In silico screening of potential compounds from begonia genus as 3CL protease (3Cl pro) SARS-CoV-2 inhibitors

Background: The emergence of Coronavirus disease (COVID-19) has been declared a pandemic and made a medical emergency worldwide. Various attempts have been made, including optimizing effective treatments against the disease or developing a vaccine. Since the SARS-CoV-2 protease crystal structure has been discovered, searching for its inhibitors by in silico technique becomes possible. Objective(s): This study aims to virtually screen the potential of phytoconstituents from the Begonia genus as 3Cl pro-SARS-CoV- 2 inhibitors, based on its crucial role in viral replication, hence making these proteases "promising" for the anti-SARS-CoV-2 target. Method(s): In silico screening was carried out by molecular docking on the web-based program DockThor and validated by a retrospective method. Predictive binding affinity (Dock Score) was used for scoring the compounds. Further molecular dynamics on Desmond was performed to assess the complex stability. Result(s): Virtual screening protocol was valid with the area under curve value 0.913. Molecular docking revealed only beta-sitosterol-3-O-beta-D-glucopyranoside with a lower docking score of -9.712 kcal/mol than positive control of indinavir. The molecular dynamic study showed that the compound was stable for the first 30 ns simulations time with Root Mean Square Deviation <3 A, despite minor fluctuations observed at the end of simulation times. Root Mean Square Fluctuation of catalytic sites HIS41 and CYS145 was 0.756 A and 0.773 A, respectively. Conclusion(s): This result suggests that beta-sitosterol-3-O-beta-Dglucopyranoside might be a prospective metabolite compound that can be developed as anti-SARS-CoV-2.Copyright © 2023, Page Press Publications. All rights reserved.

QSAR and DFT Studies of Some Tacrine-Hydroxamate Derivatives as Inhibitors of Cholinesterase (AChEs) in the Treatment of Alzheimer's Disease

Introduction: This work was devoted to an in silico investigation conducted on twenty-eight Tacrine-hydroxamate derivatives as a potential treatment for Alzheimer's disease using DFT and QSAR modeling techniques. Method(s): The data set was randomly partitioned into a training set (22 compounds) and a test set (6 compounds). Then, fourteen models were built and were used to compute the predicted pIC50 of compounds belonging to the test set. Result(s): Al built models were individualy validated using both internal and external validation methods, including the Y-Randomization test and Golbraikh and Tropsha's model acceptance criteria. Then, one model was selected for its higher R2, R2test, and Q2cv values (R2 = 0.768, R2adj = 0.713, MSE = 0.304, R2test=0.973, Q2cv = 0.615). From these outcomes, the activity of the studied compounds toward the main protease of Cholinesterase (AChEs) seems to be influenced by 4 descriptors, i.e., the total dipole moment of the molecule (mu), number of rotatable bonds (RB), molecular topology radius (MTR) and molecular topology polar surface area (MTPSA). The effect of these descriptors on the activity was studied, in particular, the increase in the total dipole moment and the topological radius of the molecule and the reduction of the rotatable bond and topology polar surface area increase the activity. Conclusion(s): Some newly designed compounds with higher AChEs inhibitory activity have been designed based on the best-proposed QSAR model. In addition, ADMET pharmacokinetic properties were carried out for the proposed compounds, the toxicity results indicate that 7 molecules are nontoxic.Copyright © 2023 Bentham Science Publishers.

Trace Elements Zinc and Selenium: Their Significance in the Conditions of the Covid-19 Pandemic

