Anti-dengue Virus Activity Research Articles

Four undescribed triterpenes from the aerial parts of Verbena officinalis

Verbena officinalis is used as a Chinese folk medicine for the treatment of rheumatism and bronchitis. Herein, four undescribed triterpenes, officinalisoids A-D (1–4), together with thirty-three known compounds (5–37) were isolated from the aerial parts of V. officinalis. The chemical structures of the new compounds were determined by spectrometric data interpretation using NMR, HRESIMS, IR and UV spectroscopy. Biological evaluation results revealed that compound 30 exhibited potential anti-inflammatory activity with IC50 value of 6.07 μM (CC50 > 50 μM) and compound 12 showed moderate anti-dengue virus activity with the IC50 value of 24.55 μM (CC50 > 50 μM).

Identification of an effective fraction from Ampelopsis Radix with anti-dengue virus activities in vitro and in vivo.

Dengue virus (DENV) infection is a global public health issue without effective therapeutic interventions. Chinese medicine with heat-clearing and detoxifying properties has been frequently used in the treatment of viral infection. Ampelopsis Radix (AR) is a traditional Chinese medicine for clearing heat and detoxification that has been widely used in the prevention and treatment of infectious diseases. However, no studies on the effects of AR against viral infection have been reported, thus far. To explore the anti-DENV activities of the fraction (AR-1) obtained from AR both in vitro and in vivo. The chemical composition of AR-1 was identified by liquid chromatography-tandem MS (LC‒MS/MS). The antiviral activities of AR-1 were studied in baby hamster kidney fibroblast BHK-21cells, ICR suckling mice and induction of interferon α/β (IFN-α/β) and IFN-γ R-/- (AG129) mice. Based on LC‒MS/MS analysis, 60 compounds (including flavonoids, phenols, anthraquinones, alkaloids and other types) were tentatively characterized from AR-1. AR-1 inhibited the cytopathic effect, the production of progeny virus and the synthesis of viral RNA and proteins by blocking DENV-2 binding to BHK-21cells. Moreover, AR-1 significantly attenuated weight loss, decreased clinical scores and prolonged the survival of DENV-infected ICR suckling mice. Critically, the viral load in blood, brain and kidney tissues and the pathological changes in brain were remarkably alleviated after AR-1 treatment. Further study on AG129 mice showed that AR-1 obviously improved the clinical manifestations and survival rate, reduced viremia, attenuated gastric distension and relieved the pathological lesions caused by DENV. In summary, this is the first report that AR-1 exhibits anti-DENV effects both in vitro and in vivo, which suggests that AR-1 may be developed as a therapeutic candidate against DENV infection.

Metabolites from Alpinia zerumbet with Anti-Dengue Virus Activity

Metabolites from Alpinia zerumbet with Anti-Dengue Virus Activity

Real-World Study on Chai-Shi-Jie-Du Granules for the Treatment of Dengue Fever and the Possible Mechanisms Based on Network Pharmacology.

Traditional Chinese medicine (TCM) is a widely used method for treating dengue fever in China. TCM improves the symptoms of patients with dengue, but there is no standard TCM prescription for dengue fever. This real-world study aimed to evaluate the effects of Chai-Shi-Jie-Du (CSJD) granules for the treatment of dengue fever and the underlying mechanisms. We implemented a multicenter real-world study, an in vitro assay and network pharmacology analysis. Patients from 5 hospitals in mainland China who received supportive western treatment in the absence or presence of CSJD were assigned to the control and CSJD groups between 1 August and 31 December 2019. Propensity score matching (PSM) was performed to correct for biases between groups. The clinical data were compared and analyzed. The antidengue virus activity of CSJD was tested in Syrian baby hamster kidney (BHK) cells using the DENV2-NGC strain. Network pharmacological approaches along with active compound screening, target prediction, and GO and KEGG enrichment analyses were used to explore the underlying molecular mechanisms. 137 pairs of patients were successfully matched according to age, sex, and the time from onset to presentation. The time to defervescence (1.7 days vs. 2.5 days, P < 0.05) and the disease course (4.1 days vs. 6.1 days, P < 0.05) were significantly shorter in the CSJD group than those in the control group. CSJD showed no anti-DENV2-NGC virus activity in BHK cells. Network pharmacology analysis revealed 108 potential therapeutic targets, and the top GO and KEGG terms were related to immunity, oxidative stress response, and the response to lipopolysaccharide. CSJD granules exhibit high potential for the treatment of dengue fever, and the therapeutic mechanisms involved could be related to regulating immunity, moderating the oxidative stress response, and the response to lipopolysaccharide.

