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 (1-3), as well as two known saponins, platycodin D3 (4), and platycoside E (5). 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.