Antiviral amentoflavone from Selaginella sinensis.

Amentoflavone and three other flavonoids were isolated from the ethanol extract of Selaginella sinensis. Amentoflavone showed potent antiviral activity against respiratory syncytial virus (RSV), with an IC50 of 5.5 microg/ml. The contents of amentoflavone in nine species of Selaginella were determined by reversed-phase HPLC. S. sinensis showed a higher content of 1.13%.