Cardiac sapogenins from Periploca forrestii

Four new cardiac sapogenins, named periplogenins D-G (1–4), one new natural product, 3β-hydroxycard-5,14,20(22)-trienolide (5), along with three known compounds, periforgenin A (6), periplogenin (7) and 3β,5β-dihydroxycard-14,20(22)-dienolide (8) were isolated from the stems and roots of Periploca forrestii. Their structures were confirmed by NMR spectroscopic analyses, ESI-MS and HRESI-MS. The results of their preliminary cytotoxic activities indicated that compound 7 had significant activity against the MG-63 cell line with an IC50 value of 3.11 μM, exhibiting a more potent inhibitory effect than adriamycin (IC50 36.31 μM).