BPR3P0128, a non-nucleoside RNA-dependent RNA polymerase inhibitor, inhibits SARS-CoV-2 variants of concern and exerts synergistic antiviral activity in combination with remdesivir.

Viral RNA-dependent RNA polymerase (RdRp), a highly conserved molecule in RNA viruses, has recently emerged as a promising drug target for broad-acting inhibitors. Through a Vero E6-based anti-cytopathic effect assay, we found that BPR3P0128, which incorporates a quinoline core similar to hydroxychloroquine, outperformed the adenosine analog remdesivir in inhibiting RdRp activity (EC50 = 0.66 µM and 3 µM, respectively). BPR3P0128 demonstrated broad-spectrum activity against various severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern. When introduced after viral adsorption, BPR3P0128 significantly decreased SARS-CoV-2 replication; however, it did not affect the early entry stage, as evidenced by a time-of-drug-addition assay. This suggests that BPR3P0128's primary action takes place during viral replication. We also found that BPR3P0128 effectively reduced the expression of proinflammatory cytokines in human lung epithelial Calu-3 cells infected with SARS-CoV-2. Molecular docking analysis showed that BPR3P0128 targets the RdRp channel, inhibiting substrate entry, which implies it operates differently-but complementary-with remdesivir. Utilizing an optimized cell-based minigenome RdRp reporter assay, we confirmed that BPR3P0128 exhibited potent inhibitory activity. However, an enzyme-based RdRp assay employing purified recombinant nsp12/nsp7/nsp8 failed to corroborate this inhibitory activity. This suggests that BPR3P0128 may inhibit activity by targeting host-related RdRp-associated factors. Moreover, we discovered that a combination of BPR3P0128 and remdesivir had a synergistic effect-a result likely due to both drugs interacting with separate domains of the RdRp. This novel synergy between the two drugs reinforces the potential clinical value of the BPR3P0128-remdesivir combination in combating various SARS-CoV-2 variants of concern.

HCV Core Protein-ISX Axis Promotes Chronic Liver Disease Progression via Metabolic Remodeling and Immune Suppression.

Chronic hepatitis C virus (HCV) infection is an important public health issue. However, knowledge on how the virus remodels the metabolic and immune response toward hepatic pathologic environment is limited. The transcriptomic and multiple evidences reveal that the HCV core protein-intestine-specific homeobox (ISX) axis promotes a spectrum of metabolic, fibrogenic, and immune modulators (e.g., kynurenine, PD-L1, and B7-2), regulating HCV-infection relevant pathogenic phenotype in vitro and in vivo. In a transgenic mice model, the HCV core protein-ISX axis enhance metabolic disturbance (particularly lipid and glucose metabolism) and immune suppression, and finally, chronic liver fibrosis in a high-fat diet (HFD)-induced disease model. Mechanistically, cells with HCV JFH-1 replicons upregulate ISX and, consequently, the expressions of metabolic, fibrosis progenitor, and immune modulators via core protein-induced nuclear factor-κB signaling. Conversely, cells with specific ISX shRNAi inhibit HCV core protein-induced metabolic disturbance and immune suppression. Clinically, the HCV core level is significantly correlated with ISX, IDOs, PD-L1, and B7-2 levels in HCC patients with HCV infection. Therefore, it highlights the significance of HCV core protein-ISX axis as an important mechanism in the development of HCV-induced chronic liver disease and can be a specific therapeutic target clinically.

Grape Seed Proanthocyanidins Inhibit Replication of the Dengue Virus by Targeting NF-kB and MAPK-Mediated Cyclooxygenase-2 Expression.

Dengue virus (DENV) infection is a serious global health issue as it causes severe dengue hemorrhagic fever and dengue shock syndrome. Since no approved therapies are available to treat DENV infection, it is necessary to develop new agents or supplements that can do this. In this study, grape seed proanthocyanidins extract (GSPE), which is widely consumed as a dietary supplement, dose-dependently suppressed the replication of four DENV serotypes. The inhibitory mechanism demonstrated that GSPE downregulated DENV-induced aberrant cyclooxygenase-2 (COX-2) expression, revealing that the inhibitory effect of the GSPE on DENV replication involved targeting DENV-induced COX-2 expression. Mechanistic studies on signaling regulation have demonstrated that GSPE significantly reduced COX-2 expression by inactivating NF-κB and ERK/P38 MAPK signaling activities. Administrating GSPE to DENV-infected suckling mice reduced virus replication, mortality, and monocyte infiltration of the brain. In addition, GSPE substantially reduced the expression of DENV-induced inflammatory cytokines associated with severe dengue disease, including tumor necrosis factor-α, nitric oxide synthase, interleukin (IL)-1, IL-6, and IL-8, suggesting that GSPE has potential as a dietary supplement to attenuate DENV infection and severe dengue.