Anti-Dengue Screening on Several Vietnamese Medicinal Plants: Experimental Evidences and Computational Analyses.

Worldwide, medicinal plants have been known for economic and geographical advantages, thus possibly holding potentiality against dengue hemorrhagic fever. The methanol/water extracts from different parts of fourteen Vietnam-based plant species were subjected for experimental screening on anti-dengue activity using baby hamster kidney cells (BHK21) and plaque reduction neutralisation test (PRNT). Firstly, the methanol/water extracts were tested against serotype dengue virus DENV-1. Seven out from nineteen extracts show the PRNT50 values less than 31.25 μg/mL. Four of the above extracts namely from Euphorbia hirta, Cordyline terminalis, Carica papaya, and Elaeagnus latifolia were chosen for testing against the serotype DENV-2. All of them exhibit good activity with the PRNT50 values less than 31.25 μg/ml, which were further fractionated to obtain hexane, ethyl acetate and butanol fractions. Anti-dengue virus activity of the fractions against four serotypes DENV-1, -2, -3 and -4 was evaluated. As results, the ethyl acetate fraction of Elaeagnus latifolia is highly active against all four serotype viruses. The structural formulae of its nine constituents were input for molecular docking simulation. The docking-based order for static inhibitability is 6-3L6P>7-3L6P>9-3L6P>2-3L6P>3-3L6P≈5-3L6P>9-3L6P>1-3L6P>8-3L6P; QSARIS-based analysis reveals the biocompatibility of the most promising ligands (4-7); ADMET-based analysis expects their pharmacological suitability. Exceptional finding on 2-3LKW hydrophilic interaction at Lys43 (with the associated Gibbs free energy of -10.3 kcal mol-1 ) raises an open explanation for inhibitory effects. The results encourage further investigations for more in-depth mechanisms and drug development, such as in vitro enzyme assays or in vitro clinical trials with natural substances from E. latifolia.

In Vitro Antiviral Activity of Potential Medicinal Plant Extracts Against Dengue and Chikungunya Viruses.

Dengue and chikungunya are two important mosquito-borne infections which are known to occur extensively in tropical and subtropical areas. Presently, there is no treatment for these viral diseases. In vitro antiviral screening of 25 extracts prepared from the plants of Vitex negundo, Plumeria alba, Ancistrocladus heyneanus, Bacopa monnieri, Anacardium occidentale, Cucurbita maxima, Simarouba glauca, and Embelia ribes using different solvents and four purified compounds (anacardic acid, chloroquinone, glaucarubinone, and methyl gallate) were carried out for their anti-dengue virus (DENV) and anti-chikungunya virus (CHIKV) activities. Maximum nontoxic concentrations of the chloroform, methanol, ethyl acetate, petroleum ether, dichloromethane, and hydroalcoholic extracts of eight plants were used. The antiviral activity was assessed by focus-forming unit assay, quantitative real-time RT-PCR, and immunofluorescence assays. Extracts from Plumeria alba, Ancistrocladus heyneanus, Bacopa monnieri, and Cucurbita maxima showed both anti-DENV and CHIKV activity while extract from Vitex negundo showed only anti-DENV activity. Among the purified compounds, anacardic acid, chloroquinone and methyl gallate showed anti-dengue activity while only methyl gallate had anti-chikungunya activity. The present study had identified the plant extracts with anti-dengue and anti-chikungunya activities, and these extracts can be further characterized for finding effective phytopharmaceutical drugs against dengue and chikungunya.

