Triterpenoid saponins with anti-inflammatory activities from Ilex pubescens roots

Seven triterpenoid saponins, named ilexsaponin I-O, along with twelve known ones, were isolated from the roots of Ilex pubescens. The structures of all compounds were elucidated by use of extensive spectroscopic methods (IR, HR-ESI-MS, and 1D and 2D NMR). Sugar residues obtained after acid hydrolysis were identified by TLC and HPLC. The in vitro anti-inflammatory effects of the triterpenoid saponins were also evaluated in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Among the isolated saponins, seven compounds were shown to inhibit LPS-induced nitric oxide (NO) and prostaglandin E₂ (PGE₂) production by suppressing the expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2), respectively, in LPS-stimulated RAW 264.7 cells. Ilexsaponin I and β-d-glucopyranosyl 3-β-[β-d-xylopyranosyl-(1 → 2)-β-d-glucopyranosyloxy]-olea-12-en-28-oate exerted more potent anti-inflammatory effects than the other compounds tested.