Adsorption of Favipiravir on pristine graphene nanosheets as a drug delivery system: a DFT study.

The efficiency of pristine graphene (GN) in the delivery process of the Favipiravir (FPV) anti-COVID-19 drug was herein revealed within the FPV⋯GN complexes in perpendicular and parallel configurations in terms of the density functional theory (DFT) method. Adsorption energy findings unveiled that the parallel configuration of FPV⋯GN complexes showed higher desirability than the perpendicular one, giving adsorption energy up to -15.95 kcal mol-1. This favorability could be interpreted as a consequence of the contribution of π-π stacking to the overall strength of the adsorption process in the parallel configuration. Frontier molecular orbitals (FMO) findings demonstrated the ability of the GN nanosheet to adsorb the FPV drug by the alteration in the EHOMO, ELUMO, and Egap values before and after the adsorption process. Based on Bader charge results, the FPV drug and GN sheet exhibited electron-donating and -accepting characters, respectively, which was confirmed by the negative sign of the computed charge transfer (Qt) values. The FPV(R)⋯T@GN complex showed the most desirable Qt value of -0.0377e, which was in synoptic with the adsorption energy pattern. Electronic properties of GN were also altered after the adsorption of the FPV drug in both configurations, with more observable changes in the parallel one. Interestingly, the Dirac point of the GN sheet coincided with the Fermi level after the adsorption process, indicating that the adsorption process unaffected the presence of the Dirac point. The occurrence of the adsorption process was also noticed by the existence of new bands and peaks in the band structure and DOS plots, respectively. Short recovery time rendered the GN nanosheet an efficient FPV drug delivery system. The obtained findings provide new insight into the biomedical applications of the GN sheet as a promising drug delivery system.

Naturally Occurring Xanthones; Biological Activities, Chemical Profiles and In Silico Drug Discovery

Xanthones are widely distributed polyphenols, present commonly in higher plants; Garcinia, Calophyllum, Hypericum, Platonia, Mangifera, Gentiana and Swertia. Xanthone tricyclic scaffold is able to interact with different biological targets, showing antibacterial and cytotoxic effects, as well as potent effects against osteoarthritis, malaria, and cardiovascular diseases. Thus, in this article we focused on pharmacological effects, applications and preclinical studies with the recent updates of xanthon´s isolated compounds from 2017-2020. We found that only α-mangostin, gambogic acid, and mangiferin, have been subjected to preclinical studies with particular emphasis on the development of anticancer, diabetes, antimicrobial and hepatoprotective therapeutics. Molecular docking calculations were performed to predict the binding affinities of xanthone-derived compounds against SARS-CoV-2 Mpro. According to the results, cratoxanthone E and morellic acid demonstrated promising binding affinities towards SARS-CoV-2 Mpro with docking scores of −11.2 and −11.0 kcal/mol, respectively. Binding features manifested the capability of cratoxanthone E and morellic acid to exhibit nine and five hydrogen bonds, respectively, with the key amino acids of the Mpro active site. In conclusion, cratoxanthone E and morellic acid are promising anti-COVID-19 drug candidates that warrant further detailed in vivo experimental estimation and clinical assessment.

The Unusual Architecture of RNA-Dependent RNA Polymerase (RdRp)'s Catalytic Chamber Provides a Potential Strategy for Combination Therapy against COVID-19.

