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1.
Viruses ; 13(12)2021 12 14.
Article in English | MEDLINE | ID: covidwho-1572668

ABSTRACT

Broad-spectrum antiviral therapies hold promise as a first-line defense against emerging viruses by blunting illness severity and spread until vaccines and virus-specific antivirals are developed. The nucleobase favipiravir, often discussed as a broad-spectrum inhibitor, was not effective in recent clinical trials involving patients infected with Ebola virus or SARS-CoV-2. A drawback of favipiravir use is its rapid clearance before conversion to its active nucleoside-5'-triphosphate form. In this work, we report a synergistic reduction of flavivirus (dengue, Zika), orthomyxovirus (influenza A), and coronavirus (HCoV-OC43 and SARS-CoV-2) replication when the nucleobases favipiravir or T-1105 were combined with the antimetabolite 6-methylmercaptopurine riboside (6MMPr). The 6MMPr/T-1105 combination increased the C-U and G-A mutation frequency compared to treatment with T-1105 or 6MMPr alone. A further analysis revealed that the 6MMPr/T-1105 co-treatment reduced cellular purine nucleotide triphosphate synthesis and increased conversion of the antiviral nucleobase to its nucleoside-5'-monophosphate, -diphosphate, and -triphosphate forms. The 6MMPr co-treatment specifically increased production of the active antiviral form of the nucleobases (but not corresponding nucleosides) while also reducing levels of competing cellular NTPs to produce the synergistic effect. This in-depth work establishes a foundation for development of small molecules as possible co-treatments with nucleobases like favipiravir in response to emerging RNA virus infections.


Subject(s)
Antimetabolites/pharmacology , Antiviral Agents/pharmacology , RNA Viruses/drug effects , Adenosine Triphosphate/metabolism , Amides/pharmacology , Animals , Cell Line , Drug Synergism , Guanosine Triphosphate/metabolism , Humans , Methylthioinosine/pharmacology , Mutation/drug effects , Phosphoribosyl Pyrophosphate/metabolism , Pyrazines/pharmacology , RNA Viruses/classification , RNA Viruses/genetics , RNA, Viral/drug effects , RNA, Viral/genetics , Virus Replication/drug effects
2.
ChemMedChem ; 16(22): 3418-3427, 2021 11 19.
Article in English | MEDLINE | ID: covidwho-1525425

ABSTRACT

Currently, limited therapeutic options are available for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). We have developed a set of pyrazine-based small molecules. A series of pyrazine conjugates was synthesized by microwave-assisted click chemistry and benzotriazole chemistry. All the synthesized conjugates were screened against the SAR-CoV-2 virus and their cytotoxicity was determined. Computational studies were carried out to validate the biological data. Some of the pyrazine-triazole conjugates (5 d-g) and (S)-N-(1-(benzo[d]thiazol-2-yl)-2-phenylethyl)pyrazine-2-carboxamide 12 i show significant potency against SARS-CoV-2 among the synthesized conjugates. The selectivity index (SI) of potent conjugates indicates significant efficacy compared to the reference drug (Favipiravir).


Subject(s)
Antiviral Agents/pharmacology , Pyrazines/pharmacology , SARS-CoV-2/drug effects , Amides/pharmacology , Animals , Antiviral Agents/chemical synthesis , Antiviral Agents/metabolism , Antiviral Agents/toxicity , Chlorocebus aethiops , Coronavirus RNA-Dependent RNA Polymerase/metabolism , Microbial Sensitivity Tests , Molecular Docking Simulation , Molecular Structure , Pyrazines/chemical synthesis , Pyrazines/metabolism , Pyrazines/toxicity , Quantitative Structure-Activity Relationship , Vero Cells
3.
Sci Rep ; 11(1): 19998, 2021 10 07.
Article in English | MEDLINE | ID: covidwho-1462031

ABSTRACT

Understanding the effects of metabolism on the rational design of novel and more effective drugs is still a considerable challenge. To the best of our knowledge, there are no entirely computational strategies that make it possible to predict these effects. From this perspective, the development of such methodologies could contribute to significantly reduce the side effects of medicines, leading to the emergence of more effective and safer drugs. Thereby, in this study, our strategy is based on simulating the electron ionization mass spectrometry (EI-MS) fragmentation of the drug molecules and combined with molecular docking and ADMET models in two different situations. In the first model, the drug is docked without considering the possible metabolic effects. In the second model, each of the intermediates from the EI-MS results is docked, and metabolism occurs before the drug accesses the biological target. As a proof of concept, in this work, we investigate the main antiviral drugs used in clinical research to treat COVID-19. As a result, our strategy made it possible to assess the biological activity and toxicity of all potential by-products. We believed that our findings provide new chemical insights that can benefit the rational development of novel drugs in the future.


