids possessed remarkable binding affinities with SARS-CoV-2 Mpro and drug-like pharmacokinetic properties. Three derivatives exhibited structural deviations lower than 1 angstrom. Conclusion: The findings of the study suggest that some of the diterpenes could be candidates as potential inhibitors for Mpro of SARS-CoV-2.

Inhibitory effects of 190 compounds against SARS-CoV-2 Mpr o protein: Molecular docking interactions.

COVID-19 has caused many deaths since the first outbreak in 2019. The burden on healthcare systems around the world has been reduced by the success of vaccines. However, population adherence and the occurrence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants are still challenging tasks to be affronted. In addition, the newly approved drug presents some limitations in terms of side effects and drug interference, highlighting the importance of searching for new antiviral agents against SARS-CoV-2. The SARS-CoV-2 main protease (Mpr o ) represents a versatile target to search for new drug candidates due to its essential role in proteolytic activities responsible for the virus replication. In this work, a series of 190 compounds, composed of 27 natural ones and 163 synthetic compounds, were screened in vitro for their inhibitory effects against SARS-CoV-2 Mpro . Twenty-five compounds inhibited Mpro with inhibitory constant values (Ki ) between 23.2 and 241 µM. Among them, a thiosemicarbazone derivative was the most active compound. Molecular docking studies using Protein Data Bank ID 5RG1, 5RG2, and 5RG3 crystal structures of Mpro revealed important interactions identified as hydrophobic, hydrogen bonding and steric interactions with amino acid residues in the active site cavity. Overall, our findings indicate the described thiosemicarbazones as good candidates to be further explored to develop antiviral leads against SARS-CoV-2. Moreover, the studies showed the importance of careful evaluation of test results to detect and exclude false-positive findings.

Natural Product-Based Screening for Lead Compounds Targeting SARS CoV-2 Mpro.

Drugs that cure COVID-19 have been marketed; however, this disease continues to ravage the world without becoming extinct, and thus, drug discoveries are still relevant. Since Mpro has known advantages as a drug target, such as the conserved nature of the active site and the absence of homologous proteins in the body, it receives the attention of many researchers. Meanwhile, the role of traditional Chinese medicine (TCM) in the control of epidemics in China has also led to a focus on natural products, with the hope of finding some promising lead molecules through screening. In this study, we selected a commercial library of 2526 natural products from plants, animals and microorganisms with known biological activity for drug discovery, which had previously been reported for compound screening of the SARS CoV-2 S protein, but had not been tested on Mpro. This library contains compounds from a variety of Chinese herbs, including Lonicerae Japonicae Flos, Forsythiae Fructus and Scutellariae Radix, which are derived from traditional Chinese medicine prescriptions that have been shown to be effective against COVID-19. We used the conventional FRET method for the initial screening. After two rounds of selection, the remaining 86 compounds were divided into flavonoids, lipids, phenylpropanoids, phenols, quinones, alkaloids, terpenoids and steroids according to the skeleton structures, with inhibition rates greater than 70%. The top compounds in each group were selected to test the effective concentration ranges; the IC50 values were as follows: (-)-gallocatechin gallate (1.522 ± 0.126 µM), ginkgolic acid C15:1 (9.352 ± 0.531 µM), hematoxylin (1.025 ± 0.042 µM), fraxetin (2.486 ± 0.178 µM), wedelolactone (1.003 ± 0.238 µM), hydroxytyrosol acetate (3.850 ± 0.576 µM), vanitiolide (2.837 ± 0.225 µM), ß,ß-dimethylacrylalkannin (2.731 ± 0.308 µM), melanin (7.373 ± 0.368 µM) and cholesteryl sodium sulfate (2.741 ± 0.234µM). In the next step, we employed two biophysical techniques, SPR and nanoDSF, to obtain KD/Kobs values: hematoxylin (0.7 µM), (-)-gallocatechin gallate (126 µM), ginkgolic acid C15:1 (227 µM), wedelolactone (0.9770 µM), ß,ß-dimethylacrylalkannin (1.9004 µM,), cholesteryl sodium sulfate (7.5950 µM) and melanin (11.5667 µM), which allowed better assessments of the binding levels. Here, seven compounds were the winners. Then, molecular docking experiments were specially performed by AutoDock Vina to analyze the mode of interactions within Mpro and ligands. We finally formulated the present in silico study to predict pharmacokinetic parameters as well as drug-like properties, which is presumably the step that tells humans whether the compounds are drug-like or not. Moreover, hematoxylin, melanin, wedelolactone, ß,ß-dimethylacrylalkannin and cholesteryl sodium sulfate are in full compliance with the "Lipinski" principle and possess reasonable ADME/T properties, they have a greater potential of being lead compounds. The proposed five compounds are also the first to be found to have potential inhibitory effects on SARS CoV-2 Mpro. We hope that the results in this manuscript may serve as benchmarks for the above potentials.

