Arbidol as a broad-spectrum antiviral: an update

Harnessing computational tools for drug discovery: An integrated computational approach to identify potential BACE-1 inhibitors

The hallmark of Alzheimer's disease (AD), a progressive neurodegenerative condition, is the buildup of amyloid-beta (Aβ) plaque, which is mainly caused by β-secretase 1 (BACE-1) activity. BACE-1 inhibition is a potentially effective treatment strategy to lower the progression of AD. In order to find possible BACE-1 inhibitors using a drug repurposing technique, this study uses an integrated computational approach that includes pharmacophore modelling, virtual screening, molecular docking, MM-GBSA, molecular dynamics (MD) simulations, in-silico ADMET profiling, and PBPK modelling. A pharmacophore model, was created with known BACE-1 inhibitors to enable virtual screening of both novel and FDA-approved chemical libraries. Top candidates with good free energy scores and strong binding affinities were found using molecular docking and MM-GBSA calculations. The stability of shortlisted Hits inside the BACE-1 active site was further validated using MD simulations, which showed that some of the important interactions were maintained across a period of 50ns. ADMET and PBPK studies predicted favorable pharmacokinetic and safety profiles for the shortlisted hits, particularly for B2 and B9. These findings identify potential candidates for future experimental validation, offering an inexpensive approach for identification of compounds as potential BACE-1 inhibitors.

The potential of RNA-binding proteins as host-targeting antivirals against RNA viruses

RNA-binding proteins (RBPs) are essential regulators of cellular RNA processes, including RNA stability, translation, and post-translational regulation. During viral infections, RBPs are key regulators of the viral cycle due to their interaction with both host and viral RNAs. Herein, we initially explore the roles of specific RBP families, namely heterogeneous nuclear ribonucleoproteins (hnRNPs), DEAD-box helicases, human antigen R (HuR), and the eukaryotic initiation factors of the eIF4F complex, in viral RNA replication, translation, and assembly. Next, we examine the potential of these RBPs as host-targeting antivirals against pandemic-prone RNA viruses that have been gaining momentum in recent years. Targeting RBPs could disrupt cellular homeostasis, leading to unintended effects on host cells; however, RBPs have been successfully targeted mainly in anticancer therapies, showcasing that their modulation can be safely achieved by drug repurposing. By disrupting key viral-RBP interactions or modulating RBP functions, such therapeutic interventions aim to inhibit viral propagation and restore normal host processes. Thus, conceivable benefits of targeting RBPs as alternative antiviral strategies include their broad-spectrum activity and potential for combination therapies with conventional antivirals, reduced or delayed resistance development, and concomitant enhancement of host immune responses. Our discussion also highlights the broader implications of leveraging host-directed therapies in an attempt to overcome viral resistance. Finally, we emphasise the need for continued innovation to refine these strategies for broad-spectrum antiviral applications.

Design, Synthesis and Anti-Influenza Virus Activity of 4-Tert-Butyl-N-(3-Oxo-1-Thia-4-Azaspiro[4.5]Dec-4-yl)Benzamide Derivatives That Target Hemagglutinin-Mediated Fusion

Hemagglutinin (HA) is a viral glycoprotein that mediates influenza virus entry into the host cell and is considered a relevant viral target. We here report the identification of a class of 4-tert-butylphenyl-substituted spirothiazolidinones as HA-mediated fusion inhibitors with specific activity against influenza A/H3N2 virus. The novel spirocyclic compounds were achieved by using one-pot cyclocondensation method and the chemical structures were characterized by IR, 1H NMR, 13C NMR, and elemental analysis. Compound 2c, bearing methyl substitutions at positions 2- and 8- of the spiro ring displayed an EC50 value against influenza A/H3N2 virus of 1.3 μM and an antiviral selectivity index of 30. The fusion-inhibiting effect of compound 2c was revealed in the polykaryon assay which is based on cell-cell fusion when influenza virus H3 HA-transfected cells are exposed to low pH. Computer-aided docking was performed to predict the possible binding pocket in the H3 HA trimer. Resistance data and in silico studies indicated that compound 2c has an overlapping binding pocket in the stem region of H3 HA with the known fusion inhibitors TBHQ and arbidol.

Synthesis and biological evaluation of substituted quinolines containing piperazine moieties against Influenza A virus

Influenza A virus (IAV) poses a serious global threat to public health. There is an urgent need to develop new anti-IAV agents due to the limitations of the current antiviral drugs in clinical practice. Herein, based on compound I-13e, we designed and synthesized 23 substituted quinoline derivatives containing piperazine moieties and evaluated their in vitro anti-IAV activity. The results showed that compounds 4a, 4c, 6c, 6f, 6g, 6i and 9a-9d (IC50s: 0.88-4.92 μM) were more active against IAV than Ribavirin. In particular, compound 9b exhibited broad-spectrum antiviral activity (IC50: 0.88-6.33 μM) and acceptable cytotoxicity. The preliminary studies on its mechanism of action indicated an inhibition of viral RNA transcription and replication. These results suggested its potential as a promising anti-IAV candidate for further investigation.

Antivirals in COVID-19: A Focus on Pediatric Cardiac Patients

The COVID-19 pandemic created an unprecedented public health crisis, driven by its rapid global spread and the urgent need for worldwide collaborative interventions to contain it. This urgency spurred the search for therapeutic agents to prevent or manage the infection. Among these, various types of antivirals emerged as a prominent treatment option, supported by a wealth of observational studies and randomized controlled trials. The results from such studies conflict, with some concluding efficacy and others the lack thereof, with variability also occurring depending on the severity of COVID-19 in the studied population. In addition, many agents have been explored using randomized controlled trials-the gold standard in evaluating the efficacy of an intervention-to only a limited degree, with most of the evidence behind their use concluded using observational studies. Thus, the sheer volume of data has made it challenging to resolve inconsistencies and determine true efficacy. Furthermore, there is a paucity in the literature regarding the use of antivirals in the pediatric population infected with COVID-19, with their use being extrapolated from the results of studies done on adult patients. As such, additional trials are needed to solidify the effectiveness of antivirals in managing COVID-19, particularly in the underexplored and especially vulnerable pediatric cardiac patients. Therefore, utilizing the results from randomized controlled trials, this narrative review evaluates the rationale behind the use of antivirals, summarizes the findings from the literature, and concludes with a focused discussion on their application in pediatric cardiac patients.

Antiviral treatment for viral pneumonia: current drugs and natural compounds

In recent years, viral pneumonia has become a significant challenge to global public health, particularly during the COVID-19 pandemic. Viral pneumonia can be caused by various viruses, including influenza virus, RSV, and adenovirus. These viruses trigger inflammatory responses by invading the respiratory epithelial cells, leading to lung damage. Existing antiviral drugs such as ribavirin, adobiravir, and oseltamivir exert their therapeutic effects by inhibiting different stages of the viral life cycle but face issues such as increasing drug resistance. Natural components like astragalus saponins, Houttuynia cordata flavonoids, and tea theaflavin-gallates have demonstrated supportive roles in antiviral treatments, capable of not only enhancing immune responses but also potentially inhibiting viral replication through multiple pathways, thereby alleviating lung damage. Although natural components cannot entirely replace traditional antiviral drugs, their role in comprehensive treatment regimens is becoming increasingly important. This review summarizes the current applications and limitations of antiviral drugs and explores the research progress and potential mechanisms of natural components in the treatment of viral pneumonia.

