Arbidol: a broad-spectrum antiviral compound that blocks viral fusion

A one-pot multicomponent tandem reaction for the rapid synthesis of 2-amino-3-benzylindoles

The simultaneous introduction of two functional groups into molecules via a one-pot process is of great importance for the synthesis of complex molecules. However, this remains a challenging task due to the need for precise control of regio- and chemo-selectivity. In this paper, we present a novel oxidative cross-dehydrogenation coupling (CDC) reaction that selectively introduces two nucleophiles at the C2,3-positions of indoles, thereby constructing the C-N and C-C bonds simultaneously in one pot. This method offers a streamlined and efficient approach for functionalizing indoles with high selectivity, expanding the synthetic toolbox for the construction of complex organic frameworks.

Targeting Two-Tetrad RNA G-Quadruplex in the SARS-CoV-2 RNA Genome Using Tetraphenylethene Derivatives for Antiviral Therapy

Targeting the specific RNA conformations that are crucial for SARS-CoV-2 replication is a viable antiviral approach. The SARS-CoV-2 genome contains GG repeats capable of forming unstable two-tetrad G-quadruplex (GQ) structures, which exist as a mix of conformations, including hairpin (Hp), intra-, and intermolecular GQs. RGQ-1, originating from the nucleocapsid gene's ORF, adopts a dynamic equilibrium of conformations, including intramolecular hairpin and G-quadruplex (Hp-GQ) structures, as confirmed by CD analysis. In this study, tetraphenylethene (TPE) derivatives were developed to target the Hp-GQ conformational equilibrium of RGQ-1. EMSA, fluorescence spectroscopy, and ITC assays confirmed that two TPE derivatives, TPE-MePy and TPE-Allyl Py, bind to RGQ-1. CD thermal melting experiments indicate that RGQ-1 is stabilized by 8.56 and 12.54 °C in the presence of TPE-MePy and TPE-Allyl Py, respectively. Additionally, luciferase assays demonstrated that TPE derivatives suppressed luciferase activity by 2.2-fold and 3.6-fold, respectively, shifting the HpGQ equilibrium toward the GQ conformation, as suggested by CD spectroscopy. Treatment of SARS-CoV-2-infected A549 cells with TPE derivatives reduced the levels of viral RNA, spikes, and nucleocapsid proteins. To explore their antiviral mechanism, preinfection and postinfection treatments were tested, revealing that the TPE derivatives specifically suppressed the postentry stages of viral replication without affecting viral entry. These findings highlight the therapeutic potential of TPE derivatives in inhibiting key gene expressions critical for SARS-CoV-2 replication.

Accelerating antiviral drug discovery: early hazard detection with a dual zebrafish and cell culture screen of a 403 compound library

The constant emergence of new viral pathogens underscores the need for continually evolving, effective antiviral drugs. A key challenge is identifying compounds that are both efficacious and safe, as many candidates fail during development due to unforeseen toxicity. To address this, the embryonic zebrafish morphology, mortality, and behavior (ZBE) screen and the SYSTEMETRIC® Cell Health Screen (CHS) were employed to evaluate the safety of 403 compounds from the Cayman Antiviral Screening Library. Of these compounds, 114 were FDA-approved, 17 were discontinued, and 97 remained on the market. CHS identified 25% (104 compounds) as toxic, with a Cell Health Index™ (CHI) > 0.5. The embryonic zebrafish model identified an additional 20% as toxic (79), bringing the total to 183. ZBEscreen flagged 19 toxic hits among compounds still on the market, seven of which were also identified by CHS. The combined use of CHS and zebrafish models enhanced hazard detection. Together, CHS and ZBEscreen identified 45.5% of the library as potentially hazardous. Notably, the zebrafish non-hazardous compounds correlated strongly with over-the-counter or prescribed antiviral drugs, confirming their known safety profile. Over 130 hazard-associated compounds warranted further investigation. Using self-organizing maps, six distinct neighborhoods of compound similarity were identified. This dual approach streamlined the early detection of hazards associated with promising leads and is expected to facilitate faster, safer antiviral discovery.

Recent report on indoles as a privileged anti-viral scaffold in drug discovery

In recent years, viral infections such as COVID-19, Zika virus, Nipah virus, Ebola, Influenza, Monkeypox, and Dengue have substantially impacted global health. These outbreaks have led to heightened global health initiatives and collaborative efforts to address and mitigate these significant threats effectively. Thus, developing antiviral treatments and research in this field has become highly important. Heterocycles, particularly indole motifs, have been a valuable resource in drug discovery, as they can be used as treatments or inspire the synthesis of new potent candidates. Indole-containing drugs, such as enfuvirtide (T-20), arbidol, and delavirdine, have demonstrated significant efficacy in treating viral diseases. This review aims to comprehensively assess the latest research and developments in novel indoles as potential scaffolds for antiviral activity. We have compiled detailed information about indoles as potential antivirals by conducting a thorough literature survey from the past ten years. The review includes discussions on synthetic protocols, inhibitory concentrations, SAR study, and computational study. This review shall identify new antiviral indoles that may help to combat new viral threats in the future.