The unusual and interesting architecture of the catalytic chamber of the SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) was recently explored using Cryogenic Electron Microscopy (Cryo-EM), which revealed the presence of two distinctive binding cavities within the catalytic chamber. In this report, first, we mapped out and fully characterized the variations between the two binding sites, BS1 and BS2, for significant differences in their amino acid architecture, size, volume, and hydrophobicity. This was followed by investigating the preferential binding of eight antiviral agents to each of the two binding sites, BS1 and BS2, to understand the fundamental factors that govern the preferential binding of each drug to each binding site. Results showed that, in general, hydrophobic drugs, such as remdesivir and sofosbuvir, bind better to both binding sites than relatively less hydrophobic drugs, such as alovudine, molnupiravir, zidovudine, favilavir, and ribavirin. However, suramin, which is a highly hydrophobic drug, unexpectedly showed overall weaker binding affinities in both binding sites when compared to other drugs. This unexpected observation may be attributed to its high binding solvation energy, which disfavors overall binding of suramin in both binding sites. On the other hand, hydrophobic drugs displayed higher binding affinities towards BS1 due to its higher hydrophobic architecture when compared to BS2, while less hydrophobic drugs did not show a significant difference in binding affinities in both binding sites. Analysis of binding energy contributions revealed that the most favorable components are the ΔEele, ΔEvdw, and ΔGgas, whereas ΔGsol was unfavorable. The ΔEele and ΔGgas for hydrophobic drugs were enough to balance the unfavorable ΔGsol, leaving the ΔEvdw to be the most determining factor of the total binding energy. The information presented in this report will provide guidelines for tailoring SARS-CoV-2 inhibitors with enhanced binding profiles.

Adsorption of Molnupiravir anti-COVID-19 drug over B12N12 and Al12N12 nanocarriers: a DFT study.

The potentiality of B12N12 and Al12N12 nanocarriers to adsorb Molnupiravir anti-COVID-19 drug, for the first time, was herein elucidated using a series of quantum mechanical calculations. Density function theory (DFT) was systematically utilized. Interaction (Eint) and adsorption (Eads) energies showed higher negative values for Molnupiravir···Al12N12 complexes compared with Molnupiravir···B12N12 analogs. Symmetry-adapted perturbation theory (SAPT) results proclaimed that the adsorption process was predominated by electrostatic forces. Notably, the alterations in the distributions of the molecular orbitals ensured that the B12N12 and Al12N12 nanocarriers were efficient candidates for delivering the Molnupiravir drug. From the thermodynamic perspective, the adsorption process of Molnupiravir drug over B12N12 and Al12N12 nanocarriers had spontaneous and exothermic nature. The ESP, QTAIM, NCI, and DOS observations exposed the tendency of BN and Al12N12 to adsorb the Molnupiravir drug. Overall, these findings proposed that the B12N12 and Al12N12 nanocarriers are efficient aspirants for the development of the Molnupiravir anti-COVID-19 drug delivery process.Communicated by Ramaswamy H. Sarma.

Chetomin, a SARS-CoV-2 3C-like Protease (3CLpro) Inhibitor: In Silico Screening, Enzyme Docking, Molecular Dynamics and Pharmacokinetics Analysis.

The emergence of the Coronavirus Disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has led to over 6 million deaths. The 3C-like protease (3CLpro) enzyme of the SARS-CoV-2 virus is an attractive druggable target for exploring therapeutic drug candidates to combat COVID-19 due to its key function in viral replication. Marine natural products (MNPs) have attracted considerable attention as alternative sources of antiviral drug candidates. In looking for potential 3CLpro inhibitors, the MNP database (>14,000 molecules) was virtually screened against 3CLpro with the assistance of molecular docking computations. The performance of AutoDock and OEDocking software in anticipating the ligand-3CLpro binding mode was first validated according to the available experimental data. Based on the docking scores, the most potent MNPs were further subjected to molecular dynamics (MD) simulations, and the binding affinities of those molecules were computed using the MM-GBSA approach. According to MM-GBSA//200 ns MD simulations, chetomin (UMHMNP1403367) exhibited a higher binding affinity against 3CLpro than XF7, with ΔGbinding values of −55.5 and −43.7 kcal/mol, respectively. The steadiness and tightness of chetomin with 3CLpro were evaluated, revealing the high stabilization of chetomin (UMHMNP1403367) inside the binding pocket of 3CLpro throughout 200 ns MD simulations. The physicochemical and pharmacokinetic features of chetomin were also predicted, and the oral bioavailability of chetomin was demonstrated. Furthermore, the potentiality of chetomin analogues −namely, chetomin A-D− as 3CLpro inhibitors was investigated. These results warrant further in vivo and in vitro assays of chetomin (UMHMNP1403367) as a promising anti-COVID-19 drug candidate.