A Review of Medicinal Plants with Anti-Dengue Virus Activity

Dengue virus is an arthropod-borne infectious agent that causes dengue disease. The virus spreads by Aedes aegypti and Aedes albopictus mosquitos. Due to the neglegent care given to the infection, the vectors as well as the virus have expanded globally and millions have already been affected by dengue infection as regards reports by ECDC, CDC and WHO. Dengue virus infection have been alleviated by erratic treatments since there is no precise formulation against it. However, there are plenteous clinical risks alongside using the drugs, this leaves human with no other choices than to reason for other alternative means of treatment to decrease the deleterious effects to minimal level. To introduce newer candidate anti-dengue pharmaceutical agent with minimal/ or no therapeutic lapses, botanical treatments have highly been recognized. Medicinal plants have been observed to be of health benefit in dengue virus infection through promoting immunocompetence, supplying pharmacological aids such as prophylactic effects, decrease viral amplification and lowering morbid condition. The potential anti-dengue activity of medicinal plants have been exemplified in the literature as the principal interest. We tried to find the existing factors behind virucidal activity of plants in the context of anti-dengue virus and the consulted publications indicated that certain flavonoids (Kaempferol-3-Orutinoside, Rutin, Hyperoside, Epicatechin Resveratrol, Quercetin, Emodin, Emodin-8-beta-D-glucoe and Polydatin), Tannins (Galic acid, Tannic acids), Alkaloids (Artesonic Acid, Homoegonol, Myristicin), Fatty acids (Methyldodecanoic acid, Dodecanoic acid, Tridecanoic acid, 12-methyl-methyl-esters, n-hexadecanoic acid), Terpenoids (Beta-asarone, Acoric acid, Andrographolide, Caryophyllene, Cyclododocane) and many others could be the major antiviral factors. This study will assist in giving better insights on anti-dengue activity of medicinal plants divulging dengue virus reliable combaters eventually. However, it is needful to conduct heightened critical clinical studies in this vein for proper verification.

Synthesis and Anti-dengue Virus Activity of 5-Ethynylimidazole-4-carboxamide (EICA) Nucleotide Prodrugs.

We previously showed that 5-ethynyl-(1-β-D-ribofuranosyl)imidazole-4-carboxamide (1; EICAR) is a potent anti-dengue virus (DENV) compound but is cytotoxic to some cell lines, while its 4-thio derivative, 5-ethynyl-(4-thio-1-β-D-ribofuranosyl)imidazole-4-carboxamide (2; 4'-thioEICAR), has less cytotoxicity but also less anti-DENV activity. Based on the hypothesis that the lower anti-DENV activity of 2 is due to reduced susceptibility to phosphorylation by cellular kinase(s), we investigated whether a monophosphate prodrug of 2 can improve its activity. Here, we first prepared two types of prodrug of 1, which revealed that the S-acyl-2-thioethyl (SATE) prodrug had stronger anti-DENV activity than the aryloxyphosphoramidate (so-called ProTide) prodrug. Based on these findings, we next prepared the SATE prodrug of 4'-thioEICAR 18. As expected, the resulting 18 showed potent anti-DENV activity, which was comparable to that of 1; however, its cytotoxicity was also increased relative to 2. Our findings suggest that prodrugs of 4'-thioribonucleoside derivatives such as EICAR (1) represent an effective approach to developing potent biologically active compounds; however, the balance between antiviral activity and cytotoxicity remains to be addressed.

Endemic and Indigenous Plants from Mascarene Islands with Antiviral Propensities.

