Panabipinoside A and panabipinoside B, two new oleanane triterpenoid saponins from the roots of Panax bipinnatifidus with nitric oxide inhibitory activity

Panax bipinnatifidus belongs to the ginseng genus and it is used in traditional Vietnamese and Chinese medicine. Phytochemical studies of the roots of this plant led to the isolation of two new oleanane triterpenoid saponins, panabipinoside A and panabipinoside B, and three known compounds, ginsennoside Ro, 3-O-beta-D-glucopyranosyl-(1 -> 3)-beta-glucuronopyranosyl oleanolic acid, and spinasaponin A 28-O-glucoside. Their structures are established by extensive spectroscopic analysis (IR, high-resolution electrospray ionization mass spectrometry, and nuclear magnetic resonance) and by comparison of the spectral data with those reported in the literature. The anti-inflammatory activity of the isolated compounds is evaluated by their inhibition of nitric oxide production in lipopolysaccharide stimulated RAW 264.7 cells. Compounds 2-5 showed inhibitory effects on nitric oxide production with IC50 values of 0.62 +/- 0.09, 0.21 +/- 0.04, 0.30 +/- 0.03, and 0.45 +/- 0.05 mu g/mL, respectively, compared to value of 8.08 +/- 0.09 mu g/mL for the positive control compound, N-G-monomethyl-L-arginine.