Within the conditions of the ongoing COVID-19 pandemic, when many questions regarding prevention and treatment strategies remain unsolved and the search for the best antiviral agents is underway, attention should be paid to the role of trace elements zinc and selenium in increasing the body's resistance to viral infections and their direct antiviral activity against SARS-CoV-2. Experimental data show that trace elements zinc and selenium not only actthrough regulating the immune response at all levels of humoral and cellular immunity, but also can play a significant role in adjuvant therapy for viral diseases. This is especially relevant in the case of COVID-19. Studies of the direct antiviral effect of these micro-elements testify to its 3 main ways to SARS-Cov-2: I - counteraction to virus replication and its transcription through: (i) their covalent binding to the SH-group of the cysteine of the main protease M(Pro) of the virus;(ii) inhibition of its RNA polymerase activity by zinc;II - preventing the penetration of the virus into cells due to blocking SH-groups of protein disulfide isomerase (RDI) of the protein of its spikes (peplomers);III - decreasing the adsorption capacity of the virus due to the blocking of the electrostatic interaction of SARS-CoV-2 peplomers and angiotensin-converting enzyme (ACE-2) in ultra-low, uncharacteristic oxidation states (Zn+1and Se-2). The intensity of the antiviral action of these trace elements may depend on their chemical form. It was found that zinc citrate (a five-membered complex of zinc with citric acid) and monoselenium citric acid obtained with the help of nanotechnology have a greater intensity of action and higher chemical purity. Taking into account the immunostimulating and direct antiviral effect of zinc and selenium, their use in the form of pharmaceuticals and dietary supplements should be considered as adjunctive therapy for SARS-CoV-2 in patients, or as a preventive strategy for uninfected people from risk groups during the spread of COVID-19.Copyright © Publisher PH <<Akademperiodyka>> of the NAS of Ukraine, 2023.

Systematic computer analysis of the pharmacology of bioflavonoids in the context of increasing the body's antiviral defenses.

Background. The rapidly developing resistance of viruses to synthetic antiviral drugs indicates the need to use substances with multitarget action (to avoid polypharmacy and to improve the safety of treatment). Objective(s): systematic analysis of the scientific literature on the pharmacology of bioflavonoids with an emphasis on their antiviral action. Material and methods. More than 150,000 references of primary sources were found in the PubMed/MEDLINE database of biomedical publications, including 3282 references on the antiviral effects of bioflavonoids. A systematic computerized analysis of this array of publications was carried out in order to identify the main directions in the pharmacology of bioflavonoids with an emphasis on their antiviral, antibacterial and immunomodulatory effects. The literature analysis was carried out using modern methods of topological and metric analysis of big data. Results. The molecular mechanisms of action of baicalin, hesperidin, rutin, quercetin, leukodelphinidin bioflavonoids and epigallocatechin-3gallate, curcumin polyphenols, their anti-inflammatory, antioxidant, antiviral, bactericidal, angioprotective, regenerative effects, and their prospects in therapy, prevention and rehabilitation of patients with COVID-19 and other respiratory viral infections were described in detail. Conclusion. Bioflavonoids and synergistic polyphenols exhibit not only multitarget antiviral effects by inhibiting the main protease, spike proteins, and other target proteins, but also pronounced anti-inflammatory, hepatoprotective, and immunomodulatory effects.Copyright © 2023 Modern Medical Technology. All rights reserved.

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.

MECHANISM AND RESISTANCE STUDIES OF SARS-CoV-2 MPRO INHIBITOR POMOTRELVIR (PBI-0451)

Background: The unprecedented scale of the COVID-19 pandemic and rapid evolution of SARS-CoV-2 variants underscores the need for broadly active inhibitors with a high barrier to resistance. The coronavirus main protease (Mpro) is an essential viral enzyme required for viral polyprotein processing and is highly conserved across human coronaviruses. Pomotrelvir (PBI-0451) is a novel Mpro inhibitor currently completing phase 2 clinical trial. Here we describe the mechanism of action, broad activity against SARS-CoV-2 clinical isolates, combination studies with other SARS-CoV-2 inhibitors and favorable resistance profile of pomotrelvir. Method(s): The kinetic parameters of pomotrelvir Mpro inhibition and its interaction with nirmaltrevir were determined in a kinetic protease assay. The IC50s of pomotrelvir on mutant Mpro proteins were measured in an endpoint Mpro assay. Combination studies of pomotrelvir with remdesivir and molnupiravir were carried out in A549-hACE2 cells infected with SARS-CoV-2 NLuc virus. Activity against SARS-CoV-2 clinical variants was assessed by infection of A549-ACE2-TMPRSS2 cells followed by immunostaining of the viral nucleocapsid protein. Result(s): Pomotrelvir is a potent competitive inhibitor of SARS-CoV-2 Mpro (Ki =2.7 nM). Binding of pomotrelvir and the Mpro inhibitor nirmatrelvir to the active site is mutually exclusive. In the SARS-CoV-2 NLuc assay, pomotrelvir is additive when combined with remdesivir or molnupiravir, two nucleoside analogs targeting viral RNA synthesis. When the effect of Mpro substitutions previously selected in a resistance study of pomotrelvir were analyzed in an enzyme assay, only Mpro-N133H showed a significant increase in IC50 (45-fold). The catalytic efficiency of Mpro-N133H is reduced by 10-fold and the recombinant virus SARSCoV-2 (WA1) -N133H is not viable, suggesting that N133H has lower replicative fitness. Lastly, pomotrelvir exhibits broad activity against all SARS-CoV-2 clinical isolates tested to date, including five omicron variants. Conclusion(s): PBI-0451 is a potent competitive inhibitor of SARS-CoV-2 Mpro and is broadly active against SARS-CoV-2 clinical isolates including omicron variants. Results from inhibitor interaction studies support the potential combination of pomotrelvir with remdesivir and molnupiravir but not nirmatrelvir. Enzymatic characterization of in vitro selected pomotrelvir resistant variants indicates they either confer no resistance or have reduced fitness.

