Antiviral activity of Arbidol against Coxsackie virus B5 in vitro and in vivo

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.

Investigating the virulence of coxsackievirus B6 strains and antiviral treatments in a neonatal murine model

Coxsackievirus B6 (CVB6), a member of the human enterovirus family, is associated with severe diseases such as myocarditis in children. However, to date, only a limited number of CVB6 strains have been identified, and their characterization in animal models has been lacking. To address this gap, in this study, a neonatal murine model of CVB6 infection was established to compare the replication and virulence of three infectious-clone-derived CVB6 strains in vivo. The results showed that following challenge with a lethal dose of CVB6 strains, the neonatal mice rapidly exhibited a series of clinical signs, such as weight loss, limb paralysis, and death. For the two high-virulence CVB6 strains, histological examination revealed myocyte necrosis in skeletal and cardiac muscle, and immunohistochemistry confirmed the expression of CVB6 viral protein in these tissues. Real-time PCR assay also revealed higher viral loads in the skeletal and cardiac muscle than in other tissues at different time points post infection. Furthermore, the protective effect of passive immunization with antisera and a neutralizing monoclonal antibody against CVB6 infection was evaluated in the neonatal mouse model. This study should provide insights into the pathogenesis of CVB6 and facilitate further research in the development of vaccines and antivirals against CVBs.

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.

Efficacy of an isoxazole-3-carboxamide analog of pleconaril in mouse models of Enterovirus-D68 and Coxsackie B5

Enteroviruses (EV) cause a number of life-threatening infectious diseases. EV-D68 is known to cause respiratory illness in children that can lead to acute flaccid myelitis. Coxsackievirus B5 (CVB5) is commonly associated with hand-foot-mouth disease. There is no antiviral treatment available for either. We have developed an isoxazole-3-carboxamide analog of pleconaril (11526092) which displayed potent inhibition of EV-D68 (IC50 58 nM) as well as other enteroviruses including the pleconaril-resistant Coxsackievirus B3-Woodruff (IC50 6-20 nM) and CVB5 (EC50 1 nM). Cryo-electron microscopy structures of EV-D68 in complex with 11526092 and pleconaril demonstrate destabilization of the EV-D68 MO strain VP1 loop, and a strain-dependent effect. A mouse respiratory model of EV-D68 infection, showed 3-log decreased viremia, favorable cytokine response, as well as statistically significant 1-log reduction in lung titer reduction at day 5 after treatment with 11526092. An acute flaccid myelitis neurological infection model did not show efficacy. 11526092 was tested in a mouse model of CVB5 infection and showed a 4-log TCID50 reduction in the pancreas. In summary, 11526092 represents a potent in vitro inhibitor of EV with in vivo efficacy in EV-D68 and CVB5 animal models suggesting it is worthy of further evaluation as a potential broad-spectrum antiviral therapeutic against EV.

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.

Antiviral potential of anthraquinones from Polygonaceae, Rubiaceae and Asphodelaceae: Potent candidates in the treatment of SARS-COVID-19, A comprehensive review

Medicinal plants are being used as an alternative source of health management to cure various human ailments. The healing role is attributed to the hidden dynamic groups of various phytoconstituents, most of which have been recorded from plants and their derivatives. Nowadays, medicinal plants have gained more attention due to their pharmacological and industrial potential. Aromatic compounds are one of the dynamic groups of secondary metabolites (SM) naturally present in plants; and anthraquinones of this group are found to be attractive due to their high bioactivity and low toxicity. They have been reported to exhibit anticancer, antimicrobial, immune-suppressive, antioxidant, antipyretic, diuretic and anti-inflammatory activities. Anthraquinones have been also shown to exhibit potent antiviral effects against different species of viruses. Though, it has been reported that a medicinal plant with antiviral activity against one viral infection may be used to combat other types of viral infections. Therefore, in this review, we explored and highlighted the antiviral properties of anthraquinones of Polygonaceae, Rubiaceae and Asphodelaceae families. Anthraquinones from these plant families have been reported for their effects on human respiratory syncytial virus and influenza virus. They are hence presumed to have antiviral potential against SARS-CoV as well. Thus, anthraquinones are potential candidates that need to be screened thoroughly and developed as drugs to combat COVID-19. The information documented in this review could therefore serve as a starting point in developing novel drugs that may help to curb the SARS-COVID-19 pandemic.

Arbidol inhibits human esophageal squamous cell carcinoma growth in vitro and in vivo through suppressing ataxia telangiectasia and Rad3-related protein kinase

Human esophageal cancer has a global impact on human health due to its high incidence and mortality. Therefore, there is an urgent need to develop new drugs to treat or prevent the prominent pathological subtype of esophageal cancer, esophageal squamous cell carcinoma (ESCC). Based upon the screening of drugs approved by the Food and Drug Administration, we discovered that Arbidol could effectively inhibit the proliferation of human ESCC in vitro. Next, we conducted a series of cell-based assays and found that Arbidol treatment inhibited the proliferation and colony formation ability of ESCC cells and promoted G1-phase cell cycle arrest. Phosphoproteomics experiments, in vitro kinase assays and pull-down assays were subsequently performed in order to identify the underlying growth inhibitory mechanism. We verified that Arbidol is a potential ataxia telangiectasia and Rad3-related (ATR) inhibitor via binding to ATR kinase to reduce the phosphorylation and activation of minichromosome maintenance protein 2 at Ser108. Finally, we demonstrated Arbidol had the inhibitory effect of ESCC in vivo by a patient-derived xenograft model. All together, Arbidol inhibits the proliferation of ESCC in vitro and in vivo through the DNA replication pathway and is associated with the cell cycle.