Investigation of Aluminum Nitride Nanocarrier for Drug Delivery Process of Favipiravir: A DFT Study

The tendency of Al12N12 nanocarrier toward adsorbing Favipiravir (FPV), an anti-COVID-19 drug, was obviously unveiled within five configurations via O∙∙∙, N∙∙∙, and F∙∙∙Al interactions. The geometric and electronic properties of Al12N12 nanocarrier, FPV drug, and FPV∙∙∙Al12N12 complexes were thoroughly evaluated in gas and water phases. Among all the studied complexes, the most preferential negative interaction and adsorption energies were ascribed to configuration A with values of –51.11 and –38.82 kcal/mol, respectively. Symmetry-adapted perturbation theory (SAPT) analysis addressed the electrostatic force as the most dominant energetic component beyond the occurrence of the adsorption process within the studied complexes. Apparently, significant changes were noticed within the distributions of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the FPV and Al12N12 before and after the adsorption process. Noticeable increments in softness and decrement in hardness were also observed after the adsorption process, ensuring strong interactions within the studied complexes. The adsorption process was also studied in the water phase. The negative values of thermodynamic parameters ensured that the adsorption process had spontaneity and exothermic nature within almost all the studied complexes. Further favorability of the adsorption of FPV was noticed over the surface of Al12N12 nanocarrier compared to the B12N12 analog. For the FPV∙∙∙B12N12 complexes, unfavorable Gibbs free energy (ΔG) values along with neglected recovery time values revealed the bare tendency of the B12N12 nanocarrier toward adsorbing FPV drug. The findings of the presented study will serve as a springboard for further research into Al12N12 nanocarrier as well as the delivery of the FPV anti-COVID-19 drug.

Eryngium creticum L.: Chemical Characterization, SARS-CoV-2 Inhibitory Activity, and In Silico Study.

Phytochemical investigation of Eryngium creticum L. has resulted in isolation of five compounds, including four compounds that are reported from the plant for the first time. Compound 1 was identified as (E)-rosmarinic acid, meanwhile, compound 2 was isolated as an (E/Z)-rosmarinic acid mixture. Interestingly, the E/Z-isomeric mixture was about 4 times as active as the single E-isomer toward the severe acute respiratory syndrome coronavirus 2 3-chymotrypsin-like protease (3CLpro), IC50 = 6.062 and 25.75 µM, respectively. Utilizing combined molecular docking and molecular dynamics (MD) techniques, the binding affinities and features of the isolated compounds were evaluated against 3CLpro. Compound 2Z demonstrated a higher binding affinity for 3CLpro than 2E , with docking scores of -8.9 and -8.5 kcal/mol and MM-GBSA/150 ns MD binding energies of -26.5 and -22.1 kcal/mol, respectively. This justifies the superior activity of the E/Z-isomeric mixture versus the single E-isomer. Structural and energetic analyses revealed the stability of 2Z and 2E compared to the reference HIV-1 protease inhibitor, lopinavir. Besides, DFT calculations demonstrated the more energetic stability of 2E compared to 2Z , which justifies the difficulty in isolating the Z-isomer in a pure form, where it readily isomerizes to the E-isomer.

Two novel oxetane containing lignans and a new megastigmane from Paronychia arabica and in silico analysis of them as prospective SARS-CoV-2 inhibitors.

The chemical characterization of the extract of the aerial parts of Paronychia arabica afforded two oxetane containing lignans, paronychiarabicine A (1) and B (2), and one new megastigmane, paronychiarabicastigmane A (3), alongside a known lignan (4), eight known phenolic compounds (5-12), one known elemene sesquiterpene (13) and one steroid glycoside (14). The chemical structures of the isolated compounds were constructed based upon the HRMS, 1D, and 2D-NMR results. The absolute configurations were established via NOESY experiments as well as experimental and TDDFT-calculated electronic circular dichroism (ECD). Utilizing molecular docking, the binding scores and modes of compounds 1-3 towards the SARS-CoV-2 main protease (Mpro), papain-like protease (PLpro), and RNA-dependent RNA polymerase (RdRp) were revealed. Compound 3 exhibited a promising docking score (-9.8 kcal mol-1) against SARS-CoV-2 Mpro by forming seven hydrogen bonds inside the active site with the key amino acids. The reactome pathway enrichment analysis revealed a correlation between the inhibition of GSK3 and GSK3B genes (identified as the main targets of megastigmane treatment) and significant inhibition of SARS-CoV-1 viral replication in infected Vero E6 cells. Our results manifest a novel understanding of genes, proteins and corresponding pathways against SARS-CoV-2 infection and could facilitate the identification and characterization of novel therapeutic targets as treatments of SARS-CoV-2 infection.