Drug resistance and possible therapeutic options against influenza A virus infection over past years

Influenza A virus infection, commonly known as the flu, has persisted in the community for centuries. Although we have yearly vaccinations to prevent seasonal flu, there remains a dire need for antiviral drugs to treat active infections. The constantly evolving genome of the influenza A virus limits the number of effective antiviral therapeutic options. Over time, antiviral drugs become inefficient due to the development of resistance, as seen with adamantanes, which are now largely ineffective against most circulating strains of the virus. Neuraminidase inhibitors have long been the drug of choice, but due to selection pressure, strains are becoming resistant to this class of drugs. Baloxavir marboxil, a drug with a novel mode of action, can be used against strains resistant to other classes of drugs but is still not available in many countries. Deep research into nanoparticles has shown they are effective as antiviral drugs, opening a new avenue of research to use them as antiviral agents with novel modes of action. As this deadly virus, which has killed millions of people in the past, continues to develop resistance, there is an urgent need for new therapeutic agents with novel modes of action to halt active infections in patients. This review article covers the available therapeutic antiviral drug options with different modes of action, their effectiveness, and resistance to various strains of influenza A virus.

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.

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.

One-pot synthesis, characterization and antiviral properties of new benzenesulfonamide-based spirothiazolidinones

A novel series of benzenesulfonamide substituted spirothiazolidinone derivatives (3a-j) were synthesized, characterized and evaluated for their antiviral activity. The spirocyclic compounds were prepared by the condensation of 4-(aminosulfonyl)-2-methoxybenzohydrazide, appropriate cyclic ketones and 2-mercaptopropionic acid in a one-pot reaction. The structures of the new compounds were established by IR, 1H NMR, 13C NMR (APT), and elemental analysis. The new compounds were evaluated in vitro antiviral activity against influenza A/H1N1, A/H3N2 and B viruses, as well as herpes simplex virus type 1 (HSV-1), respiratory syncytial virus (RSV) and yellow fever virus (YFV). Two derivatives bearing propyl (3d) and tert-butyl (3e) substituents at position 8 of the spiro ring exhibited activity against influenza A/H1N1 virus with EC50 values in the range of 35-45 µM and no cytotoxicity at 100 μM, the highest concentration tested.

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.

Palladium-Catalyzed Reaction of Indolines with Dihydropyrroles: Access to N-Alkylated Indoles

Palladium-catalyzed reaction of indolines with 1-acyl-2,3-dihydro-1H-pyrroles or 1-acyl-2,5-dihydro-1H-pyrroles in air produces N-alkylated indoles. A combination of Pd(CH3CN)2Cl2 and dppf effectively catalyzes the reaction of 1-acyl-2,3-dihydro-1H-pyrroles, and the combination of Pd(CH3CN)2Cl2 and dcypf is more effective for the reaction of 1-acyl-2,5-dihydro-1H-pyrroles. The method has a wide scope of substrates and shows good compatibility of functional groups.

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.

A combination of nirmatrelvir and ombitasvir boosts inhibition of SARS-CoV-2 replication

Antiviral therapeutics are highly effective countermeasures for the treatment of coronavirus disease 2019 (COVID-19). However, development of resistance to antivirals undermines their effectiveness. Combining multiple antivirals during patient treatment has the potential to overcome the evolutionary selective pressure towards antiviral resistance, as well as provide a more robust and efficacious treatment option. The current evidence for effective antiviral combinations to inhibit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication is limited. Here, we demonstrate a combination of nirmatrelvir with ombitasvir, to jointly bring about potent inhibition of SARS-CoV-2 replication. We developed an in vitro 384- well plate cytopathic effect assay for the evaluation of antiviral combinations against Calu-3 cells infected with SARS-CoV-2 and found, that a combination of ombitasvir and nirmatrelvir was synergistic; thereby decreasing the nirmatrelvir IC50 by approx. 16-fold. The increased potency of the nirmatrelvir-ombitasvir combination, over nirmatrelvir alone afforded a greater than 3 log10 reduction in viral titre, which is sufficient to fully prevent the detection of progeny SARS-CoV-2 viral particles at 48 h post infection. The mechanism of this potentiated effect was shown to be, in-part, due to joint inhibition of the 3-chymotrypsin-like protease via a positive allosteric modulation mechanism.

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.

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.