Micro-PET imaging of hepatitis C virus NS3/4A protease activity using a protease-activatable retention probe.

Hepatitis C virus (HCV) NS3/4A protease is an attractive target for direct-acting antiviral agents. Real-time tracking of the NS3/4A protease distribution and activity is useful for clinical diagnosis and disease management. However, no approach has been developed that can systemically detect NS3/4A protease activity or distribution. We designed a protease-activatable retention probe for tracking HCV NS3/4A protease activity via positron emission topography (PET) imaging. A cell-penetrating probe was designed that consisted of a cell-penetrating Tat peptide, HCV NS3/4A protease substrate, and a hydrophilic domain. The probe was labeled by fluorescein isothiocyanate (FITC) and 124I in the hydrophilic domain to form a TAT-ΔNS3/4A-124I-FITC probe. Upon cleavage at NS3/4A substrate, the non-penetrating hydrophilic domain is released and accumulated in the cytoplasm allowing PET or optical imaging. The TAT-ΔNS3/4A-FITC probe selectively accumulated in NS3/4A-expressing HCC36 (NS3/4A-HCC36) cells/tumors and HCV-infected HCC36 cells. PET imaging showed that the TAT-ΔNS3/4A-124I-FITC probe selectively accumulated in the NS3/4A-HCC36 xenograft tumors and liver-implanted NS3/4A-HCC36 tumors, but not in the control HCC36 tumors. The TAT-ΔNS3/4A-124I-FITC probe can be used to represent NS3/4 protease activity and distribution via a clinical PET imaging system allowing. This strategy may be extended to detect any cellular protease activity for optimization the protease-based therapies.

Novel Aporphine- and Proaporphine-Clerodane Hybrids Identified from the Barks of Taiwanese Polyalthia longifolia (Sonn.) Thwaites var. pendula with Strong Anti-DENV2 Activity.

Hybrid natural products produced via mixed biosynthetic pathways are unique and often surprise one with unexpected medicinal properties in addition to their fascinating structural complexity/diversity. In view of chemical structures, hybridization is a way of diversifying natural products usually through dimerization of two similar or dissimilar subcomponents through a C-C or N-C covalent linkage. Here, we report four structurally attractive diterpene-alkaloid conjugates polyalongarins A-D (1-4), clerodane-containing aporphine and proaporphine alkaloids, the first of its kind from the barks of Taiwanese Polyalthia longifolia (Sonn.) Thwaites var. pendula. In addition to conventional spectroscopic analysis, single crystal X-ray crystallography was employed to determine the chemical structures and stereo-configurations of 1. Compounds 1-4 were subsequently subjected to in vitro antiviral examination against DENV2 by evaluating the expression level of the NS2B protein in DENV2-infected Huh-7 cells. These compounds display encouraging anti-DENV2 activity with superb EC50 (2.8-6.4 µM) and CC50 values (50.4-200 µM). The inhibitory mechanism of 1-4 on NS2B was further explored drawing on in-silico molecular docking analysis. Based on calculated binding affinities and predicted interactions between the functional groups of 1-4 and the allosteric-site residues of the DENV2 NS2B-NS3 protease, our analysis concludes that the clerodane-aporphine/proaporphine-type hybrids are novel and effective DENV NS2B-NS3 protease inhibitors.

Sulforaphane suppresses dengue virus replication by inhibition of dengue protease and enhancement of antiviral interferon response through Nrf2-mediated heme oxygenase-1 induction.