Promising Role of Emodin as Therapeutics to Against Viral Infections

Emodin is an anthraquinone derivative that is widely present in natural plants and has a wide spectrum of pharmacological effects, such as antibacterial, anti-inflammatory, anti-fibrotic and anticancer and so on. Through reviewing studies on antiviral effect of emodin in the past decades, we found that emodin exhibits ability of inhibiting the infection and replication of more than 10 viruses in vitro and in vivo, including herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), coxsackievirus B (CVB), hepatitis B virus (HBV), influenza A virus (IAV), SARS-CoV, viral haemorrhagic septicaemia rhabdovirus (VHSV), enterovirus 71 (EV71), dengue virus serotype 2 (DENV-2) and Zika virus (ZIKV). Therefore, this review aims to summarize the antiviral effect of emodin, in order to provide reference and hopes to support the further investigations.

Fighting Enteroviral Infections to Prevent Type 1 Diabetes

Enteroviruses (EVs), especially coxsackieviruses B (CVB), are believed to trigger or accelerate islet autoimmunity in genetically susceptible individuals that results in type 1 diabetes (T1D). Therefore, strategies are needed to fight against EV infections. There are no approved antiviral drugs currently available, but various antiviral drugs targeting viral or host cell proteins and vaccines have recently shown potential to combat CVB infections and may be used as new therapeutic strategies to prevent or reduce the risk of T1D and/or preserve β-cell function among patients with islet autoantibodies or T1D.

Efficacy and safety of arbidol (umifenovir) in patients with COVID-19: A systematic review and meta-analysis

OBJECTIVE

To provide the latest evidence for the efficacy and safety of arbidol (umifenovir) in COVID-19 treatment.

METHODS

A literature systematic search was carried out in PubMed, Cochrane Library, Embase, and medRxiv up to May 2021. The Cochrane risk of bias tool and Newcastle-Ottawa scale were used to assess the quality of included studies. Meta-analysis was performed using RevMan 5.3.

RESULTS

Sixteen studies were met the inclusion criteria. No significant difference was observed between arbidol and non-antiviral treatment groups neither for primary outcomes, including the negative rate of PCR (NR-PCR) on Day 7 (risk ratio [RR]: 0.94; 95% confidence interval (CI): 0.78-1.14) and Day 14 (RR: 1.10; 95% CI: 0.96-1.25), and PCR negative conversion time (PCR-NCT; mean difference [MD]: 0.74; 95% CI: -0.87 to 2.34), nor secondary outcomes (p > .05). However, arbidol was associated with higher adverse events (RR: 2.24; 95% CI: 1.06-4.73). Compared with lopinavir/ritonavir, arbidol showed better efficacy for primary outcomes (p < .05). Adding arbidol to lopinavir/ritonavir also led to better efficacy in terms of NR-PCR on Day 7 and PCR-NCT (p < .05). There was no significant difference between arbidol and chloroquine in primary outcomes (p > .05). No remarkable therapeutic effect was observed between arbidol and other agents (p > .05).

CONCLUSION

The present meta-analysis showed no significant benefit of using arbidol compared with non-antiviral treatment or other therapeutic agents against COVID-19 disease. High-quality studies are needed to establish the efficacy and safety of arbidol 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.

Insights into SARS-CoV-2: Medicinal Chemistry Approaches to Combat Its Structural and Functional Biology

Coronavirus disease 2019, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is still a pandemic around the world. Currently, specific antiviral drugs to control the epidemic remain deficient. Understanding the details of SARS-CoV-2 structural biology is extremely important for development of antiviral agents that will enable regulation of its life cycle. This review focuses on the structural biology and medicinal chemistry of various key proteins (Spike, ACE2, TMPRSS2, RdRp and M^pro) in the life cycle of SARS-CoV-2, as well as their inhibitors/drug candidates. Representative broad-spectrum antiviral drugs, especially those against the homologous virus SARS-CoV, are summarized with the expectation they will drive the development of effective, broad-spectrum inhibitors against coronaviruses. We are hopeful that this review will be a useful aid for discovery of novel, potent anti-SARS-CoV-2 drugs with excellent therapeutic results in the near future.

Preliminary Anti-Coxsackie Activity of Novel 1-[4-(5,6-dimethyl(H)- 1H(2H)-benzotriazol-1(2)-yl)phenyl]-3-alkyl(aryl)ureas

BACKGROUND

Coxsackievirus infections are associated with cases of aseptic meningitis, encephalitis, myocarditis, and some chronic disease.