An Update on SARS-CoV-2 Clinical Trial Results-What We Can Learn for the Next Pandemic

The coronavirus disease 2019 (COVID-19) pandemic has claimed over 7 million lives worldwide, providing a stark reminder of the importance of pandemic preparedness. Due to the lack of approved antiviral drugs effective against coronaviruses at the start of the pandemic, the world largely relied on repurposed efforts. Here, we summarise results from randomised controlled trials to date, as well as selected in vitro data of directly acting antivirals, host-targeting antivirals, and immunomodulatory drugs. Overall, repurposing efforts evaluating directly acting antivirals targeting other viral families were largely unsuccessful, whereas several immunomodulatory drugs led to clinical improvement in hospitalised patients with severe disease. In addition, accelerated drug discovery efforts during the pandemic progressed to multiple novel directly acting antivirals with clinical efficacy, including small molecule inhibitors and monoclonal antibodies. We argue that large-scale investment is required to prepare for future pandemics; both to develop an arsenal of broad-spectrum antivirals beyond coronaviruses and build worldwide clinical trial networks that can be rapidly utilised.

Base Metal-Controlled Chemodivergent Cyclization of Propargylamines for the Atom-Economic Synthesis of Nitrogen Heterocycles

Herein, a base metal-enabled chemodivergent cyclization of propargylamines for the atom-economic construction of nitrogen heterocycles has been developed. Due to the different modes of activation of metal to propargylamine, copper-catalyzed 6-endo-dig cyclization generates functionalized 2-substitued quinoline-4-carboxylates, while iron-promoted cascade amino Claisen rearrangement, aromatization, and aza-Michael addition afford diverse 2-substituted indole-3-carboxylate derivatives. Excellent selectivity, broad functional group tolerance, mild conditions, and flexible late-stage functionalization illustrate the high efficiency and synthetic utility of this chemodivergent reaction.

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.

Palladium-catalyzed synthesis of 2,3-disubstituted indoles via arylation of ortho-alkynylanilines with arylsiloxanes

In this study, we report the electrophilic cyclization of N,N-dimethyl-o-alkynylanilines with arylsiloxanes in the presence of [Pd(OAc)2] and Ag2O catalytic system, which leads to the efficient synthesis of indoles, similar to the one that is obtained through Larock indole synthesis. A range of aryl(trimethoxy)silanes with EDGs and EWGs were successfully utilized for the synthesis of a diverse variety of substituted indoles via the cleavage of the C-Si bond. This protocol exhibits good functional group tolerance and wide substrate scope to provide 2,3-diaryl-N-methylindoles in 26-88% yields.

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.

COVID-19: An Overview of SARS-CoV-2 Variants-The Current Vaccines and Drug Development

The world is presently in crisis facing an outbreak of a health-threatening microorganism known as COVID-19, responsible for causing uncommon viral pneumonia in humans. The virus was first reported in Wuhan, China, in early December 2019, and it quickly became a global concern due to the pandemic. Challenges in this regard have been compounded by the emergence of several variants such as B.1.1.7, B.1.351, P1, and B.1.617, which show an increase in transmission power and resistance to therapies and vaccines. Ongoing researches are focused on developing and manufacturing standard treatment strategies and effective vaccines to control the pandemic. Despite developing several vaccines such as Pfizer/BioNTech and Moderna approved by the U.S. Food and Drug Administration (FDA) and other vaccines in phase 4 clinical trials, preventive measures are mandatory to control the COVID-19 pandemic. In this review, based on the latest findings, we will discuss different types of drugs as therapeutic options and confirmed or developing vaccine candidates against SARS-CoV-2. We also discuss in detail the challenges posed by the variants and their effect on therapeutic and preventive interventions.

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.

Molecular Modeling of Viral Type I Fusion Proteins: Inhibitors of Influenza Virus Hemagglutinin and the Spike Protein of Coronavirus

The fusion of viral and cell membranes is one of the basic processes in the life cycles of viruses. A number of enveloped viruses confer fusion of the viral envelope and the cell membrane using surface viral fusion proteins. Their conformational rearrangements lead to the unification of lipid bilayers of cell membranes and viral envelopes and the formation of fusion pores through which the viral genome enters the cytoplasm of the cell. A deep understanding of all the stages of conformational transitions preceding the fusion of viral and cell membranes is necessary for the development of specific inhibitors of viral reproduction. This review systematizes knowledge about the results of molecular modeling aimed at finding and explaining the mechanisms of antiviral activity of entry inhibitors. The first section of this review describes types of viral fusion proteins and is followed by a comparison of the structural features of class I fusion proteins, namely influenza virus hemagglutinin and the S-protein of the human coronavirus.

