The present study was undertaken to investigate the effect of a major compound of Alternanthera philoxeroides, 3-O-β-D-glucopyranosiduronic acid 28-β-D-glucopyranosyl-oleanolate or chikusetsusaponins IVa (compound 1), on the production of nitric oxide (NO) in lipopolydaccharide (LPS)-stimulated RAW 264.7 macrophage cells.The results showed that compound 1 significantly suppressed NO production in a dose-dependent manner. The studies on structure-activity relationship of compound 1 have demonstrated that both acid and alkaline hydrolysis products, compound 1a (oleanolic acid) and compound 1b (oleanolic acid 3-O-β-D-glucoronide), also exhibited significant NO inhibitory activity, with the relative potency was compound 1b > compound 1 > compound 1a, respectively.