Antiviral resistance and inefficiency of available antiviral drugs to effectively treat viral infections have prompted many researchers worldwide to explore medicinal plants and their isolated compounds as alternative antivirals. The rich flora from the Mascarene Islands has also been thoroughly studied for their wide therapeutic activities, including their antiviral properties. The aim of this review is to highlight the antiviral propensities of Mascarene endemic and indigenous medicinal plants. A review of the literature was conducted via major databases and other primary sources of information. The inhibitory concentration/effective dose causing 50% viral inhibition (IC50/ED50), cytotoxic concentration causing 50% reduction in cell viability (CC50), and selectivity index (SI) were reported, and mechanisms of antiviral action were also discussed. Stillingia lineata was the most effective against chikungunya virus (SI: 10.9), and among its isolated compounds, 12-O-acetylphorbol-13(2″-methyl)- butyrate and 12-deoxyphorbol- 13(2″-methyl)butyrate were the most potent and selective inhibitors of chikungunya virus replication (SI: 41 and >240, respectively). 12-O-acetylphorbol-13(2″-methyl)- butyrate, 12β-O-[nona- 2Z,4E,6E-trienoyl]-4α-deoxyphorbol-13-butyrate, 12-deoxyphorbol-13(2″-methyl)butyrate, and 12-deoxyphorbol-13-[8'-oxohexadeca-2E,4E,6E-trienoate showed strong selective antiviral effect on human immunodeficiency virus-I (SI: 36-899) and II (SI: 33-2056). Obetia ficifolia and Erythroxylon laurifolium were most active against the herpes virus (SI: 18.5 and 16, respectively). Labourdonnaisia glauca showed potent anti-poliovirus activity (SI: 40), while Badula insularis, Labourdonnaisia glauca and Myonima violacea were active against rhinovirus (SI: 1.3-2.5). Both anti-zika and anti-dengue virus activities were reported for Aphloia theiformis, Doratoxylon apetalum, Phyllanthus phillyreifolius and Psiloxylon mauritianum. Promising spectrum of antiviral properties notably against zika, dengue, chikungunya, polio-, rhino-, herpes, and human immunodeficiency viruses were presented by the Mascarene plants suggesting them as viable candidates for the potential development of effective natural antiviral drugs.

Dengue virus-free defective interfering particles have potent and broad anti-dengue virus activity

Dengue virus (DENV) is spread from human to human through the bite of the female Aedes aegypti mosquito and leads to about 100 million clinical infections yearly. Treatment options and vaccine availability for DENV are limited. Defective interfering particles (DIPs) are considered a promising antiviral approach but infectious virus contamination has limited their development. Here, a DENV-derived DIP production cell line was developed that continuously produced DENV-free DIPs. The DIPs contained and could deliver to cells a DENV serotype 2 subgenomic defective-interfering RNA, which was originally discovered in DENV infected patients. The DIPs released into cell culture supernatant were purified and could potently inhibit replication of all DENV serotypes in cells. Antiviral therapeutics are limited for many viral infection. The DIP system described could be re-purposed to make antiviral DIPs for many other RNA viruses such as SARS-CoV-2, yellow fever, West Nile and Zika viruses.

A Cyclic Phosphoramidate Prodrug of 2'-Deoxy-2'-Fluoro-2'-C-Methylguanosine for the Treatment of Dengue Virus Infection.