Metabolism-Guided Selective Androgen Receptor Antagonists: Design, Synthesis, and Biological Evaluation for Activity against Enzalutamide-Resistant Prostate Cancer

A major challenge for new drug discovery in the area of androgen receptor (AR) antagonists lies in predicting the druggable properties that will enable small molecules to retain their potency and stability during further studies in vitro and in vivo. Indole (compound 8) is a first-in-class AR antagonist with very high potency (IC50 = 0.085 μM) but is metabolically unstable. During the metabolic studies described herein, we synthesized new small molecules that exhibit significantly improved stability while retaining potent antagonistic activity for an AR. This structure-activity relationship (SAR) study of more than 50 compounds classified with three classes (Class I, II, and III) and discovered two compounds (32c and 35i) that are potent AR antagonists (e.g., IC50 = 0.021 μM, T1/2 = 120 min for compound 35i). The new antagonists exhibited improved in vivo pharmacokinetics (PK) with high efficacy antiandrogen activity in Hershberger and antiandrogen Enz-Res tumor xenograft models that overexpress AR (LNCaP-AR).

Domino Aza-Michael-SNAr-Heteroaromatization Route to C5-Substituted 1-Alkyl-1H-Indole-3-Carboxylic Esters

A new synthesis of C5-substituted 1-alkyl-1H-indole-3-carboxylic esters is reported. A series of methyl 2-arylacrylate aza-Michael acceptors were prepared with aromatic substitution to activate them towards SNAr reaction. Subsequent reaction with a series of primary amines generated the title compounds. Initially, the sequence was expected to produce indoline products, but oxidative heteroaromatization intervened to generate the indoles. The reaction proceeded under anhydrous conditions in DMF at 23–90 °C using equimolar quantities of the acrylate and the amine with 2 equiv. of K2CO3 to give 61–92% of the indole products. The reaction involves an aza-Michael addition, followed by SNAr ring closure and heteroaromatization. Since the reactions were run under nitrogen, the final oxidation to the indole likely results from reaction with dissolved oxygen in the DMF. Substrates incorporating a 2-arylacrylonitrile proved too reactive to prepare using our protocol. The synthesis of the reaction substrates, their relative reactivities, and mechanistic details of the conversion are discussed.

Design, Synthesis and In Vitro Evaluation of Spirooxindole-Based Phenylsulfonyl Moiety as a Candidate Anti-SAR-CoV-2 and MERS-CoV-2 with the Implementation of Combination Studies

The search for an effective anti-viral to inhibit COVID-19 is a challenge for the specialized scientific research community. This work investigated the anti-coronavirus activity for spirooxindole-based phenylsulfone cycloadducts in a single and combination protocols. The newly designed anti-SARS-CoV-2 therapeutics spirooxindoles synthesized by [3 + 2] cycloaddition reactions represent an efficient approach. One-pot multicomponent reactions between phenyl vinyl sulfone, substituted isatins, and amines afforded highly stereoselective anti-SARS-CoV-2 therapeutics spirooxindoles with three stereogenic centers. Herein, the newly synthesized spirooxindoles were assessed individually against the highly pathogenic human coronaviruses and proved to be highly potent and safer. Interestingly, the synergistic effect by combining the potent, tested spirooxindoles resulted in an improved antiviral activity as well as better host-cell safety. Compounds 4i and 4d represented the most potent activity against MERS-CoV with IC₅₀ values of 11 and 23 µM, respectively. Both compounds 4c and 4e showed equipotent activity with the best IC₅₀ against SARS-CoV-2 with values of 17 and 18 µM, respectively, then compounds 4d and 4k with IC₅₀ values of 24 and 27 µM, respectively. Then, our attention oriented to perform a combination protocol as anti-SARS-CoV-2 for the best compounds with a different binding mode and accompanied with different pharmacophores. Combination of compound 4k with 4c and combination of compounds 4k with 4i proved to be more active and safer. Compounds 4k with 4i displayed IC₅₀ = 3.275 µM and half maximal cytotoxic-concentration CC₅₀ = 11832 µM. MD simulation of the most potential compounds as well as in silico ADMET properties were investigated. This study highlights the potential drug-like properties of spirooxindoles as a cocktail anti-coronavirus protocol.

Selective Iron Catalyzed Synthesis of N-Alkylated Indolines and Indoles

Whereas iron catalysts usually promote catalyzed C3-alkylation of indole derivatives via a borrowing-hydrogen methodology using alcohols as the electrophilic partners, this contribution shows how to switch the selectivity towards N-alkylation. Thus, starting from indoline derivatives, N-alkylation was efficiently performed using a tricarbonyl(cyclopentadienone) iron complex as the catalyst in trifluoroethanol in the presence of alcohols leading to the corresponding N-alkylated indoline derivatives in 31-99 % yields (28 examples). The one-pot, two-step strategy for the selective N-alkylation of indolines is completed by an oxidation to give the corresponding N-alkylated indoles in 31-90 % yields (15 examples). This unprecedented oxidation methodology involves an iron salt catalyst associated with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) and a stoichiometric amount of t-BuOOH at room temperature.

