Isolation, purification and structure identification of two phenolic glycosides from the roots of Incarvillea younghusbandii Sprague and their antioxidant activities.

Using a bioassay-guided fractionation technique, two compounds were isolated from the roots of Incarvillea younghusbandii Sprague through silica gel, reverse-phase C18 column chromatography and reverse-phase HPLC. Their structures were identified as acteoside (1) and isoacteoside (2) by ESI-MS, GC-MS, 1D- and 2D-NMR. 1 and 2 showed *OH scavenging capacity similar with benzoic acid, higher O2*- (or *OH) scavenging capacity than ascorbic acid, far higher hepatic LPO inhibitory activities than 2, 6-di-tert-butyl-4-methylphenol (BHT) or ascorbic acid, and more powerful effect on protecting erythrocytes from oxidative damage than ascorbic acid. The *OH scavenging capacity was positively proportional to the concentrations of 1 and 2 ranging from 0.015 6 to 0.500 0 mg x mL(-1). The hepatic LPO inhibitory activities increased with the increasing concentrations of 1 and 2 from 0.001 9 to 0.250 0 mg x mL(-1), but decreased slightly with the increasing concentration from 0.250 0 to 1.0000 mg x L(-1).