Antiviral activity of sophoridine against enterovirus 71 in vitro

Ethnopharmacological relevance: Enterovirus 71 (EV71) has a propensity to cause hand-foot-and-mouth disease (HFMD) epidemics associated with neurological sequelae. Unfortunately, no drugs are currently available for the clinical treatment of EV71 infections. Sophoridine (SRI) is one of the most abundant alkaloids in Sophora flavescens Aiton (Leguminosae), which has been used to treat fever, throat inflammation, cancer, and other diseases. Materials and methods: In this study, we found that SRI inhibits EV71 infection in Vero cells. To study the antiviral activity of SRI, Vero cells were divided into 3 treatment groups based on the timing of SRI dosing: prior to viral adsorption (Group A), during viral adsorption (Group B), and after viral adsorption (Group C). We further revealed the antiviral activity of SRI with the attachment assay and the penetration assay. For Group A, 50% viability of Vero cells was observed at a SRI concentration of 61.39 mu g/mL, whereas for Groups B, 50% viability was observed at SRI concentrations of 196.86 mu g/mL. Furthermore, 29.7% cell viability was observed even at a SRI concentration of 1000 mu g/mL in Groups C. The results show that SRI was highly effective against EV71 when Vero cells were pretreated with SRI for 2 h (Group A). Further researches indicate SRI was highly effective at inhibiting EV71 attachment when the SRI concentrations over 250 mu g/mL (P < 0.001). Conclusions: We have shown that Vero cell viability increases when SRI is administered prior to viral adsorption. This suggests that SRI has the considerable potential as an antiviral for EV71 disease prevention.