METHODS

A series of benzo[d][1,2,3]triazol-1(2)-yl derivatives (here named benzotriazol-1(2)-yl) (4a-i, 5a-h, 6a-e, g, i, j and 7a-f, h-j) were designed, synthesized and in vitro evaluated for cytotoxicity and antiviral activity against two important human enteroviruses (HEVs) members of the Picornaviridae family [Coxsackievirus B 5 (CVB-5) and Poliovirus 1 (Sb-1)].

RESULTS

Compounds 4c (CC50 >100 μM; EC50 = 9 μM), 5g (CC50 >100 μM; EC50 = 8 μM), and 6a (CC50 >100 μM; EC50 = 10 μM) were found active against CVB-5. With the aim of evaluating the selectivity of action of this class of compounds, a wide spectrum of RNA (positive- and negativesense), double-stranded (dsRNA) or DNA viruses were also assayed. For none of them, significant antiviral activity was determined.

CONCLUSION

These results point towards a selective activity against CVB-5, an important human pathogen that causes both acute and chronic diseases in infants, young children, and immunocompromised patients.

Co-administration of Favipiravir and the Remdesivir Metabolite GS-441524 Effectively Reduces SARS-CoV-2 Replication in the Lungs of the Syrian Hamster Model

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread worldwide since December 2019, causing coronavirus disease 2019 (COVID-19). Although vaccines for this virus have been developed rapidly, repurposing drugs approved to treat other diseases remains an invaluable treatment strategy. Here, we evaluated the inhibitory effects of drugs on SARS-CoV-2 replication in a hamster infection model and in in vitro assays. Favipiravir significantly suppressed virus replication in hamster lungs. Remdesivir inhibited virus replication in vitro, but was not effective in the hamster model. However, GS-441524, a metabolite of remdesivir, effectively suppressed virus replication in hamsters. Co-administration of favipiravir and GS-441524 more efficiently reduced virus load in hamster lungs than did single administration of either drug for both the prophylactic and therapeutic regimens; prophylactic co-administration also efficiently inhibited lung inflammation in the infected animals. Furthermore, pretreatment of hamsters with favipiravir and GS-441524 effectively protected them from virus transmission via respiratory droplets upon exposure to infected hamsters. Repurposing and co-administration of antiviral drugs may help combat COVID-19. IMPORTANCE During a pandemic, repurposing drugs that are approved for other diseases is a quick and realistic treatment option. In this study, we found that co-administration of favipiravir and the remdesivir metabolite GS-441524 more effectively blocked SARS-CoV-2 replication in the lungs of Syrian hamsters than either favipiravir or GS-441524 alone as part of a prophylactic or therapeutic regimen. Prophylactic co-administration also reduced the severity of lung inflammation. Moreover, co-administration of these drugs to naive hamsters efficiently protected them from airborne transmission of the virus from infected animals. Since both drugs are nucleotide analogs that interfere with the RNA-dependent RNA polymerases of many RNA viruses, these findings may also help encourage co-administration of antivirals to combat future pandemics.

Effects of SARS-CoV-2 and its functional receptor ACE2 on the cardiovascular system

The clinical manifestations of COVID-19 are mainly respiratory symptoms, but some patients present with cardiovascular system disease such as palpitations and shortness of breath as the first or secondary symptoms. In this paper, we describe the characteristics of SARS-CoV‑2 and its functional receptor angiotensin-converting enzyme 2 (ACE2). Furthermore, we explore the impact of virus-induced myocardial damage, decreased ACE2 activity, immune imbalance, hypoxemia, and heart damage caused by antiviral drugs.

Synthesis, molecular modeling and antiviral activity of novel 5-fluoro-1H-indole-2,3-dione 3-thiosemicarbazones

In this work, novel 5-fluoro-1-methyl/ethyl-1H-indole-2,3-dione 3-[4-(substituted phenyl)-thiosemicarbazones] 6a-n and 7a-n were synthesized. The antiviral effects of the compounds were tested against HSV-1 (KOS), HSV-2 (G) HSV-1 TK^- KOS ACV^r and VV in HEL cell cultures using acyclovir and ganciclovir as standards, and Coxsackie B4 virus in Vero cell cultures using ribavirin and mycophenolic acid as standards. R₂ ethyl substituted 7 derivatives were found effective against viruses tested. R₁ 4-CF₃ substituted 7d, R₁ 4-OCH₃ substituted 7 g and R₁ 3-Cl substituted 7 l showed activity against HSV-1 (KOS), HSV-2 (G) HSV-1 TK^- KOS ACV^r and VV. Whereas only R₁ 4-Br substituted 7n has selective activity against coxsackie B4 virus. Molecular modelingstudies of 7d and 7l were performed to determine binding side on HSV-1 glycoprotein B and D, HSV-2 glycoprotein B structures.

