Triterpenoids from Ainsliaea latifolia and Their Cyclooxyenase-2 (COX-2) Inhibitory Activities.

Eight new triterpenoids were isolated from Ainsliaea latifolia. The structures of these compounds were elucidated by interpretation of spectroscopic data, including HRESIMS and NMR data. Compounds 4-6 are identified as rare trinorcucurbitane or tetranorcucurbitane triterpenoids. The absolute configurations of compounds 1 and 2 were confirmed by Snatzke's method. All compounds were evaluated for their inhibition against cyclooxyenase-2 (COX-2), in which compound 4 showed significant inhibitory effect against COX-2 with IC50 value of 3.98 ± 0.32 μM, comparable to that of positive control NS-398 (IC50 4.14 ± 0.28 μM).