The Study Of Anti-RSV Of Ephedra Sinica Water Extract In Vitro

Objective:1,In order to find the new drug for respiratory syncytial virus(RSV) infection treatment, we study the effect and mechanism of anti-respiratory syncytial virus of the water extract of Ephedra Sinica.Methods:1,We decoct the Chinese medicine Ephedra Sinica by adding water, then drainaging and filtering it under the negative pressure before we collect the filtrate. We concentrate the medicial solution and make it into Ephedra Sinica water extract using the method of vacuum evaporation.2,The cytotoxicity of Ephedra Sinica water extract was tested by MTT assay and visual observation using the method of cell culture in vitro.3,Antiviral activity of the Ephedra Sinica water extract was tested by the method of cell culture using ribavirin as positive control. The median effective concentrations (50% effective concentration, EC₅₀) of the Ephedra Sinica water extract and ribavirin were tested by the plaque reduction method. Using the CPE inhibition assay, the cytopathic effect of the drugs in the inhibition assay for virus absorption and penetration were tested, and the direct effect of it on RSV was also be determined. Antiviral activity of Ephedra Sinica at different concentrations in the time-course were tested by the plaque reduction method.Result: 1,The median cytotoxicity concentration(50% cytotoxicity concentration, CC₅₀) of Ephedra Sinica was 12.58 mg/ml and 12.21 mg/ml by visual assessment and MTT assay respectively. The median cytotoxicity concentration of ribavirin was 0.42 mg/ml by visual assessment and it was 0.44 mg/ml by MTT assay. Using the plaque reduction method, the median effective concentration(50% effective concentration, EC₅₀) of the extract of Ephedra Sinica was 3.74 mg/ml and the median effective concentration of the ribavirin was 35.66μg/ml. The selectivity index(SI) of Ephedra Sinica was 3.26 and the SI of ribavirin was 12.34.2,Ephedra Sinica and ribavirin could inhibit RSV adhering to the cells(P<0.01) , they could also inhibit RSV penetrating into the cells (P<0.05); Ephedra Sinica also showed direct inhibition on RSV(P<0.05); the groups of 5.00mg/ml,4.00mg/ml,3.20 mg/ml,2.56 mg/ml of Ephedra Sinica water extract showed obvious effect of inhibition on RSV when it was added in 8 hours after RSV infection(P<0.01); ribavirin also showed obvious effect of inhibition on RSV when it was added in 8 hours after RSV infection(P<0.01).3,The difference of the medication with different strength groups and the difference of medication at different times had statistical signifycance by Factorial Analysis. There was interaction between the time and the strength of medication. The higher the concentration, the earlier the administration time, more effects on virus inhibitation. The lower the concerntration, the later the treatment began, least effects on virus inhibitation.Conclusion:1,5.00mg/ml Ephedra Sinica water extract could inhibit RSV adhering to the cells, it also could inhibit RSV penetrating into the cells.2,Ephedra Sinica water extract at the concentration of 2.50mg/ml had direct inhibition on RSV.3,the groups of 5.00mg/ml,4.00mg/ml,3.20mg/ml,2.56 mg/ml of Ephedra Sinica water extract had anti-RSV effect when it was added in 8h after RSV infection. There were a dose-dependent response and phase realationship of Ephedra Sinica in inhibiting RSV.4,Ephedra Sinica water extract showed potent inhibition on RSV in vitro.