Hemagglutinin Stability Determines Influenza A Virus Susceptibility to a Broad-Spectrum Fusion Inhibitor Arbidol

Understanding mechanisms of resistance to antiviral inhibitors can reveal nuanced features of targeted viral mechanisms and, in turn, lead to improved strategies for inhibitor design. Arbidol is a broad-spectrum antiviral that binds to and prevents the fusion-associated conformational changes in the trimeric influenza A virus (IAV) hemagglutinin (HA). The rate-limiting step during the HA-mediated membrane fusion is the release of the hydrophobic fusion peptides from a conserved pocket on HA. Here, we investigated how destabilizing or stabilizing mutations in or near the fusion peptide affect viral sensitivity to Arbidol. The degree of sensitivity was proportional to the extent of fusion-peptide stability on the prefusion HA: stabilized mutants were more sensitive, and destabilized ones were resistant to Arbidol. Single-virion membrane fusion experiments for representative wild-type (WT) and mutant viruses demonstrated that resistance is a direct consequence of fusion-peptide destabilization not requiring reduced Arbidol binding to HA. Our results support the model whereby the probability of individual HAs extending to engage the target membrane is determined by the composite of two critical forces: a "tug" on the fusion peptide by HA rearrangements near the Arbidol binding site and the key interactions stabilizing the fusion peptide in the prefusion pocket. Arbidol increases and destabilizing mutations decrease the free-energy cost for fusion-peptide release, accounting for the observed resistance. Our findings have broad implications for fusion inhibitor design, viral mechanisms of resistance, and our basic understanding of HA-mediated membrane fusion.

Synthesis and Biological Evaluation of Umifenovir Analogues as Anti-SARS-CoV-2 Agents

The unprecedented novel coronavirus disease 2019 (COVID-19) pandemic is a threat to global health and the economy. Since the outbreak of COVID-19, great effort has been made to reposition existing drugs to shorten development timelines, in addition to vaccine development and drug discovery campaigns. Umifenovir is a broad-spectrum antiviral agent used to treat influenza in China and Russia and is currently undergoing clinical trials for the treatment of COVID-19. In this article, the synthesis of umifenovir analogues and their biological evaluation are reported. The inhibitory activities of analogues against the binding of the spike glycoprotein (S-protein) of the novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) to the ACE2 receptor, which is a possible mode of action for umifenovir to inhibit viral infection, were investigated.

Conserved coronavirus proteins as targets of broad-spectrum antivirals

Coronaviruses are a class of single-stranded, positive-sense RNA viruses that have caused three major outbreaks over the past two decades: Middle East respiratory syndrome-related coronavirus (MERS-CoV), severe acute respiratory syndrome coronavirus (SARS-CoV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). All outbreaks have been associated with significant morbidity and mortality. In this study, we have identified and explored conserved binding sites in the key coronavirus proteins for the development of broad-spectrum direct acting anti-coronaviral compounds and validated the significance of this conservation for drug discovery with existing experimental data. We have identified four coronaviral proteins with highly conserved binding site sequence and 3D structure similarity: PLpro, Mpro, nsp10-nsp16 complex(methyltransferase), and nsp15 endoribonuclease. We have compiled all available experimental data for known antiviral medications inhibiting these targets and identified compounds active against multiple coronaviruses. The identified compounds representing potential broad-spectrum antivirals include: GC376, which is active against six viral Mpro (out of six tested, as described in research literature); mycophenolic acid, which is active against four viral PLpro (out of four); and emetine, which is active against four viral RdRp (out of four). The approach described in this study for coronaviruses, which combines the assessment of sequence and structure conservation across a viral family with the analysis of accessible chemical structure - antiviral activity data, can be explored for the development of broad-spectrum drugs for multiple viral families.

A trial of arbidol hydrochloride in adults with COVID-19

BACKGROUND

To date, there is no effective medicine to treat coronavirus disease 2019 (COVID-19), and the antiviral efficacy of arbidol in the treatment for COVID-19 remained equivocal and controversial. The purpose of this study was to evaluate the efficacy and safety of arbidol tablets in the treatment of COVID-19.

METHODS

This was a prospective, open-label, controlled and multicenter investigator-initiated trial involving adult patients with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Patients were stratified 1:2 to either standard-of-care (SOC) or SOC plus arbidol tablets (oral administration of 200 mg per time, three times a day for 14 days). The primary endpoint was negative conversion of SARS-CoV-2 within the first week. The rates and 95% confidential intervals were calculated for each variable.