Versisterol, a new endophytic steroid with 3CL protease inhibitory activity from Avicennia marina (Forssk.) Vierh.† † Electronic supplementary information (ESI) available. See https://doi.org/10.1039/d2ra00877g

A new epoxy ergostane sterol, named versisterol, was isolated from Aspergillus versicolor, an endophytic fungus from Avicennia marina. The structure of the isolated compound was deduced by means of one- and two-dimensional NMR and high-resolution mass spectrometry. The absolute stereochemistry was elucidated by NOESY analysis, and experimental and calculated time-dependent density functional theory (TD-DFT) circular dichroism spectroscopy. Versisterol inhibited 3CL protease (3CLpro) with an IC50 value of 2.168 ± 0.09 μM. Binding affinities and molecular interactions of versisterol towards 3CLpro were scrutinized and compared to lopinavir with the help of the combination of docking computations and molecular dynamics (MD) simulation. In silico calculations demonstrated a comparable binding affinity of versisterol with a docking score of −9.4 kcal mol−1, and MM-GBSA binding energy over 200 ns MD simulation of −29.1 kcal mol−1, with respect to lopinavir (−9.8 and −32.2 kcal mol−1, respectively). These findings suggested that versisterol can be an auspicious prototype for developing new 3CLpro drug candidates against COVID-19. A new epoxy ergostane sterol, named versisterol, was isolated from Aspergillus versicolor, an endophytic fungus from Avicennia marina.

Flavonoids of Zinnia elegans: Chemical profile and, in vitro antioxidant and in silico anti-COVID-19 activities

Chemical profiles of total alcohol extract and various derived fractions of aerial parts of Zinnia elegans were studied. Accordingly, eight flavonoids were isolated from the ethyl acetate derived fraction based on the antioxidant assay-guided purification, using DPPH and phosphomolybdate complex assays. Eventually, the binding affinities and features of the eight isolated flavonoids were investigated using the molecular docking technique towards SARS-CoV-2 and human targets –namely main protease (Mpro), papain-like protease (PLpro), RNA-dependent RNA polymerase (RdRp), receptor-binding domain (RBD), helicase (NSP13), human angiotensin‐converting enzyme 2 (ACE2), and human neuropilin-1 (NRP1). Docking calculations unveiled the surpass binding affinity of glabrisoflavone with Mpro, PLpro, RdRp, RBD, NSP13, ACE2, and NRP1, with docking scores of −9.2, −7.4, −6.9, −6.9, −8.5, −9.0, and −7.6 kcal/mol, respectively. Binding mode analysis manifested the capability of glabrisoflavone to form several hydrogen bonds with the key amino acid residues inside the active sites of the targets. Besides, 25 ns molecular dynamics (MD) simulations combined with molecular mechanics-generalized Born surface area (MM-GBSA) binding energy calculations were executed to inspect the binding affinity of glabrisoflavone and compared to an anti-HIV-1 protease inhibitor (darunavir). MM-GBSA calculations demonstrated greater glabrisoflavone affinity for the PLpro, RdRp, RBD and NRP1 over darunavir. Nevertheless, MM-GBSA calculations displayed equal or lower glabrisoflavone affinity against Mpro, NSP13 and ACE2 compared to darunavir. The current study obviously emphasizes the fitness of the glabrisoflavone as an auspicious clinical drug candidate for further development and future in vivo and in vitro evaluations towards viral targets and human targets.

Exploring Toxins for Hunting SARS-CoV-2 Main Protease Inhibitors: Molecular Docking, Molecular Dynamics, Pharmacokinetic Properties, and Reactome Study.