No Substrate Left behind-Mining of Shotgun Proteomics Datasets Rescues Evidence of Proteolysis by SARS-CoV-2 3CLpro Main Protease.

Proteolytic processing is the most ubiquitous post-translational modification and regulator of protein function. To identify protease substrates, and hence the function of proteases, terminomics workflows have been developed to enrich and detect proteolytically generated protein termini from mass spectrometry data. The mining of shotgun proteomics datasets for such 'neo'-termini, to increase the understanding of proteolytic processing, is an underutilized opportunity. However, to date, this approach has been hindered by the lack of software with sufficient speed to make searching for the relatively low numbers of protease-generated semi-tryptic peptides present in non-enriched samples viable. We reanalyzed published shotgun proteomics datasets for evidence of proteolytic processing in COVID-19 using the recently upgraded MSFragger/FragPipe software, which searches data with a speed that is an order of magnitude greater than many equivalent tools. The number of protein termini identified was higher than expected and constituted around half the number of termini detected by two different N-terminomics methods. We identified neo-N- and C-termini generated during SARS-CoV-2 infection that were indicative of proteolysis and were mediated by both viral and host proteases-a number of which had been recently validated by in vitro assays. Thus, re-analyzing existing shotgun proteomics data is a valuable adjunct for terminomics research that can be readily tapped (for example, in the next pandemic where data would be scarce) to increase the understanding of protease function and virus-host interactions, or other diverse biological processes.

Green and rapid and instrumental one-pot method for the synthesis of imidazolines having potential anti-SARS-CoV-2 main protease activity.

The Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2) is responsible for ongoing epidemics in humans and some other mammals and has been declared a public health emergency of international concern. In this project, several small non-peptide molecules were synthesized to inhibit the major proteinase (Mpro) of SARS-CoV-2 using rational strategies of drug design and medicinal chemistry. Mpro is a key enzyme of coronaviruses and plays an essential role in mediating viral replication and transcription in human lung epithelial and stem cells, making it an attractive drug target for SARS-CoV. The antiviral potential of imidazoline derivatives as inhibitors of (SARS-CoV-2) Mpro was evaluated using in-silico techniques such as molecular docking simulation, molecular dynamics (MD), and ADMET prediction. The docking scores of these imidazoline derivatives were compared to that of the N3 crystal inhibitor and showed that most of these compounds, particularly compound E07, interacted satisfactorily in the active site of the coronavirus and strongly interacted with the residues (Met 165, Gln 166, Met 165, His 41, and Gln 189). Furthermore, the results were confirmed by MD simulations after exposure to long-term MD simulations and ADMET predictions.