Subject(s)
Antiviral Agents/metabolism , COVID-19/drug therapy , Drug Discovery , SARS-CoV-2/drug effects , Adenine/adverse effects , Adenine/analogs & derivatives , Adenine/metabolism , Adenine/pharmacology , Adenosine/adverse effects , Adenosine/analogs & derivatives , Adenosine/metabolism , Adenosine/pharmacology , Adenosine Monophosphate/adverse effects , Adenosine Monophosphate/analogs & derivatives , Adenosine Monophosphate/metabolism , Adenosine Monophosphate/pharmacology , Alanine/adverse effects , Alanine/analogs & derivatives , Alanine/metabolism , Alanine/pharmacology , Amides/adverse effects , Amides/metabolism , Amides/pharmacology , Antiviral Agents/adverse effects , Antiviral Agents/pharmacology , COVID-19/metabolism , Chloroquine/adverse effects , Chloroquine/analogs & derivatives , Chloroquine/metabolism , Chloroquine/pharmacology , Drug Design , Humans , Metabolic Networks and Pathways , Molecular Docking Simulation , Nitro Compounds/adverse effects , Nitro Compounds/metabolism , Nitro Compounds/pharmacology , Pyrazines/adverse effects , Pyrazines/metabolism , Pyrazines/pharmacology , Pyrrolidines/adverse effects , Pyrrolidines/metabolism , Pyrrolidines/pharmacology , Ribavirin/adverse effects , Ribavirin/metabolism , Ribavirin/pharmacology , SARS-CoV-2/metabolism , Thiazoles/adverse effects , Thiazoles/metabolism , Thiazoles/pharmacology
4.
EBioMedicine ; 72: 103595, 2021 Oct.
Article in English | MEDLINE | ID: covidwho-1433162

ABSTRACT

BACKGROUND: Favipiravir and Molnupiravir, orally available antivirals, have been reported to exert antiviral activity against SARS-CoV-2. First efficacy data have been recently reported in COVID-19 patients. METHODS: We here report on the combined antiviral effect of both drugs in a SARS-CoV-2 Syrian hamster infection model. The infected hamsters were treated twice daily with the vehicle (the control group) or a suboptimal dose of each compound or a combination of both compounds. FINDINGS: When animals were treated with a combination of suboptimal doses of Molnupiravir and Favipiravir at the time of infection, a marked combined potency at endpoint is observed. Infectious virus titers in the lungs of animals treated with the combination are reduced by ∼5 log10 and infectious virus are no longer detected in the lungs of >60% of treated animals. When start of treatment was delayed with one day a reduction of titers in the lungs of 2.4 log10 was achieved. Moreover, treatment of infected animals nearly completely prevented transmission to co-housed untreated sentinels. Both drugs result in an increased mutation frequency of the remaining viral RNA recovered from the lungs of treated animals. In the combo-treated hamsters, an increased frequency of C-to-T mutations in the viral RNA is observed as compared to the single treatment groups which may explain the pronounced antiviral potency of the combination. INTERPRETATION: Our findings may lay the basis for the design of clinical studies to test the efficacy of the combination of Molnupiravir/Favipiravir in the treatment of COVID-19. FUNDING: stated in the acknowledgment.


Subject(s)
Amides/therapeutic use , COVID-19/drug therapy , Cytidine/analogs & derivatives , Hydroxylamines/therapeutic use , Lung/virology , Pyrazines/therapeutic use , Amides/pharmacology , Animals , Antiviral Agents/pharmacology , Antiviral Agents/therapeutic use , COVID-19/transmission , Cytidine/pharmacology , Cytidine/therapeutic use , Disease Models, Animal , Drug Therapy, Combination , Female , Hydroxylamines/pharmacology , Mesocricetus , Pyrazines/pharmacology , RNA, Viral , Treatment Outcome , Viral Load
5.
Nat Commun ; 12(1): 1735, 2021 03 19.
Article in English | MEDLINE | ID: covidwho-1387332

ABSTRACT

Despite no or limited pre-clinical evidence, repurposed drugs are massively evaluated in clinical trials to palliate the lack of antiviral molecules against SARS-CoV-2. Here we use a Syrian hamster model to assess the antiviral efficacy of favipiravir, understand its mechanism of action and determine its pharmacokinetics. When treatment is initiated before or simultaneously to infection, favipiravir has a strong dose effect, leading to reduction of infectious titers in lungs and clinical alleviation of the disease. Antiviral effect of favipiravir correlates with incorporation of a large number of mutations into viral genomes and decrease of viral infectivity. Antiviral efficacy is achieved with plasma drug exposure comparable with those previously found during human clinical trials. Notably, the highest dose of favipiravir tested is associated with signs of toxicity in animals. Thereby, pharmacokinetic and tolerance studies are required to determine whether similar effects can be safely achieved in humans.


Subject(s)
Amides/pharmacology , Antiviral Agents/pharmacology , COVID-19/drug therapy , Pyrazines/pharmacology , SARS-CoV-2/drug effects , Animals , COVID-19/virology , Chlorocebus aethiops , Cricetinae , Disease Models, Animal , Female , Genome, Viral , Lung/virology , Mesocricetus , SARS-CoV-2/genetics , Vero Cells , Viral Load/drug effects
6.
Molecules ; 25(19)2020 Oct 06.
Article in English | MEDLINE | ID: covidwho-1389458

ABSTRACT

A novel series of some hydrazones bearing thiazole moiety were generated via solvent-drop grinding of thiazole carbohydrazide 2 with various carbonyl compounds. Also, dehydrative-cyclocondensation of 2 with active methylene compounds or anhydrides gave the respective pyarzole or pyrazine derivatives. The structures of the newly synthesized compounds were established based on spectroscopic evidences and their alternative syntheses. Additionally, the anti-viral activity of all the products was tested against SARS-CoV-2 main protease (Mpro) using molecular docking combined with molecular dynamics simulation (MDS). The average binding affinities of the compounds 3a, 3b, and 3c (-8.1 ± 0.33 kcal/mol, -8.0 ± 0.35 kcal/mol, and -8.2 ± 0.21 kcal/mol, respectively) are better than that of the positive control Nelfinavir (-6.9 ± 0.51 kcal/mol). This shows the possibility of these three compounds to effectively bind to SARS-CoV-2 Mpro and hence, contradict the virus lifecycle.