Potential drugs for the treatment of the novel coronavirus pneumonia (COVID-19) in China

The fight against the novel coronavirus pneumonia (namely COVID-19) that seriously harms human health is a common task for all mankind. Currently, development of drugs against the novel coronavirus (namely SARS-CoV-2) is quite urgent. Chinese medical workers and scientific researchers have found some drugs to play potential therapeutic effects on COVID-19 at the cellular level or in preliminary clinical trials. However, more fundamental studies and large sample clinical trials need to be done to ensure the efficacy and safety of these drugs. The adoption of these drugs without further testing must be careful. The relevant articles, news, and government reports published on the official and Preprint websites, PubMed and China National Knowledge Infrastructure (CNKI) databases from December 2019 to April 2020 were searched and manually filtered. The general pharmacological characteristics, indications, adverse reactions, general usage, and especially current status of the treatment of COVID-19 of those potentially effective drugs, including chemical drugs, traditional Chinese medicines (TCMs), and biological products in China were summarized in this review to guide reasonable medication and the development of specific drugs for the treatment of COVID-19.

Assessment of a new arbidol derivative against herpes simplex virus II in human cervical epithelial cells and in BALB/c mice

As one of the highly contagious forms, herpes simplex virus type 2 (HSV-2) commonly caused severe genital diseases and closely referred to the HIV infection. The lack of effective vaccines and drug-resistance proclaimed the preoccupation for alternative antiviral agents against HSV-2. Molecules bearing indole nucleus presented diverse biological properties involving antiviral and anti-inflammatory activities. In this study, one of the indole molecules, arbidol derivative (ARD) was designed and synthesized prior to the evaluation of its anti-HSV-2 activity. Our data showed that the ARD effectively suppressed HSV-2-induced cytopathic effects and the generation of progeny virus, with 50% effective concentrations of 3.386 and 1.717 μg/mL, respectively. The results of the time-course assay suggested that the ARD operated in a dual antiviral way by interfering virus entry and impairing the earlier period of viral cycle during viral DNA synthesis. The ARD-mediated HSV-2 inhibition was partially attained by blocking NF-κB pathways and down-regulating the expressions of several inflammatory cytokines. Furthermore, in vivo studies showed that oral administration of ARD protected BALB/c mice from intravaginal HSV-2 challenge by alleviating serious vulval lesions and histopathological changes in the target organs. Besides, the treatment with ARD also made the levels of viral protein, NF-κB protein and inflammatory cytokines lower, in consistent with the in-vitro studies. Collectively, ARD unveiled therapeutic potential for the prevention and treatment of HSV-2 infections.

The antiviral activity of arbidol hydrochloride against herpes simplex virus type II (HSV-2) in a mouse model of vaginitis

Objective

HSV-2 infection has increased significantly in recent years, which is closely associated with cervical cancer and HIV infection. The lack of success in vaccine development and the emergence of drug resistance to commonly used drugs emphasize the urgent need for alternative antivirals against HSV-2 infection. Arbidol (ARB) has been demonstrated to be a broad spectrum antiviral drug that exhibits immunomodulatory properties that affect the HSV-2 life cycle. This study investigated the efficacy and mechanism of ARB against HSV-2 in vivo and in vitro to further explore the clinical application of ARB.

Methods

The efficacy of ARB on HSV-2 infection in vitro was examined by CPE and MTT assays. A vaginitis model was established to monitor changes in histopathology and inflammatory cytokine (IL-2, IL-4, TNF-α and TGF-β) expression by H&E staining and ELISA, respectively, and the efficacy of ARB was evaluated accordingly. Furthermore, flow cytometry was used to determine the ratio of CD4⁺/CD8⁺ T cells in the peripheral blood of the vaginitis animals. Considering the balance of efficacy and pharmacokinetics, ARB ointment was strictly prepared to observe formulation efficacy differences compared to the oral dosing form.

Results

The results showed that, in vitro, the TC₅₀ and IC₅₀ of ARB were 32.32 μg/mL and 4.77 μg/mL (SI = 6.82), respectively, indicating that ARB presents effective activity against HSV-2 in a dose-dependent manner. The results of the time-course assay suggested that 25 μg/mL ARB affected the late stage of HSV-2 replication. However, ARB did not inhibit viral attachment or cell penetration. The in vivo results showed that ARB ointment can improve the survival rate, prolong the survival time and reduce the reproductive tract injury in mice infected with HSV-2, regulate cytokine expression; and balance the CD4⁺ and CD8⁺ T lymphocyte ratio in the peripheral blood to participate in the regulation of immune response.

Conclusion

ARB showed anti-HSV-2 activity in vitro in a dose-dependent manner and played a role in inhibiting the late replication cycle of the virus. The vaginitis model was successfully established, according to immunomodulation outcomes, responded better to ARB in ointment form than in oral form.

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ARB showed anti-HSV-2 activity in vitro in a dose-dependent manner.

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ARB inhibited the late replication cycle of HSV-2.

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ARB ointment participated in the regulation of immune response to reduce the reproductive tract injury.

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ARB in ointment form responded to vaginitis better than in oral form.

