Cytotoxic Triterpenoid Saponins from the Stems of Gordonia longicarpa

Nine new triterpenoid saponins named longicarposides A-I (1-9), together with three known saponins (10-12), were isolated from the stems of Gordonia longicarpa. The structures of the saponins were elucidated by a combination of 1D and 2D NMR techniques, mass spectrometry, and chemical methods. They were characterized to be oleanane-type saponins with sugar moieties linked to C-3 of the aglycone. Cytotoxic activities of these saponins were evaluated against five human tumor cell lines (HCT-8, Bel-7402, BGC-823, A549, and A2780) by using the MTT in vitro assay. Compounds 5, 7, 8, 10, and 11 exhibited potent cytotoxic activity with IC50 values of 1.42-8.42 mu M, while 6, 9, and 12 showed selective cytotoxic activity toward the tested cell lines.