Fig. 2.

Evaluation of antiviral activity of a water extract of Glycyrrhiza uralensis against coxsackievirus A16 and enterovirus 71. (A) Antiviral activity of Glycyrrhiza uralensis water extract. Vero cells in triplicate samples were pretreated with the water extract of Glycyrrhiza uralensis at 100, 300, and 1000 μg/ml for 2 h or mock treated, the cells were then infected with CVA16 or EV71 (both at MOI=0.3) for 72 h. Cytopathic effect due to virus infection was determined with an MTT assay. The inhibition rates, presented as a percentage, were calculated as described in Section 2. Acyclovir (ACV) at 10 μM was used as an antiviral positive control for CVA16. Statistical significance was determined by one-way ANOVA (* denotes P<0.05 and ** denotes P<0.01). (B, C) Glycyrrhiza uralensis water extract treatment reduces infectious virion production. Vero cells were treated with the extract at 1000 μg/ml or mock treated for 2 h. The cells were then infected with CVA16 (B) or EV71 (C). The infected cells and the culture supernatants were harvested at 48 h PI. Infectious virions in those samples were titrated with secondary infection assays. Data are presented as mean±standard errors of triplicate samples. The results are representative of three independent experiments.