Polyphylla saponin I has antiviral activity against influenza A virus.

OBJECTIVE In the present study, the antiviral effects of polyphylla saponin I isolated from Parispolyphylla on influenza A virus are investigated both in vitro and in vivo. METHODS Column chromatography and reversed phase liquid chromatography separation technology were used to extract and purify polyphylla saponin I. The purity of polyphylla saponin I was assayed by high performance liquid chromatography. Methyl thiazolyl tetrazolium assay and analyses of cytopathic effects were performed to examine the antiviral activity of polyphylla saponin I upon MDCK cells infected with influenza A virus. Model mice were made by intranasal inoculation of influenza a virus. Mice infected with influenza A virus were orally administered polyphylla saponin I and oseltamivir twice a day for 5 days to study their antiviral efficacy in vivo. RESULTS Polyphylla saponin I had no cytotoxicity on MDCK cells at the concentration of 50 μg/mL. Polyphylla saponin I (6.25, 12.5, 25 and 50 μg/mL) and oseltamivir (40 μg/mL) had remarkable inactivation effects on influenza A virus, prevention effects on influenza A virus adsorption on MDCK cells, and inhibitory effects on the reproduction of influenza A virus in MDCK cells. In addition, polyphylla saponin I (5 and 10 mg/kg), and oseltamivir (3 mg/kg) significantly reduced viral hemagglutination titer, improved the pathologic histology of lung tissues, and decreased the mortality of mice infected with influenza A virus. Polyphylla saponin I (5 and 10 mg/kg) prolonged the survival time of mice from 8.5±0.3 days to 13.2±0.5 days, with the prolonged life rates being 49.4% and 55.3%, respectively. CONCLUSION Polyphylla saponin I has antiviral activity on influenza A virus both in vitro and in vivo.