α-Glucosidase inhibitory and antioxidant properties and antidiabetic activity of Hypericum ascyron L.

Different solvent extracts of Hypericum ascyron L. were evaluated by alpha-glucosidase inhibitory activity and DPPH, ABTS and FRAP assays, respectively, for antioxidant properties in vitro. EtOAC and MeOH extracts showed stronger inhibiting activity against alpha-glucosidase and rat intestinal alpha-glucosidase compared with acarbose as positive control. Eight known compounds were isolated from EtOAC and MeOH extracts and screened for alpha-glucosidase inhibitory and antioxidant activities. Kaempferol and ursolic acid were active compounds of alpha-glucosidase inhibitory effect in EtOAC extract. Quercetin-3-O-beta-d-galactoside, quercetin-3-O-beta-d-glucoside and kaempferol from EtOAC and MeOH extracts showed moderate or lightly low antioxidant activity with BHT as positive control. The antidiabetic activity of EtOAC and MeOH extracts was determined in vivo. After intragastric administration of EtOAC extract (500 mg/kg body weight per day) and MeOH extract (500 mg/kg) to groups of on alloxan-induced diabetic mice for 8 days, the level of blood glucose in serum significantly decreased (P < 0.01 and P < 0.05, respectively), the blood lipid level of TC and TG lowered, and the oxidant stress and oxidative damage to tissues were inhibited by decreasing the level of MDA (P < 0.01 and P < 0.01, respectively) and lightly increasing the level of SOD. The result showed that H. ascyron may be a good sources of natural antioxidants and alpha-glucosidase inhibitor using for the therapy of hyperglycemic and its complication.