RESULTS

A total of 99 patients with laboratory-confirmed SARS-CoV-2 infection were enrolled; 66 were assigned to the SOC plus arbidol tablets group, and 33 to the SOC 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 (70.3% [45/64] vs. 42.4% [14/33]; difference of conversion rate 27.9%; 95% confidence interval [CI], 7.7%-48.1%; P  = 0.008). Compared to those in the SOC group, patients receiving arbidol tablets had a shorter duration of clinical recovery (median 7.0 days vs. 12.0 days; hazard ratio [HR]: 1.877, 95% CI: 1.151-3.060, P = 0.006), symptom of fever (median 3.0 days vs. 12.0 days; HR: 18.990, 95% CI: 5.350-67.410, P < 0.001), as well as hospitalization (median 12.5 days vs. 20.0 days; P < 0.001). Moreover, the addition of arbidol tablets to SOC led to more rapid normalization of declined blood lymphocytes (median 10.0 days vs. 14.5 days; P > 0.05). The most common adverse event in the arbidol tablets group was the elevation of transaminase (5/200, 2.5%), and no one withdrew from the study due to adverse events or disease progression.

CONCLUSIONS

SOC plus arbidol tablets significantly increase the negative conversion rate of SARS-CoV-2 within the first week anas, accelerate the recovery of COVID-19 patients. During the treatment with arbidol tablets, we find no significant serious adverse events.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, NCT04260594, www.clinicaltrials.gov/ct2/show/NCT04260594?term=NCT04260594&draw=2&rank=1.

Therapeutic approaches and vaccination in fighting COVID-19 infections: A review

Coronavirus disease 2019 (COVID-19) is a remarkably contagious and pathogenic viral infection arising from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which first appeared in Wuhan, China. For the time being, COVID-19 is not treated with a specific therapy. The Food and Drug Administration (FDA) has approved Remdesivir as the first drug to treat COVID-19. However, many other therapeutic approaches are being investigated as possible treatments for COVID-19. As part of this review, we discussed the development of various drugs, their mechanism of action, and how they might be applied to different cases of COVID-19 patients. Furthermore, this review highlights an update in the emergence of new prophylactic or therapeutic vaccines against COVID-19. In addition to FDA or The World Health Organization (WHO) approved vaccines, we intended to incorporate the latest published data from phase III trials about different COVID-19 vaccines and provide clinical data released on the networks or peer-review journals.

A Sustainable Strategy for Solid-Phase Extraction of Antiviral Drug from Environmental Waters by Immobilized Hydrogen Bond Acceptor

Deep eutectic solvents are a new generation of green solvents composed of hydrogen bond acceptors and donors. However, when used as extractants in liquid–liquid separation, they are difficult to recycle and easy to lose. In order to solve these problems, herein, immobilized hydrogen bond acceptor adsorbent material was prepared for the separation and enrichment of antiviral drug arbidol from seven kinds of environmental water samples by in situ formation of hydrophobic deep eutectic solvents. The structure, morphology and thermal stability of the adsorbents were characterized, the separation and enrichment conditions for the targeted analyte were optimized, and the adsorption thermodynamics and kinetics were investigated. It was found that the adsorbent material could effectively enrich trace arbidol with the recovery more than 95% at the concentration above 7.5 ng/mL, and the enrichment factor was as high as 634.7. Coexisting substances, such as NaCl, KCl, CaCl₂ and MgCl₂, did not interfere with the adsorption of arbidol, even if their concentration was high, up to 1.0 mol/L, and the relative recovery for real samples was in the range from 92.5% to 100.3%. Furthermore, the immobilized hydrogen bond acceptor could be recycled and reused, and the recovery of arbidol was still above 95% after 12 adsorption–desorption cycles. The mechanism study demonstrates that the synergistic effect of hydrogen bonding and π-π stacking is the primary factor for the high adsorption efficiency.

Development of a hybrid alphavirus-SARS-CoV-2 pseudovirion for rapid quantification of neutralization antibodies and antiviral drugs

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein (S)-pseudotyped viruses are commonly used for quantifying antiviral drugs and neutralizing antibodies. Here, we describe the development of a hybrid alphavirus-SARS-CoV-2 (Ha-CoV-2) pseudovirion, which is a non-replicating SARS-CoV-2 virus-like particle composed of viral structural proteins (S, M, N, and E) and an RNA genome derived from a fast-expressing alphaviral vector. We validated Ha-CoV-2 for rapid quantification of neutralization antibodies, antiviral drugs, and viral variants. In addition, as a proof of concept, we used Ha-CoV-2 to quantify the neutralizing antibodies from an infected and vaccinated individual and found that the one-dose vaccination with Moderna mRNA-1273 greatly increased the anti-serum titer by approximately 6-fold. The post-vaccination serum can neutralize all nine variants tested. These results demonstrate that Ha-CoV-2 can be used as a robust platform for the rapid quantification of neutralizing antibodies against SARS-CoV-2 and its emerging variants.