Dengue virus (DENV) infection is a life-threatening disease that causes severe dengue hemorrhagic fever and dengue shock syndrome. There is currently no effective therapeutic agent or widely used vaccine for treating DENV infections. In this study, sulforaphane (SFN), an antioxidant phytocompound, exhibited significant antiviral activity, with a half-inhibitory concentration value of 5.8 ± 0.7 µM to suppress viral RNA replication. Mechanistic studies demonstrated that SFN-induced heme oxygenase-1 (HO-1) expression, which inhibited viral protease activity, leading to the restoration of antiviral interferon (IFN) responses against DENV replication. Its antiviral activity can be attenuated by the knockdown of HO-1 expression by short hairpin RNA and blockage of activity with a specific inhibitor, supporting the contention that HO-1 induction contributes to the anti-DENV activity of SFN. SFN also stimulated HO-1 induction through an Nrf2-dependent pathway. SFN effectively prolonged the survival rate and reduced the virus titer in DENV-infected ICR suckling mice with activated expression of interferon-stimulated genes. The anti-DENV activity of SFN was also observed in the IFN-deficient AG129 mouse model. Collectively, SFN represents significant anti-DENV activity in vitro and in vivo and is a promising drug candidate or dietary supplement against DENV.

Prinsepiae Nux Extract Activates NRF2 Activity and Protects UVB-Induced Damage in Keratinocyte.

Ultraviolet B (UVB) is one of the most important environmental factors that cause extrinsic aging through increasing intracellular reactive oxygen species (ROS) production in the skin. Due to its protective roles against oxidative stress, nuclear factor erythroid-2-related factor (NRF2) has been traditionally considered as a target for skin aging prevention. Here, we identified the extract of Prinsepiae Nux, a top-grade drug listed in Shen Nong Ben Cao Jing, as a potent NRF2 activator by high-throughput screening. A bioassay-guided fractionation experiment revealed that NRF2-activating components were concentrated in the 90% methanol (MP) fraction. MP fraction significantly increased the expression of NRF2 and HO-1 protein and upregulated HO-1 and NQO1 mRNA expression in HaCaT cells. Moreover, MP fraction pre-treatment dramatically reversed UVB-induced depletion of NRF2 and HO-1, accumulation of intracellular ROS, NF-κB activation, and the upregulation of pro-inflammatory genes. Finally, the qualitative analysis using UPLC-tandem mass spectroscopy revealed the most abundant ion peak in MP fraction was identified as α-linolenic acid, which was further proved to activate NRF2 signaling. Altogether, the molecular evidence suggested that MP fraction has the potential to be an excellent source for the discovery of natural medicine to treat/prevent UVB-induced skin damage.

Persistent cryoglobulinemia after antiviral treatment is associated with advanced fibrosis in chronic hepatitis C patients.

BACKGROUND: High dosage and longer duration of antiviral treatment has been suggested to treat cryoglobulinemia patients. We aimed to investigate the efficacy of antiviral treatment in cryoglobulinemia patients and analyze the associated factors of persistent cryoglobulinemia. METHODS: Totally 148 patients after completion of anti-HCV treatment were enrolled in our study. Serum cryoglobulinemia precipitation was assessed and analyzed for the associated factors after antiviral therapy. RESULTS: Fifty-one (34.5%) out of 148 patients were positive for serum cryoglobulinemia after completion of antiviral therapy. In multivariate analysis, advanced fibrosis (Odds Ratio [OR]- 4.13, 95% Confidence Interval [95% CI]- 1.53-11.17, p = 0.005) and platelet counts (OR-0.98, 95% CI- 0.97-0.99, p = 0.010) were independently and significantly associated with persistent cryoglobulinemia. The factors associated with the persistent cryoglobulinemia in SVR patients were advanced fibrosis (OR-1.93, 95% CI- 1.02-3.65, p = 0.041) and platelet count (OR-0.98, 95% CI- 0.96-0.99, p = 0.041) by multivariate analysis. Multivariate logistic regression analysis showed persistent (OR-4.83, 95% CI- 1.75-13.36, p = 0.002) was significantly associated with advanced fibrosis in patients with cryoglobulinemia follow up after antiviral therapy. CONCLUSIONS: The prevalence of the persistent cryoglobulinemia is 34.5% after completing antiviral therapy and it is associated with advanced fibrosis, also HCV clearance.

