Abstract

Three undescribed seco -ursane stereoisomers , ilexcornutosides A – C, two undescribed triterpenoid saponins , ilexcornutosides D – E, and 11 known triterpenoids were isolated from the leaves of Ilex cornuta Lindl. & Paxton. Ilexcornutosides A – C and F with the same planar structures are unique 13(18)-ene-18,19- seco -ursane skeleton triterpenoids, identified as (3 S ,12 R )-3- O -[ β - d -glucopyranosyl-(1 → 2)- α - l -arabinopyranosyl]-12-hydroxyl-19-oxo-18,19-secours-13(18)-en-28,21-lactone. Among them, ilexcornutosides A and F (or ilexcornutosides B and C) are a pair of diastereomers at the C-20 position; ilexcornutosides A and C (or ilexcornutosides B and F) are a pair of diastereomers with epimerization at the C-21. Their structures were established by extensive spectroscopic (IR, 1D and 2D NMR , and HR-ESI-MS) and chemical analyses. The absolute configurations of ilexcornutosides A, B, D and F were determined by a single crystal X-ray diffraction analysis with a Cu Kα radiation . The inhibitory effect of ilexcornutosides A – F on the PPARγ expression was assessed in the 3T3-L1-Lenti- PPARγ -Luc cells using a single luciferase reporter assay. Ilexcornutosides A and C showed a comparable activity in decrease of the PPARγ expression to the positive control (T0070907) at 5  μ M.