The main protease (Mpro) is a potential druggable target in SARS-CoV-2 replication. Herein, an in silico study was conducted to mine for Mpro inhibitors from toxin sources. A toxin and toxin-target database (T3DB) was virtually screened for inhibitor activity towards the Mpro enzyme utilizing molecular docking calculations. Promising toxins were subsequently characterized using a combination of molecular dynamics (MD) simulations and molecular mechanics-generalized Born surface area (MM-GBSA) binding energy estimations. According to the MM-GBSA binding energies over 200 ns MD simulations, three toxins-namely philanthotoxin (T3D2489), azaspiracid (T3D2672), and taziprinone (T3D2378)-demonstrated higher binding affinities against SARS-CoV-2 Mpro than the co-crystalized inhibitor XF7 with MM-GBSA binding energies of -58.9, -55.9, -50.1, and -43.7 kcal/mol, respectively. The molecular network analyses showed that philanthotoxin provides a ligand lead using the STRING database, which includes the biochemical top 20 signaling genes CTSB, CTSL, and CTSK. Ultimately, pathway enrichment analysis (PEA) and Reactome mining results revealed that philanthotoxin could prevent severe lung injury in COVID-19 patients through the remodeling of interleukins (IL-4 and IL-13) and the matrix metalloproteinases (MMPs). These findings have identified that philanthotoxin-a venom of the Egyptian solitary wasp-holds promise as a potential Mpro inhibitor and warrants further in vitro/in vivo validation.

In-silico drug repurposing and molecular dynamics puzzled out potential SARS-CoV-2 main protease inhibitors.

Herein, the DrugBank database which contains 10,036 approved and investigational drugs was explored deeply for potential drugs that target SARS-CoV-2 main protease (Mpro). Filtration process of the database was conducted using three levels of accuracy for molecular docking calculations. The top 35 drugs with docking scores > -11.0 kcal/mol were then subjected to 10 ns molecular dynamics (MD) simulations followed by molecular mechanics-generalized Born surface area (MM-GBSA) binding energy calculations. The results showed that DB02388 and Cobicistat (DB09065) exhibited potential binding affinities towards Mpro over 100 ns MD simulations, with binding energy values of -49.67 and -46.60 kcal/mol, respectively. Binding energy and structural analyses demonstrated the higher stability of DB02388 over Cobicistat. The potency of DB02388 and Cobicistat is attributed to their abilities to form several hydrogen bonds with the essential amino acids inside the active site of Mpro. Compared to DB02388 and Cobicistat, Darunavir showed a much lower binding affinity of -34.83 kcal/mol. The present study highlights the potentiality of DB02388 and Cobicistat as anti-COVID-19 drugs for clinical trials. Communicated by Ramaswamy H. Sarma.

Natural-like products as potential SARS-CoV-2 Mpro inhibitors: in-silico drug discovery.

In December 2019, a COVID-19 epidemic was discovered in Wuhan, China, and since has disseminated around the world impacting human health for millions. Herein, in-silico drug discovery approaches have been utilized to identify potential natural products (NPs) as Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) main protease (Mpro) inhibitors. The MolPort database that contains over 100,000 NPs was screened and filtered using molecular docking techniques. Based on calculated docking scores, the top 5,000 NPs/natural-like products (NLPs) were selected and subjected to molecular dynamics (MD) simulations followed by molecular mechanics-generalized Born surface area (MM-GBSA) binding energy calculations. Combined 50 ns MD simulations and MM-GBSA calculations revealed nine potent NLPs with binding affinities (ΔGbinding) > -48.0 kcal/mol. Interestingly, among the identified NLPs, four bis([1,3]dioxolo)pyran-5-carboxamide derivatives showed ΔGbinding > -56.0 kcal/mol, forming essential short hydrogen bonds with HIS163 and GLY143 amino acids via dioxolane oxygen atoms. Structural and energetic analyses over 50 ns MD simulation demonstrated NLP-Mpro complex stability. Drug-likeness predictions revealed the prospects of the identified NLPs as potential drug candidates. The findings are expected to provide a novel contribution to the field of COVID-19 drug discovery.Communicated by Ramaswamy H. Sarma.