Structure-Based Identification and Analysis of Viral Protease Inhibitors Targeting SARS CoV-2 Virus Replication

The re-emergence of SARS-CoV, known as SARS-CoV-2, has proven extremely infectious that has infected a huge population worldwide. SARS-CoV-2 genome is translated into polyproteins that is processed by virus-specific protease enzymes. 3CLprotease is named as the main protease (Mpro) enzyme that cleaves nsp4 to nsp16. This crucial role of Mpro makes this enzyme a prime and promising antiviral target. Till date, there is no effective commercially available drug against COVID-19 and launching a new drug into the market is a complicated and time-consuming process. Therefore, drug repurposing is a new but familiar approach to reduce the time and cost of drug discovery. We have used a high-throughput virtual screening approach to examine FDA approved library, natural compound library, and LOPAC 1280 (Library of Pharmacologically Active Compounds, Sigma-Aldrich, St. Louis, MO) library against Mpro. Primary screening identified potential drug molecules for the target, among which ten molecules were studied further using biophysical and biochemical techniques. SPR was used to validate the binding of inhibitors to purified Mpro and using FRET-based biochemical protease assay these inhibitors were confirmed to have Mpro inhibitory activity. Based on the kinetic studies, the antiviral efficacy of these compounds was further analysed by cell-culture based antiviral assays. Four out of ten molecules inhibited SARS-CoV-2 replication in Vero cells at a concentration range of 12.5 to 50 muM. The antiviral activity was evaluated by RT-PCR assay and TCID50 experiments. The co-crystallization of Mpro in complex with inhibitor for determining their structures is being carried out. Collectively, this study will provide valuable mechanistic and structural insights for development of effective antiviral therapeutics against SARS-CoV-2.

Investigation of antiviral substances in Covid 19 by Molecular Docking: In Silico Study

Aims: This paper aimed to investigate the antiviral drugs against Sars-Cov-2 main protease (MPro) using in silico methods. Material(s) and Method(s): A search was made for antiviral drugs in the PubChem database and antiviral drugs such as Bictegravir, Emtricitabine, Entecavir, Lamivudine, Tenofovir, Favipiravir, Hydroxychloroquine, Lopinavir, Oseltamavir, Remdevisir, Ribavirin, Ritonavir were included in our study. The protein structure of Sars-Cov-2 Mpro (PDB ID: 6LU7) was taken from the Protein Data Bank (www.rcsb. Org) system and included in our study. Molecular docking was performed using AutoDock/Vina, a computational docking program. Protein-ligand interactions were performed with the AutoDock Vina program. 3D visualizations were made with the Discovery Studio 2020 program. N3 inhibitor method was used for our validation. Result(s): In the present study, bictegravir, remdevisir and lopinavir compounds in the Sars-Cov-2 Mpro structure showed higher binding affinity compared to the antiviral compounds N3 inhibitor, according to our molecular insertion results. However, the favipiravir, emtricitabine and lamuvidune compounds were detected very low binding affinity. Other antiviral compounds were found close binding affinity with the N3 inhibitor. Conclusion(s): Bictegravir, remdevisir and lopinavir drugs showed very good results compared to the N3 inhibitor. Therefore, they could be inhibitory in the Sars Cov-2 Mpro target.Copyright © 2023 Oner E et al.