Heme oxygenase-1 inhibits DENV-induced endothelial hyperpermeability and serves as a potential target against dengue hemorrhagic fever.

Dengue virus (DENV) is a cause of vascular endothelial dysfunction and vascular leakage, which are characterized as hallmarks of dengue hemorrhagic fever or dengue shock syndrome, which become a severe global health emergency with substantial morbidity and mortality. Currently, there are still no promising therapeutics to alleviate the dengue-associated vascular hemorrhage in a clinical setting. In the present study, we first observed that heme oxygenase-1 (HO-1) expression level was highly suppressed in severe DENV-infected patients. In contrast, the overexpression of HO-1 could attenuate DENV-induced pathogenesis, including plasma leakage and thrombocytopenia, in an AG129 mouse model. Our data indicate that overexpression of HO-1 or its metabolite biliverdin can maintain endothelial integrity upon DENV infection in vitro and in vivo. We further characterized the positive regulatory effect of HO-1 on the endothelial adhesion factor vascular endothelial-cadherin to decrease DENV-induced endothelial hyperpermeability. Subsequently, we confirmed that two medicinal plant-derived compounds, andrographolide, and celastrol, widely used as a nutritional or medicinal supplement are useful to attenuate DENV-induced plasma leakage through induction of the HO-1 expression in DENV-infected AG129 mice. In conclusion, our findings reveal that induction of the HO-1 signal pathway is a promising option for the treatment of DENV-induced vascular pathologies.

(E)-Guggulsterone Inhibits Dengue Virus Replication by Upregulating Antiviral Interferon Responses through the Induction of Heme Oxygenase-1 Expression.

Dengue virus (DENV) infection, which causes dengue fever, dengue hemorrhagic fever, and dengue shock syndrome, is a severe global health problem in tropical and subtropical areas. There is no effective vaccine or drug against DENV infection. Thus, the development of anti-DENV agents is imperative. This study aimed to assess the anti-DENV activity of (E)-guggulsterone using a DENV infectious system. A specific inhibitor targeting signal molecules was used to evaluate the molecular mechanisms of action. Western blotting and qRT-PCR were used to determine DENV protein expression and RNA replication, respectively. Finally, an ICR suckling mouse model was used to examine the anti-DENV activity of (E)-guggulsterone in vivo. A dose-dependent inhibitory effect of (E)-guggulsterone on DENV protein synthesis and RNA replication without cytotoxicity was observed. The mechanistic studied revealed that (E)-guggulsterone stimulates Nrf2-mediated heme oxygenase-1 (HO-1) expression, which increases the antiviral interferon responses and downstream antiviral gene expression by blocking DENV NS2B/3B protease activity. Moreover, (E)-guggulsterone protected ICR suckling mice from life-threatening DENV infection. These results suggest that (E)-guggulsterone can be a potential supplement for controlling DENV replication.

Discovery of Zika Virus NS2B/NS3 Inhibitors That Prevent Mice from Life-Threatening Infection and Brain Damage.

Zika virus (ZIKV) infection, which initially was endemic only in Africa and Asia, is rapidly spreading throughout Europe, Oceania, and the Americas. Although there have been enormous efforts, there is still no approved drug to treat ZIKV infection. Herein, we report the synthesis and biological evaluation of agents with noncompetitive mechanism of the ZIKV NS2B/NS3 protease inhibition through the binding to an allosteric site. Compounds 1 and 2 showed potent activity in both enzymatic and cellular assays. Derivative 1 efficiently reduced the ZIKV protein synthesis and the RNA replication and prevented the mice from life-threatening infection and the brain damage caused by ZIKV infection in a ZIKV mouse model.

Discovery of 4-Anilinoquinolinylchalcone Derivatives as Potential NRF2 Activators.