Blue Biotechnology: Computational Screening of Sarcophyton Cembranoid Diterpenes for SARS-CoV-2 Main Protease Inhibition.

The coronavirus pandemic has affected more than 150 million people, while over 3.25 million people have died from the coronavirus disease 2019 (COVID-19). As there are no established therapies for COVID-19 treatment, drugs that inhibit viral replication are a promising target; specifically, the main protease (Mpro) that process CoV-encoded polyproteins serves as an Achilles heel for assembly of replication-transcription machinery as well as down-stream viral replication. In the search for potential antiviral drugs that target Mpro, a series of cembranoid diterpenes from the biologically active soft-coral genus Sarcophyton have been examined as SARS-CoV-2 Mpro inhibitors. Over 360 metabolites from the genus were screened using molecular docking calculations. Promising diterpenes were further characterized by molecular dynamics (MD) simulations based on molecular mechanics-generalized Born surface area (MM-GBSA) binding energy calculations. According to in silico calculations, five cembranoid diterpenes manifested adequate binding affinities as Mpro inhibitors with ΔGbinding < -33.0 kcal/mol. Binding energy and structural analyses of the most potent Sarcophyton inhibitor, bislatumlide A (340), was compared to darunavir, an HIV protease inhibitor that has been recently subjected to clinical-trial as an anti-COVID-19 drug. In silico analysis indicates that 340 has a higher binding affinity against Mpro than darunavir with ΔGbinding values of -43.8 and -34.8 kcal/mol, respectively throughout 100 ns MD simulations. Drug-likeness calculations revealed robust bioavailability and protein-protein interactions were identified for 340; biochemical signaling genes included ACE, MAPK14 and ESR1 as identified based on a STRING database. Pathway enrichment analysis combined with reactome mining revealed that 340 has the capability to re-modulate the p38 MAPK pathway hijacked by SARS-CoV-2 and antagonize injurious effects. These findings justify further in vivo and in vitro testing of 340 as an antiviral agent against SARS-CoV-2.

Multi-Subunit SARS-CoV-2 Vaccine Design Using Evolutionarily Conserved T- and B- Cell Epitopes.

The SARS-CoV-2 pandemic has created a public health crisis worldwide. Although vaccines against the virus are efficiently being rolled out, they are proving to be ineffective against certain emerging SARS-CoV-2 variants. The high degree of sequence similarity between SARS-CoV-2 and other human coronaviruses (HCoV) presents the opportunity for designing vaccines that may offer protection against SARS-CoV-2 and its emerging variants, with cross-protection against other HCoVs. In this study, we performed bioinformatics analyses to identify T and B cell epitopes originating from spike, membrane, nucleocapsid, and envelope protein sequences found to be evolutionarily conserved among seven major HCoVs. Evolutionary conservation of these epitopes indicates that they may have critical roles in viral fitness and are, therefore, unlikely to mutate during viral replication thus making such epitopes attractive candidates for a vaccine. Our designed vaccine construct comprises of twelve T and six B cell epitopes that are conserved among HCoVs. The vaccine is predicted to be soluble in water, stable, have a relatively long half-life, and exhibit low allergenicity and toxicity. Our docking results showed that the vaccine forms stable complex with toll-like receptor 4, while the immune simulations predicted that the vaccine may elicit strong IgG, IgM, and cytotoxic T cell responses. Therefore, from multiple perspectives, our multi-subunit vaccine design shows the potential to elicit a strong immune-protective response against SARS-CoV-2 and its emerging variants while carrying minimal risk for causing adverse effects.

Chemical constituents from coconut waste and their in silico evaluation as potential antiviral agents against SARS-CoV-2.