Novel derivatives of thiohydantoin-containing tetrahydro-β-carboline possess activity against influenza virus at late stages of viral cycle without affecting viral neuraminidase

Influenza infection represents a serious challenge for virological surveillance and healthcare systems in all countries globally. Despite obvious success in control of influenza through vaccination and antiviral drug development, this infection remains poorly controlled due to antigenic drift and fast selection of drug-resistant viral variants. The design of novel drugs with alternative targets and mechanisms of action is, therefore, an important goal for medical science worldwide. In the current study, we describe the chemical synthesis of novel tetrahydro-β-carboline derivatives containing a thiohydantoin fragment, as well as their antiviral activity against influenza virus A/Puerto Rico/8/34 (H1N1). In general, the library of compounds was of low toxicity. Of the 23 compounds under investigation, 10 (43.5%) displayed a selectivity index (SI) of 10 or higher, their activity strongly exceeding that of the reference compound rimantadine. The most active compounds have also demonstrated suppressing activity against the phylogenetically distinct influenza virus of type B. These compounds, similar to the reference compound zanamivir, were active at very late stages of the viral cycle (4-6 h postinfection), suggesting interference with processes of virion assembly and budding. However, no direct inhibiting activity against viral neuraminidase has been demonstrated. The results obtained can be considered as a rationale for further structural optimization and study of this group as potential broad-range antivirals effective against influenza viruses.

Potential Broad-Spectrum Antiviral Agents: A Key Arsenal Against Newly Emerging and Reemerging Respiratory RNA Viruses

Respiratory viral infections present significant global health challenges, causing substantial morbidity and mortality, particularly among highly susceptible components of the population. The emergence of pandemics and epidemics, such as those caused by influenza viruses and coronaviruses, emphasizes the urgent need for effective antiviral therapeutics. In this review, we explore the potential of broad-spectrum antiviral agents targeting respiratory RNA viruses, including influenza viruses, coronaviruses, respiratory syncytial virus, human metapneumovirus, human parainfluenza viruses, and rhinoviruses. Various broad-spectrum direct-acting and host-targeting antivirals are discussed, including monoclonal antibodies targeting conserved regions of viral surface proteins, molecules interfering with host cell receptors or viral replication machinery, viral protease inhibitors, siRNA therapies, ribonuclease, and 3D8 scFv. Advancements in host-targeting approaches to reduce resistance and RNA-based therapeutics offer significant potential for combating respiratory viral threats. Despite challenges, broad-spectrum antiviral agents represent a crucial strategy, particularly when specific viral pathogens are unidentified or rapid intervention is essential, such as during pandemics or outbreaks.

Advancements in the development of antivirals against SARS-Coronavirus

Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) caused an outbreak in 2002-2003, spreading to 29 countries with a mortality rate of about 10%. Strict quarantine and infection control methods quickly stopped the spread of the disease. Later research showed that SARS-CoV came from animals (zoonosis) and stressed the possibility of a similar spread from host to human, which was clearly shown by the COVID-19 outbreak. The COVID-19 pandemic, instigated by SARS-CoV-2, has affected 776 million confirmed cases and more than seven million deaths globally as of Sept 15, 2024. The existence of animal reservoirs of coronaviruses continues to pose a risk of re-emergence with improved fitness and virulence. Given the high death rate (up to 70 percent) and the high rate of severe sickness (up to 68.7 percent in long-COVID patients), it is even more critical to identify new therapies as soon as possible. This study combines research on antivirals that target SARS coronaviruses that have been conducted over the course of more than twenty years. It is a beneficial resource that might be useful in directing future studies.

Natural and Synthetic Coumarins as Potential Drug Candidates against SARS-CoV-2/COVID-19

COVID-19, an airborne disease caused by a betacoronavirus named SARS-- CoV-2, was officially declared a pandemic in early 2020, resulting in more than 770 million confirmed cases and over 6.9 million deaths by September 2023. Although the introduction of vaccines in late 2020 helped reduce the number of deaths, the global effort to fight COVID-19 is far from over. While significant progress has been made in a short period, the fight against SARS-CoV-2/COVID-19 and other potential pandemic threats continues. Like AIDS and hepatitis C epidemics, controlling the spread of COVID-19 will require the development of multiple drugs to weaken the virus's resistance to different drug treatments. Therefore, it is essential to continue developing new drug candidates derived from natural or synthetic small molecules. Coumarins are a promising drug design and development scaffold due to their synthetic versatility and unique physicochemical properties. Numerous examples reported in scientific literature, mainly by in silico prospection, demonstrate their potential contribution to the rapid development of drugs against SARS-CoV-2/COVID-19 and other emergent and reemergent viruses.

A Glimpse for the subsistence from pandemic SARS-CoV-2 infection

COVID-19 is an emerging viral pandemic caused by SARS-CoV-2, which is the causative agent of unprecedented disease-causing public health threats globally. Worldwide, this outbreak is wreaking havoc due to failure in risk assessment regarding the urgency of the pandemic. As per the reports, many secondary complications which include neurological, nephrological, gastrointestinal, cardiovascular, immune, and hepatic abnormalities, are linked with COVID -19 infection which is associated with prominent respiratory disorders including pneumonia. Hindering the initial binding of the virus with Angiotensin-converting enzyme 2 (ACE2) through the spike protein is one potential boulevard of monoclonal antibodies. Although some drug regimens and vaccines have shown safety in trials, none have been entirely successful yet. This review highlights, some of the potential antibodies (tocilizumab, Sarilumab, Avdoralimab, Lenzilumab, Interferon (alfa /beta /gamma)) screened against SARS-CoV-2 and the most promising drugs (Favipiravir, Hydroxychloroquine, Niclosamide, Ribavirin, Baricitinib, Remdesivir, Arbidol Losartan, Ritonavir, Lopinavir, Baloxavir, Nitazoxanide, Camostat) in various stages of development with their synthetic protocol and their clinical projects are discussed to counter COVID -19.

Plausible mechanism of drug resistance and side-effects of COVID-19 therapeutics: a bottleneck for its eradication

BACKGROUND

COVID-19 pandemic has turned our world upside down by meddling with our normal lives. While there is no definitive drug against SARS-CoV-2, antiviral drugs that are already in the market, are being repurposed against it, could now complete long-term as well as all age-specific investigations, and they are successful in saving millions of lives. Nevertheless, side-effects are emergingly seen in the patients undergoing treatment, and ineffectiveness is increasingly found due to the emerging notorious variants of the virus. Many of them are also facing serious co-infections including black fungus, Zika, and H1N1 virus to name a few.

OBJECTIVES

Therefore, this review highlights both drug resistance, their side-effects, and the significance for proper and long-term clinical trials of all age groups including children.

METHODS

We have explored and proposed the mechanisms of drug resistance that may arise due to the misuse or overuse of drugs based on available experimental reports.

RESULTS

The review provides solutions to the aforesaid issues of drug-resistance and side-effects by providing combination therapies, ancillary treatments, and other preventive strategies that can be useful in preventing drawbacks thereby curbing COVID-19 or similar future infections to maintain our normal lives.

CONCLUSION

COVID-19 and its long-term effects, if any, can be eradicated with strategic and mindful use of related therapeutics in a controlled manner.

