Morin Hydrate Inhibits Influenza Virus entry into Host Cells and Has Anti-inflammatory Effect in Influenzainfected Mice

Influenza virus is the major cause of seasonal and pandemic flu. Currently, oseltamivir, a potent and selective inhibitor of neuraminidase of influenza A and B viruses, is the drug of choice for treating patients with influenza virus infection. However, recent emergence of oseltamivir-resistant influenza viruses has limited its efficacy. Morin hydrate (3,5,7,2′,4′-pentahydroxyflavone) is a flavonoid isolated from Morus alba L. It has antioxidant, anti-inflammatory, neuroprotective, and anticancer effects partly by the inhibition of the NF-кB signaling pathway. However, its effects on influenza virus have not been studied. We evaluated the antiviral activity of morin hydrate against influenza A/Puerto Rico/8/1934 (A/ PR/8; H1N1) and oseltamivir-resistant A/PR/8 influenza viruses in vitro. To determine its mode of action, we carried out time course experiments, and time of addition, hemolysis inhibition, and hemagglutination assays. The effects of the co-administration of morin hydrate and oseltamivir were assessed using the murine model of A/PR/8 infection. We found that morin hydrate reduced hemagglutination by A/PR/8 in vitro. It alleviated the symptoms of A/PR/8-infection, and reduced the levels of pro-inflammatory cytokines and chemokines, such as TNF-α and CCL2, in infected mice. Co-administration of morin hydrate and oseltamivir phosphate reduced the virus titers and attenuated pulmonary inflammation. Our results suggest that morin hydrate exhibits antiviral activity by inhibiting the entry of the virus.

Anti-Human Rhinovirus 1B Activity of Dexamethasone viaGCR-Dependent Autophagy Activation

OBJECTIVES: Human rhinoviruses (HRVs) are the major cause of the common cold. Currently there is no registered, clinically effective, antiviral chemotherapeutic agent to treat diseases caused by HRVs. In this study, the antiviral activity of dexamethasone (DEX) against HRV1B was examined. METHODS: The anti–HRV1B activity of DEX was assessed by sulforhodamine B assay in HeLa cells, and by RT-PCR in the lungs of HRV1B-infected mice. Histological evaluation of HRV1B-infected lungs was performed and a histological score was given. Anti-HRV1B activity of DEX via the glucocorticoid receptor (GCR)-dependent autophagy activation was assessed by blocking with chloroquine diphosphate salt or bafilomycin A1 treatment. RESULTS: In HRV1B-infected HeLa cells, treatment with DEX in a dose-dependent manner, resulted in a cell viability of > 70% indicating that HRV1B viral replication was reduced by DEX treatment. HRV1B infected mice treated with DEX, had evidence of reduced inflammation and a moderate histological score. DEX treatment showed antiviral activity against HRV1B via GCR-dependent autophagy activation. CONCLUSION: This study demonstrated that DEX treatment showed anti-HRV1B activity via GCR-dependent autophagy activation in HeLa cells and HRV1B infected mice. Further investigation assessing the development of topical formulations may enable the development of improved DEX effectiveness.