Eleven compounds were isolated from the ethyl acetate extract of Cocos nucifera L endocarp, jezonofol 1, scirpusin A 2, cassigarol G 3, maackin A 4, threoguiacyl glycerol-8'-vanillic acid ether 5, erythroguiacyl glycerol-8'-vanillic acid ether 6, apigenin-7-O-ß-D-glucoside 7, piceatannol 8, p-hydroxy-benzoic acid 9, protocatechuic acid 10 and vanillic acid 11. Compounds 1-7 were isolated for the first time from the plant. The isolated compounds were virtually screened against four critical components of severe acute respiratory syndrome corona virus 2 (SARS-CoV-2), the main protease (Mpro), papain-like protease (PLpro), nonstructural protein 13 (nsp13) and RNA dependent RNA polymerase (RdRp). Stilbene dimers 1-4 showed remarkable binding affinities towards the investigated targets (binding energy <-7.6 kcal/mol). Compounds 1, 3 and 4 interacted with the catalytic dyad (Cys145-His41) at the active pocket of Mpro which is essential for achieving good inhibitory activity. Compounds 1-3 showed molecular interaction with the conserved ubiquitin-specific protease residues of PLpro, responsible for binding ability at different active sites of nsp13, which are crucial for decreasing the resistance caused by viral immune evasion. Compounds 2 and 3 showed the ability to bind at different active sites of nsp13, which is a key binding site for reducing antiviral resistance. Finally, compounds 1-3 showed the ability to bind with RdRp before and after RNA binding. Our findings suggested that the dimeric stilbene skeleton is a promising candidate for developing anti-COVID-19 drugs. Particularly, 1, 2 and 3, showed a promiscuity pattern binding to multiple targets of SARS-CoV-2 replication. Herein, 20 ns molecular dynamics (MD) simulations combined with molecular mechanics-generalized Born surface area (MM-GBSA) binding energy calculations were performed to estimate the binding affinity of the most potent three compounds against the viral SARS-CoV-2 targets. MM-GBSA calculations unveiled the outshine potency of compound 1 towards PLpro with a binding energy of -60.7 kcal/mol. Structural and energetic analyses over 20 ns MD simulation displayed the high stability of compound 1 in complex with PLpro. The list of the compounds was considered herein forms a primer for clinical investigation in COVID-19 patients and directing for further antiviral examinations. Drug likeness properties of compounds 1-4 were evaluated.

Repurposing potential of posaconazole and grazoprevir as inhibitors of SARS-CoV-2 helicase.

As the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) pandemic engulfs millions worldwide, the quest for vaccines or drugs against the virus continues. The helicase protein of SARS-CoV-2 represents an attractive target for drug discovery since inhibition of helicase activity can suppress viral replication. Using in silico approaches, we have identified drugs that interact with SARS-CoV-2 helicase based on the presence of amino acid arrangements matching binding sites of drugs in previously annotated protein structures. The drugs exhibiting an RMSD of ≤ 3.0 Å were further analyzed using molecular docking, molecular dynamics (MD) simulation, and post-MD analyses. Using these approaches, we found 12 drugs that showed strong interactions with SARS-CoV-2 helicase amino acids. The analyses were performed using the recently available SARS-CoV-2 helicase structure (PDB ID: 5RL6). Based on the MM-GBSA approach, out of the 12 drugs, two drugs, namely posaconazole and grazoprevir, showed the most favorable binding energy, - 54.8 and - 49.1 kcal/mol, respectively. Furthermore, of the amino acids found conserved among all human coronaviruses, 10/11 and 10/12 were targeted by, respectively, grazoprevir and posaconazole. These residues are part of the crucial DEAD-like helicase C and DEXXQc_Upf1-like/ DEAD-like helicase domains. Strong interactions of posaconazole and grazoprevir with conserved amino acids indicate that the drugs can be potent against SARS-CoV-2. Since the amino acids are conserved among the human coronaviruses, the virus is unlikely to develop resistance mutations against these drugs. Since these drugs are already in use, they may be immediately repurposed for SARS-CoV-2 therapy.

Carotane sesquiterpenes from Ferula vesceritensis: in silico analysis as SARS-CoV-2 binding inhibitors.