A small molecule compound targeting hemagglutinin inhibits influenza A virus and exhibits broad-spectrum antiviral activity

Influenza A virus (IAV) is a widespread pathogen that poses a significant threat to human health, causing pandemics with high mortality and pathogenicity. Given the emergence of increasingly drug-resistant strains of IAV, currently available antiviral drugs have been reported to be inadequate to meet clinical demands. Therefore, continuous exploration of safe, effective and broad-spectrum antiviral medications is urgently required. Here, we found that the small molecule compound J1 exhibited low toxicity both in vitro and in vivo. Moreover, J1 exhibits broad-spectrum antiviral activity against enveloped viruses, including IAV, respiratory syncytial virus (RSV), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), human coronavirus OC43 (HCoV-OC43), herpes simplex virus type 1 (HSV-1) and HSV-2. In this study, we explored the inhibitory effects and mechanism of action of J1 on IAV in vivo and in vitro. The results showed that J1 inhibited infection by IAV strains, including H1N1, H7N9, H5N1 and H3N2, as well as by oseltamivir-resistant strains. Mechanistic studies have shown that J1 blocks IAV infection mainly through specific interactions with the influenza virus hemagglutinin HA2 subunit, thereby blocking membrane fusion. BALB/c mice were used to establish a model of acute lung injury (ALI) induced by IAV. Treatment with J1 increased survival rates and reduced viral titers, lung index and lung inflammatory damage in virus-infected mice. In conclusion, J1 possesses significant anti-IAV effects in vitro and in vivo, providing insights into the development of broad-spectrum antivirals against future pandemics.

Arbidol, an antiviral drug, identified as a sodium channel blocker with anticonvulsant activity

BACKGROUND AND PURPOSE

Sodium channel blockers (SCBs) have traditionally been utilized as anti-seizure medications by primarily targeting the inactivation process. In a drug discovery project aiming at finding potential anticonvulsants, we have identified arbidol, originally an antiviral drug, as a potent SCB. In order to evaluate its anticonvulsant potential, we have thoroughly examined its biophysical properties as well as its effects on animal seizure models.

EXPERIMENTAL APPROACH

Patch clamp recording was used to investigate the electrophysiological properties of arbidol, as well as the binding and unbinding kinetics of arbidol, carbamazepine and lacosamide. Furthermore, we evaluated the anticonvulsant effects of arbidol using three different seizure models in male mice.

KEY RESULTS

Arbidol effectively suppressed neuronal epileptiform activity by blocking sodium channels. Arbidol demonstrated a distinct mode of action by interacting with both the fast and slow inactivation of Nav1.2 channels compared with carbamazepine and lacosamide. A kinetic study suggested that the binding and unbinding rates might be associated with the specific characteristics of these three drugs. Arbidol targeted the classical binding site of local anaesthetics, effectively inhibited the gain-of-function effects of Nav1.2 epileptic mutations and exhibited varying degrees of anticonvulsant effects in the maximal electroshock model and subcutaneous pentylenetetrazol model but had no effect in the pilocarpine-induced status epilepticus model.

CONCLUSIONS AND IMPLICATIONS

Arbidol shows promising potential as an anticonvulsant agent, providing a unique mode of action that sets it apart from existing SCBs.

Photoredox-Catalyzed Cross-Coupling of In Situ Generated Quinoxalinones with Indoles for the Synthesis of Tertiary Alcohols

A visible light-driven photoredox-catalyzed direct C(sp2)-H functionalization of N-H free indoles with quinoxalinones generated in situ from 2,2-dihydroxy-1H-indene-1,3(2H)-dione and phenylene-1,2-diamines has been reported with the aid of Na2-Eosin Y as the photocatalyst and the Hünig base as the sacrificial electron and proton donor. The reaction provides easy access to a variety of quaternary-centered C-3 selective indole-substituted tertiary alcohols in good yields. Mechanistic studies demonstrated the realization of photoredox-catalyzed in situ quinoxalinone formation and their proton-coupled single electron reduction to the corresponding ketyl radicals followed by cross-coupling with indoles. The potential applications of the synthesized tertiary alcohols in photoacid-catalyzed carbon-carbon and carbon-sulfur bond-forming reactions feature the key findings of the present work.

Fighting the flu: a brief review on anti-influenza agents

The influenza virus causes one of the most prevalent and lethal infectious viral diseases of the respiratory system; the disease progression varies from acute self-limiting mild fever to disease chronicity and death. Although both the preventive and treatment measures have been vital in protecting humans against seasonal epidemics or sporadic pandemics, there are several challenges to curb the influenza virus such as limited or poor cross-protection against circulating virus strains, moderate protection in immune-compromised patients, and rapid emergence of resistance. Currently, there are four US-FDA-approved anti-influenza drugs to treat flu infection, viz. Rapivab, Relenza, Tamiflu, and Xofluza. These drugs are classified based on their mode of action against the viral replication cycle with the first three being Neuraminidase inhibitors, and the fourth one targeting the viral polymerase. The emergence of the drug-resistant strains of influenza, however, underscores the need for continuous innovation towards development and discovery of new anti-influenza agents with enhanced antiviral effects, greater safety, and improved tolerability. Here in this review, we highlighted commercially available antiviral agents besides those that are at different stages of development including under clinical trials, with a brief account of their antiviral mechanisms.

Antiviral drugs in animal-derived matrices: A review

The ban of antiviral drugs in food-producing animals in several parts of the world, latest by Commission Delegated Regulation (EU) 2022/1644, has increased the need for food control laboratories to develop analytical methods and perform official controls. However, little is known about antiviral drugs, their use, and its analysis in food-producing animals in the EU. This review aims to provide insights into relevant viruses, antiviral drugs, and animal-derived matrices for analytical method development and monitoring purposes to implement in food control laboratories. For years, animal viruses, such as African swine fever and avian influenza, have caused many outbreaks. Besides, they led to large economic losses due to the applied control measures and a lack of available treatments. Considering these losses and the known effectiveness of authorized human antiviral drugs in different organisms, medicines such as amantadine in Chinese poultry have been misused. Various analytical methods, including screening assays and sensors (published 2016-2023), and mass spectrometry methods (published 2012-2023) have been outlined in this review for the monitoring of antiviral drugs in animal-derived matrices. However, pharmacokinetics information on metabolite formation and distribution of these substances in different animal-derived matrices is incomplete. Additionally, apart from a few countries, there is a lack of available data on the potential misuse of different antiviral drugs in animal-derived matrices. Although a handful of important antiviral drugs, such as influenza, broad-spectrum, antiretroviral, and herpes drugs, and animal-derived matrices, such as chicken muscle, are identified, the priority of the scope should be further specified by closing the aforementioned gaps.

Protective Effect of Indole-3-Aldehyde in Murine COVID-19-Associated Pulmonary Aspergillosis

Aspergillus fumigatus is an environmental fungus recently included in the fungal high-priority pathogens by the World Health Organization. While immunodeficiency and/or pre-existing lung damage represent a well-recognized fertile ground for fungal growth, it is increasingly being recognized that severe viral infections may similarly favor A. fumigatus colonization and infection, as recently experienced in the Coronavirus disease 2019 (COVID-19) pandemic. Herein, in a murine model of COVID-19-associated pulmonary aspergillosis (CAPA), obtained by the concomitant exposure to the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Spike protein and A. fumigatus conidia, we found that the microbial compound indole-3-aldehyde (3-IAld) was able to ameliorate CAPA by working at multiple levels during viral infection and fungal superinfection, including epithelial barrier protection, promotion of antiviral responses, and limiting viral replication. As a consequence, 3-IAld limited the pathogenic sequelae of fungal superinfection as revealed by the controlled fungal burden and restrained inflammatory pathology. These results point to indole compounds as potential agents to prevent CAPA.