A neonatal mouse model of central nervous system infections caused by Coxsackievirus B5

As one of the key members of the coxsackievirus B group, coxsackievirus B5 (CV-B5) can cause many central nervous system diseases, such as viral encephalitis, aseptic meningitis, and acute flaccid paralysis. Notably, epidemiological data indicate that outbreaks of CV-B5-associated central nervous system (CNS) diseases have been reported worldwide throughout history. In this study, which was conducted to promote CV-B5 vaccine and anti-virus drug research, a 3-day-old BALB/c mouse model was established using a CV-B5 clinical isolate (CV-B5/JS417) as the challenge strain. Mice challenged with CV-B5/JS417 exhibited a series of neural clinical symptoms and death with necrosis of neuronal cells in the cerebral cortex and the entire spinal cord, hindlimb muscles, and cardiomyocytes. The viral load of each tissue at various post-challenge time points suggested that CV-B5 replicated in the small intestine and was subsequently transmitted to various organs via viremia; the virus potentially entered the brain through the spinal axons, causing neuronal cell necrosis. In addition, this mouse model was used to evaluate the protective effect of a CV-B5 vaccine. The results indicated that both the inactivated CV-B5 vaccine and anti-CVB5 serum significantly protected mice from a lethal infection of CV-B5/JS417 by producing neutralizing antibodies. In summary, the first CV-B5 neonatal mouse model has been established and can sustain CNS infections in a manner similar to that observed in humans. This model will be a useful tool for studies on pathogenesis, vaccines, and anti-viral drug evaluations.

The Antiviral Drug Arbidol Inhibits Zika Virus

There are many emerging and re-emerging globally prevalent viruses for which there are no licensed vaccines or antiviral medicines. Arbidol (ARB, umifenovir), used clinically for decades in several countries as an anti-influenza virus drug, inhibits many other viruses. In the current study, we show that ARB inhibits six different isolates of Zika virus (ZIKV), including African and Asian lineage viruses in multiple cell lines and primary human vaginal and cervical epithelial cells. ARB protects against ZIKV-induced cytopathic effects. Time of addition studies indicate that ARB is most effective at suppressing ZIKV when added to cells prior to infection. Moreover, ARB inhibits pseudoviruses expressing the ZIKV Envelope glycoprotein. Thus, ARB, a broadly acting anti-viral agent with a well-established safety profile, inhibits ZIKV, likely by blocking viral entry.

Quinoxaline derivatives as new inhibitors of coxsackievirus B5

Enteroviruses are among the most common and important human pathogens for which there are no specific antiviral agents approved by the US Food and Drug Administration so far. Particularly, coxsackievirus infections have a worldwide distribution and can cause many important diseases. We here report the synthesis of new 14 quinoxaline derivatives and the evaluation of their cytotoxicity and antiviral activity against representatives of ssRNA, dsRNA and dsDNA viruses. Promisingly, three compounds showed a very potent and selective antiviral activity against coxsackievirus B5, with EC₅₀ in the sub-micromolar range (0.3-0.06 μM). A combination of experimental techniques (i.e. virucidal activity, time of drug addition and adsorption assays) and in silico modeling studies were further performed, aiming to understand the mode of action of the most active, selective and not cytotoxic compound, the ethyl 4-[(2,3-dimethoxyquinoxalin-6-yl)methylthio]benzoate (6).

Antiviral activity of arbidol hydrochloride against herpes simplex virus I in vitro and in vivo

Herpes simplex virus type 1 (HSV-1) causes significant human diseases ranging from skin lesions to encephalitis, especially in neonates and immunocompromised hosts. The discovery of novel anti-HSV-1 drugs with low toxicity is required for public health. Arbidol hydrochloride (ARB) is an indole derivative molecule with broad-spectrum antiviral activity. In this study, the antiviral effects of ARB against HSV-1 infection were evaluated in vitro and in vivo. The results showed that ARB presents significant inhibitory effect on HSV-1 plaque formation and generation of progeny virus, with EC50 values (50% effective concentration) of 5.39 µg/mL (10.49 µM) and 2.26 µg/mL (4.40 µM), respectively. Moreover, time-of-addition and time-of-removal assays further suggested that ARB has viral inhibitory effects when added up to 12 h post-infection (p.i.), which could be further corroborated by determining the expression of viral immediate-early (ICP4, ICP22 and ICP27), early (ICP8 and UL42) and late (gB, gD, gH, VP1/2 and VP16) genes by real-time quantitative PCR as well as the expression of viral protein ICP4 and ICP8 at 6 h and 12 h p.i. Results of the in vivo study showed that ARB could reduce guinea pig skin lesions caused by HSV-1 infection. Conclusively, this report offers new perspectives in the search for therapeutic measures in the treatment of HSV-1 infection.