Activation of nuclear factor erythroid-2-related factor 2 (NRF2) has been proven to be an effective means to prevent the development of cancer, and natural curcumin stands out as a potent NRF2 activator and cancer chemopreventive agent. In this study, we have synthesized a series of 4-anilinoquinolinylchalcone derivatives, and used a NRF2 promoter-driven firefly luciferase reporter stable cell line, the HaCaT/ARE cells, to screen a panel of these compounds. Among them, (E)-3-{4-[(4-acetylphenyl)amino]quinolin-2-yl}-1-(4-fluorophenyl)prop-2-en-1-one (13b) significantly increased NRF2 activity in the HaCaT cell with a half maximal effective concentration (EC50) value of 1.95 µM. Treatment of compound 13b upregulated HaCaT cell NRF2 expression at the protein level. Moreover, the mRNA level of NRF2 target genes, heme oxygenase-1 (HO-1), glutamate-cysteine ligase catalytic subunit (GCLC), and glucose-6-phosphate dehydrogenase (G6PD) were significantly increased in HaCaT cells upon the compound 13b treatment. The molecular docking results exhibited that the small molecule 13b is well accommodated by the bound region of Kelch-like ECH-associated protein 1 (Keap1)-Kelch and NRF2 through stable hydrogen bonds and hydrophobic interaction, which contributed to the enhancement of affinity and stability between the ligand and receptor. Compound 13b has been identified as the lead compound for further structural optimization.

MicroRNA-155 inhibits dengue virus replication by inducing heme oxygenase-1-mediated antiviral interferon responses.

MicroRNAs (miRNAs) have been reported to directly alter the virus life cycle and virus-host interactions, and so are considered promising molecules for controlling virus infection. In the present study, we observed that miR-155 time-dependently downregulated upon dengue virus (DENV) infection. In contrast, exogenous overexpression of miR-155 appeared to limit viral replication in vitro, suggesting that the low levels of miR-155 would be beneficial for DENV replication. In vivo, overexpression of miR-155 protected ICR suckling mice from the life-threatening effects of DENV infection and reduced virus propagation. Further investigation revealed that the anti-DENV activity of miR-155 was due to target Bach1, resulting in the induction of the heme oxygenase-1 (HO-1)-mediated inhibition of DENV NS2B/NS3 protease activity, ultimately leading to induction of antiviral interferon responses, including interferon-induced protein kinase R (PKR), 2'-5'-oligoadenylate synthetase 1 (OAS1), OAS2, and OAS3 expression, against DENV replication. Collectively, our results provide a promising new strategy to manage DENV infection by modulation of miR-155 expression.

Liraglutide Inhibits Hepatitis C Virus Replication Through an AMP Activated Protein Kinase Dependent Mechanism.

Insulin resistance and diabetes are both associated with chronic hepatitis C virus (HCV) infection, and the glucagon-like peptide-1(GLP-1) receptor agonist, liraglutide, is a common therapy for diabetes. Our aim was to investigate whether liraglutide treatment can inhibit HCV replication. A cell culture-produced HCV infectious system was generated by transfection of in vitro-transcribed genomic JFH-1 ribonucleic acid (RNA) into Huh-7.5 cells. Total RNA samples were extracted to determine the efficiency of HCV replication. The Ava5 cells were treated with liraglutide and cell viability was calculated. A Western blot analysis of the protein expression was performed. The immunoreactive blot signals were also detected. Liraglutide activated GLP-1 receptors in the HCV infectious system, and inhibited subgenomic HCV RNA replication in the HuH-7.5 cells. The Western blot analysis revealed both HCV protein and replicon RNA were reduced after treatment with liraglutide in a dose-dependent manner. Liraglutide decreased the cell viability of HCV RNA at an optimum concentration of 120 µg/mL, activated the 5' adenosine monophosphate-activated protein kinase (AMPK) and the phosphorylated- transducer of regulated cyclic adenosine monophosphate (CAMP) response element-binding protein 2 (TORC2), thereby decreasing the cell viability of phosphoenolpyruvate carboxykinase (PEPCK) and G6pase RNA Therefore, we conclude that liraglutide can inhibit HCV replication via an AMPK/TORC2-dependent pathway.

Elevated interleukin-4 levels predicted advanced fibrosis in chronic hepatitis C.

