Structures and Tumor Cell Lines Proliferation Activities of Triterpenes Isolated from Astilbe grandis

A total of seven compounds, including four triterpene acids and three triterpene lactones, were isolated from the ethanolic extract of the roots of Astilbe grandis Stapf ex Wils. Two of the triterpene lactones (1-2) were never reported before and compounds 3-5 were isolated for the first time from the plant. The structures of these compounds were all identified by spectroscopic analysis. Compounds 1-2 were analyzed by 2D NMR and their absolute configurations were determined using experimental CD in comparison with calculated ECD values. The structure of compound 1 was also further confirmed by single crystal X-ray diffraction analysis. The cytotoxicity of compounds 1-7 on A549, Caco-2, H460 and Skov-3 tumor cells were all evaluated using CCK-8. They all exhibited positive inhibitory effects on Caco-2 tumor cells with IC50 less than10 mu M, while the inhibitory effects on H460 tumor cells were more moderate. Unfortunately, they displayed little apparent cytotoxicity to the other two types of cells.