Diversifying the chloroquinoline scaffold against SARS-CoV-2 main protease: Virtual screening approach using cross-docking, SiteMap analysis and molecular dynamics simulation

The absence of designated remedies for coronavirus disease 19 (Covid-19) and the lack of treatment protocols drove scientists to propose new small molecules and to attempt to repurpose existing drugs against various targets of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in order to bring forward efficient solutions. The main protease (Mpro) is one of the most promising drug targets due to its crucial role in fighting viral replic-ation. Several antiviral drugs have been used in an attempt to overcome the pandemic, such as hydroxychloroquine (HCQ). Despite its perceived positive outcomes in the beginning of the disease, HCQ was associated with several drawbacks, such as insolubility, toxicity, and cardiac adverse effects. There-fore, in the present study, a structure-based virtual screening approach was performed to identify structurally modified ligands of the chloroquinoline (CQ) scaffold with good solubility, absorption, and permeation aimed at eventually suggesting a more dependable alternative. PDB ID:7BRP Mpro was chosen as the most reliable receptor after cross-docking calculation using 30 crystal struc-tures. Then, a SiteMap analysis was performed and a total of 231,456 structur-ally modified compounds of the CQ scaffold were suggested. After Lipinski criteria filtration, 64,312 molecules were docked and their MM-GBSA free binding energy were calculated. Next, ADME descriptors were calculated, and 12 molecules with ADME properties better than that of HCQ were identified. The resulting molecules were subjected to molecular dynamics (MD) simul-ation for 100 ns. The results of the study indicate that 3 molecules (CQ_22;CQ_2 and CQ_5) show better interactions and stability with the Mpro receptor. Binding interaction analysis indicates that GLU143, THR26, and HIS41 amino acids are potential binding hot-spot residues for the remaining 3 ligands.

DFT, molecular docking and ADME prediction of tenofovir drug as a promising therapeutic inhibitor of SARS-CoV-2 M-pro

In the present work, at first, DFT calculations were carried out to study the molecular structure of the tenofovir at B3LYP/MidiX level of theory and in the water as solvent. The HOMO/LUMO molecular orbitals, excitation energies and oscillator strengths of investigated drug were also calculated and presented. NBO analysis was performed to illustrate the intramolecular rehybridization and electron density delocalization. In the following, a molecular docking study was performed for screening of effective available tenofovir drug which may act as an efficient inhibitor for the SARS-CoV-2 M-pro. The binding energy value showed a good binding affinity between the tenofovir and SARS-CoV-2 Mpro with binding energy of-47.206 kcal/mol. Therefore, tenofovir can be used for possible application against the SARS-CoV-2 M-pro.

The research progress of SARS-CoV-2 main protease inhibitors from 2020 to 2022.

The novel coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread worldwide. The main protease (Mpro) of SARS-CoV-2 plays a central role in viral replication and transcription and represents an attractive drug target for fighting COVID-19. Many SARS-CoV-2 Mpro inhibitors have been reported, including covalent and noncovalent inhibitors. The SARS-CoV-2 Mpro inhibitor PF-07321332 (Nirmatrelvir) designed by Pfizer has been put on the market. This paper briefly introduces the structural characteristics of SARS-CoV-2 Mpro and summarizes the research progress of SARS-CoV-2 Mpro inhibitors from the aspects of drug repurposing and drug design. These information will provide a basis for the drug development of treating the infection of SARS-CoV-2 and even other coronaviruses in the future.

Discovery of quinazolin-4-one-based non-covalent inhibitors targeting the severe acute respiratory syndrome coronavirus 2 main protease (SARS-CoV-2 Mpro).