Subject(s)
Antiviral Agents/chemical synthesis , Betacoronavirus/enzymology , Hydrazones/chemical synthesis , Protease Inhibitors/chemical synthesis , Pyrazines/chemical synthesis , Pyrazoles/chemical synthesis , Viral Nonstructural Proteins/antagonists & inhibitors , Antiviral Agents/pharmacology , Betacoronavirus/chemistry , Betacoronavirus/drug effects , Binding Sites , COVID-19 , Coronavirus 3C Proteases , Coronavirus Infections/drug therapy , Cysteine Endopeptidases/chemistry , Cysteine Endopeptidases/metabolism , Drug Discovery , Humans , Hydrazones/pharmacology , Molecular Docking Simulation , Molecular Dynamics Simulation , Pandemics , Pneumonia, Viral/drug therapy , Protease Inhibitors/pharmacology , Protein Binding , Protein Conformation, alpha-Helical , Protein Conformation, beta-Strand , Protein Interaction Domains and Motifs , Pyrazines/pharmacology , Pyrazoles/pharmacology , SARS-CoV-2 , Thermodynamics , User-Computer Interface , Viral Nonstructural Proteins/chemistry , Viral Nonstructural Proteins/metabolism
7.
FEBS Lett ; 595(18): 2366-2382, 2021 09.
Article in English | MEDLINE | ID: covidwho-1363633

ABSTRACT

Favipiravir is a broad-spectrum inhibitor of viral RNA-dependent RNA polymerase (RdRp) currently being used to manage COVID-19. Accumulation of mutations in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RdRp may facilitate antigenic drift, generating favipiravir resistance. Focussing on the chain-termination mechanism utilized by favipiravir, we used high-throughput interface-based protein design to generate > 100 000 designs of the favipiravir-binding site of RdRp and identify mutational hotspots. We identified several single-point mutants and designs having a sequence identity of 97%-98% with wild-type RdRp, suggesting that SARS-CoV-2 can develop favipiravir resistance with few mutations. Out of 134 mutations documented in the CoV-GLUE database, 63 specific mutations were already predicted as resistant in our calculations, thus attaining ˜ 47% correlation with the sequencing data. These findings improve our understanding of the potential signatures of adaptation in SARS-CoV-2 against favipiravir.


Subject(s)
Amides/pharmacology , Antiviral Agents/pharmacology , Pyrazines/pharmacology , RNA, Viral/genetics , RNA-Dependent RNA Polymerase/genetics , SARS-CoV-2/drug effects , SARS-CoV-2/genetics , Drug Resistance, Viral/genetics , Mutation/genetics , Point Mutation/genetics
8.
Mol Syst Biol ; 17(8): e10239, 2021 08.
Article in English | MEDLINE | ID: covidwho-1335457

ABSTRACT

Understanding the mechanism of SARS-CoV-2 infection and identifying potential therapeutics are global imperatives. Using a quantitative systems pharmacology approach, we identified a set of repurposable and investigational drugs as potential therapeutics against COVID-19. These were deduced from the gene expression signature of SARS-CoV-2-infected A549 cells screened against Connectivity Map and prioritized by network proximity analysis with respect to disease modules in the viral-host interactome. We also identified immuno-modulating compounds aiming at suppressing hyperinflammatory responses in severe COVID-19 patients, based on the transcriptome of ACE2-overexpressing A549 cells. Experiments with Vero-E6 cells infected by SARS-CoV-2, as well as independent syncytia formation assays for probing ACE2/SARS-CoV-2 spike protein-mediated cell fusion using HEK293T and Calu-3 cells, showed that several predicted compounds had inhibitory activities. Among them, salmeterol, rottlerin, and mTOR inhibitors exhibited antiviral activities in Vero-E6 cells; imipramine, linsitinib, hexylresorcinol, ezetimibe, and brompheniramine impaired viral entry. These novel findings provide new paths for broadening the repertoire of compounds pursued as therapeutics against COVID-19.


Subject(s)
Antiviral Agents/pharmacology , COVID-19/drug therapy , Drug Evaluation, Preclinical/methods , Virus Internalization/drug effects , Angiotensin-Converting Enzyme 2/genetics , Angiotensin-Converting Enzyme 2/metabolism , Animals , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , COVID-19/genetics , COVID-19/virology , Chlorocebus aethiops , Drug Repositioning , HEK293 Cells , Host-Pathogen Interactions/drug effects , Host-Pathogen Interactions/physiology , Humans , Imidazoles/pharmacology , Pyrazines/pharmacology , SARS-CoV-2/drug effects , SARS-CoV-2/pathogenicity , Salmeterol Xinafoate/pharmacology , Vero Cells
9.
Cell Rep ; 35(1): 108940, 2021 04 06.
Article in English | MEDLINE | ID: covidwho-1157178

ABSTRACT

SARS-CoV-2 has currently precipitated the COVID-19 global health crisis. We developed a medium-throughput drug-screening system and identified a small-molecule library of 34 of 430 protein kinase inhibitors that were capable of inhibiting the SARS-CoV-2 cytopathic effect in human epithelial cells. These drug inhibitors are in various stages of clinical trials. We detected key proteins involved in cellular signaling pathways mTOR-PI3K-AKT, ABL-BCR/MAPK, and DNA-damage response that are critical for SARS-CoV-2 infection. A drug-protein interaction-based secondary screen confirmed compounds, such as the ATR kinase inhibitor berzosertib and torin2 with anti-SARS-CoV-2 activity. Berzosertib exhibited potent antiviral activity against SARS-CoV-2 in multiple cell types and blocked replication at the post-entry step. Berzosertib inhibited replication of SARS-CoV-1 and the Middle East respiratory syndrome coronavirus (MERS-CoV) as well. Our study highlights key promising kinase inhibitors to constrain coronavirus replication as a host-directed therapy in the treatment of COVID-19 and beyond as well as provides an important mechanism of host-pathogen interactions.


