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 O^•₂^– (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·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·mL⁻¹, but decreased slightly with the increasing concentration from 0.250 0 to 1.000 0 mg·mL⁻¹.