Triterpenes and triterpene saponins from the stems of Akebia trifoliata

To characterize the stems of Akebia trifoliata chemically, a detailed phytochemical examination was carried out on A. trifoliata stems, with particular attention to the triterpene and triterpene saponin constituents, and resulted in the isolation of three new triterpenes (1-3) and three new triterpene saponins (11-13), together with seven known triterpenes (4-10) and 12 known triterpene saponins (14-25). The structures of the new compounds were determined on the basis of spectroscopic analysis, including two-dimensional NMR spectroscopic data, and the results of hydrolysis. Four saponins (22-25), which were obtained in good yields and were not isolated from Akebia quinata stems, are concluded to be applicable as marker compounds in chemically distinguishing between A. trifoliata and A. quinata by conventional TLC examination. To the best our knowledge, the current work is the first chemical investigation of A. trifoliata.