Accelerating antiviral discovery by combining machine learning with structural biology

COVID Moonshot is an international open science consortium aiming to discover oral antiviral against SARS-CoV-2, targeting the main protease. Launched in Feb 2020, Moonshot went from fragment hits to development candidates which are now under preclinical evaluation. In my talk, I will discuss Moonshot's journey, specifically how the combination of machine learning and structural biology has accelerated our design-make-test cycle. I will also discuss our vision for pandemic preparedness, and early results from AI-driven Structure Enabled Antiviral Platform (ASAP). ASAP is a NIH-funded antiviral drug discovery center which builds on COVID Moonshot's approach to target flaviviruses, enteroviruses, and coronaviruses. We are applying machine learning to generate potent chemical matter from crystallographic fragment hits, and leveraging high throughput library synthesis guided by models to rapidly expand on promising hits. Aiming to achieve pandemic preparedness, I will also discuss our approaches to preempting resistance, and how these strategic considerations impact drug-hunting.Copyright © 2023 The American Society for Biochemistry and Molecular Biology, Inc.

Dual Modulators of Selected Plant Secondary Metabolites Targeting COVID-19 Main Protease and Interleukin-2: An In-Silico Approach based Novel Hypothesis

Background: Owing to the recent scenario on this ongoing Coronavirus pandemic outbreak around the world, the present study has been undertaken. Aim(s): In this study, we adopted two strategies, i.e., via computational method, a search for the novel plant secondary metabolites from the Indian Traditional Medicine to target and combat the enduring novel 2019 CoVs main protease that causes pneumonia, followed by the effect of these selected secondary metabolites on the host's immune system for their immunomodulatory potential on Interleukin-2. Method(s): A detailed literature review has been done to identify the assorted plant secondary metabolites from the natural sources, which have been extensively used traditionally for their immunomodulatory potential. Next, the resulting compounds have processed for the molecular docking study to predict whether the compounds have the potency to fight against 2019-CoVs protein or it could have the ten-dency to battle the cytokines, which are responsible for the immune response of the host, thereby pre-venting the CoVs caused infection in humans. Furthermore, to explore molecular mechanics, the in-silico docking study with COVID-19 Mpro and Interleukin-2 has been performed. Results & Discussion: Among the six secondary metabolites selected, five compounds showed its possible promising potency with COVID-19 and IL-2 proteins, which are compared with the standard drug Remdesivir, one of the anti-viral drugs for treating and managing the present coronavirus condition and an IL-2 inhibitor, which is the native IL-2 ligand protein (i.e., from PDB Id-1PW6) itself. Besides, based on the docking scores, the Curcumin (from Curcuma longa) showed the highest score towards these two targets taken for this study. The identified compounds have a promising binding affinity with the Mpro receptors, in the narrow range of binding energy for the protein PDB Id: 6LU7 and the score range between-10.9102 to-19.8790 kcal/mol: when compared to the standard-21.8600 kcal/mol. Whereas, the binding affinity with the Interleukin-2 receptor, for the protein PDB Id: 1PW6 the range between-11.3899 to-17.1366 kcal/mol: when compared to that of standard-16.9554 kcal/mol. Conclusion(s): Our result findings demonstrate that the integrated Indian traditional herbal treatment might be hopefully used for the viral respiratory infection due to either it may have acted directly on the viral protein or through regulating the immune response, which could lead to the rapid drug discovery of the drug leads with clinical potency towards the novel infectious disease, where there is no drug or vaccines are available.Copyright © 2021 Bentham Science Publishers.

In-silico Discovery of Fungal Metabolites Bergenin, Quercitrin and Dihy-droartemisinin as Potential Inhibitors against Main Protease of SARS-CoV-2