Toxic mechanisms of the antiviral drug arbidol on microalgae in algal bloom water at transcriptomic level

Increasing antivirals in surface water caused by their excessive consumption pose serious threats to aquatic organisms. Our recent research found that the input of antiviral drug arbidol to algal bloom water can induce acute toxicity to the growth and metabolism of Microcystis aeruginosa, resulting in growth inhibition, as well as decrease in chlorophyll and ATP contents. However, the toxic mechanisms involved remained obscure, which were further investigated through transcriptomic analysis in this study. The results indicated that 885-1248 genes in algae were differentially expressed after exposure to 0.01-10.0 mg/L of arbidol, with the majority being down-regulated. Analysis of commonly down-regulated genes found that the cellular response to oxidative stress and damaged DNA bonding were affected, implying that the stress defense system and DNA repair function of algae might be damaged. The down-regulation of genes in porphyrin metabolism, photosynthesis, carbon fixation, glycolysis, tricarboxylic acid cycle, and oxidative phosphorylation might inhibit chlorophyll synthesis, photosynthesis, and ATP supply, thereby hindering the growth and metabolism of algae. Moreover, the down-regulation of genes related to nucleotide metabolism and DNA replication might influence the reproduction of algae. These findings provided effective strategies to elucidate toxic mechanisms of contaminants on algae in algal bloom water.

Drug repurposing for respiratory infections

Respiratory infections such as Coronavirus disease 2019 are a substantial worldwide health challenge, frequently resulting in severe sickness and death, especially in susceptible groups. Conventional drug development for respiratory infections faces obstacles such as extended timescales, substantial expenses, and the rise of resistance to current treatments. Drug repurposing is a potential method that has evolved to quickly find and reuse existing medications for treating respiratory infections. Drug repurposing utilizes medications previously approved for different purposes, providing a cost-effective and time-efficient method to tackle pressing medical needs. This chapter summarizes current progress and obstacles in repurposing medications for respiratory infections, focusing on notable examples of repurposed pharmaceuticals and their probable modes of action. The text also explores the significance of computational approaches, high-throughput screening, and preclinical investigations in identifying potential candidates for repurposing. The text delves into the significance of regulatory factors, clinical trial structure, and actual data in confirming the effectiveness and safety of repurposed medications for respiratory infections. Drug repurposing is a valuable technique for quickly increasing the range of treatments for respiratory infections, leading to better patient outcomes and decreasing the worldwide disease burden.

Modular Biomimetic Strategy Enables Discovery and SAR Exploration of Oxime Macrocycles as Influenza A Virus (H1N1) Inhibitors

Although vaccination remains the prevalent prophylactic means for controlling Influenza A virus (IAV) infections, novel structural antivirus small-molecule drugs with new mechanisms of action for treating IAV are highly desirable. Herein, we describe a modular biomimetic strategy to expeditiously achieve a new class of macrocycles featuring oxime, which might target the hemagglutinin (HA)-mediated IAV entry into the host cells. SAR analysis revealed that the size and linker of the macrocycles play an important role in improving potency. Particularly, as a 14-membered macrocyclic oxime, 37 exhibited potent inhibitory activity against IAV H1N1 with an EC50 value of 23 nM and low cytotoxicity, which alleviated cytopathic effects and protected cell survival obviously after H1N1 infection. Furthermore, 37 showed significant synergistic activity with neuraminidase inhibitor oseltamivir in vitro.

Retracted and republished from: "The current state of research on influenza antiviral drug development: drugs in clinical trial and licensed drugs"

Influenza viruses (IVs) threaten global human health due to the high morbidity, infection, and mortality rates. Currently, the influenza drugs recommended by the Food and Drug Administration are oseltamivir, zanamivir, peramivir, and baloxavir marboxil. These recommended antivirals are currently effective for major subtypes of IVs as the compounds target conserved domains in neuraminidase or polymerase acidic (PA) protein. However, this trend may gradually change due to the selection of antiviral drugs and the natural evolution of IVs. Therefore, there is an urgent need to develop drugs related to the treatment of influenza to deal with the next pandemic. Here, we summarized the cutting-edge research in mechanism of action, inhibitory activity, and clinical efficacy of drugs that have been approved and drugs that are still in clinical trials for influenza treatment. We hope this review will provide up-to-date and comprehensive information on influenza antivirals and generate hypotheses for screens and development of new broad-spectrum influenza drugs in the near future.

Medicinal chemistry strategies toward broad-spectrum antiviral agents to prevent next pandemics

The pandemic and tremendous impact of severe acute respiratory syndrome coronavirus 2 alert us, despite great achievements in prevention and control of infectious diseases, we still lack universal and powerful antiviral strategies to rapidly respond to the potential threat of serious infectious disease. Various highly contagious and pathogenic viruses, as well as other unknown viruses may appear or reappear in human society at any time, causing a catastrophic epidemic. Developing broad-spectrum antiviral drugs with high security and efficiency is of great significance for timely meeting public health emergency and protecting the lives and health of the people. Hence, in this review, we summarized diverse broad-spectrum antiviral targets and corresponding agents from a medicinal chemistry prospective, compared the pharmacological advantages and disadvantages of different targets, listed representative agents, showed their structures, pharmacodynamics and pharmacokinetics characteristics, and conducted a critical discussion on their development potential, in the hope of providing up-to-date guidance for the development of broad-spectrum antivirals and perspectives for applications of antiviral therapy.

Entry inhibitors as arenavirus antivirals

Arenaviruses belonging to the Arenaviridae family, genus mammarenavirus, are enveloped, single-stranded RNA viruses primarily found in rodent species, that cause severe hemorrhagic fever in humans. With high mortality rates and limited treatment options, the search for effective antivirals is imperative. Current treatments, notably ribavirin and other nucleoside inhibitors, are only partially effective and have significant side effects. The high lethality and lack of treatment, coupled with the absence of vaccines for all but Junín virus, has led to the classification of these viruses as Category A pathogens by the Centers for Disease Control (CDC). This review focuses on entry inhibitors as potential therapeutics against mammarenaviruses, which include both New World and Old World arenaviruses. Various entry inhibition strategies, including small molecule inhibitors and neutralizing antibodies, have been explored through high throughput screening, genome-wide studies, and drug repurposing. Notable progress has been made in identifying molecules that target receptor binding, internalization, or fusion steps. Despite promising preclinical results, the translation of entry inhibitors to approved human therapeutics has faced challenges. Many have only been tested in in vitro or animal models, and a number of candidates showed efficacy only against specific arenaviruses, limiting their broader applicability. The widespread existence of arenaviruses in various rodent species and their potential for their zoonotic transmission also underscores the need for rapid development and deployment of successful pan-arenavirus therapeutics. The diverse pool of candidate molecules in the pipeline provides hope for the eventual discovery of a broadly effective arenavirus antiviral.