The COVID-19 pandemic caused by SARS-CoV-2 continues to pose a great threat to public health while various vaccines are available worldwide. Main protease (Mpro) has been validated as an effective anti-COVID-19 drug target. Using medicinal chemistry and rational drug design strategies, we identified a quinazolin-4-one series of nonpeptidic, noncovalent SARS-CoV-2 Mpro inhibitors based on baicalein, 5,6,7-trihydroxy-2-phenyl-4H-chromen-4-one. In particular, compound C7 exhibits superior inhibitory activity against SARS-CoV-2 Mpro relative to baicalein (IC50 = 0.085 ± 0.006 and 0.966 ± 0.065 µM, respectively), as well as improved physicochemical and drug metabolism and pharmacokinetics (DMPK) properties. In addition, C7 inhibits viral replication in SARS-CoV-2-infected Vero E6 cells more effectively than baicalein (EC50 = 1.10 ± 0.12 and 5.15 ± 1.64 µM, respectively) with low cytotoxicity (CC50 ＞ 50 µM). An X-ray co-crystal structure reveals a non-covalent mechanism of action, and a noncanonical binding mode not observed by baicalein. These results suggest that C7 represents a promising lead for development of more effective SARS-CoV-2 Mpro inhibitors and anti-COVID-19 drugs.

Designing Potential Inhibitors of SARS-CoV-2 Mpro Using Deep Learning and Steered Molecular Dynamic Simulations

The COVID-19 pandemic raised an unprecedented race in biotechnology in search for effective therapies and a preventive vaccine. Scientists worldwide have been attempting to stop the viral infection by interfering with the biological function of the SARS-CoV-2 main protease (Mpro), a critical protein required for viral transcription and replication during infection. In this study, we employed an effective approach integrating deep learning model calculations and steered molecular dynamic simulations to generate highly promising inhibitors of SARS-CoV-2 Mpro. First, using deep learning calculations, a natural molecule that was identified as a potential inhibitor of SARS-CoV-2 Mpro was chemically altered to boost its ligand-binding affinity to the Mpro protease. The proposed compounds were then verified using steered molecular dynamic simulations to estimate their binding free energies to SARS-CoV-2 Mpro. The procedure was repeated until the binding free energies of the proposed compounds did not improve further. Overall, one proposed compound was shown to have a high nanomolar affinity, and two others were estimated to possess nanomolar affinities for SARS-CoV-2 Mpro, indicating that they are highly promising inhibitors of the protease. Absorption, distribution, metabolism, and excretion and toxicity analysis show that all three chemicals are drug-like compounds following the MACCS-II Drug Data Report database, orally absorbed, tightly attached to the plasma membrane, and noncarcinogenic in rats. The results obtained potentially support COVID-19 treatment. [ FROM AUTHOR] Copyright of Journal of Computational Biophysics & Chemistry is the property of World Scientific Publishing Company and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)

Identification of inhibitors of the RdRp and Mpro enzymes of SARS-CoV-2 virus by structural homology

TCOVID-19 has enormously impacted global public health due to the high infection and mortality rates associated with the SARS-CoV-2 virus-causing disease. The World Health Organization (WHO) approved 10 safe and effective vaccines. However, there are still significant limitations to their administration in developing countries and remote locations. Concerns remain about the emergence of virus variants that may evade immunity acquired through vaccination. In addition to preventing infection, effective therapeutic agents are needed to treat patients diagnosed with COVID-19. Under this context, the present study aimed to perform a structure-based virtual screening of the protease (Mpro) and RNA-dependent RNA polymerase (RdRp) enzymes of SARS-CoV-2. For this purpose, homologous protein inhibitors belonging to different viruses were tested. Multiple sequence alignment of these enzymes allowed us to recognize the high conservation of these enzymes between species, especially of the regions comprising the inhibitor binding sites. Therefore, it follows that it is possible to employ a redirection approach to inhibitors that were designed to treat other viral diseases. Molecular docking experiments identified that RTP inhibitors (binding affinity = -7.3 kcal/mol) and V3D (binding affinity = -8.0 kcal/mol) are excellent inhibitors of RdRp and Mpro, respectively. These results suggest that these molecules can virtually bind and inhibit the activity of RdRp and Mpro and thus constitute potential drugs to combat SARS-CoV-2. © 2022 by the authors.

In Silico Design of New Dual Inhibitors of SARS-CoV-2 MPRO through Ligand- and Structure-Based Methods.

