Steroidal Saponins from the Underground Parts of Hosta longipes and Their Inhibitory Activity on Tumor Promoter-Induced Phospholipid Metabolism

Phytochemical study on the underground parts of Hosta longipes gave six new steroidal saponins together with a known one. The structures of the new compounds were determined by detailed analysis of their 1H-and 13C-NMR spectra including two-dimensional NMR spectroscopy, acid-catalyzed hydrolysis followed by chemical correlation, and by comparison with spectral data of known compounds. The isolated saponins and their aglycones were examined for inhibitory activity on 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated 32P-incorporation into phospholipids of HeLa cells to identify new antitumor-promoter compounds.