A guide to COVID-19 antiviral therapeutics: a summary and perspective of the antiviral weapons against SARS-CoV-2 infection

Antiviral therapies are integral in the fight against SARS-CoV-2 (i.e. severe acute respiratory syndrome coronavirus 2), the causative agent of COVID-19. Antiviral therapeutics can be divided into categories based on how they combat the virus, including viral entry into the host cell, viral replication, protein trafficking, post-translational processing, and immune response regulation. Drugs that target how the virus enters the cell include: Evusheld, REGEN-COV, bamlanivimab and etesevimab, bebtelovimab, sotrovimab, Arbidol, nitazoxanide, and chloroquine. Drugs that prevent the virus from replicating include: Paxlovid, remdesivir, molnupiravir, favipiravir, ribavirin, and Kaletra. Drugs that interfere with protein trafficking and post-translational processing include nitazoxanide and ivermectin. Lastly, drugs that target immune response regulation include interferons and the use of anti-inflammatory drugs such as dexamethasone. Antiviral therapies offer an alternative solution for those unable or unwilling to be vaccinated and are a vital weapon in the battle against the global pandemic. Learning more about these therapies helps raise awareness in the general population about the options available to them with respect to aiding in the reduction of the severity of COVID-19 infection. In this 'A Guide To' article, we provide an in-depth insight into the development of antiviral therapeutics against SARS-CoV-2 and their ability to help fight COVID-19.

Indole-containing pharmaceuticals: targets, pharmacological activities, and SAR studies

Indole is a prestigious heterocyclic skeleton widely found in both naturally-occurring and biologically-active compounds. Pharmaceutical agents containing an indole skeleton in their framework possess a wide range of pharmacological properties, including antiviral, antitumor, analgesic, and other therapeutic activities, and many indole-containing drugs have been proven to have excellent pharmacokinetic and pharmacological effects. Over the past few decades, the FDA has approved over 40 indole-containing drugs for the treatment of various clinical conditions, and the development of indole-related drugs has attracted significant attention from medicinal chemists. This review aims to provide an overview of all the approved drugs that contain an indole nucleus, focusing on their targets, pharmacological activities, and SAR studies.

The environmental risks of antiviral drug arbidol in eutrophic lake: Interactions with Microcystis aeruginosa

The environmental risks resulting from the increasing antivirals in water are largely unknown, especially in eutrophic lakes, where the complex interactions between algae and drugs would alter hazards. Herein, the environmental risks of the antiviral drug arbidol towards the growth and metabolism of Microcystis aeruginosa were comprehensively investigated, as well as its biotransformation mechanism by algae. The results indicated that arbidol was toxic to Microcystis aeruginosa within 48 h, which decreased the cell density, chlorophyll-a, and ATP content. The activation of oxidative stress increased the levels of reactive oxygen species, which caused lipid peroxidation and membrane damage. Additionally, the synthesis and release of microcystins were promoted by arbidol. Fortunately, arbidol can be effectively removed by Microcystis aeruginosa mainly through biodegradation (50.5% at 48 h for 1.0 mg/L arbidol), whereas the roles of bioadsorption and bioaccumulation were limited. The biodegradation of arbidol was dominated by algal intracellular P450 enzymes via loss of thiophenol and oxidation, and a higher arbidol concentration facilitated the degradation rate. Interestingly, the toxicity of arbidol was reduced after algal biodegradation, and most of the degradation products exhibited lower toxicity than arbidol. This study revealed the environmental risks and transformation behavior of arbidol in algal bloom waters.

Arbidol attenuates liver fibrosis and activation of hepatic stellate cells by blocking TGF-β1 signaling

Chronic liver diseases (CLD) impact over 800 million people globally, causing about 2 million deaths annually. Arbidol (ARB), an indole-derivative used to treat influenza virus infection, was extensively used during COVID-19 pandemic in China. In recent years, studies have shown that ARB, compared to other antiviral drugs, exhibits greater liver-protective efficacy, indicating a potential hepatoprotective effect beyond its antiviral activity. However, the mechanism remains unclear. In this study, we investigated the impact of ARB on liver injury/fibrosis in bile duct ligated (BDL) mice and its effect on spontaneous and transforming growth factor β1 (TGF-β1)-induced activation of primary cultured hepatic stellate cells (HSCs). Oral administration of ARB significantly ameliorated BDL-induced liver injury/fibrosis as reflected by decreased serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), reduced collagen deposition, and diminished mRNA expression of fibrosis markers. ARB notably inhibited spontaneous and TGF-β1-induced activation of primary cultured HSCs. Moreover, ARB also drastically attenuated mRNA expression levels of platelet-derived growth factor receptor (Pdgfr), transforming growth factor-beta receptor (Tgfbr) 1, Tgfbr2, matrix metalloproteinase (Mmp)-2, and Mmp-9 in activated HSCs. We further demonstrate that ARB mitigated Smad2/3 phosphorylation in both TGF-β1 treated HSCs and BDL mice. These data together demonstrate that the therapeutic efficacy of ARB on liver fibrosis is independent of its antiviral activity and likely is achieved by blocking TGF-β1 signaling-mediated HSC activation.

Effect of anti-COVID-19 drugs on patients with cancer

The clinical treatment of patients with cancer who are also diagnosed with coronavirus disease (COVID-19) has been a challenging issue since the outbreak of COVID-19. Therefore, it is crucial to understand the effects of commonly used drugs for treating COVID-19 in patients with cancer. Hence, this review aims to provide a reference for the clinical treatment of patients with cancer to minimize the losses caused by the COVID-19 pandemic. In this study, we also focused on the relationship between COVID-19, commonly used drugs for treating COVID-19, and cancer. We specifically investigated the effect of these drugs on tumor cell proliferation, migration, invasion, and apoptosis. The potential mechanisms of action of these drugs were discussed and evaluated. We found that most of these drugs showed inhibitory effects on tumors, and only in a few cases had cancer-promoting effects. Furthermore, inappropriate usage of these drugs may lead to irreversible kidney and heart damage. Finally, we have clarified the use of different drugs, which can provide useful guidance for the clinical treatment of cancer patients diagnosed with COVID-19.

Drugs targeting structural and nonstructural proteins of the chikungunya virus: A review

Chikungunya virus (CHIKV) is a single positive-stranded RNA virus of the Togaviridae family and Alphavirus genus, with a typical lipid bilayer envelope structure, and is the causative agent of human chikungunya fever (CHIKF). The U.S. Food and Drug Administration has recently approved the first chikungunya vaccine, Ixchiq; however, vaccination rates are low, and CHIKF is prevalent owing to its periodic outbreaks. Thus, developing effective anti-CHIKV drugs in clinical settings is imperative. Viral proteins encoded by the CHIKV genome play vital roles in all stages of infection, and developing therapeutic agents that target these CHIKV proteins is an effective strategy to improve CHIKF treatment efficacy and reduce mortality rates. Therefore, in the present review article, we aimed to investigate the basic structure, function, and replication cycle of CHIKV and comprehensively outline the current status and future advancements in anti-CHIKV drug development, specifically targeting nonstructural (ns) proteins, including nsP1, nsP2, nsP3, and nsP4 and structural proteins such as capsid (C), E3, E2, 6K, and E1.

