Protective effect of a polyphenolic rich extract from Magnolia officinalis bark on influenza virus-induced pneumonia in mice

Magnolia officinalis bark is used in traditional Chinese medicine for the treatment of cough, colds, fever, chronic bronchitis and stomach ailments.To investigate therapeutic effects of polyphenol rich extract from M. officinalis bark (MPE) in influenza virus A-infected mice, and to provide evidence for the inflammation response and immunomodulatory potential during infection.Mice were infected with influenza virus A (IVA) and MPE at doses of 10 and 20mg/kg were orally administrated daily for 5 days after challenge. The levels of serum L-6 and TNF-α were determined by ELISA while protein expressions of NF-κB and TLR3 were detected by western blotting analysis.MPE exhibited significant therapeutical effects on reducing levels of serum NO, IL-6 and TNF-α, inhibiting pneumonia, decreasing lung viral titers and sensitizing IVA-induced apoptosis through down-regulation of NF-κB and TLR3 protein expression in the lung tissue of IVA-infected mice.MPE could exhibit preventive and therapeutical effects on IVA-infected mice as a suppressor of the production of inflammatory mediators, NO and pro-inflammatory cytokines, TNF-α and IL-6. These effects appeared to be mediated, at least in part, by an inhibition of TLR3 and NF-κB activation. Therefore, MPE could provide a safe and effective therapeutic approach for influenza and its subsequent viral pneumonia.