Subject(s)
Antiviral Agents/pharmacology , COVID-19/drug therapy , DNA Damage , Isoxazoles/pharmacology , Pyrazines/pharmacology , SARS-CoV-2/physiology , Virus Replication/drug effects , A549 Cells , Animals , COVID-19/metabolism , COVID-19/pathology , Chlorocebus aethiops , Drug Evaluation, Preclinical , HEK293 Cells , HeLa Cells , Humans , MAP Kinase Signaling System/drug effects , Middle East Respiratory Syndrome Coronavirus/metabolism , Vero Cells
10.
Int J Infect Dis ; 106: 33-35, 2021 May.
Article in English | MEDLINE | ID: covidwho-1144720

ABSTRACT

As of October 2020, there is still no specific drug to treat COVID-19 as it rages worldwide. Favipiravir, indicated for the treatment of new and re-emerging influenza infections, has been suggested to be effective against SARS-CoV-2, although this is not yet fully validated. We administered favipiravir to a 64-year-old female patient with COVID-19. Her symptoms resolved quickly after the start of treatment, with reduction of SARS-CoV-2 viral load, but she developed a fever again on day 12. Since the fever was relieved by discontinuation of favipiravir, and based on positive results with a drug-induced lymphocyte stimulation test, we diagnosed her with favipiravir-induced drug fever. A decrease in the serum concentration of favipiravir was observed along with resolution of the fever. The present case suggests that drug fever should be considered in the differential diagnosis of relapsing fever episodes in COVID-19 patients receiving favipiravir.


Subject(s)
Amides/adverse effects , COVID-19/drug therapy , COVID-19/immunology , Fever/chemically induced , Lymphocyte Activation/drug effects , Pyrazines/adverse effects , Amides/pharmacology , Amides/therapeutic use , COVID-19/diagnosis , Female , Humans , Middle Aged , Pyrazines/pharmacology , Pyrazines/therapeutic use , Viral Load/drug effects
11.
Eur J Pharmacol ; 890: 173720, 2021 Jan 05.
Article in English | MEDLINE | ID: covidwho-1071294

ABSTRACT

COVID-19 has intensified into a global pandemic with over a million deaths worldwide. Experimental research analyses have been implemented and executed with the sole rationale to counteract SARS-CoV-2, which has initiated potent therapeutic strategy development in coherence with computational biology validation focusing on the characterized viral drug targets signified by proteomic and genomic data. Spike glycoprotein is one of such potential drug target that promotes viral attachment to the host cellular membrane by binding to its receptor ACE-2 via its Receptor-Binding Domain (RBD). Multiple Sequence alignment and relative phylogenetic analysis revealed significant sequential disparities of SARS-CoV-2 as compared to previously encountered SARS-CoV and MERS-CoV strains. We implemented a drug re-purposing approach wherein the inhibitory efficacy of a cluster of thirty known drug candidates comprising of antivirals, antibiotics and phytochemicals (selection contingent on their present developmental status in underway clinical trials) was elucidated by subjecting them to molecular docking analyses against the spike protein RBD model (developed using homology modelling and validated using SAVES server 5.0) and the composite trimeric structures of spike glycoprotein of SARS-CoV-2. Our results indicated that Camostat, Favipiravir, Tenofovir, Raltegravir and Stavudine showed significant interactions with spike RBD of SARS-CoV-2. Proficient bioavailability coupled with no predicted in silico toxicity rendered them as prospective alternatives for designing and development of novel combinatorial therapy formulations for improving existing treatment regimes to combat COVID-19.


Subject(s)
Antiviral Agents/pharmacology , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/metabolism , Amides/pharmacology , Anti-Bacterial Agents/pharmacology , Binding Sites , COVID-19/drug therapy , Drug Repositioning , Esters , Gabexate/analogs & derivatives , Gabexate/pharmacology , Guanidines , Molecular Docking Simulation , Phytochemicals/pharmacology , Protein Binding , Pyrazines/pharmacology , Raltegravir Potassium/pharmacology , Stavudine/pharmacology , Tenofovir/pharmacology
12.
Proc Natl Acad Sci U S A ; 118(7)2021 02 16.
Article in English | MEDLINE | ID: covidwho-1060504

ABSTRACT

The RNA polymerase inhibitor favipiravir is currently in clinical trials as a treatment for infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), despite limited information about the molecular basis for its activity. Here we report the structure of favipiravir ribonucleoside triphosphate (favipiravir-RTP) in complex with the SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) bound to a template:primer RNA duplex, determined by electron cryomicroscopy (cryoEM) to a resolution of 2.5 Å. The structure shows clear evidence for the inhibitor at the catalytic site of the enzyme, and resolves the conformation of key side chains and ions surrounding the binding pocket. Polymerase activity assays indicate that the inhibitor is weakly incorporated into the RNA primer strand, and suppresses RNA replication in the presence of natural nucleotides. The structure reveals an unusual, nonproductive binding mode of favipiravir-RTP at the catalytic site of SARS-CoV-2 RdRp, which explains its low rate of incorporation into the RNA primer strand. Together, these findings inform current and future efforts to develop polymerase inhibitors for SARS coronaviruses.