Preclinical and Clinical Investigations of Potential Drugs and Vaccines for COVID-19 Therapy: A Comprehensive Review With Recent Update

The COVID-19 pandemic-led worldwide healthcare crisis necessitates prompt societal, ecological, and medical efforts to stop or reduce the rising number of fatalities. Numerous mRNA based vaccines and vaccines for viral vectors have been licensed for use in emergencies which showed 90% to 95% efficacy in preventing SARS-CoV-2 infection. However, safety issues, vaccine reluctance, and skepticism remain major concerns for making mass vaccination a successful approach to treat COVID-19. Hence, alternative therapeutics is needed for eradicating the global burden of COVID-19 from developed and low-resource countries. Repurposing current medications and drug candidates could be a more viable option for treating SARS-CoV-2 as these therapies have previously passed a number of significant checkpoints for drug development and patient care. Besides vaccines, this review focused on the potential usage of alternative therapeutic agents including antiviral, antiparasitic, and antibacterial drugs, protease inhibitors, neuraminidase inhibitors, and monoclonal antibodies that are currently undergoing preclinical and clinical investigations to assess their effectiveness and safety in the treatment of COVID-19. Among the repurposed drugs, remdesivir is considered as the most promising agent, while favipiravir, molnupiravir, paxlovid, and lopinavir/ritonavir exhibited improved therapeutic effects in terms of elimination of viruses. However, the outcomes of treatment with oseltamivir, umifenovir, disulfiram, teicoplanin, and ivermectin were not significant. It is noteworthy that combining multiple drugs as therapy showcases impressive effectiveness in managing individuals with COVID-19. Tocilizumab is presently employed for the treatment of patients who exhibit COVID-19-related pneumonia. Numerous antiviral drugs such as galidesivir, griffithsin, and thapsigargin are under clinical trials which could be promising for treating COVID-19 individuals with severe symptoms. Supportive treatment for patients of COVID-19 may involve the use of corticosteroids, convalescent plasma, stem cells, pooled antibodies, vitamins, and natural substances. This study provides an updated progress in SARS-CoV-2 medications and a crucial guide for inventing novel interventions against COVID-19.

Simultaneous quantification method for multiple antiviral drugs in serum using isotope dilution liquid chromatography-tandem mass spectrometry

We describe the simultaneous quantification of six antiviral drugs in serum based on high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). The target drugs-hydroxychloroquine, chloroquine, favipiravir, umifenovir, ritonavir, and lopinavir-were extracted and purified from serum with 75 % v/v methanol as the precipitant reagent. The six analytes were clearly separated within 15 min using gradient elution and mixed-mode stationary phase. The measurement accuracy and precision were assured by adopting isotopes as internal standards. The optimized measurement procedure was strictly validated in linearity, sensitivity, accuracy, and precision. To confirm the robustness of the method in matrix, the method was additionally applied to various types of serum, namely hyperlipidemic and hyperglycemic serum. The method was then applied to assess the stability of the drugs in serum in order to set sample handling and storage guides for laboratory testing. Lastly, the method was implemented in different LC-MS systems to confirm its applicability across similar equipment commonly used in clinical testing laboratories. The overall results show that the optimized protocol is suitable for the accurate, simultaneous quantification of the six antiviral drugs in serum, and it is anticipated to satisfactorily serve as a reference protocol for the analysis of a wide range of other antiviral drugs for drug monitoring with various purposes.

Sunlight-induced degradation of COVID-19 antivirals arbidol in natural aquatic environments: Mechanisms, pathways and toxicity

Insights into COVID-19 antivirals' environmental fate and ecological risk are urgently required due to their increasing concentrations in aquatic environments, which have rarely been studied. Herein, we first investigated the photochemical transformation and the resulting alterations in toxicity of arbidol, an antiviral drug with relatively higher toxicity. The photolysis of arbidol was rapid with a rate constant of 0.106 min-1 due to its superior ultraviolet light absorption, in which the direct photolysis was predominated with a contribution of 91.5%. Despite its substantial photolysis, only 14.45% of arbidol was mineralized after 100 min, implying that arbidol and its products might have a long-term impact on aquatic environment. It was inferred that arbidol was photolyzed mainly via the loss of thiophenol, bromine, and alkylamine, based on twelve photolytic products identified. Notably, the experimental results demonstrated that the photolysis process increased the acute toxicity of arbidol, and the toxicity prediction indicated that the ecotoxicity of two photolytic products was very high with LC50 values below 0.1 mg/L. Due to the co-effect of multiple constituents, the photolytic rate observed in wastewater treatment plant effluent and in river water was comparable to that in ultra-pure water, while it was slightly enhanced in lake water. The presence of dissolved organic matter suppressed arbidol photolysis, while NO3- exhibited a promotion effect. These results would be of great significance to assess the fate and risk of COVID-19 antivirals in natural aquatic environments.

Influenza virus cell entry and targeted antiviral development

Influenza virus infection is currently one of the most prevalent and transmissible diseases in the world causing local outbreaks every year. It has the potential to cause devastating global pandemics as well. The development of anti-influenza drugs possessing novel mechanisms of action is urgently needed to control the spread of influenza infections; thus, drugs that inhibit influenza virus entry into target cells are emerging as a hot research topic. In addition to discussing the biological significance of hemagglutinin in viral replication, this article provides recent updates on the natural products, small molecules, proteins, peptides, and neutralizing antibody-like proteins that have anti-influenza potency.

The current state of research on influenza antiviral drug development: drugs in clinical trial and licensed drugs

Influenza viruses (IVs) threaten global human health due to the high morbidity, infection, and mortality rates. Currently, the influenza drugs recommended by the FDA are oseltamivir, zanamivir, peramivir, and baloxavir marboxil. Notably, owing to the high variability of IVs, no drug exists that can effectively treat all types and subtypes of IVs. Moreover, the current trend of drug resistance is likely to continue as the viral genome is constantly mutating. Therefore, there is an urgent need to develop drugs related to the treatment of influenza to deal with the next pandemic. Here, we summarized the cutting-edge research in mechanism of action, inhibitory activity, and clinical efficacy of drugs that have been approved and drugs that are still in clinical trials for influenza treatment. We hope this review will provide up-to-date and comprehensive information on influenza antivirals and generate hypotheses for screens and development of new broad-spectrum influenza drugs in the near future.

Indole-Based Compounds as Potential Drug Candidates for SARS-CoV-2

The COVID-19 pandemic has posed a significant threat to society in recent times, endangering human health, life, and economic well-being. The disease quickly spreads due to the highly infectious SARS-CoV-2 virus, which has undergone numerous mutations. Despite intense research efforts by the scientific community since its emergence in 2019, no effective therapeutics have been discovered yet. While some repurposed drugs have been used to control the global outbreak and save lives, none have proven universally effective, particularly for severely infected patients. Although the spread of the disease is generally under control, anti-SARS-CoV-2 agents are still needed to combat current and future infections. This study reviews some of the most promising repurposed drugs containing indolyl heterocycle, which is an essential scaffold of many alkaloids with diverse bio-properties in various biological fields. The study also discusses natural and synthetic indole-containing compounds with anti-SARS-CoV-2 properties and computer-aided drug design (in silico studies) for optimizing anti-SARS-CoV-2 hits/leads.

Multicenter, randomized controlled, open label evaluation of the efficacy and safety of arbidol hydrochloride tablets in the treatment of influenza-like cases

OBJECTIVE

To study the efficacy and safety of arbidol hydrochloride tablets as a treatment for influenza-like diseases.

METHODS

In this multicenter, randomized, controlled, open label study, a total of 412 influenza-like cases were collected from 14 hospitals in seven regions of Hebei Province from September 2021 to March 2022. Patients were randomly divided into two groups. The control group (n = 207) were administered oseltamivir phosphate capsules for five days and the experimental group (n = 205) were administered arbidol hydrochloride tablets for five days. The primary endpoint was the time to normal body temperature, and the secondary endpoints included the time to remission of influenza symptoms, incidence of influenza-like complications, and incidence of adverse reactions.