Two sesquiterpenes, 8α-anisate-dauc-4-ene-3,9-dione (webiol anisate) (1) and 10α-acetoxy-6α-benzoate-jaeschkeanadiol (2) as well as, ten known analogues (3-10), and two sesquiterpene coumarins (11-12) were isolated from an organic root extract of Ferula vesceritensis (Fam. Apiaceae). Chemical structures were elucidated based on IR, 1D- and 2D-NMR and HRMS, spectroscopic analyses. With molecular overlap observed between two protease inhibitors that are being examined as anti-COVID-19 drugs, and sesquiterpenes isolated here, metabolite molecular docking calculations were made using the main protease (Mpro), which is required for viral multiplication as well as RNA-dependent RNA polymerase (RdRp). In silico binding-inhibition analysis predicted that select F. vesceritensis sesquiterpenes can bind to these enzymes required for viral replication. Structures of the isolated constituents were also consistent with the chemo-systematic grouping of F. vesceritensis secondary metabolites with other Ferula species.

Rutin and flavone analogs as prospective SARS-CoV-2 main protease inhibitors: In silico drug discovery study.

Coronavirus disease 2019 (COVID-19) is a new pandemic characterized by quick spreading and illness of the respiratory system. To date, there is no specific therapy for Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2). Flavonoids, especially rutin, have attracted considerable interest as a prospective SARS-CoV-2 main protease (Mpro) inhibitor. In this study, a database containing 2017 flavone analogs was prepared and screened against SARS-CoV-2 Mpro using the molecular docking technique. According to the results, 371 flavone analogs exhibited good potency towards Mpro with docking scores less than -9.0 kcal/mol. Molecular dynamics (MD) simulations, followed by molecular mechanics-generalized Born surface area (MM/GBSA) binding energy calculations, were performed for the top potent analogs in complex with Mpro. Compared to rutin, PubChem-129-716-607 and PubChem-885-071-27 showed better binding affinities against SARS-CoV-2 Mpro over 150 ns MD course with ΔGbinding values of -69.0 and -68.1 kcal/mol, respectively. Structural and energetic analyses demonstrated high stability of the identified analogs inside the SARS-CoV-2 Mpro active site over 150 ns MD simulations. The oral bioavailabilities of probable SARS-CoV-2 Mpro inhibitors were underpinned using drug-likeness parameters. A comparison of the binding affinities demonstrated that the MM/GBSA binding energies of the identified flavone analogs were approximately three and two times less than those of lopinavir and baicalein, respectively. In conclusion, PubChem-129-716-607 and PubChem-885-071-27 are promising anti-COVID-19 drug candidates that warrant further clinical investigations.

In Silico Evaluation of Prospective Anti-COVID-19 Drug Candidates as Potential SARS-CoV-2 Main Protease Inhibitors.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a recently emanating human infectious coronavirus that causes COVID-19 disease. On 11th March 2020, it has been announced as a pandemic by the World Health Organization (WHO). Recently, several repositioned drugs have been subjected to clinical investigations as anti-COVID-19 drugs. Here, in silico drug discovery tools were utilized to evaluate the binding affinities and features of eighteen anti-COVID-19 drug candidates against SARS-CoV-2 main protease (Mpro). Molecular docking calculations using Autodock Vina showed considerable binding affinities of the investigated drugs with docking scores ranging from - 5.3 to - 8.3 kcal/mol, with higher binding affinities for HIV drugs compared to the other antiviral drugs. Molecular dynamics (MD) simulations were performed for the predicted drug-Mpro complexes for 50 ns, followed by binding energy calculations utilizing molecular mechanics-generalized Born surface area (MM-GBSA) approach. MM-GBSA calculations demonstrated promising binding affinities of TMC-310911 and ritonavir towards SARS-CoV-2 Mpro, with binding energy values of - 52.8 and - 49.4 kcal/mol, respectively. Surpass potentialities of TMC-310911 and ritonavir are returned to their capabilities of forming multiple hydrogen bonds with the proximal amino acids inside Mpro's binding site. Structural and energetic analyses involving root-mean-square deviation, binding energy per-frame, center-of-mass distance, and hydrogen bond length demonstrated the stability of TMC-310911 and ritonavir inside the Mpro's active site over the 50 ns MD simulation. This study sheds light on HIV protease drugs as prospective SARS-CoV-2 Mpro inhibitors.