The viral main protease is one of the most attractive targets among all key enzymes involved in the life cycle of SARS-CoV-2. Considering its mechanism of action, both the catalytic and dimerization regions could represent crucial sites for modulating its activity. Dual-binding the SARS-CoV-2 main protease inhibitors could arrest the replication process of the virus by simultaneously preventing dimerization and proteolytic activity. To this aim, in the present work, we identified two series' of small molecules with a significant affinity for SARS-CoV-2 MPRO, by a hybrid virtual screening protocol, combining ligand- and structure-based approaches with multivariate statistical analysis. The Biotarget Predictor Tool was used to filter a large in-house structural database and select a set of benzo[b]thiophene and benzo[b]furan derivatives. ADME properties were investigated, and induced fit docking studies were performed to confirm the DRUDIT prediction. Principal component analysis and docking protocol at the SARS-CoV-2 MPRO dimerization site enable the identification of compounds 1b,c,i,l and 2i,l as promising drug molecules, showing favorable dual binding site affinity on SARS-CoV-2 MPRO.

In-silico study: docking simulation and molecular dynamics of peptidomimetic fullerene-based derivatives against SARS-CoV-2 Mpro.

COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, has become a global pandemic resulting in significant morbidity and mortality. This study presents 12 new peptidomimetic fullerene-based derivatives in three groups that are investigated theoretically as SARS-CoV-2 Mpro inhibitors to increase the chance of treating COVID-19. Studied compounds are designed and optimized at B88-LYP/DZVP method. Molecular descriptors results show the stability and reactivity of the compounds with Mpro, especially in the 3rd group (Ser compounds). However, Lipinski's Rule of Five values indicates that the compounds are not suitable as oral drugs. Furthermore, molecular docking simulations are carried out to investigate the binding affinity and interaction modes of the top five compounds (compounds 1, 9, 11, 2, and 10) with the Mpro protein, which have the lowest binding energy. Molecular dynamics simulations are also performed to evaluate the stability of the protein-ligand complexes with compounds 1 and 9 and compare them with natural substrate interaction. The analysis of RMSD, H-bonds, Rg, and SASA indicates that both compounds 1 (Gly-α acid) and 9 (Ser-α acid) have good stability and strong binding affinity with the Mpro protein. However, compound 9 shows slightly better stability and binding affinity compared to compound 1.

Development of 2-chloroquinoline based heterocyclic frameworks as dual inhibitors of SARS-CoV-2 MPro and PLPro.

Evolution of new variants of SARS-CoV-2 warrant the need for the continued efforts in identifying target-oriented new drugs. Dual targeting agents against MPro and PLPro not only overcome the incomplete efficacy but also the drug resistance, which is common problem. Since both these are cysteine proteases, we designed 2-chloroquinoline based molecules with additional imine moiety in the middle as possible nucleophilic warheads. In the first round of design and synthesis, three molecules (C3, C4 and C5) inhibited (Ki < 2 µM) only MPro by binding covalently to C145 and one molecule (C10) inhibited both the proteases non-covalently (Ki < 2 µM) with negligible cytotoxicity. Further conversion of the imine in C10 to azetidinone (C11) improved the potency against both the enzymes in the nanomolar range (820 nM against MPro and 350 nM against PLPro) with no cytotoxicity. Conversion of imine to thiazolidinone (C12), reduced the inhibition by 3-5 folds against both the enzymes. Biochemical and computational studies suggest that C10-C12 bind in the substrate binding pocket of MPro and in the BL2 loop of the PLPro. Since these dual inhibitors have least cytotoxicity, they could be further explored as therapeutics against the SARS-CoV-2 and other analogous viruses.

Geraniin as a potential inhibitor of SARS-CoV-2 3CLpro.