RESULTS

Before treatment, there was no significant difference between the two groups in general conditions, blood routine, body temperature, or symptom severity. After treatment, there was no significant difference between the groups in the mean time to fever remission (59.24 h ± 25.21 vs. 61.05 h ± 29.47) or the mean time to remission of influenza symptoms (57.31 h ± 30.19 vs. 62.02 h ± 32.08). Survival analyses using Log-rank and Wilcoxon bilateral tests showed that there was no significant difference in fever relief time or influenza symptom relief time between the two groups. Regarding the incidence of complications and adverse events, there was only one case of tracheitis, one case of nausea, one case of vomiting, and one case of dizziness in the control group. In the experimental group, there was one case of nausea, one case of vomiting, and one case of drowsiness. In addition, one patient in the control group was hospitalized for urinary calculi.

CONCLUSION

There was no significant difference between the patients with influenza-like cases treated with arbidol hydrochloride tablets and those treated with oseltamivir phosphate capsules. Further, the patients treated with arbidol hydrochloride tablets had fewer adverse reactions, and thus, the tablets were safe to use.

Arbidol increases the survival rate by mitigating inflammation in suckling mice infected with human coronavirus OC43 virus

Human coronavirus OC43 (HCoV-OC43) often causes common cold and is able to neuroinvasive, but it can also induce lower respiratory tract infections (LRTI) especially in children and the elderly adults with underlying diseases. HCoV-OC43 infections currently have no approved antiviral treatment. Arbidol (ARB) is a broad-spectrum antiviral and is an antiviral medication for the treatment of influenza used in Russia and China. Due to its multiple mechanisms of action, such as inhibition of viral fusion and entry, immunomodulation, and modulation of host cell signaling pathways, ARB has the potential to be an effective treatment option for viral infections. Therefore, the study aims to investigate the activities of ARB against HCoV-OC43 infections. Suckling mice were infected with HCoV-OC43 and treated with ARB (50, 25 and 12.5 mg/kg/d) by gavage once daily for 4 days. the survival rates and body weight were recorded, the viral titer was measured by real-time quantitative polymerase chain reaction, cytokine levels were measured by Bio-Plex assays. Histopathological changes of the lungs and brain were analyzed. Our results show ARB increased the survival rate, reduced viral copy numbers in the lung, mitigated pro-inflammatory cytokine production, and improved brain and lung histopathology significantly without any significant toxicity or side effects in vivo. Our results suggest ARB could be a promising approach for the prevention and treatment of HCoV-OC43 while further studies are needed to address these possibilities and the underlying mechanism.

Arbidol: The current demand, strategies, and antiviral mechanisms

BACKGROUND

High morbidity and mortality of influenza virus infection have made it become one of the most lethal diseases threatening public health; the lack of drugs with strong antiviral activity against virus strains exacerbates the problem.

METHODS

Two independent researchers searched relevant studies using Embase, PubMed, Web of Science, Google Scholar, and MEDLINE databases from its inception to December 2022.

RESULTS

Based on the different antiviral mechanisms, current antiviral strategies can be mainly classified into virus-targeting approaches such as neuraminidase inhibitors, matrix protein 2 ion channel inhibitors, polymerase acidic protein inhibitors and other host-targeting antivirals. However, highly viral gene mutation has underscored the necessity of novel antiviral drug development. Arbidol (ARB) is a Russian-made indole-derivative small molecule licensed in Russia and China for the prevention and treatment of influenza and other respiratory viral infections. ARB also has inhibitory effects on many other viruses such as severe acute respiratory syndrome coronavirus 2, Coxsackie virus, respiratory syncytial virus, Hantaan virus, herpes simplex virus, and hepatitis B and C viruses. ARB is a promising drug which can not only exert activity against virus at different steps of virus replication cycle, but also directly target on hosts before infection to prevent virus invasion.

CONCLUSION

ARB is a broad-spectrum antiviral drug that inhibits several viruses in vivo and in vitro, with high safety profile and low resistance; the antiviral mechanisms of ARB deserve to be further explored and more high-quality clinical studies are required to establish the efficacy and safety of ARB.

Potential treatments of COVID-19: Drug repurposing and therapeutic interventions

The coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The infection is caused when Spike-protein (S-protein) present on the surface of SARS-CoV-2 interacts with human cell surface receptor, Angiotensin-converting enzyme 2 (ACE2). This binding facilitates SARS-CoV-2 genome entry into the human cells, which in turn causes infection. Since the beginning of the pandemic, many different therapies have been developed to combat COVID-19, including treatment and prevention. This review is focused on the currently adapted and certain other potential therapies for COVID-19 treatment, which include drug repurposing, vaccines and drug-free therapies. The efficacy of various treatment options is constantly being tested through clinical trials and in vivo studies before they are made medically available to the public.

Revisiting the COVID-19 Pandemic: An Insight into Long-Term Post-COVID Complications and Repurposing of Drugs

SARS-CoV-2 is a highly contagious and dangerous coronavirus that has been spreading around the world since late December 2019. Severe COVID-19 has been observed to induce severe damage to the alveoli, and the slow loss of lung function led to the deaths of many patients. Scientists from all over the world are now saying that SARS-CoV-2 can spread through the air, which is a very frightening prospect for humans. Many scientists thought that this virus would evolve during the first wave of the pandemic and that the second wave of reinfection with the coronavirus would also be very dangerous. In late 2020 and early 2021, researchers found different genetic versions of the SARS-CoV-2 virus in many places around the world. Patients with different types of viruses had different symptoms. It is now evident from numerous case studies that many COVID-19 patients who are released from nursing homes or hospitals are more prone to developing multi-organ dysfunction than the general population. Understanding the pathophysiology of COVID-19 and its impact on various organ systems is crucial for developing effective treatment strategies and managing long-term health consequences. The case studies highlighted in this review provide valuable insights into the ongoing health concerns of individuals affected by COVID-19.

A Comparison of Etiology, Pathogenesis, Vaccinal and Antiviral Drug Development between Influenza and COVID-19

Influenza virus and coronavirus, two kinds of pathogens that exist widely in nature, are common emerging pathogens that cause respiratory tract infections in humans. In December 2019, a novel coronavirus SARS-CoV-2 emerged, causing a severe respiratory infection named COVID-19 in humans, and raising a global pandemic which has persisted in the world for almost three years. Influenza virus, a seasonally circulating respiratory pathogen, has caused four global pandemics in humans since 1918 by the emergence of novel variants. Studies have shown that there are certain similarities in transmission mode and pathogenesis between influenza and COVID-19, and vaccination and antiviral drugs are considered to have positive roles as well as several limitations in the prevention and control of both diseases. Comparative understandings would be helpful to the prevention and control of these diseases. Here, we review the study progress in the etiology, pathogenesis, vaccine and antiviral drug development for the two diseases.

Antiviral Approaches against Influenza Virus

Preventing and controlling influenza virus infection remains a global public health challenge, as it causes seasonal epidemics to unexpected pandemics. These infections are responsible for high morbidity, mortality, and substantial economic impact. Vaccines are the prophylaxis mainstay in the fight against influenza. However, vaccination fails to confer complete protection due to inadequate vaccination coverages, vaccine shortages, and mismatches with circulating strains. Antivirals represent an important prophylactic and therapeutic measure to reduce influenza-associated morbidity and mortality, particularly in high-risk populations. Here, we review current FDA-approved influenza antivirals with their mechanisms of action, and different viral- and host-directed influenza antiviral approaches, including immunomodulatory interventions in clinical development. Furthermore, we also illustrate the potential utility of machine learning in developing next-generation antivirals against influenza.

