New triterpenoid saponins from the roots of Platycodon grandiflorum

Bioassay-directed fractionation of the antiviral active fraction of the roots of Platycodon grandiflorum leads to the isolation of three new triterpenoid saponins, platycosides G1–G3 (), as well as two known saponins, platycodin D3 (), and platycoside E (). The structures of the new compounds were elucidated on the basis of their spectral data and chemical evidences. The isolated saponins were tested for their antiviral activities against respiratory syncytial virus (RSV), herpes simplex type 1 virus (HSV-1) and influenza type A virus (Flu A). Compound showed weak anti-RSV activity.