Secondary metabolites from spice and herbs as potential multitarget inhibitors of SARS-CoV-2 proteins

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been responsible for the current global pandemic that has caused a death toll of >1.12 million worldwide and number continues to climb in several countries. Currently, there are neither specific antiviral drugs nor vaccines for the treatment and prevention of COVID-19. We screened in silico, a group of natural spice and herbal secondary metabolites (SMs) for their inhibition efficacy against multiple target proteins of SARS-CoV-2 as well as the human angiotensin-converting enzyme 2 protein. Docking and simulation results indicated that epicatechin, embelin, hesperidin, cafestol, murrayanine and murrayaquinone-A have higher inhibition efficacy over at least one of the known antiviral drugs such as Hydroxychloroquine, Remdesivir and Ribavirin. Combination of these potentially effective SMs from their respective plant sources was analysed, and its absorption and acute oral toxicity were examined in Wistar rats and classified as category 5 as per the Globally Harmonized System. The identified SMs may be useful in the development of preventive nutraceuticals, food supplements and antiviral drugs.Communicated by Ramaswamy H. Sarma.

Broad-Spectrum Activity of Small Molecules Acting against Influenza a Virus: Biological and Computational Studies

Influenza still represents a problematic disease, involving millions of people every year and causing hundreds of thousands of deaths. Only a few drugs are clinically available. The search for an effective weapon is still ongoing. In this scenario, we recently identified new drug-like compounds with antiviral activity toward two A/H1N1 Influenza virus strains, which were demonstrated to interfere with the processes mediated by hemagglutinin (HA). In the present work, the compound’s ability to act against the A/H3N2 viral strain has been evaluated in hemagglutination inhibition (HI) assays. Two of the five tested compounds were also active toward the A/H3N2 Influenza virus. To validate the scaffold activity, analogue compounds of two broad-spectrum molecules were selected and purchased for HI testing on both A/H1N1 and A/H3N2 Influenza viruses. Forty-three compounds were tested, and four proved to be active toward all three viral strains. A computational study has been carried out to depict the HA binding process of the most interesting compounds.

Investigational antiviral drugs for the treatment of COVID-19 patients

In the current pandemic of coronavirus disease 2019 (COVID-19), antiviral drugs are at the center of attention because of their critical role against severe acute respiratory disease syndrome coronavirus 2 (SARS-CoV-2). In addition to designing new antivirals against SARS-COV-2, a drug repurposing strategy is a practical approach for treating COVID-19. A brief insight about antivirals would help clinicians to choose the best medication for the treatment of COVID-19. In this review, we discuss both novel and repurposed investigational antivirals, focusing on in vitro, in vivo, and clinical trial studies.

Simulation of Molecular Dynamics of SARS-CoV-2 S-Protein in the Presence of Multiple Arbidol Molecules: Interactions and Binding Mode Insights

In this work, we evaluated the antiviral activity of Arbidol (Umifenovir) against SARS-CoV-2 using a pseudoviral system with the glycoprotein S of the SARS-CoV-2 virus on its surface. In order to search for binding sites to protein S of the virus, we described alternative binding sites of Arbidol in RBD and in the ACE-2-RBD complex. As a result of our molecular dynamics simulations combined with molecular docking data, we note the following fact: wherever the molecules of Arbidol bind, the interaction of the latter affects the structural flexibility of the protein. This interaction may result both in a change in the shape of the domain-enzyme binding interface and simply in a change in the structural flexibility of the domain, which can subsequently affect its affinity to the enzyme. In addition, we examined the possibility of Arbidol binding in the stem part of the surface protein. The possibility of Arbidol binding in different parts of the protein is not excluded. This may explain the antiviral activity of Arbidol. Our results could be useful for researchers searching for effective SARS-CoV-2 virus inhibitors targeting the viral entry stage.

Aerobic copper-mediated domino process for the synthesis of 3-(trifluoromethylseleno)indoles

An aerobic copper-mediated domino reaction for the synthesis of 3-(trifluoromethylseleno)indoles from trifluoromethylselenolation of N-Ts 2-alkynylaniline with [(bpy)CuSeCF3]2 is reported. This reaction proceeds through a sequential oxidation, alkyne coordination, and deprotonation...

