In vitro antiviral and immunomodulatory activity of arbidol and structurally related derivatives in herpes simplex virus type 1-infected human keratinocytes (HaCat)

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.

Antiviral Approaches against Influenza Virus

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

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.

Indole - a promising pharmacophore in recent antiviral drug discovery

The bicyclic molecule indole has been in the limelight because of its numerous pharmacological potencies. It is used as an excellent scaffold in drug discovery of medicinal drugs such as antimicrobials, anticancer agents, antihypertensives, anti-proliferative agents and anti-inflammatory agents. In spite of its diverse therapeutic activity, it is used as a key pharmacophore in synthesizing the most potent biological agents. Besides, viral infections are ubiquitous and their prevention and cure have become a great challenge. In this regard, the design of indole-containing antiviral drugs is accomplished to combat viral infections. A lot of research is being carried out towards antiviral drug discovery by many researchers round the clock. Herein, the antiviral activity of recently discovered indole scaffolds is compiled and critically evaluated to give a meaningful summary. In addition, the structure-activity relationship of remarkable antiviral agents is discussed. Also, the structural motifs attributed to noteworthy antiviral properties are highlighted to guide future antiviral research.

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.

Transcriptome profiling of alphaherpesvirus-infected cells treated with the HIV-integrase inhibitor raltegravir reveals profound and specific alterations in host transcription

Anti-microbial compounds typically exert their action by directly interfering with one or more stages of the pathogen's life cycle. However, some compounds also have secondary effects on the host that aid in pathogen clearance. Raltegravir is a human immunodeficiency virus (HIV)-integrase inhibitor that has been shown to alter the host immune response to HIV in addition to its direct antiviral effect. Interestingly, raltegravir can also directly inhibit the replication of various herpesviruses. However, the host-targeted effects of this drug in the context of a herpesvirus infection have not been explored. Here, we used felid alphaherpesvirus 1 (FHV-1), a close relative of human alphaherpesvirus 1 (HHV-1) that similarly causes ocular herpes, to characterize the host-targeted effects of raltegravir on corneal epithelial cells during an alphaherpesvirus infection. Using RNA deep sequencing, we found that raltegravir specifically boosts the expression of anti-angiogenic factors and promotes metabolic homeostasis in FHV-1-infected cells. In contrast, few changes in host gene transcription were found in uninfected cells. Importantly, we were able to demonstrate that these effects were specific to raltegravir and independent of the direct-acting antiviral effect of the drug, since treatment with the DNA polymerase inhibitor phosphonoacetic acid did not induce these host-targeted effects. Taken together, these results indicate that raltegravir has profound and specific effects on the host transcription profile of herpesvirus-infected cells that may contribute to the overall antiviral activity of the drug and could provide therapeutic benefits in vivo. Furthermore, this study provides a framework for future efforts evaluating the host-targeted effects of anti-microbial compounds.

Arbidol: a quarter-century after. Past, present and future of the original Russian antiviral

The present review is concerned with the synthesis and structure–activity relationship studies of Arbidol and its structural analogues. The latter are roughly divided into several unequal parts: indole- and benzofuran-based compounds, benzimidazole and imidazopyridine bioisosteres and ring-expanded quinoline derivatives. Much attention is focused on various types of antiviral activity of the above-mentioned Arbidol congeners, as well as of the parent compound itself. Features of Arbidol synthesis and metabolic changes are also discussed.

The bibliography includes 166 references.

Structural insight into the optimization of ethyl 5-hydroxybenzo[g]indol-3-carboxylates and their bioisosteric analogues as 5-LO/m-PGES-1 dual inhibitors able to suppress inflammation

The release of pro-inflammatory mediators, such as prostaglandines (PGs) and leukotrienes (LTs), arising from the arachidonic acid (AA) cascade, play a crucial role in initiating, maintaining, and regulating inflammatory processes. New dual inhibitors of 5-lipoxygenase (5-LO) and microsomal prostaglandin E₂ synthase-1 (mPGES-1), that block, at the same time, the formation of PGE₂ and LTs, are currently emerged as a highly interesting drug candidates for better pharmacotherapie of inflammation-related disorders. Following our previous studies, we here performed a detailed structure-based design of benzo[g]indol-3-carboxylate derivatives, disclosing several new key factors that affect both enzyme activity. Ethyl 2-(3,4-dichlorobenzyl)-5-hydroxy-1H-benzo[g]indole-3-carboxylate (4b, RAF-01) and ethyl 2-(3,4-dichlorophenyl)-5-hydroxy-1H-benzo[g]indole-3-carboxylate (7h, RAF-02) emerged as the most active compounds of the series. Additionally, together with selected structure based analogues, both derivatives displayed significant in vivo anti-inflammatory properties. In conclusion, modeling and experimental studies lead to the discovery of new candidate compounds prone to further developments as multi-target inhibitors of the inflammatory pathway.

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.