Monophosphate prodrug analogs of 2'-deoxy-2'-fluoro-2'-C-methylguanosine have been reported as potent inhibitors of hepatitis C virus (HCV) RNA-dependent RNA polymerase. These prodrugs also display potent anti-dengue virus activities in cellular assays although their prodrug moieties were designed to produce high levels of triphosphate in the liver. Since peripheral blood mononuclear cells (PBMCs) are among the major targets of dengue virus, different prodrug moieties were designed to effectively deliver 2'-deoxy-2'-fluoro-2'-C-methylguanosine monophosphate prodrugs and their corresponding triphosphates into PBMCs after oral administration. We identified a cyclic phosphoramidate, prodrug 17, demonstrating well-balanced anti-dengue virus cellular activity and in vitro stability profiles. We further determined the PBMC concentration of active triphosphate needed to inhibit virus replication by 50% (TP50). Compound 17 was assessed in an AG129 mouse model and demonstrated 1.6- and 2.2-log viremia reductions at 100 and 300 mg/kg twice a day (BID), respectively. At 100 mg/kg BID, the terminal triphosphate concentration in PBMCs exceeded the TP50 value, demonstrating TP50 as the target exposure for efficacy. In dogs, oral administration of compound 17 resulted in high PBMC triphosphate levels, exceeding the TP50 at 10 mg/kg. Unfortunately, 2-week dog toxicity studies at 30, 100, and 300 mg/kg/day showed that "no observed adverse effect level" (NOAEL) could not be achieved due to pulmonary inflammation and hemorrhage. The preclinical safety results suspended further development of compound 17. Nevertheless, present work has proven the concept that an efficacious monophosphate nucleoside prodrug could be developed for the potential treatment of dengue virus infection.

Repurposing of N-Acetylcysteine for the Treatment of Dengue Virus-Induced Acute Liver Failure.

The prevalence of dengue infection-induced acute liver damage is increasing from time to time. Since it has no specific antiviral treatment in the world, people in endemic areas suffer more from dengue disorders. Thus, there is a need for searching options for the treatment of dengue-induced acute liver failure. N-acetylcysteine, which is used for the treatment of nasal congestion disorder and paracetamol overdose toxicity, could be used as a definitive therapy for dengue virus-induced acute liver disease. Therefore, this review discusses the therapeutic use of N-acetylcysteine for dengue-induced acute liver disease. Various case reports and case series showed that patients received NAC recovered from their clinical status. Additionally, a preclinical study showed that N-acetylcysteine has anti-dengue virus activity. Thus, N-acetylcysteine could be used as a definitive therapy in dengue virus-induced hepatitis. This might encourage researchers to further investigate the importance of N-acetylcysteine for dengue virus-induced hepatitis.

Antiviral activity of astragaloside II, astragaloside III and astragaloside IV compounds against dengue virus: Computational docking and in vitro studies

This study was aimed to identify the phytocompounds possessing anti-dengue virus activity using in silico and in vitro approaches. A total of 7000 phytocompounds were virtually screened against protein targets (envelope, NS2b/NS3, and NS5) of dengue virus using iGEMDOCK and individually docked using Maestro 10.7 module of Schrödinger software. In vitro cytotoxicity and antiviral studies were performed using vero cell line. Finally, three phytocompounds namely astragaloside II, astragaloside III, and astragaloside IV were screened based on their highest binding energy values against protein targets. Astragaloside III exhibited the highest interaction energy value of −8.718 kcal/mol and −8.447 kcal/mol against envelope, and NS2b/NS3 targets, respectively. Astragaloside IV exhibited −7.244 kcal/mol against SAM site, and −9.179 kcal/mol against RNA cap site of NS5 targets. In silico ADMET analysis revealed that astragaloside II, III, and IV were non-mutagenic and non-carcinogenic in nature and these compounds were also non-toxic to vero cells upto 1000 μg/mL. Against dengue virus serotype 3, astragaloside II exhibited substantial antiviral activity at the concentration of 1.56 μg/mL followed by astragaloside III at 6.25 μg/mL and astragaloside IV at 12.5 μg/mL. Also, against dengue serotype 1, astragaloside II showed the maximum antiviral activity at 1.56 μg/mL followed by astragaloside III and IV at 3.125 μg/mL. This study concludes that astragaloside II, III, and IV compounds had potential in vitro anti-dengue virus activity.

New pestallic acids and diphenylketone derivatives from the marine alga-derived endophytic fungus Pestalotiopsis neglecta SCSIO41403.