Geraniin is a polyphenolic compound first isolated from Geranium thunbergii. The major protease (Mpro), namely 3 C-like protease (3CLpro), of coronaviruses is considered an attractive drug target as it is essential for the processing and maturation of viral polyproteins. Thus, our primary goal is to explore the efficiency of geraniin on 3CLpro of SARS-CoV-2 using the computational biology strategy. In this work, we studied the anti-coronavirus effect of geraniin in vitro and its potential inhibitory mode against the 3CLpro of SARS-CoV-2. We found that geraniin inhibited HCoV-OC43 coronavirus-infected cells during the attachment and penetration phases. Molecular docking and dynamics simulations exhibited that geraniin had a strong binding affinity and high stable binding to 3CLpro of SARS-CoV-2. Geraniin showed a strong inhibitory activity on coronavirus and may be a potential inhibitor of SARS-CoV-2 3CLpro.

Molecular insights to the binding interactions of APNS containing HIV-protease inhibitors against SARS-CoV-2 Mpro: an in silico approach towards drug repurposing.

SARS-CoV-2 Mpro is one of the most vital enzymes of the new coronavirus-2 (SARS-CoV-2) and is a crucial target for drug discovery. Unfortunately, there is not any potential drugs available to combat the action of SARS-CoV-2 Mpro. Based on the reports HIV-protease inhibitors can be applied against the SARS by targeting the SARS-CoV-1 Mpro, we have chosen few clinically trialed experimental and allophenylnorstatine (APNS) containing HIV-protease inhibitors (JE-2147, JE-533, KNI-227, KNI-272 & KNI-1931), to examine their binding affinities with SARS-CoV-2 Mpro and to assess their potential to check for a possible drug candidate against the protease. Here, we have chosen a methodology to understand the binding mechanism of these five inhibitors to SARS-CoV-2 Mpro by merging molecular docking, molecular dynamics (MD) simulation and MM-PBSA based free energy calculations. Our estimations disclose that JE-2147 is highly effective (ΔGBind = -28.31 kcal/mol) due to an increased favorable van der Waals (ΔEvdw) interactions and decreased solvation (ΔGsolv) energies between the inhibitor and viral protease. JE-2147 shows a higher level of interactions as compared to JE-533 (-6.85 kcal/mol), KNI-227 (-18.36 kcal/mol), KNI-272 (-15.69 kcal/mol) and KNI-1931 (-21.59 kcal/mol) against SARS-CoV-2 Mpro. Binding contributions of important residues (His41, Met49, Cys145, His164, Met165, Glu166, Pro168, Gln189, etc.) from the active site or near the active site regions with ≥1.0 kcal/mol suggest a potent binding of the inhibitors. It is anticipated that the current study of binding interactions of these APNS containing inhibitors can pitch some valuable insights to design the significantly effective anti-SARS-CoV-2 Mpro drugs.Communicated by Ramaswamy H. Sarma.

Setomimycin as a potential molecule for COVID­19 target: in silico approach and in vitro validation.

COVID-19 pandemic caused by the SARS-CoV-2 virus has led to a worldwide crisis. In view of emerging variants time to time, there is a pressing need of effective COVID-19 therapeutics. Setomimycin, a rare tetrahydroanthracene antibiotic, remained unexplored for its therapeutic uses. Herein, we report our investigations on the potential of setomimycin as COVID-19 therapeutic. Pure setomimycin was isolated from Streptomyces sp. strain RA-WS2 from NW Himalayan region followed by establishing in silico as well as in vitro anti-SARS-CoV-2 property of the compound against SARS-CoV-2 main protease (Mpro). It was found that the compound targets Mpro enzyme with an IC50 value of 12.02 ± 0.046 µM. The molecular docking study revealed that the compound targets Glu166 residue of Mpro enzyme, hence preventing dimerization of SARS-CoV-2 Mpro monomer. Additionally, the compound also exhibited anti-inflammatory and anti-oxidant property, suggesting that setomimycin may be a viable option for application against COVID-19 infections.