In vitro antiviral effect of Cortex Mori Radicis water extracts against influenza viruses

Cortex Mori Radicis (CMR) is root peel of Morus alba L, which is widely distributed throughout Asia including South Korea, China, and Japan. CMR has been used to treat diseases such as cough, headache, edema and diabetes. The antiviral effect of CMR on influenza virus had not been reported until now.

In this study, we demonstrate the anti-influenza viral activity of CMR water extract (WCMR) in murine Raw 264.7 macrophage cells. Pretreatment of WCMR reduced viral replication in a dose-dependent manner, as evaluated using a green fluorescent protein (GFP)-tagged influenza virus in the cells. Consistently, we found that the expressions of viral proteins were decreased in the presence of WCMR, compared with no treatment, through immunoblot analysis and immunofluorescence. To investigate the underlying mechanism on antiviral efficacy of WCMR, we checked whether WCMR could affect the type I IFN production and proinflammatory cytokine activation. WCMR remarkably activated STAT-1 and TBK at both 4 h and 24 h post-treatment, dose-dependently. Furthermore, the pretreatment of WCMR increased the phosphorylation levels of ERK and JNK in the cells. These result implies WCMR induced the production of type I IFN including pro-inflammatory cytokines and subsequent stimulation of antiviral state in the cells.

In conclusion, the pretreatment of WCMR suppresses viral replication and viral gene expression via type I IFN activation and proinflammatory cytokine such as STAT-1, TBK, ERK, and JNK, followed by induction of antiviral state, in murine Raw 264.7 macrophage cells.

• References

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