The Location of the Protonated and Unprotonated Forms of Arbidol in the Membrane: A Molecular Dynamics Study

Abstract

Arbidol is a potent broad-spectrum antiviral molecule for the treatment and prophylaxis of many viral infections. Viruses that can be inhibited by arbidol include enveloped and non-enveloped viruses, RNA and DNA viruses, as well as pH-independent and pH-dependent ones. These differences in viral types highlight the broad spectrum of Arb antiviral activity and, therefore, it must affect a common viral critical step. Arbidol incorporates rapidly into biological membranes, and some of its antiviral effects might be related to its capacity to interact with and locate into the membrane. However, no information is available of the molecular basis of its antiviral mechanism/s. We have aimed to locate the protonated (Arp) and unprotonated (Arb) forms of arbidol in a model membrane system. Both Arb and Arp locate in between the hydrocarbon acyl chains of the phospholipids but its specific location and molecular interactions differ from each other. Whereas both Arb and Arp average location in the membrane palisade is a similar one, Arb tends to be perpendicular to the membrane surface, whereas Arp tends to be parallel to it. Furthermore, Arp, in contrast to Arb, seems to interact stronger with POPG than with POPC, implying the existence of a specific interaction between Arp, the protonated from, with negatively charged phospholipids. This data would suggest that the active molecule of arbidol in the membrane is the protonated one, i.e., the positively charged molecule. The broad antiviral activity of arbidol would be defined by the perturbation it exerts on membrane structure and therefore membrane functioning.

Graphical Abstract

Electronic supplementary material

The online version of this article (doi:10.1007/s00232-016-9876-3) contains supplementary material, which is available to authorized users.

Antiviral effect of emodin from Rheum palmatum against coxsakievirus B5 and human respiratory syncytial virus in vitro

Viral infections are the major causes of morbidity and mortality in elderly people and young children throughout the world. The most common pathogens include coxsackie virus (CV) and respiratory syncytial virus (RSV). However, no antiviral agents with low toxicity and drug resistance are currently available in clinic therapy. The present study aimed to examine the antiviral activities of emodin (an ingredient of Rheum palmatum) against CVB5 and RSV infections, in an attempt to discover new antiviral agents for virus infection. The monomer emodin was extracted and isolated from Rheum palmatum. The antiviral activities of emodin on HEp-2 cells were evaluated, including virus replication inhibition, virucidal and anti-absorption effects, by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tet-razolium bromide (MTT) assay and plaque reduction assay (PRA). The kinetics of virus inhibition by emodin in a period of 14 h was further determined by plaque assay and quantitative real time PCR (qPCR). Cytokine (IFN-γ, TNF-α) mRNA expressions after emodin treatment (7.5, 15, 30 μmol/L) were also assessed by qPCR post-infection. The results showed that emodin had potent inhibitory activities against CVB5 and RSV, with the 50% effective concentration (EC₅₀) ranging from 13.06 to 14.27 μmol/L and selectivity index (SI) being 5.38–6.41 μmol/L. However, emodin couldn’t directly inactivate the viruses or block their absorption to cells. It acted as a biological synthesis inhibitor against CVB₄ and RSV in a concentration- and time-dependent manner, especially during the first 0–4 h post-infection. Moreover, emodin could decrease the mRNA expression of IFN-α but enhance TNF-γ expression significantly compared to the viral controls in vitro. Our results provide a molecular basis for development of emodin as a novel and safe antiviral agent for human enterovirus and respiratory virus infection in the clinical therapy.

Synthesis and antiviral properties of novel indole-based thiosemicarbazides and 4-thiazolidinones

A novel series of indolylthiosemicarbazides (6a–6g) and their cyclization products, 4-thiazolidinones (7a–7g), have been designed, synthesized and evaluated, in vitro, for their antiviral activity against a wide range of DNA and RNA viruses. Compounds 6a, 6b, 6c and 6d exhibited notable antiviral activity against Coxsackie B4 virus, at EC₅₀ values ranging from 0.4 to 2.1 μg/mL. The selectivity index (ratio of cytotoxic to antivirally effective concentration) values of these compounds were between 9 and 56. Besides, 6b, 6c and 6d also inhibited the replication of two other RNA viruses, Sindbis virus and respiratory syncytial virus, although these EC₅₀ values were higher compared to those noted for Coxsackie B4 virus. The SAR analysis indicated that keeping the free thiosemicarbazide moiety is crucial to obtain this antiviral activity, since the cyclization products (7a–7g) did not produce any antiviral effect.

Evaluation of antiviral efficacy of ribavirin, arbidol, and T-705 (favipiravir) in a mouse model for Crimean-Congo hemorrhagic fever

BACKGROUND

Mice lacking the type I interferon receptor (IFNAR-/- mice) reproduce relevant aspects of Crimean-Congo hemorrhagic fever (CCHF) in humans, including liver damage. We aimed at characterizing the liver pathology in CCHF virus-infected IFNAR-/- mice by immunohistochemistry and employed the model to evaluate the antiviral efficacy of ribavirin, arbidol, and T-705 against CCHF virus.

