Five New Triterpenoid Saponins from the Rhizomes of Panacis majoris and Their Antiplatelet Aggregation Activity.

Five new triterpenoid saponins (-) and four known triterpenoid saponins, ginsenoside Re (), majonoside R (), 24()-majonoside R (), and ginsenoside Rf (), were isolated from the rhizomes of . The structures of new compounds were elucidated as (20,24,25*)-6-O-[-D-glucopyranosyl-(1 → 2)--D-glucopyranosyl]-dammar-20,24-epoxy-3,6,12,25,26-pentaol (), (20,24,25)-6-O-[-D-glucopyranosyl-(1 → 2)--D-glucopyranosyl]-dammar-20,24-epoxy-3,6,12,25,26-pentaol (), (20)-6-O-[-D-glucopyranosyl-(1 → 2)--D-glucopyranosyl]-dammar-20,25-epoxy-3,6,12,24-tetraol (), 6-O-[-D-glucopyranosyl-(1 → 2)--D-glucopyranosyl]-dammar-3,6,12,20,24,25-hexaol (), and 6-O-[-D-glucop-yranosyl-(1 → 2)--D-glucopyranosyl]-dammar-25(26)-ene-3,6,12,20,24-pentaol () on the basis of extensive spectral analysis and chemical methods. Ginsenoside Re was isolated from the plant for the first time. The similarities of the nine compounds lie in the fact that their aglycones are conjoined with the same glucopyranose moieties, the same linkage of the glycosyl chains, and the same glycosylation sites, while they have a varied C-17 side chain. Compounds and exhibited moderate antiplatelet aggregation activities induced by adenosine diphosphate with IC values of 23.24 and 18.43 µM, respectively. Compound displayed moderate inhibition of arachidonic acid-induced platelet aggregation with an IC value of 30.11 µM.