The antiviral effect of 7-hydroxyisoflavone against Enterovirus 71 in vitro.

Enterovirus 71 (EV71) is the major causative agent of hand foot and mouth disease. And EV71 causes epidemics worldwide, particularly in the Asia-Pacific region. Unfortunately, currently there is no approved vaccine or antiviral drug for EV71-induced disease prevention and therapy. In screening for anti-EV71 candidates, we found that 7-hydroxyisoflavone was active against EV71. 7-Hydroxyisoflavone exhibited strong antiviral activity against three different EV71 strains. The 50% inhibitory concentration range was between 3.25 and 4.92 μM by cytopathic effect assay. 7-Hydroxyisoflavone could reduce EV71 viral RNA and protein synthesis in a dose-dependent manner. Time course study showed that treatment of Vero cells with 7-hydroxyisoflavone at indicated times after EV71 inoculation (0-6 h) resulted in significant antiviral activity. Results showed that 7-hydroxyisoflavone acted at an early step of EV71 replication. 7-Hydroxyisoflavone also exhibited strong antiviral activity against coxsackievirus B2, B3, and B6. In short, 7-hydroxyisoflavone may be used as a lead compound for anti-EV71 drug development.