METHODOLOGY/PRINCIPAL FINDINGS

CCHF virus-infected IFNAR-/- mice died 2-6 days post infection with elevated aminotransferase levels and high virus titers in blood and organs. Main pathological alteration was acute hepatitis with extensive bridging necrosis, reactive hepatocyte proliferation, and mild to moderate inflammatory response with monocyte/macrophage activation. Virus-infected and apoptotic hepatocytes clustered in the necrotic areas. Ribavirin, arbidol, and T-705 suppressed virus replication in vitro by ≥3 log units (IC50 0.6-2.8 µg/ml; IC90 1.2-4.7 µg/ml). Ribavirin [100 mg/(kg×d)] did not increase the survival rate of IFNAR-/- mice, but prolonged the time to death (p<0.001) and reduced the aminotransferase levels and the virus titers. Arbidol [150 mg/(kg×d)] had no efficacy in vivo. Animals treated with T-705 at 1 h [15, 30, and 300 mg/(kg×d)] or up to 2 days [300 mg/(kg×d)] post infection survived, showed no signs of disease, and had no virus in blood and organs. Co-administration of ribavirin and T-705 yielded beneficial rather than adverse effects.

CONCLUSIONS/SIGNIFICANCE

Activated hepatic macrophages and monocyte-derived cells may play a role in the proinflammatory cytokine response in CCHF. Clustering of infected hepatocytes in necrotic areas without marked inflammation suggests viral cytopathic effects. T-705 is highly potent against CCHF virus in vitro and in vivo. Its in vivo efficacy exceeds that of the current standard drug for treatment of CCHF, ribavirin.

Synthesis and anti-influenza virus activity of 4-oxo- or thioxo-4,5-dihydrofuro[3,4-c]pyridin-3(1H)-ones

A target-free approach was applied to discover anti-influenza viral compounds, where influenza infected Madin-Darby canine kidney cells were treated 7500 different small organic chemicals individually and reduction of virus-induced cytopathic effect was measured. One of the hit compounds was (Z)-1-((5-fluoro-1H-indol-3-yl)methylene)-6-methyl-4-thioxo-4,5-dihydrofuro[3,4-c]pyridin-3(1H)-one (15a) with half-maximal effective concentrations of 17.4-21.1μM against influenza A/H1N1, A/H3N2 and B viruses without any cellular toxicity at 900μM. To investigate the structure-activity relationships, two dozens of the hit analogs were synthesized. Among them, 15g, 15j, 15q, 15s, 15t and 15x had anti-influenza viral activity comparable or superior to that of the initial hit. The anti-influenza viral compounds efficiently suppressed not only viral protein level of the infected cells but also production of viral progeny in the culture supernatants in a dose-dependent manner. Based on a mode-of-action study, they did not affect virus entry or RNA replication. Instead, they suppressed viral neuraminidase activity. This study is the first to demonstrate that dihydrofuropyridinones could serve as lead compounds for the discovery of alternative influenza virus inhibitors.

Arbidol as a broad-spectrum antiviral: an update

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Arbidol (ARB) is licensed in Russia and China for the treatment of influenza and other viral infections.

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ARB inhibits a large panel of viral pathogens, enveloped or not.

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ARB displays a dual binding activity to lipid membranes and to viral or cellular proteins.

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It blocks viral endocytosis and replication in membranous intracellular compartments.

Arbidol (ARB) is a Russian-made small indole-derivative molecule, licensed in Russia and China for prophylaxis and treatment of influenza and other respiratory viral infections. It also demonstrates inhibitory activity against other viruses, enveloped or not, responsible for emerging or globally prevalent infectious diseases such as hepatitis B and C, gastroenteritis, hemorrhagic fevers or encephalitis. In this review, we will explore the possibility and pertinence of ARB as a broad-spectrum antiviral, after a careful examination of its physico-chemical properties, pharmacokinetics, toxicity, and molecular mechanisms of action. Recent studies suggest that ARB’s dual interactions with membranes and aromatic amino acids in proteins may be central to its broad-spectrum antiviral activity. This could impact on the virus itself, and/or on cellular functions or critical steps in virus-cell interactions, thereby positioning ARB as both a direct-acting antiviral (DAA) and a host-targeting agent (HTA). In the context of recent studies in animals and humans, we will discuss the prospective clinical use of ARB in various viral infections.

A review of non-nucleoside anti-hepatitis B virus agents

Hepatitis B Virus is the most common cause of chronic liver disease worldwide. Currently approved agents of chronic HBV infection treatment include interferon and nucleoside analogues. However, the side effects of interferon and the viral resistance of nucleoside analogues make the current treatment far from satisfactory. Therefore, new drugs with novel structures and mechanisms are needed. Recently, a number of non-nucleoside HBV inhibitors have been obtained from natural sources or prepared by synthesis/semi-synthesis. Some of them exhibited potent anti-HBV activity with novel mechanisms. These compounds provide useful information for the medicinal chemist to develop novel non-nucleoside compounds as anti-HBV agents.

Antiviral and anti-inflammatory activity of arbidol hydrochloride in influenza A (H1N1) virus infection

AIM

To investigate the effects of arbidol hydrochloride (ARB), a widely used antiviral agent, on the inflammation induced by influenza virus.