Background: Emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has given rise to COVID-19 pandemic, which has become a wreaking havoc worldwide. Therefore, there is an urgent need to find out novel drugs to combat SARS-CoV-2 in-fection. In this backdrop, the present study aimed to assess potent bioactive compounds from different fungi as potential inhibitors of SARS-CoV-2 main protease (Mpro) using an in-silico analysis. Method(s): High-Resolution Liquid Chromatography Mass Spectrometry analysis (HR-LCMS) was used for the bioactive profiling of ethanolic crude extract of Dictyophora indusiata, Geastrum tri-plex and Cyathus stercoreus. Of which, only bergenin (D. indusiata), quercitrin (G. triplex) and di-hydroartemisinin (C. stercoreus) were selected based on their medicinal uses, binding score and the active site covered. The 6LU7, a protein crystallographic structure of SARS-CoV-2 Mpro, was docked with bergenin, quercitrin and dihydroartemisinin using Autodock 4.2. Result(s): A total of 118 bioactive compounds were analyzed from the crude extract of used fungi and identified using HR LC/MS analysis. The binding energies obtained were-7.86,-10.29 and-7.20 kcal/mol, respectively, after docking analysis. Bergenin, quercitrin and dihydroartemisinin formed hydrogen bond, electrostatic interactions and hydrophobic interactions with foremost active site amino acids THR190, GLU166, GLN189, GLY143, HIS163, HIS164, CYS145 and PHE140. Conclusion(s): Present investigation suggests that these three compounds may be used as alternative inhibitors against SARS-CoV-2 Mpro. However, further research is necessary to assess in vitro potential of these compounds. To the best of our knowledge, the present investigation reported these three bioactive compounds of fungal origin for the first time.Copyright © 2021 Bentham Science Publishers.

Discovery of Potential Inhibitors of SARS-CoV-2 (COVID-19) Main Protease (Mpro) from Nigella Sativa (Black Seed) by Molecular Docking Study

Purpose: A new human coronavirus (SARS-CoV-2), triggering pneumonia, is termed as Coronavirus Disease-19 (COVID-19). There is an alarming situation now as this new virus is spreading around the world. At present, there are no specific treatments for COVID-19. Nigella sativa is known as Prophetic Medicine as its use has been mentioned in Prophetic Hadith, as a natural remedy for all the diseases except death. Seeds and oils of N. sativa have a long history of folklore usage in various systems of medicine such as Unani and Tibb, Ayurveda and Siddha in the treatment of different diseases and ailments. The aim of this research is to provide a potential inhibitor of SARS-CoV-2 Mpro. Method(s): The Molecular docking tool was used to optimize the binding affinities of chemical constituents of N. sativa with SARS-CoV-2 Mpro. Result(s): Many constituents from N. Sativa have shown better binding affinity than reported drugs with SARS-CoV-2 Mpro i.e., the alpha-hederin, Stigmasterol glucoside, Nigellidine-4-O-sulfite, Nigellidine, Sterol-3-beta-D-glucoside, Dithymoquinone, beta-sitosterol have binding affinities (kcal/mol) of-9,-8.1,-8,-7.7,-7.7,-7.4,-7.4, and-6.9 and number of hydrogen bonds formed are 06, 04, 03, 03, 03, 00, and 01, respectively. Conclusion(s): There is rationale and pre-clinical evidence of the effectiveness of N. Sativa that it may be helpful for the treatment of COVID-19 and can serve as a potential natural candidate. However, more studies should be conducted to collect high-quality data and scientific evidence of N. Sativa to use it against COVID-19 clinically.Copyright © 2021 Bentham Science Publishers.

An In-silico Multi-Targeted Approach in Search of Potential Drug Candi-date(s) Against SARS-CoV-2 Lung Infection

Background: The multitargeted computational approach for the design of drugs to treat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) lung infection from herbal sources may lead to compound(s) that is/are safe (derived from natural sources), effective (act on predefined targets) and broad spectrum (active in both, adult and juvenile population). Objective(s): The present work aims at developing a specific and effective treatment for a lung infection in both the adult and juvenile population, caused due to SARS-CoV-2 through a computational approach. Method(s): A systematic virtual screening of 27 phytoconstituents from 11 Indian herbs with antiviral, anti-inflammatory, and immunomodulatory activity was performed. After applying the Lipinski rule of five, 19 compounds that fitted well were subjected to molecular docking studies using Molegro virtual docker 6.0 with two targets viz. SARS-CoV-2 main protease (Mpro) (PDB ID 6LU7) and ACE receptor (PDB ID 6M0J). The best-docked complexes were used to develop a merged feature pharmacophore using Lig-andscout software, to know the structural requirements to develop multitarget inhibitor(s) of SARS-CoV-2. Drug likeliness and ADMET studies were also performed. Result(s): The results revealed that Syringin, a glycoside from Tinospora cordifolia, has a good binding affinity towards both targets as compared to Remdesivir. Furthermore, drug likeliness and ADMET studies established its better bioavailability and low toxicity. Conclusion(s): The pharmacophores developed from protein-ligand complexes provided an important understanding to design multitarget inhibitor(s) of SARS-CoV-2 to treat COVID-19 lung infection in both the adult and juvenile populations. Syringin may be subjected to further wet-lab studies to establish the results obtained through in-silico studies.Copyright © 2022 Bentham Science Publishers.