Three new carboxylic acid derivatives, pestallic acids F and G (1 and 2), pestalotiopyrone N (3), and a new diphenylketone derivative named neopestalone (5) were obtained from the liquid cultures of marine alga-derived endophytic fungus Pestalotiopsis neglecta SCSIO41403, along with six known compounds (4, 6-10). The structures of those new compounds were elucidated mainly by analysis of their NMR and MS data. The isolated compounds were evaluated for their anti-Dengue virus and COX-2 inhibitory activities, and two diphenylketone derivatives (5 and 6) exhibited obvious COX-2 inhibitory activities, with the IC50 values being 5.8 and 3.4 μM, respectively.

Antiviral activity and chemical characterization of Cissus erosa (Vitaceae) ethanol extracts

Abstract Cissus erosa (Vitaceae), popularly known in Brazil as Cipó-fogo, is a medicinal plant used in the treatment of warts and external ulcers. The present study aimed to evaluate the activity of stems and leaves ethanol extracts of C. erosa against the Dengue and Zika virus by the MTT colorimetric method and to carry on the phytochemical characterization of active extracts by high performance liquid chromatography coupled to mass spectrometry (UPLC-MS). Only the leaves ethanol extract showed anti-Dengue virus activity EC50 18.2 µg/ml (SI &gt; 27.5) and low cytotoxicity for LLCMK2 cells (CC50 &gt; 500 mg/ml). Both extracts (stems and leaves) showed anti-Zika virus activity with EC50 of 45.8 mg/ml and 82.8 mg/ml, respectively. These extracts presented CC50 of 309.2 µg/ml (leaves) and 387.6 µg/ml (stems) to Vero cells. Analysis by CCD and HPLC-DAD detected the presence of triterpenes, steroids, flavonoids and tannins. UPLC-MS analyses of these extracts, allowed the identification of the majority of flavonoids present known as vitexin, isovitexin, orientin, isoorientin and two flavones derivatives, methoxyluteolin-6(8)-C-hexosyl and luteolin-7,4’-di-O-glycosylflavone. The results of the phytochemical studies here described suggest that flavonoids and terpenoids are the substances that contribute to the antiviral activity of the ethanol extracts within this species.

A New Lignanamide Derivative and Bioactive Constituents of Lycium chinense

A new lignanamide derivative, lycichinenamide (1), has been isolated from the root barks of Lycium chinense together with nine known compounds, lyciumamide H (2), 5,2′-dihydroxy-6,7,8,6′-tetramethoxyflavone (3), 7α,8β-3′-O-methylcedrusin (4), smiglabrol (5), trans-N-caffeoyltyramine (6), vanillic acid (7), syringic acid (8), 2,6-dimethoxy-1,4-benzoquinone (9), and 1,5-dihydroxy-2-isoprenyl-3-methoxyxanthone (10). The structure of the new compound 1 was determined through spectroscopic and MS analyses. Among the isolates, lycichinenamide (1), lyciumamide H (2), smiglabrol (5), and trans-N-caffeoyltyramine (6) showed potent inhibition with IC50 values of 18.5 ± 2.1, 21.8 ± 1.8, 12.4 ± 0.3, and 24.6 ± 2.0 μM, respectively, against LPS-induced NO generation. In addition, 1,5-dihydroxy-2-isoprenyl-3-methoxyxanthone (10) exhibited anti-Dengue virus activity with IC50 value of 22.4 ± 1.6 μM against Dengue virus serotype 2 strain PL046.

An Antiviral Peptide from Alopecosa nagpag Spider Targets NS2B-NS3 Protease of Flaviviruses.

