Study On The Efficacy And Mechanism Of Mulgedium Tataricum And Yeast β-Glucan Against H1N1 Influenza Virus

Influenza,referred to as influenza for short,is a respiratory tract infection caused by influenza virus.Influenza can be seasonal and sporadic,posing a serious threat to public safety.Due to the strong variability of influenza virus,the protection of vaccines is limited.In addition,the emergence of drug-resistant strains and the side effects of some drugs have limited the application of existing antiviral drugs.Therefore,it is an important way to prevent and treat influenza by developing antiviral drugs with good curative effect and small side effects.In this study,the alcohol extract of Mulgedium tataricum and yeastβ-glucan were selected as the research subjects to explore the efficacy and mechanism of action against H1N1influenza virus.1.Study on the efficacy and mechanism of endive alcohol extract against H1N1influenza virusIn this study,Balb/C mice were infected with 24 LD₅₀H1N1 influenza A/Puerto Rico/8/34 strains（PR8 strains）and then given high,medium and low doses（1800mg/kg/d,1200 mg/kg/d and 600 mg/kg/d）of endive alcohol extract by gavage for five consecutive days.The results showed that medium-dose alcohol extract of Mulgedium tataricum could significantly delay onset time,alleviate clinical symptoms of influenza,reduce mortality and prolong survival time.Besides,it can alleviate the pathological changes in the lung,and significantly reduce the lung index,the viral load in the lung tissue,and the expression of lung pro-inflammatory factors.High-and low-dose ethanol extracts of Mulgedium tataricum could delay the onset of disease,reduce the viral load in the lung tissue and the expression of pro-inflammatory factors in the lung,but had no significant improvement in the clinical symptoms and pathological changes.The above results indicated that the alcohol extract of Mulgedium tataricum had good anti-H1N1 influenza virus and anti-inflammatory effect,and the antiviral effect at 1200 mg/kg/d was the best.The results of in vitro inhibition tests of the Mulgedium tataricum ethanol extract on hemagglutinin and neuraminidase of PR8 strain virus showed that the Mulgedium tataricum ethanol extract can inhibit neuraminidase activity,but has no inhibition on hemagglutinin.The effect of Mulgedium tataricum ethanol extract on the virus life cycle in MDCK cells was determined,and the results showed that the Mulgedium tataricum ethanol extract significantly inhibited the virus invasion.The results of the above in vitro experiments showed that the alcohol extract of Mulgedium tataricum had a direct antiviral effect.The results of in vivo and in vitro experiments showed that the endive alcohol extract had good anti-H1N1 influenza virus effect in mice and cells,mainly by interfering with the invasive links in the influenza virus replication cycle,down-regulating the expression of inflammatory cytokines,and reducing inflammatory response to exert the anti-influenza virus effect.2.Study on the efficacy and mechanism of yeastβ-glucan against H1N1influenza virusIn the in vivo pharmacodynamic experiment of yeastβ-glucan in mice,high,medium and low doses of yeastβ-glucan（160 mg/kg/d,80 mg/kg/d,and 40 mg/kg/d）were administered intragastrically to mice 7 days before infection,and high,medium and low doses of yeastβ-glucan（160 mg/kg/d,80 mg/kg/d,and 40 mg/kg/d）were administered intragastrically to mice infected with 10 LD₅₀H1N1 for 2 h until day 15.The results showed that high,medium and low doses of yeastβ-glucan could increase the survival rate of mice to 100%,significantly reduce the clinical symptoms of influenza infection,improve the pathological changes of lung tissue,and significantly reduce the lung index and lung virus titer of mice.In addition,high,medium and low doses of yeastβ-glucan could significantly down-regulate the expression of inflammatory cytokines caused by influenza virus.Therefore,yeastβ-glucan has a significant anti-H1N1 influenza virus and reducing inflammatory response in vivo.In summary,the alcohol extracts of Mulgedium tataricum have antiviral effect in vivo and in vitro,not only inhibiting the invasion of viruses,but also regulating the immune response and inflammatory response of the body.Yeastβ-glucan has significant anti-influenza effect in vivo,and it can reduce lung injury and regulate inflammatory response caused by influenza virus.This study provided a theoretical basis for the development of anti-influenza virus drugs such as Mulgedium tataricum alcohol extract and yeastβ-glucan.