Novel Coronavirus Disease 2019 (COVID-19) Current Update: Perspective on Epidemiology, Diagnosis, Drug Targets and Vaccines

Background: A novel coronavirus disease, 2019-nCoV (COVID-19), was reported first in Wuhan, the capital of Hubei, China, in late December 2019 and subsequently reached pandemic level affecting around 213 countries. As of 24th May 2020, the total number of positive cases confirmed is 5,446,514 and 344,754 death reports worldwide. COVID-19 infection causes pneumonia-like severe respiratory infection and acute lung failure. Severe acute respiratory syndrome coron-avirus 2 (SARS-CoV-2) is a positive-sense single-stranded RNA beta coronavirus that is a confirmed causative agent of COVID-19. SARS-CoV-2 may use angiotensin-converting enzyme 2 (ACE2), unlike the receptor utilized by SARS-CoV (emerged in 2002) to infect humans. People with a history of hypertension, chronic obstructive pulmonary disease, diabetes, cardiovascular disease are more susceptible to SARS-CoV-2. Objective(s): The purpose of this review was to help the society to distinguish and deal with SARS-CoV-2, and make available a reference for forthcoming studies. Method(s): Recently, diagnostic primer sets on the SARS-CoV-2 genome have been identified. The receptor-binding domain of SARS-COV-2 highlighted the mode by which beta-CoV recognizes ACE2. Various diagnostic tools are available to differentiate and identify SARS-CoV-2 infection as RT-PCR, antigen detection assay, and antibody detection assay. Different strategies have been employed to control the SARS-CoV-2, considering various drug targets like the main protease (3-CLPro), papain-like protease (PLpro), helicase (NSP13), RNA dependent RNA polymerase (RdR-p), and viral envelope (E) protein. Conclusion(s): In the present review, we have updated details of transmission, pathogenesis, genome structure, diagnostic criteria, clinical characteristics, therapeutics, and vaccine development of the SARS-CoV-2 infection, which may be significant in the control and response to the COVID-19 out-break.Copyright © 2021 Bentham Science Publishers.

Protease Activity in the Excretory-Secretory Products of Nymphal Stage of Linguatula Serrata: First Detection of a Metalloprotease

The aim of this study was to evaluate the presence of proteases and determine the main protease present in the excretory-secretory products (ESPs) from nymphal stage of Linguatula serrata. Infected mesenteric lymph nodes of goats were collected from Tabriz slaughterhouse, northwestern Iran. Recovered Linguatula serrata nymphs were immersed in culture medium (MEM), then ESPs were collected and protease activity in presence of specific inhibitors was assayed. Protease enzyme was fur-ther characterised by SDS-PAGE. The results of this study showed that the main protease in the ESPs from the nymphal stage of L. serrata was a metalloprotease that was resistant to heat. In conclusion, these data show that a major protease secreted by the larval stage of L. serrata exhibited properties that may play a role in the pathogenesis of L. serrata nymphs.Copyright © 2023, Trakia University. All rights reserved.

Revealing Potential Binding Affinity of FDA Approved Therapeutics Targeting Main Protease (3CLpro) in Impairing Novel Coronavirus (SARS-CoV-2) Replication that Causes COVID-19

