Minor triterpenoid acids from an aqueous extract of Uncaria rhynchophylla

Seventeen minor triterpenoid acids (1-17) were isolated from an aqueous decoction of Uncaria rhynchophylla by a combinatory application of column chromatography using multiple stationary phases, including macroporous adsorbent resin, MCI resin, Sephadex LH-20, Toyopearl HW-40C, silica gel, and C18 reversed phase silica gel, combined with separation techniques of flash chromatography (FC) and high performance liquid chromatography (HPLC). Their structures were determined by analysis of HR-ESI-MS, UV, CD, and IR as well as 1D and 2D NMR spectroscopic data, of which eight new compounds (1-8) are named successively uncarinic acids Q-X, while the structures of 2 and 7 were confirmed by single crystal X-ray diffraction. In the in vitro assays, 27-hydroxyolean-12-en-28-oic acid (17) inhibited TGF-β-induced HSC-T6 cell activation at the concentration of 5 μmol·L^-1.