Study on effect and mechanism of volatile oil of Schizonepetae Herba and its essential components against influenza virus

Abstract

To observe the effect of volatile oil of Schizonepetae Herba (VOSH), and its essential components-menthone and pulegone against anti-influenza virus A/PR/8/34 (H1N1) in vivo and in vitro, as well as the signaling mechanism of its toll-like receptor/interferon (TLR/IFN). The lung-adapted PR-8 virus model was prepared in mice. They were administered with preventive and therapeutic drugs, and the hemagglutination titer of model animals was determined to evaluate in vivo effect against H1N1. ELISA test was conducted to observe the effect on IFN-alpha, IFN-beta, IL-2, IL-6 and TNF-alpha in serum, as well as IFN-beta secretion in H1N1 infected MDCK supernatant. Real-time RT-PCR was employed to observe the expression levels of IRAK4 and TLR3 mRNA. The in vivo experiment shows that the hemagglutination titer was significantly decreased when the mice were treated with VOSH (0.266 mg x kg(-1)), menthone(0.5 mg x kg(-1)) and pulegone (0.19 mg x kg(-1)) in therapeutic way; VOSH (0.226 mg x kg(-1)) had a significant effect on increasing serum levels of IFN-alpha, IL-2; Methone (0.5 mg x kg(-1)) had a significant effect on increasing serum levels of IFN-beta; Methone (0.5 mg x kg(-1)) and pulegone (0.19 mg x kg(-1)) had a significant effect on decreasing serum levels of IL-6; VOSH (0.452, 0.226 mg x kg(-1)) and pulegone (0.19 mg x kg(-1)) had a significant effect on decreasing serum levels TNF-alpha. The in vitro experiment showed that the expression levels of IRAK4 mRNA and IFN-beta were significantly increased in VOHS (0.1 g x L(-1)) and pulegone (0.1 g x L(-1)) groups; and the menthone (0.25 g x L(-1)) group showed a significant rise in the expression levels of IRAK4 mRNA, but a notable decline in TLR3 mRNA. The administration with VOSH, methone and pulegone in therapeutic way can significantly decrease the hemagglutination titer, which demonstrates the anti-virus effect of the administration in therapeutic way, but no notable efficacy of the administration in preventive way. The in vivo anti-virus mechanism is related to regulation of IFN-alpha, IFN-beta and IL-2.