In our continuous chemical investigation on the marine-derived fungus Dichotomomyces cejpii F31-1, two new polyketides dichocetides B-C (1, 2), two new alkaloids dichotomocejs E-F (3, 4), and three known fumiquinozalines: scequinadoline A (5), quinadoline A (6), and scequinadoline E (7) were discovered from the culture broth and the mycelium in the culture medium, by the addition of l-tryptophan and l-phenylalanine. Their chemical structures were established by one dimensional (1D), two dimensional (2D) nuclear magnetic resonance (NMR) and high resolution mass spectrometry (HR-MS) data. Among them, scequinadoline A (5) exhibited significant inhibitory activity against dengue virus serotype 2 production by standard plaque assay, equivalent to the positive control andrographlide. Scequinadoline A (5) possesses the potential for further development as a dengue virus inhibitor.

Kaempferol, a plant-derived flavonoid, has been reported to have activity against Japanese encephalitis virus (JEV) in BHK-21 cells. To determine the broader utility of this compound, we initially evaluated the activity of kaempferol against JEV and dengue virus (DENV) in HEK293T/17 cells. Results showed no significant antiviral activity against either virus. We subsequently investigated the activity of kaempferol against both JEV and DENV in BHK-21 cells. Results showed a significant inhibition of JEV infection but, surprisingly, a significant enhancement of DENV infection. The effect of kaempferol on both host protein expression and transcription was investigated and both transcriptional and translational inhibitory effects were observed, although a more marked effect was observed on host cell protein expression. Markedly, while GRP78 was increased in DENV infected cells treated with kaempferol, it was not increased in JEV infected cells treated with kaempferol. These results show that cellular alteration induced by one compound can have opposite effects on viruses from the same family, suggesting the presence of distinct replication strategies for these two viruses.

Infections with the mosquito-transmitted dengue virus (DENV) are a pressing public health problem in many parts of the world. The recently released commercial vaccine for DENV has encountered some problems, and there is still no effective drug to treat infections. Vitamin D has a well characterized role in calcium and phosphorus homeostasis, but additionally has a role in the immune response to bacterial and viral pathogens. In this study a number of fused bicyclic derivatives of 1H-pyrrolo[1,2]imidazol-1-one with vitamin D receptor (VDR) agonist activity were evaluated for possible anti-DENV activity. The results showed that five of the compounds were able to significantly inhibit DENV infection. The most effective compound, ZD-3, had an EC₅₀ value of 7.47 μM and a selective index of 52.75. The compounds were only effective when used as a post-infection treatment and treatment significantly reduced levels of infection, virus output, DENV protein expression and genome copy number. These results suggest that these VDR agonists have the potential for future development as effective anti-DENV agents.

Background: Zika virus (ZIKV) is a mosquito transmitted virus spread primarily byAedesspecies mosquitoes that can cause disease in humans, particularly when infection occurs in pregnancy where the virus can have a significant impact on the developing fetus. Despite this, there remains no prophylactic agent or therapeutic treatment for infection. Baicalein is a trihydroxyflavone, that is found in some traditional medicines commonly used in Asia, and has been shown to have several activities including antiviral properties. Importantly, studies have shown baicalein to be safe and well tolerated in humans, increasing its potential utilization.Methods: This study sought to determine the anti-ZIKV activity of baicalein using a human cell line (A549). Cytotoxicity of baicalein was determined by the MTT assay, and the effect on ZIKV infection determined by treating A549 cells with baicalien at different time points in the infection process. Parameters including level of infection, virus production, viral protein expression and genome copy number were assessed by flow cytometry, plaque assay, western blot and quantitative RT-PCR, respectively.Results: The results showed that baicalein had a half-maximal cytotoxic concentration (CC₅₀) of > 800 µM, and a half-maximal effective concentration (EC₅₀) of 124.88 µM. Time-of-addition analysis showed that baicalein had an inhibitory effect on ZIKV infection at the adsorption and post-adsorption stages. Moreover, baicalein also exerted a significant viral inactivation activity on ZIKV (as well as on dengue virus and Japanese encephalitis virus) virions.Conclusion: Baicalein has now been shown to possess anti-ZIKV activity in a human cell line.

Fatty acid synthase (FASN) has been shown to be critical in the replication of several viruses of the genus Orthoflavivirus. In this study the role two inhibitors of FASN that work through different mechanisms were investigated in dengue virus (DENV) and Zika virus (ZIKV) infections. Triclosan is a FASN inhibitor that targets the enol reductase domain of FASN, while lapatinib exerts an effect on FASN through acting on HER2, an upstream regulator of FASN. After determining cytotoxicity, a comprehensive analysis of the effect of these drugs in DENV 2 and ZIKV infection was undertaken. The results showed that triclosan had moderate antiviral activity against both DENV 2 (EC₅₀ = 10.21 µM; Selective index (SI) = 3.99) and ZIKV ( EC₅₀ = 22.84 µM; SI = 5.49). Lapatinib had reasonable activity against DENV 2 (EC₅₀ = 4.9 µM; SI = 26.09), but computer modeling suggested that lapatinib had the potential to be a directly acting antiviral by binding to NS5. The result of that analysis suggested that lapatinib was a better fit with ZIKV NS5 than DENV NS5, and this was confirmed as the EC₅₀ for lapatinib towards ZIKV was was 2 µM and the calculated SI was 37.92. The results of triclosan are consistent with other studies that use inhibitors that target other domains of FASN, suggesting that simply targeting the enzymatic activity of FASN is insufficient for therapeutic drug development, but that lapatinib, or similar molecules may have real therapeutic potential.

Objectives: The inherited genetic disorder beta0-thalassemia/Hb E disease is associated with the over-suppression of the master regulator of iron homeostasis, the peptide hormone hepcidin. How developing erythroid cells mediate the suppression of hepcidin remains controversial, although a number of inhibitors have been proposed. Methods: To investigate the ability of erythroid cells to suppress hepcidin expression in liver cells, conditioned media from the culture of in vitro differentiating erythroblasts (from normal controls and beta0-thalassemia/Hb E patients) was used to treat HepG2 cells, and the effects on hepcidin expression were assayed by real-time quantitative PCR and confocal microscopy. Results: Early activation followed by later suppression of hepcidin expression was seen posttreatment. Markedly, however, no significant differences were observed between suppression of hepcidin as mediated by media from the culture of erythroblasts from normal controls and beta0-thalassemia/Hb E patients Discussion: Previous studies investigating the suppression of hepcidin expression in beta0-thalassemia/Hb E disease have used patient-derived serum samples, which are complex fluids with contributions from multiple cell types. This study has developed a simple in vitro system that allows investigation of how a single cell type mediates hepcidin expression. The results support proposals that over-suppression of hepcidin seen in beta-thalassemia/Hb E patients is a consequence of the increased mass of erythropoiesis and not defects in the signaling process per se. Conclusion: The in vitro cell system developed here allows further investigation into the processes mediating erythroid cell suppression of liver hepcidin expression in both normal and pathological states.