Subject(s)
Amides/pharmacology , Coronavirus RNA-Dependent RNA Polymerase/metabolism , Enzyme Inhibitors/pharmacology , Pyrazines/pharmacology , SARS-CoV-2/ultrastructure , Amides/chemistry , Coronavirus RNA-Dependent RNA Polymerase/antagonists & inhibitors , Coronavirus RNA-Dependent RNA Polymerase/chemistry , Cryoelectron Microscopy/methods , Enzyme Inhibitors/chemistry , Pyrazines/chemistry , Ribonucleotides/chemistry , SARS-CoV-2/drug effects , SARS-CoV-2/enzymology , Single Molecule Imaging/methods
13.
Mol Cancer Res ; 19(4): 549-554, 2021 04.
Article in English | MEDLINE | ID: covidwho-1058113

ABSTRACT

The outbreak of the novel coronavirus disease 2019 (COVID-19) has emerged as one of the biggest global health threats worldwide. As of October 2020, more than 44 million confirmed cases and more than 1,160,000 deaths have been reported globally, and the toll is likely to be much higher before the pandemic is over. There are currently little therapeutic options available and new potential targets are intensively investigated. Recently, Bruton tyrosine kinase (BTK) has emerged as an interesting candidate. Elevated levels of BTK activity have been reported in blood monocytes from patients with severe COVID-19, compared with those from healthy volunteers. Importantly, various studies confirmed empirically that administration of BTK inhibitors (acalabrutinib and ibrutinib) decreased the duration of mechanical ventilation and mortality rate for hospitalized patients with severe COVID-19. Herein, we review the current information regarding the role of BTK in severe acute respiratory syndrome coronavirus 2 infections and the suitability of its inhibitors as drugs to treat COVID-19. The use of BTK inhibitors in the management of COVID-19 shows promise in reducing the severity of the immune response to the infection and thus mortality. However, BTK inhibition may be contributing in other ways to inhibit the effects of the virus and this will need to be carefully studied.


Subject(s)
Agammaglobulinaemia Tyrosine Kinase/antagonists & inhibitors , Antiviral Agents/pharmacology , COVID-19/drug therapy , Adenine/analogs & derivatives , Adenine/pharmacology , Agammaglobulinaemia Tyrosine Kinase/metabolism , Antiviral Agents/adverse effects , Benzamides/pharmacology , COVID-19/complications , COVID-19/enzymology , Humans , Lung/drug effects , Lung/virology , Molecular Targeted Therapy , Neoplasms/drug therapy , Neoplasms/virology , Piperidines/pharmacology , Protein Kinase Inhibitors/adverse effects , Protein Kinase Inhibitors/pharmacology , Pyrazines/pharmacology , Thrombosis/drug therapy , Thrombosis/virology
14.
Expert Opin Ther Pat ; 31(4): 325-337, 2021 Apr.
Article in English | MEDLINE | ID: covidwho-1039698

ABSTRACT

Introduction: The current SARS-CoV-2 pandemic urgently demands for both prevention and treatment strategies. RNA-dependent RNA-polymerase (RdRp), which has no counterpart in human cells, is an excellent target for drug development. Given the time-consuming process of drug development, repurposing drugs approved for other indications or at least successfully tested in terms of safety and tolerability, is an attractive strategy to rapidly provide an effective medication for severe COVID-19 cases.Areas covered: The currently available data and upcominSg studies on RdRp which can be repurposed to halt SARS-CoV-2 replication, are reviewed.Expert opinion: Drug repurposing and design of novel compounds are proceeding in parallel to provide a quick response and new specific drugs, respectively. Notably, the proofreading SARS-CoV-2 exonuclease activity could limit the potential for drugs designed as immediate chain terminators and favor the development of compounds acting through delayed termination. While vaccination is awaited to curb the SARS-CoV-2 epidemic, even partially effective drugs from repurposing strategies can be of help to treat severe cases of disease. Considering the high conservation of RdRp among coronaviruses, an improved knowledge of its activity in vitro can provide useful information for drug development or drug repurposing to combat SARS-CoV-2 as well as future pandemics.


Subject(s)
Antiviral Agents/pharmacology , COVID-19/drug therapy , RNA-Dependent RNA Polymerase/antagonists & inhibitors , SARS-CoV-2/drug effects , Adenosine Monophosphate/analogs & derivatives , Adenosine Monophosphate/pharmacology , Alanine/analogs & derivatives , Alanine/pharmacology , Amides/pharmacology , Cytidine/analogs & derivatives , Cytidine/pharmacology , Drug Development , Drug Repositioning , Humans , Hydroxylamines/pharmacology , Pyrazines/pharmacology , RNA-Dependent RNA Polymerase/chemistry , SARS-CoV-2/enzymology
15.
Ann Palliat Med ; 10(1): 707-720, 2021 Jan.
Article in English | MEDLINE | ID: covidwho-1030457

ABSTRACT

The whole world is battling through coronavirus disease 2019 (COVID-19) which is a fatal pandemic. In the early 2020, the World Health Organization (WHO) declared it as a global health emergency without definitive treatments and preventive approaches. In the absence of definitive therapeutic agents, this thorough review summarizes and outlines the potency and safety of all molecules and therapeutics which may have potential antiviral effects. A number of molecules and therapeutics licensed or being tested for some other conditions were found effective in different in vitro studies as well as in many small sample-sized clinical trials and independent case studies. However, in those clinical trials, there were some limitations which need to be overcome to find the most promising antiviral against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In conclusion, many of above-mentioned antivirals seems to have some therapeutic effects but none of them have been shown to have a strong evidence for their proper recommendation and approval in the treatment of COVID-19. Constantly evolving new evidences, exclusive adult data, language barrier, and type of study (observational, retrospective, small-sized clinical trials, or independent case series) resulted to the several limitations of this review. The need for multicentered, large sample-sized, randomized, placebo-controlled trials on COVID-19 patients to reach a proper conclusion on the most promising antiviral agent is warranted.