Flaviviruses are single-stranded RNA viruses predominantly transmitted by the widely distributed Aedes mosquitoes in nature. As important human pathogens, the geographic reach of Flaviviruses and their threats to public health are increasing, but there is currently no approved specific drug for treatment. In recent years, the development of peptide antivirals has gained much attention. Natural host defense peptides which uniquely evolved to protect the hosts have been shown to have antiviral properties. In this study, we firstly collected the venom of the Alopecosa nagpag spider from Shangri-La County, Yunnan Province. A defense peptide named Av-LCTX-An1a (Antiviral-Lycotoxin-An1a) was identified from the spider venom, and its anti-dengue serotype-2 virus (DENV2) activity was verified in vitro. Moreover, a real-time fluorescence-based protease inhibition assay showed that An1a functions as a DENV2 NS2B–NS3 protease inhibitor. Furthermore, we also found that An1a restricts zika virus (ZIKV) infection by inhibiting the ZIKV NS2B–NS3 protease. Together, our findings not only demonstrate that An1a might be a candidate for anti-flavivirus drug but also indicate that spider venom is a potential resource library rich in antiviral precursor molecules.

A New Isochromeno[4,3-b]Chromen-7(5H)-One Derivative and Bioactive Constituents of Filipendula kiraishiensis

A new isochromeno[4,3-b]chromen-7(5H)-one derivative, 8-hydroxy-3,10-dimethoxyisochromeno [4,3-b]chromen-7(5H)-one (1), has been isolated from the aerial part of Filipendula kiraishiensis, together with seven known compounds. The structure of the new compound 1 was determined through spectroscopic and MS analyses. Among the isolates, luteolin (2), rutin (3), quercetin (4), and isoquercitrin (5) showed potent inhibition with IC50 values of 24.2 ± 1.2, 18.6 ± 1.3, 10.2 ± 0.5, and 12.2 ± 1.0 μM, respectively, against LPS-induced NO generation. In addition, 8-hydroxy-3,10-dimethoxyisochromeno[4,3-b]chromen-7(5H)-one (1) exhibited anti-Dengue virus activities with IC50 value of 22.4 ± 1.6 μM against Dengue virus serotype 2 strain PL046.

A small molecule inhibitor of ER-to-cytosol protein dislocation exhibits anti-dengue and anti-Zika virus activity

Infection with flaviviruses, such as dengue virus (DENV) and the recently re-emerging Zika virus (ZIKV), represents an increasing global risk. Targeting essential host elements required for flavivirus replication represents an attractive approach for the discovery of antiviral agents. Previous studies have identified several components of the Hrd1 ubiquitin ligase-mediated endoplasmic reticulum (ER)-associated degradation (ERAD) pathway, a cellular protein quality control process, as host factors crucial for DENV and ZIKV replication. Here, we report that CP26, a small molecule inhibitor of protein dislocation from the ER lumen to the cytosol, which is an essential step for ERAD, has broad-spectrum anti-flavivirus activity. CP26 targets the Hrd1 complex, inhibits ERAD, and induces ER stress. Ricin and cholera toxins are known to hijack the protein dislocation machinery to reach the cytosol, where they exert their cytotoxic effects. CP26 selectively inhibits the activity of cholera toxin but not that of ricin. CP26 exhibits a significant inhibitory activity against both DENV and ZIKV, providing substantial protection to the host cells against virus-induced cell death. This study identified a novel dislocation inhibitor, CP26, that shows potent anti-DENV and anti-ZIKV activity in cells. Furthermore, this study provides the first example of the targeting of host ER dislocation with small molecules to combat flavivirus infection.

Synthesis and biological evaluation of novel imidazole nucleosides as potential anti-dengue virus agents.

In this work, we developed imidazole nucleoside derivatives with anti-dengue virus (DENV) activity was examined. First, compounds in a nucleosides library were screened to find lead compounds which inhibit replication of DENV. As a result, 5-ethynyl-(1-β-d-ribofuranosyl)imidazole-4-carboxamide (1; EICAR) and its 4-carbonitrile derivative EICNR (2) were selected as promising antiviral compounds. However, both of them also exhibited cytotoxicity. In order to develop an effective and less toxic compound, 4'-thio and 4'-seleno derivatives of EICAR and EICNR 3-6 were prepared. The resulting 4'-thioEICAR and 4'-thioEICNR showed inhibitory effect on DENV replication without cytotoxicity as potent as ribavirin, a positive control.