Inhibition of the infectivity and inflammatory response of influenza virus by Arbidol hydrochloride in vitro and in vivo (mice and ferret)

Influenza virus infections are the main contagious respiratory disease with high levels of morbidity and mortality worldwide. Antiviral drugs are indispensable for the prophylaxis and treatment of influenza and other respiratory viral infections. In this study, the Arbidol hydrochloride (ARB), which has been licensed in Russia and China, is used to investigate its anti-viral and anti-inflammatory efficacy in vitro and in vivo. The antiviral results in vitro showed that ARB had a better inhibition on Influenza virus A/PR/8/34 (H1N1), A/Guangdong/GIRD07/09 (H1N1), A/Aichi/2/68 (H3N2), A/HK/Y280/97 (H9N2) with IC₅₀ ranging from 4.4 to 12.1μM. The further mechanisms study demonstrated that ARB is able to inhibit hemagglutinin-mediated hemolysis at concentration of 3.91-15.63μg/mL. The anti-inflammatory efficacy in vitro indicated that IL-6, IP-10, MCP-1, RANTES and TNF-α levels were diminished by ARB at concentrations of 22.6 and 18.8μM. The in vivo results in mice model displayed that the survival rates of mice administered 25mg/mL and 45mg/mL ARB were 40% and 50% respectively. And also, ARB can inhibit the decrease of body weight at 45mg/mL and inhibit the increase of mice lung index at 25mg/mL and 45mg/mL comparing to virus group. In ferret model, the ARB-treated ferrets showed a fever that peaked at 2 dpi and gradually decreased beginning at 3 dpi while relatively high temperatures were observed until 4 dpi in the virus group. The ARB-treated group scored 0-1 in the activity level at 2 dpi and 3 dpi at all time points. The transcription levels of cytokines in the respiratory tract of ferrets were detected at 3 dpi. Several proinflammatory cytokines induced by influenza (IL-10, TNF-α, IL-8 and IL-6) were down-regulated by post-treatment with ARB. The histopathological results of ferret lung displayed that ARB can alleviate the influenza virus induced lung lesions. Our results clarified the activity of ARB in both suppressing virus propagation and modulating the expression of inflammatory cytokines in vitro and in vivo, it can be as an effective drug to treat the influenza virus infection.

The delivery of arbidol by salt engineering: synthesis, physicochemical properties and pharmacokinetics

The aim of the present study was to evaluate the feasibility of using the methanesulfonic salt of arbidol in order to improve its aqueous solubility and thus oral bioavailability. Arbidol mesylate (AM) was synthesized and then characterized using nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), and its apparent solubility and octanol-water partition coefficient were also studied. The results of NMR, IR, PXRD, SEM and DSC tests confirmed the salt formation. The apparent solubility of AM in water was 32-fold higher than that of the commercial product. A superior pH-dependent profile and an improved dissolution rate of AM were obtained in a variety of solutions with different pH values. In addition, AM exhibited a relatively higher peak plasma concentration (1460 versus 1297 ng/mL) and an increased AUC_0-t (2475 versus 1277 ng/mL × h) when comparing with the commercial product, indicating the improved bioavailability of the drug. This study suggests that AM may be able to improve the therapeutic efficacy of arbidol, which rendering it to be a promising candidate for further development.

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.

The Synthetic Antiviral Drug Arbidol Inhibits Globally Prevalent Pathogenic Viruses

Arbidol (ARB) is a synthetic antiviral originally developed to combat influenza viruses. ARB is currently used clinically in several countries but not in North America. We have previously shown that ARB inhibits in vitro hepatitis C virus (HCV) by blocking HCV entry and replication. In this report, we expand the list of viruses that are inhibited by ARB and demonstrate that ARB suppresses in vitro infection of mammalian cells with Ebola virus (EBOV), Tacaribe arenavirus, and human herpesvirus 8 (HHV-8). We also confirm suppression of hepatitis B virus and poliovirus by ARB. ARB inhibited EBOV Zaire Kikwit infection when added before or at the same time as virus infection and was less effective when added 24 h after EBOV infection. Experiments with recombinant vesicular stomatitis virus (VSV) expressing the EBOV Zaire glycoprotein showed that infection was inhibited by ARB at early stages, most likely at the level of viral entry into host cells. ARB inhibited HHV-8 replication to a similar degree as cidofovir. Our data broaden the spectrum of antiviral efficacy of ARB to include globally prevalent viruses that cause significant morbidity and mortality.

IMPORTANCE

There are many globally prevalent viruses for which there are no licensed vaccines or antiviral medicines. Some of these viruses, such as Ebola virus or members of the arenavirus family, rapidly cause severe hemorrhagic diseases that can be fatal. Other viruses, such as hepatitis B virus or human herpesvirus 8 (HHV-8), establish persistent infections that cause chronic illnesses, including cancer. Thus, finding an affordable, effective, and safe drug that blocks many viruses remains an unmet medical need. The antiviral drug arbidol (ARB), already in clinical use in several countries as an anti-influenza treatment, has been previously shown to suppress the growth of many viruses. In this report, we expand the list of viruses that are blocked by ARB in a laboratory setting to include Ebola virus, Tacaribe arenavirus, and HHV-8, and we propose ARB as a broad-spectrum antiviral drug that may be useful against hemorrhagic viruses.