Subject(s)
Antiviral Agents/therapeutic use , COVID-19/therapy , Adenosine Monophosphate/analogs & derivatives , Adenosine Monophosphate/pharmacology , Adenosine Monophosphate/therapeutic use , Alanine/analogs & derivatives , Alanine/pharmacology , Alanine/therapeutic use , Amides/pharmacology , Amides/therapeutic use , Antibodies, Monoclonal, Humanized/pharmacology , Antibodies, Monoclonal, Humanized/therapeutic use , Azetidines/pharmacology , Azetidines/therapeutic use , Chloroquine/pharmacology , Chloroquine/therapeutic use , Drug Combinations , Humans , Hydroxychloroquine/pharmacology , Hydroxychloroquine/therapeutic use , Immunization, Passive , Indoles/pharmacology , Indoles/therapeutic use , Interferons/pharmacology , Interferons/therapeutic use , Ivermectin/pharmacology , Ivermectin/therapeutic use , Lopinavir/pharmacology , Lopinavir/therapeutic use , Nitro Compounds , Oseltamivir/pharmacology , Oseltamivir/therapeutic use , Purines/pharmacology , Purines/therapeutic use , Pyrazines/pharmacology , Pyrazines/therapeutic use , Pyrazoles/pharmacology , Pyrazoles/therapeutic use , Ribavirin/pharmacology , Ribavirin/therapeutic use , Ritonavir/pharmacology , Ritonavir/therapeutic use , Sulfonamides/pharmacology , Sulfonamides/therapeutic use , Thiazoles/pharmacology , Thiazoles/therapeutic use
16.
Expert Rev Anti Infect Ther ; 19(8): 1029-1037, 2021 08.
Article in English | MEDLINE | ID: covidwho-998153

ABSTRACT

INTRODUCTION: At this time, there is no specific therapeutic or vaccine for treatment of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Hence, available drugs for treatment of other viral infections may be useful to treat COVID-19. AREAS COVERED: The focus of the current review was studying the main characteristics of favipiravir and its usefulness to treat COVID-19. An electronic search was done by using Pubmed and Google scholar. EXPERT OPINION: Based on the mechanism of action and safety of favipiravir, the drug may be a promising candidate for compassionate use against the SARS-CoV-2 infection. Favipiravir has a wide range of activity against many single-stranded RNA viruses, is well tolerated in humans and has a high barrier to resistance. However, high doses of the agent are necessary to obtain an efficient antiviral activity. Favipiravir is teratogen in pregnant women and associated with the hyperuricemia. Therefore, the administration of the drug should be well controlled. Investigating the antiviral prophylactic potency of favipiravir and search for its pro-drugs and/or analogs showing improved activity and/or safety are critical.


Subject(s)
Amides/therapeutic use , Antiviral Agents/therapeutic use , COVID-19/drug therapy , Pyrazines/therapeutic use , Adult , Amides/adverse effects , Amides/pharmacology , Antiviral Agents/adverse effects , Antiviral Agents/pharmacology , Female , Humans , Pregnancy , Pyrazines/adverse effects , Pyrazines/pharmacology
17.
Molecules ; 25(23)2020 Dec 03.
Article in English | MEDLINE | ID: covidwho-963646

ABSTRACT

The RNA-dependent RNA polymerase (RdRp) is an essential enzyme for the viral replication process, catalyzing the viral RNA synthesis using a metal ion-dependent mechanism. In recent years, RdRp has emerged as an optimal target for the development of antiviral drugs, as demonstrated by recent approvals of sofosbuvir and remdesivir against Hepatitis C virus (HCV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), respectively. In this work, we overview the main sequence and structural features of the RdRp of emerging RNA viruses such as Coronaviruses, Flaviviruses, and HCV, as well as inhibition strategies implemented so far. While analyzing the structural information available on the RdRp of emerging RNA viruses, we provide examples of success stories such as for HCV and SARS-CoV-2. In contrast, Flaviviruses' story has raised attention about how the lack of structural details on catalytically-competent or ligand-bound RdRp strongly hampers the application of structure-based drug design, either in repurposing and conventional approaches.