BACKGROUND: Cytokine imbalance has been associated with chronic hepatitis C virus (HCV) infection. We hypothesized that cytokines have an important role in fibrosis development in HCV infection. METHODS: Data of 92 patients were analyzed retrospectively. Fluorescent Bead immunoassay was used to measure the following serum cytokine levels: Interferon γ, tumor necrosis factor α, interleukin (IL)-1ß, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, and IL-12. Various statistical analyses were used as appropriate. RESULTS: Of the 92 HCV-infected patients, 49 (53.3%) were male, 23 (25%) patients had advanced (fibrosis grades 3-4) fibrosis, and the mean age of the study population was 51.9 ± 9.4 years. Elevation of baseline IL-4 level (>490 pg/mL) was associated with liver fibrosis grade by χ test (odds ratio [OR] = 2.99; 95%, CI = 1.02-8.78; p = 0.042) and multivariate logistic regression (OR = 4.26; 95% CI = 1.13-16.02; p = 0.032). Also, IL-4 had strong diagnostic value in advanced liver fibrosis by using area under receiver operating characteristics curve analysis. Assessment of fibrosis score was consequently developed from our findings and compared with other noninvasive serum markers to assess liver fibrosis. CONCLUSION: This study provides evidence that increased IL-4 expression predicted advanced liver fibrosis in treatment of naive HCV-infected patients. The newly developed "FIL4" score had good predictive value for advanced fibrosis before treatment and this value was even strong in HCV-genotype 1b patients.

Elevated serum ferritin level associated with hepatic steatosis and fibrosis in hepatitis C virus-infected patients.

BACKGROUND: Serum ferritin is an indicator of iron accumulation in a human body, and it is frequently elevated in patients with systemic inflammatory state in chronic hepatitis C (CHC). Iron accumulation is associated with hepatic fibrosis, steatosis, and unfavorable outcome in CHC patients. We studied the status of elevated serum ferritin level and its association with the liver fibrosis or steatosis in Taiwanese CHC patients. METHODS: Seven hundred and thirty-eight Taiwanese CHC patients were consecutively included in this study. Laboratory analysis, four indexes of fibrosis (FIB4), histological assessment of fibrosis, and steatosis were assessed by appropriate elevation of serum ferritin level. RESULTS: Three hundred and one patients (40.8%) had elevated serum ferritin level (sex-specific threshold >1.5 × upper limit of normal). Serum iron level (odds ratio [OR], 1.02; 95% CI, 1.01%-1.03%, p < 0.001), female gender (OR, 1.49; 95% CI, 1.07%-2.08%, p = 0.018), serum gamma-glutamyl transferase level (OR, 1.007; 95% CI, 1.003%-1.01%, p < 0.001), steatosis grade (OR, 1.56; 95% CI, 1.13%-2.16%, p = 0.006), and FIB4 ≥3.25 (OR, 1.63; 95% CI, 1.18%-2.27%, p = 0.003) indexes were associated with high serum ferritin level by multivariate logistic regression analysis. Patients with steatosis (>5%) were associated with older age (OR, 1.01; 95% CI, 1.00%-1.03%, p = 0.015), body mass index (OR, 1.10; 95% CI, 1.05%-1.15%, p < 0.001), and elevated serum ferritin level (OR, 1.001; 95% CI, 1.00%-1.001%, p = 0.024) by multivariate logistic regression analysis. Serum ferritin level also associated with high FIB4 (≥3.25) (OR, 1.001; 95% CI, 1.001%-1.002%, p = 0.010) when multivariate model adjusted together with advanced liver fibrosis by biopsy. CONCLUSION: Elevated serum ferritin level was noted in 40.8% of Taiwanese CHC patients, and the serum ferritin level was associated with liver steatosis and high FIB4.

MicroRNA-let-7c suppresses hepatitis C virus replication by targeting Bach1 for induction of haem oxygenase-1 expression.

MicroRNAs are small noncoding RNAs that are central factors between hepatitis C virus (HCV) and host cellular factors for viral replication and liver disease progression, including liver fibrosis, cirrhosis and hepatocellular carcinoma. In the present study, we found that overexpressing miR-let-7c markedly reduced HCV replication because it induced haem oxygenase-1 (HO-1) expression by targeting HO-1 transcriptional repressor Bach1, ultimately leading to stimulating an antiviral interferon response and blockade of HCV viral protease activity. In contrast, the antiviral actions of miR-let-7c were attenuated by miR-let-7c inhibitor treatment, exogenously expressing Bach1 or suppressing HO-1 activity and expression. A proposed model indicates a key role for miR-let-7c targeting Bach1 to transactivate HO-1-mediated antiviral actions against HCV. miR-let-7c may serve as an attractive target for antiviral development.