Background: Spread of COVID-19 attains a crucial transition in reveling its pandemic across the boundaries. In combating the infection caused by SARS-CoV-2, there is a spectrum of ideal strategies that have been adopted globally, of which repurposing of approved drugs considerably having high clinical relevance. 3-chymotrypsin-like protease (3CL pro) is considered to be the potential target for the researchers as it is highly essential for cleavage of polyprotein to get 16 nonstructural proteins (called nsp1-nsp16). These proteins are highly essential for viral replication and hence become a primary target for enzyme inhibitors. 3CL pro, having a structural projectile helical chain with biologically active site involved in processing viral polyproteins that are evolved from RNA genome translation. Objective(s): The major objective of the present investigation is to evaluate the enzyme inhibition potential of FDA approved therapeutic leads in targeting 3CLpro that medicates the viral replication. Method(s): Docking calculations were carried out for an array of FDA approved molecules which leads to a notable few molecules such as Emtricitabine, Oseltamivir, Ganciclovir, Chloroquine, Baricitinib, Favipiravir, Lopinavir, Ritonavir, Remdesivir, Ribavirin, Tenofovir, Umifenovir, Carbapenam, Ertap-enem and Imipenam which have both specificity and selectivity in terms of binding efficiency against 3CL proenzyme. Result(s): A combinatorial evaluation employing in-silico screening shows a major lead for remdesivir which possesses a substantial affinity to 3CL pro binding on core amino acid residues, such as Leu 27, His 41, Gly 143, Cys 145, His 164, Met 165, Glu 166, Pro 168 and His 172 which share the biological significance in mediating enzymatic action. Results of docking simulation by Autodock over a host of FDA approved molecules show high degree of selectivity and specificity in the increasing order of binding capacity;Remdesivir> Ertapenem> Imipenam> Tenofovir> Umifenovir> Chloroquine> Lopinavir> Ritonavir> Emtricitabine> Ganciclovir> Baricitinib> Ribavirin>Oseltamivir>Favipiravir> Carbapenam. Conclusion(s): Till date, there is no known cure attained for treating COVID-19 infection. In conclusion, lead molecules from already approved sources provoke promising potential which grabs the attention of the clinicians in availing potential therapeutic candidate as a drug of choice in the clinical management of COVID-19 time-dependently.Copyright © 2020 Bentham Science Publishers.

Screening for Potential Traditional Herbal Inhibitors Against 3-Chymo-trypsin-like Main Protease (3CLpro) from Four Different Coronaviruses: An in silico Approach

Background: The recent outbreak of the COVID-19 pandemic has raised a global health concern due to the unavailability of any vaccines or drugs. The repurposing of traditional herbs with broad-spectrum anti-viral activity can be explored to control or prevent a pandemic. Objective(s): The 3-chymotrypsin-like main protease (3CLpro), also referred to as the "Achilles' heel" of the coronaviruses (CoVs), is highly conserved among CoVs and is a potential drug target. 3CLpro is essential for the virus' life cycle. The objective of the study was to screen and identify broad--spectrum natural phytoconstituents against the conserved active site and substrate-binding site of 3CLpro of HCoVs. Method(s): Herein, we applied the computational strategy based on molecular docking to identify potential phytoconstituents for the non-covalent inhibition of the main protease 3CLpro from four different CoVs, namely, SARS-CoV-2, SARS-CoV, HCoV-HKU1, and HCoV-229E. Result(s): Our study shows that natural phytoconstituents in Triphala (a blend of Emblica officinalis fruit, Terminalia bellerica fruit, and Terminalia chebula fruit), namely chebulagic acid, chebulinic acid, and elagic acid, exhibited the highest binding affinity and lowest dissociation constants (Ki), against the conserved 3CLpro main protease of SARSCoV-2, SARS-CoV, HCoV-HKU1, and HCoV-229E. Besides, phytoconstituents of other herbs like Withania somnifera, Glycyrrhiza glabra, Hyssopus officinalis, Camellia sinensis, Prunella vulgaris, and Ocimum sanctum also showed good binding affinity and lower Ki against the active site of 3CLpro. The top-ranking phyto-constituents' binding interactions clearly showed strong and stable interactions with amino acid residues in the catalytic dyad (CYS-HIS) and substrate-binding pocket of the 3CLpro main proteases. Conclusion(s): This study provides a valuable scaffold for repurposing traditional herbs with anti--CoV activity to combat SARS-CoV-2 and other HCoVs until the discovery of new therapies.Copyright © 2021 Bentham Science Publishers.