Subject(s)
Antiviral Agents/chemistry , Antiviral Agents/pharmacology , RNA Viruses/enzymology , RNA-Dependent RNA Polymerase/chemistry , Amides/chemistry , Amides/pharmacology , Coronavirus/drug effects , Coronavirus/enzymology , Coronavirus/genetics , Drug Design , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Flavivirus/drug effects , Flavivirus/enzymology , Flavivirus/genetics , Hepacivirus/drug effects , Hepacivirus/enzymology , Hepacivirus/genetics , Humans , Pyrazines/chemistry , Pyrazines/pharmacology , RNA Virus Infections/epidemiology , RNA Viruses/drug effects , RNA-Dependent RNA Polymerase/antagonists & inhibitors , RNA-Dependent RNA Polymerase/metabolism , Small Molecule Libraries/chemistry , Small Molecule Libraries/pharmacology
18.
Trials ; 21(1): 935, 2020 Nov 19.
Article in English | MEDLINE | ID: covidwho-934299

ABSTRACT

OBJECTIVES: The GETAFIX trial will test the hypothesis that favipiravir is a more effective treatment for COVID-19 infection in patients who have early stage disease, compared to current standard of care. This study will also provide an important opportunity to investigate the safety and tolerability of favipiravir, the pharmacokinetic and pharmacodynamic profile of this drug and mechanisms of resistance in the context of COVID-19 infection, as well as the effect of favipiravir on hospitalisation duration and the post COVID-19 health and psycho-social wellbeing of patients recruited to the study. TRIAL DESIGN: GETAFIX is an open label, parallel group, two arm phase II/III randomised trial with 1:1 treatment allocation ratio. Patients will be randomised to one of two arms and the primary endpoint will assess the superiority of favipiravir plus standard treatment compared to standard treatment alone. PARTICIPANTS: This trial will recruit adult patients with confirmed positive valid COVID-19 test, who are not pregnant or breastfeeding and have no prior major co-morbidities. This is a multi-centre trial, patients will be recruited from in-patients and outpatients from three Glasgow hospitals: Royal Alexandra Hospital; Queen Elizabeth University Hospital; and the Glasgow Royal Infirmary. Patients must meet all of the following criteria: 1. Age 16 or over at time of consent 2. Exhibiting symptoms associated with COVID-19 3. Positive for SARS-CoV-2 on valid COVID-19 test 4. Point 1, 2, 3, or 4 on the WHO COVID-19 ordinal severity scale at time of randomisation. (Asymptomatic with positive valid COVID-19 test, Symptomatic Independent, Symptomatic assistance needed, Hospitalized, with no oxygen therapy) 5. Have >=10% risk of death should they be admitted to hospital as defined by the ISARIC4C risk index: https://isaric4c.net/risk 6. Able to provide written informed consent 7. Negative pregnancy test (women of childbearing potential*) 8. Able to swallow oral medication Patients will be excluded from the trial if they meet any of the following criteria: 1. Renal impairment requiring, or likely to require, dialysis or haemofiltration 2. Pregnant or breastfeeding 3. Of child bearing potential (women), or with female partners of child bearing potential (men) who do not agree to use adequate contraceptive measures for the duration of the study and for 3 months after the completion of study treatment 4. History of hereditary xanthinuria 5. Other patients judged unsuitable by the Principal Investigator or sub-Investigator 6. Known hypersensitivity to favipiravir, its metabolites or any excipients 7. Severe co-morbidities including: patients with severe hepatic impairment, defined as: • greater than Child-Pugh grade A • AST or ALT > 5 x ULN • AST or ALT >3 x ULN and Total Bilirubin > 2xULN 8. More than 96 hours since first positive COVID-19 test sample was taken 9. Unable to discontinue contra-indicated concomitant medications This is a multi-centre trial, patients will be recruited from in-patients and outpatients from three Glasgow hospitals: Royal Alexandra Hospital; Queen Elizabeth University Hospital; and the Glasgow Royal Infirmary. INTERVENTION AND COMPARATOR: Patients randomised to the experimental arm of GETAFIX will receive standard treatment for COVID-19 at the discretion of the treating clinician plus favipiravir. These patients will receive a loading dose of favipiravir on day 1 of 3600mg (1800mg 12 hours apart). On days 2-10, patients in the experimental arm will receive a maintenance dose of favipiravir of 800mg 12 hours apart (total of 18 doses). Patients randomised to the control arm of the GETAFIX trial will receive standard treatment for COVID-19 at the discretion of the treating clinician. MAIN OUTCOMES: The primary outcome being assessed in the GETAFIX trial is the efficacy of favipiravir in addition to standard treatment in patients with COVID-19 in reducing the severity of disease compared to standard treatment alone. Disease severity will be assessed using WHO COVID 10 point ordinal severity scale at day 15 +/- 48 hours. All randomised participants will be followed up until death or 60 days post-randomisation (whichever is sooner). RANDOMISATION: Patients will be randomised 1:1 to the experimental versus control arm using computer generated random sequence allocation. A minimisation algorithm incorporating a random component will be used to allocate patients. The factors used in the minimisation will be: site, age (16-50/51-70/71+), history of hypertension or currently obsess (BMI>30 or obesity clinically evident; yes/no), 7 days duration of symptoms (yes/no/unknown), sex (male/female), WHO COVID-19 ordinal severity score at baseline (1/2or 3/4). BLINDING (MASKING): No blinding will be used in the GETAFIX trial. Both participants and those assessing outcomes will be aware of treatment allocation. NUMBERS TO BE RANDOMISED (SAMPLE SIZE): In total, 302 patients will be randomised to the GETAFIX trial: 151 to the control arm and 151 to the experimental arm. There will be an optional consent form for patients who may want to contribute to more frequent PK and PD sampling. The maximum number of patients who will undergo this testing will be sixteen, eight males and eight females. This option will be offered to all patients who are being treated in hospital at the time of taking informed consent, however only patients in the experimental arm of the trial will be able to undergo this testing. TRIAL STATUS: The current GETAFIX protocol is version 4.0 12th September 2020. GETAFIX opened to recruitment on 26th October 2020 and will recruit patients over a period of approximately six months. TRIAL REGISTRATION: GETAFIX was registered on the European Union Drug Regulating Authorities Clinical Trials (EudraCT) Database on 15th April 2020; Reference number 2020-001904-41 ( https://www.clinicaltrialsregister.eu/ctr-search/trial/2020-001904-41/GB ). GETAFIX was registered on ISRCTN on 7th September 2020; Reference number ISRCTN31062548 ( https://www.isrctn.com/ISRCTN31062548 ). FULL PROTOCOL: The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol. The study protocol has been reported in accordance with the Standard Protocol Items: Recommendations for Clinical Interventional Trials (SPIRIT) guidelines (see Additional file 2).