Avocado (Persea americana) fruit extract (2R,4R)-1,2,4-trihydroxyheptadec-16-yne inhibits dengue virus replication via upregulation of NF-κB-dependent induction of antiviral interferon responses.

Dengue virus (DENV) caused millions of infections around the world annually. Co-infection with different serotypes of DENV is associated with dengue hemorrhagic shock syndrome, leading to an estimate of 50% death rate. No approved therapies are currently available for the treatment of DENV infection. Hence, novel anti-DENV agents are urgently needed for medical therapy. Here we demonstrated that a natural product (2 R,4 R)-1,2,4-trihydroxyheptadec-16-yne (THHY), extracted from avocado (Persea americana) fruit, can inhibit DENV-2 replication in a concentration-dependent manner and efficiently suppresses replication of all DENV serotypes (1-4). We further reveal that the NF-κB-mediated interferon antiviral response contributes to the inhibitory effect of THHY on DENV replication. Using a DENV-infected ICR suckling mouse model, we found that THHY treatment caused an increased survival rate among mice infected with DENV. Collectively, these findings support THHY as a potential agent to control DENV infection.

Prostasin Impairs Epithelial Growth Factor Receptor Activation to Suppress Dengue Virus Propagation.

BACKGROUND: Dengue virus (DENV), a common and widely spread arbovirus, causes life-threatening diseases, such as dengue hemorrhagic fever or dengue shock syndrome. There is currently no effective therapeutic or preventive treatment for DENV infection. METHODS: Next-generation sequencing analysis revealed that prostasin expression was decreased upon DENV infection. Prostasin expression levels were confirmed by real-time quantitative polymerase chain reaction in patients with dengue fever and a DENV-infected mice model. Short hairpin RNA against EGFR and LY294002 were used to investigate the molecular mechanism. RESULTS: Based on clinical studies, we first found relatively low expression of prostasin, a glycosylphosphatidyl inositol-anchored membrane protease, in blood samples from patients with dengue fever compared with healthy individuals and a high correlation of prostasin expression and DENV-2 RNA copy number. DENV infection significantly decreased prostasin RNA levels of in vivo and in vitro models. By contrast, exogenous expression of prostasin could protect ICR suckling mice from life-threatening DENV-2 infection. Mechanistic studies showed that inhibition of DENV propagation by prostasin was due to reducing expression of epithelial growth factor receptor, leading to suppression of the Akt/NF-κB-mediated cyclooxygenase-2 signaling pathway. CONCLUSION: Our results demonstrate that prostasin expression is a noteworthy clinical feature and a potential therapeutic target against DENV infection.

Discovery of 3-Amino-2-Hydroxypropoxyisoflavone Derivatives as Potential Anti-HCV Agents.

Synthesis and anti-hepatitis C virus (anti-HCV) effects of certain 3-amino-2-hydroxy-propoxy isoflavone derivatives, 6a⁻i, were described. The known 3-(3,4-dimethoxyphenyl)-7-(oxiran-2-ylmethoxy)-4H-chromen-4-one (5) was reacted with substituted amines to give the desired isoflavone derivatives, 6a⁻i. Among them, 7-{3-[(3,4-dimethoxy-phenethyl)amino]-2-hydroxypropoxy}-3-(3,4-dimethoxyphenyl)-4H-chromen-4-one (6b) was the most active, exhibiting approximately 2-fold higher anti-HCV effects than standard antiviral drug ribavirin (EC50 of 6.53 vs. 13.16 µM). In addition, compound 6b was less cytotoxic than ribavirin. The selectivity index (SI) of 6b is approximately 2.6-fold higher than ribavirin. The compounds 6e, 6h, and 6i were also found to possess higher anti-HCV effects than ribavirin. Compound 6b was found to inhibit the HCV RNA expression in Ava5 cells in a dose-dependent manner; furthermore, we found that the antiviral mechanism of compounds 6b, 6e, 6h, and 6i gave rise to induction of HO-1 expression. With the HO-1 promoter-based analysis, we found compounds 6b, 6e, 6h, and 6i induced HO-1 expression through increasing Nrf-2 binding activity. Taken together, compound 6b may serve as a potential lead compound for developing novel anti-HCV agents.