Base-mediated chalcogenoaminative annulation of 2-alkynylanilines for direct access to 3-sulfenyl/selenyl-1H-indoles

An efficient and transition metal-free synthesis of 3-sulfenyl/selenyl-1H-indoles via a base-assisted chalcogenoaminative annulation of 2-alkynyl aniline with disulfides/diselenides is described. A series of 2-alkynylanilines were found compatible with dichalcogenides in this transformation providing 3-sulfenyl/selenyl-1H-indoles in good to excellent yields. The presented methodology has the advantages of easily available raw materials, functional group tolerance, and a wide range of substrates that provide access to 3-sulfenylindoles and 3-selenylindoles.

Real-world experience of arbidol for Omicron variant of SARS-CoV-2

Background

At a crucial time with the rapid spread of Omicron severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus variant globally, we conducted a study to evaluate the efficacy and safety of arbidol tablets in the treatment of this variant.

Methods

From Mar 26 to April 26, 2022, we conducted a prospective, open-labeled, controlled, and investigator-initiated trial involving adult patients with confirmed Omicron variant infection. Patients with asymptomatic or mild clinical status were stratified 1:2 to receive either standard-of-care (SOC) or SOC plus arbidol tablets (oral administration of 200 mg per time, three times a day for 5 days). The primary endpoint was the negative conversion rate within the first week.

Results

A total of 367 patients were enrolled in the study; 246 received arbidol tablet treatment, and 121 were in the control group. The negative conversion rate of SARS-CoV-2 within the first week in patients receiving arbidol tablets was significantly higher than that of the SOC group [47.2% (116/246) vs. 35.5% (43/121); odds ratio (OR), 1.619; 95% confidence interval (CI): 1.034-2.535; P=0.035]. Compared to those in the SOC group, patients receiving arbidol tablets had a shorter negative conversion time [median 8.3 vs. 10.0 days; hazard ratio (HR), 0.645; 95% CI: 0.516-0.808; P<0.001], and a shorter duration of hospitalization (median 11.4 vs. 13.7 days; HR, 1.214; 95% CI: 0.966-1.526; P<0.001). Moreover, the addition of arbidol tablets led to better recovery of declined blood lymphocytes, CD3⁺, CD4⁺, and CD8⁺ cell counts. The most common adverse event (AE) was transaminase elevation in patients treated with arbidol tablets (3/246, 1.2%). No one withdrew from the study due to AEs or disease progression.

Conclusions

As a whole, arbidol may represent an effective and safe treatment in asymptomatic-mild patients suffering from Omicron variant during the pandemic of coronavirus disease 2019 (COVID-19).

Umifenovir Epigenetically Targets the IL-10 Pathway in Therapy against Coxsackievirus B4 Infection

Umifenovir, a broad-spectrum nonnucleoside antiviral drug, has a promising efficacy against coxsackievirus B4 (CVB4) infection, but its mechanism remains unclear. CVB4 is a common human single-stranded RNA virus that belongs to the Picornaviridae family and the Enterovirus genus. Enterovirus can cause severe diseases, such as meningitis, myocarditis, pancreatitis, insulin-dependent diabetes, and several other diseases, in both adults and children. We have previously demonstrated the critical role of interleukin 10 (IL-10) in promoting CVB4 infection and the downregulation of IL-10 by umifenovir. To further explore the underlying mechanisms of umifenovir, we characterized the epigenetic regulation of IL-10 in IL-10 knockout RAW264.7 cells and a BALB/c mouse splenocyte model. Mechanistically, we found that umifenovir inhibited CVB4-activated IL-10 by enhancing the methylation level of the repressive histones H3K9me3 and H3K27me3 while reducing the acetylation level of the activating histone H3K9ac in the promoter region of the IL-10 gene. Furthermore, using a chromosome conformation capture approach, we discovered that CVB4 infection activated the IL-10 gene by forming an intrachromosomal interaction between the IL-10 gene promoter and an intronic enhancer of the downstream MK2 (mitogen-activated protein kinase [MAPK]-activated protein kinase 2 [MAPKAPK2]) gene, a critical component of the p38-MAPK signaling pathway, which is required for IL-10 gene expression. However, umifenovir treatment abolished this spatial conformation and chromatin interaction, thus reducing the continuous expression of IL-10 and subsequent CVB4 replication. In conclusion, this study reveals a novel epigenetic mechanism by which umifenovir controls CVB4 infections, thus laying a theoretical foundation for therapeutic use of umifenovir. IMPORTANCE Viral infections are major threats to human health because of their strong association with a variety of inflammation-related diseases, especially cancer. Many antiviral drugs are performing poorly in treating viral infections. This is probably due to the immunosuppressive effect of highly expressed IL-10, which is caused by viral infection. Umifenovir is a broad-spectrum antiviral drug. Our recent studies showed that umifenovir has a significant inhibitory effect on CVB4 infection and can reduce IL-10 expression caused by CVB4. However, another antiviral drug, rupintrivir, showed good antiviral activity but had no effect on the expression of IL-10. This suggests that the regulation of IL-10 expression is a key part of the antiviral mechanism of umifenovir. Therefore, due to the dual function of the inhibition of CVB4 replication and the regulation of immune antiviral pathway, the mechanism of umifenovir is of great value to study.

Influenza antivirals and their role in pandemic preparedness

Effective antivirals provide crucial benefits during the early phase of an influenza pandemic, when vaccines are still being developed and manufactured. Currently, two classes of viral protein-targeting drugs, neuraminidase inhibitors and polymerase inhibitors, are approved for influenza treatment and post-exposure prophylaxis. Resistance to both classes has been documented, highlighting the need to develop novel antiviral options that may include both viral and host-targeted inhibitors. Such efforts will form the basis of management of seasonal influenza infections and of strategic planning for future influenza pandemics. This review focuses on the two classes of approved antivirals, their drawbacks, and ongoing work to characterize novel agents or combination therapy approaches to address these shortcomings. The importance of these topics in the ongoing process of influenza pandemic planning is also discussed.

COVID-19: A state of art on immunological responses, mutations, and treatment modalities in riposte

Over the last few years, the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) unleashed a global public health catastrophe that had a substantial influence on human physical and mental health, the global economy, and socio-political dynamics. SARS-CoV-2 is a respiratory pathogen and the cause of ongoing COVID-19 pandemic, which testified how unprepared humans are for pandemics. Scientists and policymakers continue to face challenges in developing ideal therapeutic agents and vaccines, while at the same time deciphering the pathology and immunology of SARS-CoV-2. Challenges in the early part of the pandemic included the rapid development of diagnostic assays, vaccines, and therapeutic agents. The ongoing transmission of COVID-19 is coupled with the emergence of viral variants that differ in their transmission efficiency, virulence, and vaccine susceptibility, thus complicating the spread of the pandemic. Our understanding of how the human immune system responds to these viruses as well as the patient groups (such as the elderly and immunocompromised individuals) who are often more susceptible to serious illness have both been aided by this epidemic. COVID-19 causes different symptoms to occur at different stages of infection, making it difficult to determine distinct treatment regimens employed for the various clinical phases of the disease. Unsurprisingly, determining the efficacy of currently available medications and developing novel therapeutic strategies have been a process of trial and error. The global scientific community collaborated to research and develop vaccines at a neck-breaking speed. This review summarises the overall picture of the COVID-19 pandemic, different mutations in SARS-CoV-2, immune response, and the treatment modalities against SARS-CoV-2.