Subject(s)
Amides/therapeutic use , Antiviral Agents/therapeutic use , Coronavirus Infections/drug therapy , Pneumonia, Viral/drug therapy , Pyrazines/therapeutic use , Adult , Amides/administration & dosage , Amides/pharmacokinetics , Amides/pharmacology , Antiviral Agents/administration & dosage , Antiviral Agents/pharmacokinetics , Antiviral Agents/pharmacology , Betacoronavirus/genetics , Betacoronavirus/isolation & purification , COVID-19 , Case-Control Studies , Coronavirus Infections/classification , Coronavirus Infections/epidemiology , Coronavirus Infections/virology , Female , Hospitalization , Humans , Male , Pandemics/classification , Pneumonia, Viral/classification , Pneumonia, Viral/epidemiology , Pneumonia, Viral/virology , Pyrazines/administration & dosage , Pyrazines/pharmacokinetics , Pyrazines/pharmacology , SARS-CoV-2 , Safety , Scotland/epidemiology , Severity of Illness Index , Treatment Outcome
19.
Drug Res (Stuttg) ; 71(3): 166-170, 2021 Mar.
Article in English | MEDLINE | ID: covidwho-919370

ABSTRACT

A recent outbreak of coronavirus disease 2019 (COVID-19) caused by the novel coronavirus designated as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) started in Wuhan, China, at the end of 2019 and then spread rapidly all over the world. However, there are no specific antiviral therapies for COVID-19, using the agents which approved or in development for other viral infections is one of the potentially quickest ways to find treatment for this new viral infection. Favipiravir is an effective agent that acts as a nucleotide analog that selectively inhibits the viral RNA dependent RNA polymerase or causes lethal mutagenesis upon incorporation into the virus RNA. In view of recent studies and discussion on favipiravir, in this mini review we aimed to summarize the clinical trials studying the efficacy and safety of favipiravir in patients with COVID-19.


Subject(s)
Amides/therapeutic use , Antiviral Agents/therapeutic use , COVID-19/drug therapy , Coronavirus RNA-Dependent RNA Polymerase/antagonists & inhibitors , Pyrazines/therapeutic use , SARS-CoV-2/drug effects , Amides/pharmacology , Antiviral Agents/pharmacology , COVID-19/virology , Clinical Trials as Topic , Humans , Mutagenesis/drug effects , Pyrazines/pharmacology , RNA, Viral/drug effects , RNA, Viral/genetics , SARS-CoV-2/enzymology , SARS-CoV-2/genetics , Treatment Outcome
20.
BMC Res Notes ; 13(1): 527, 2020 Nov 11.
Article in English | MEDLINE | ID: covidwho-917943

ABSTRACT

OBJECTIVES: The aim of this study was to use Ligand-based pharmacophore modelling approach for four established antiviral drugs, namely remdesivir, lopinavir, ritonavir and hydroxychloroquine for COVID-19 inhibitors as training sets. In this study Twenty vanillin derivatives together with monolaurin and tetrodotoxin were used as test sets to evaluate as potential SARS-CoV-2 inhibitors. The Structure-based pharmacophore modelling approach was also performed using 5RE6, 5REX and 5RFZ in order to analyse the binding site and ligand-protein complex interactions. RESULTS: The pharmacophore modelling mode of 5RE6 displayed two Hydrogen Bond Acceptors (HBA) and one Hydrophobic (HY) interaction. Besides, the pharmacophore model of 5REX showed two HBA and two HY interactions. Finally, the pharmacophore model of 5RFZ showed three HBA and one HY interaction. Based on ligand-based approach, 20 Schiff-based vanillin derivatives, showed strong MPro inhibition activity. This was due to their good alignment and common features to PDB-5RE6. Similarly, monolaurin and tetrodotoxin displayed some significant activity against SARS-CoV-2. From structure-based approach, vanillin derivatives (1) to (12) displayed some potent MPro inhibition against SARS-CoV-2. Favipiravir, chloroquine and hydroxychloroquine also showed some significant MPro inhibition.


Subject(s)
Antiviral Agents/pharmacology , Betacoronavirus/drug effects , Chloroquine/pharmacology , Cysteine Proteinase Inhibitors/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Amides/chemistry , Amides/pharmacology , Antiviral Agents/chemistry , Benzaldehydes/chemistry , Chloroquine/chemistry , Computer Simulation , Coronavirus 3C Proteases , Cysteine Endopeptidases , Cysteine Proteinase Inhibitors/chemistry , Humans , Hydroxychloroquine/chemistry , Hydroxychloroquine/pharmacology , Laurates/chemistry , Laurates/pharmacology , Microbial Sensitivity Tests , Models, Molecular , Monoglycerides/chemistry , Monoglycerides/pharmacology , Pyrazines/chemistry , Pyrazines/pharmacology , SARS-CoV-2 , Structure-Activity Relationship , Tetrodotoxin/chemistry , Tetrodotoxin/pharmacology
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