METHODS

MDCK cells were infected with seasonal influenza A/FM/1/47 (H1N1) or pandemic influenza A/Hubei/71/2009 (H1N1). In vitro cytotoxicity and antiviral activity of ARB was determined using MTT assay. BALB/c mice were infected with A/FM/1/47 (H1N1). Four hours later the mice were administered ARB (45, 90, and 180 mg·kg(-1)·d(-1)) or the neuraminidase inhibitor oseltamivir (22.5 mg·kg(-1)·d(-1)) via oral gavage once a day for 5 d. Body-weight, median survival time, viral titer, and lung index of the mice were measured. The levels of inflammatory cytokines were examined using real-time RT-PCR and ELISA.

RESULTS

Both H1N1 stains were equally sensitive to ARB as tested in vitro. In the infected mice, ARB (90 and 180 mg·kg(-1)·d(-1)) significantly decreased the mortality, alleviated virus-induced lung lesions and viral titers. Furthermore, ARB suppressed the levels of IL-1β, IL-6, IL-12, and TNF-α, and elevated the level of IL-10 in the bronchoalveolar lavage fluids and lung tissues. However, ARB did not significantly affect the levels of IFN-α and IFN-γ, but reduced the level of IFN-β1 in lung tissues at 5 dpi. In peritoneal macrophages challenged with A/FM/1/47 (H1N1) or poly I:C, ARB (20 μmol/L) suppressed the levels of IL-1β, IL-6, IL-12, and TNF-α, and elevated the level of IL-10. Oseltamivir produced comparable alleviation of virus-induced lung lesions with more reduction in the viral titers, but less effective modulation of the inflammatory cytokines.

CONCLUSION

ARB efficiently inhibits both H1N1 stains and diminishes both viral replication and acute inflammation through modulating the expression of inflammatory cytokines.

Glucuronidation of the broad-spectrum antiviral drug arbidol by UGT isoforms

OBJECTIVES

The aim of this work was to identify the uridine glucuronosyltransferase (UGT) isoforms involved in the metabolism of the broad-spectrum antiviral drug arbidol.

METHODS

A human liver microsome (HLM) incubation system was employed to catalyse the formation of arbidol glucuronide. The glucuronidation activity of commercially recombinant UGT isoforms towards arbidol was screened. A combination of kinetic analysis and chemical inhibition study was used to determine the UGT isoforms involved in arbidol's glucuronidation.

KEY FINDINGS

The arbidol glucuronide was detected when arbidol was incubated with HLMs in the presence of UDP-glucuronic acid. The Eadie-Hofstee plot showed that glucuronidation of arbidol was best fit to the Michaelis-Menten kinetic model, and K(m) and apparent V(max) were calculated to be 8.0 ± 0.7 μm and 2.03 ± 0.05 nmol/min/mg protein, respectively. Assessment of a panel of recombinant UGT isoforms revealed that UGT1A1, UGT1A3 and UGT1A9 could catalyse the glucuronidation of arbidol. Kinetic analysis and chemical inhibition study demonstrated that UGT1A9 was the predominant UGT isoform involved in arbidol glucuronidation in HLMs.

CONCLUSIONS

The major contribution of UGT1A9 towards arbidol glucuronidation was demonstrated in this study.

Structural characterization of arbidol®

Crystal structures of two compounds – 1-methyl-2-phenylthiomethyl-3-carbethoxy-4-dimetylaminomethyl-5-hydroxy-6-bromoindole (1) and its hydrochloride monohydrate (2), known also as antiviral drug arbidol®, were determined from single-crystal and powder diffraction data, respectively. In 1, the hydroxyl and dimethyläamino groups are involved in a strong intramolecular O—H…N hydrogen bond [O…N 2.550(4) Å]. In 2, the protonation site is dimethylamino group but not the carbon bearing the ester group.

Membranotropic effects of arbidol, a broad anti-viral molecule, on phospholipid model membranes

Arbidol, a broad and potent antiviral molecule, incorporates rapidly into membranes. To gain further insight into the mode of action of Arbidol, since the exact antiviral mechanism of Arbidol is unknown, I examined its interaction and effects on model membranes composed of saturated phospholipids by performing a detailed biophysical study using calorimetry and infrared spectroscopy. Arbidol interacts and modifies the physicochemical properties of the phospholipids in the membrane, having a significant effect on negatively charged phospholipids but a minor one on zwitterionic phospholipids. The data suggest that Arbidol is located at the interface of the membrane, participates in hydrogen bonding either with water or the phospholipid or both, and decreases the hydrogen bonding network of the phospholipids giving place to a phospholipid phase similar to the dehydrated solid one. The significant effects produced on negatively charged phospholipids suggest that the active molecule of Arbidol in the membrane is the protonated one, that is, the positively charged molecule. These data suggest that the potent antiviral effects of Arbidol are mediated at least in part through its membranotropic effects, likely giving place to the formation of perturbed membrane structures. These modifications interfere with proper membrane functioning and should be responsible for its broad antiviral activity.