Investigating novel thiazolyl-indazole derivatives as scaffolds for SARS-CoV-2 MPro inhibitors

COVID-19 is a global pandemic caused by infection with the SARS-CoV-2 virus. Remdesivir, a SARS-CoV-2 RNA polymerase inhibitor, is the only drug to have received widespread approval for treatment of COVID-19. The SARS-CoV-2 main protease enzyme (MPro), essential for viral replication and transcription, remains an active target in the search for new treatments. In this study, the ability of novel thiazolyl-indazole derivatives to inhibit MPro is evaluated. These compounds were synthesized via the heterocyclization of phenacyl bromide with (R)-carvone, (R)-pulegone and (R)-menthone thiosemicarbazones. The binding affinity and binding interactions of each compound were evaluated through Schrodinger Glide docking, AMBER molecular dynamics simulations, and MM-GBSA free energy estimation, and these results were compared with similar calculations of MPro binding various 5-mer substrates (VKLQA, VKLQS, VKLQG) and a previously identified MPro tight-binder X77. From these simulations, we can see that binding is driven by residue specific interactions such as pi-stacking with His41, and S/pi interactions with Met49 and Met165. The compounds were also experimentally evaluated in a MPro biochemical assay and the most potent compound containing a phenylthiazole moiety inhibited protease activity with an IC50 of 92.9 muM. This suggests that the phenylthiazole scaffold is a promising candidate for the development of future MPro inhibitors.Copyright © 2022 The Authors

Virtual Screening of the Flavonoids Compounds with the SARS-CoV-2 3C-like Protease as the Lead Compounds for the COVID-19

As of 1st of September 2020, the COVID-19 pandemic has reached an unprecedented level of more than 25 million cases with more than 850,000 deaths. Moreover, all the drug candidates are still undergoing testing in clinical trials. In this regard, a breakthrough in drug design is neces-sary. One strategy to devise lead compounds is leveraging natural products as a lead source. Sever-al companies and research institutes are currently developing anti-SARS-CoV-2 lead from natural products. Flavonoids are well known as a class of antiviral compounds library. The objective of this research is to employ virtual screening methods for obtaining the best lead compounds from the library of flavonoid compounds. This research employed virtual screening methods that com-prised of downloading the protein and lead compound structures, QSAR analysis prediction, itera-tions of molecular docking simulation, and ADME-TOX simulation for toxicity prediction. The QSAR analysis found that the tested compounds have broad-spectrum antiviral activity, and some of them exhibit specific binding to the 3C-like Protease of the Coronavirus. Moreover, juglanin was found as the compound with the fittest binding with the Protease enzyme of SARS-CoV-2. Al-though most of the tested compounds are deemed toxic by the ADME-Tox test, further research should be conducted to comprehend the most feasible strategy to deliver the drug to the infected lung cells. The juglanin compound is selected as the fittest candidate as the SARS-CoV-2 lead compound in the tested flavonoid samples. However, further research should be conducted to observe the lead delivery method to the cell.Copyright © 2021 Bentham Science Publishers.

Identification of Flavonoids as Potent Inhibitors Against MERS-CoV 3C-like Protease

In 2012, a coronavirus was isolated from a patient with severe pneumonia. This beta-coronavirus, which appeared in Saudi Arabia, was named Middle East Respiratory Syndrome Coro-navirus (MERS-CoV). MERS-CoV is the sixth identified coronavirus that has the ability to infect humans. The Middle East respiratory syndrome-coronavirus (MERS-CoV) is a zoonotic pathogen transmitted between animals and humans. To date, MERS-CoV is responsible for an epidemic that is still ongoing, but limited to the Arabian Peninsula, with a total number of more than 2000 cases identified and a mortality rate of around 35%. The largest outbreaks of human-to-human transmission were reported in Jeddah in 2014 and South Korea in 2015. This infection causes a high mortality rate and no vaccine or medical countermeasures are currently available. Currently, no specific treatment or vaccine is available against this virus. The current challenge is to contain the epidemic and continue research efforts to develop a vaccine and a treatment. Certain flavonoids inhibit the replication of viral RNA and have therapeutic potential against viruses and bacteria. Therefore, it is suggested that flavonoids with these characteristics can be used as models to develop potent inhibi-tors of MERS-CoV. This work reviews current knowledge and provides an update on MERS-CoV and MERS-CoV 3Clpro virology, epidemiology, clinical features, and the use of flavonoids as potential inhibitors and therapeutic agents for MERS-CoV, and MERS-CoV 3Clpro. This review tries to elucidate the structure-activity relationships (SAR) of varied polyphenols against MERS-CoV 3C-like protease (3Clpro).Copyright © 2022 Bentham Science Publishers.