Recent Advancements on COVID-19: A Comprehensive Review

Over the last few decades, there have been several global outbreaks of severe respiratory infections. The causes of these outbreaks were coronaviruses that had infected birds, mammals and humans. The outbreaks predominantly caused respiratory tract and gastrointestinal tract symptoms and other mild to very severe clinical signs. The current coronavirus disease-2019 (COVID-19) outbreak, caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a rapidly spreading illness affecting millions of people worldwide. Among the countries most affected by the disease are the United States of America (USA), India, Brazil, and Russia, with France recording the highest infection, morbidity, and mortality rates. Since early January 2021, thousands of articles have been published on COVID-19. Most of these articles were consistent with the reports on the mode of transmission, spread, duration, and severity of the sickness. Thus, this review comprehensively discusses the most critical aspects of COVID-19, including etiology, epidemiology, pathogenesis, clinical signs, transmission, pathological changes, diagnosis, treatment, prevention and control, and vaccination.

Clinical Antiviral Drug Arbidol Inhibits Infection by SARS-CoV-2 and Variants through Direct Binding to the Spike Protein

Arbidol (ARB) is a broad-spectrum antiviral drug approved in Russia and China for the treatment of influenza. ARB was tested in patients as a drug candidate for the treatment at the early onset of COVID-19 caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Despite promising clinical results and multiple ongoing trials, preclinical data are lacking and the molecular mechanism of action of ARB against SARS-CoV-2 remains unknown. Here, we demonstrate that ARB binds to the spike viral fusion glycoprotein of the SARS-CoV-2 Wuhan strain as well as its more virulent variants from the United Kingdom (strain B.1.1.7) and South Africa (strain B.1.351). We pinpoint the ARB binding site on the S protein to the S2 membrane fusion domain and use an infection assay with Moloney murine leukemia virus (MLV) pseudoviruses (PVs) pseudotyped with the S proteins of the Wuhan strain and the new variants to show that this interaction is sufficient for the viral cell entry inhibition by ARB. Finally, our experiments reveal that the ARB interaction leads to a significant destabilization and eventual lysosomal degradation of the S protein in cells. Collectively, our results identify ARB as the first clinically approved small molecule drug binder of the SARS-CoV-2 S protein and place ARB among the more promising drug candidates for COVID-19.

Meta-analysis of arbidol versus lopinavir/ritonavir in the treatment of coronavirus disease 2019

Objectives

To systematically evaluate the efficacy and safety of arbidol and lopinavir/ritonavir (LPV/r) in the treatment of coronavirus disease 2019 (COVID‐19) using a meta‐analysis method.

Methods

The China Knowledge Network, VIP database, WanFang database PubMed database, Embase database, and Cochrane Library were searched for a collection of comparative studies on arbidol and lopinavir/ritonavir in the treatment of COVID‐19. Meta‐analysis was used to evaluate the efficacy and safety of Arbidol and lopinavir/ritonavir in the treatment of COVID‐19.

Results

The results of the systematic review indicated that Arbidol had a higher positive‐to‐negative conversion rate of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) nucleic acid on Day 7 (p = 0.03), a higher positive‐to‐negative conversion rate of SARS‐CoV‐2 nucleic acid on Day 14 (p = 0.006), a higher improvement rate of chest computed tomography on Day 14 (p = 0.02), a lower incidence of adverse reactions (p = 0.002) and lower rate of mortality (p = 0.007). There was no difference in the rate of cough disappearance on Day 14 (p = 0.24) or the rate of severe/critical illness (p = 0.07) between the two groups.

Conclusions

Arbidol may be superior to lopinavir/ritonavir in the treatment of COVID‐19. However, due to the small number of included studies and the number of patients, high‐quality multicenter large‐sample randomized double‐blind controlled trials are still needed for verification.

Synthesis and biological evaluation of novel rhodanine-based structures with antiviral activity towards HHV-6 virus

An increased awareness of diseases associated with Human herpesvirus 6 (HHV-6) infection or reactivation has resulted in a growing interest in the evaluation of the best treatment options available for the clinical management of HHV-6 disease. However, no compound has yet been approved exclusively for HHV-6 infection treatment. For this reason, the identification of anti-HHV6 compounds provides a valuable opportunity for developing efficient antiviral therapies. A possible target for antiviral drugs is the virus-cell fusion step. In this study, we synthetized potential fusion intermediates inhibitors based on the rhodanine structure. The obtained derivatives were tested for cytotoxicity and for antiviral activity in human cells infected with HHV6. Level of infection was monitored by viral DNA quantification at different time points up to 7 days post infection. Among the synthetized derivatives, 9e showed a significative inhibitory effect on viral replication that lasted over 7 days, probably attributable to the particular combination of hydrophilic and hydrophobic substituents to the rhodanine moiety. Our results support the use of these amphipathic fusion inhibitors for the treatment of HHV-6 infections.