α-Glucosidase Inhibition and Antihyperglycemic Activity of Phenolics from the Flowers of Edgeworthia gardneri.

The flowers of Edgeworthia gardneri are consumed as an herbal tea in Tibet with potential health benefits. To complement the current knowledge regarding the chemical composition and antihyperglycemic activity of the flower of E. gardneri, two new phenolics, gardnerol A and B (1 and 2), along with 19 known phenolics were isolated from the flower of E. gardneri. All isolates were evaluated for their inhibitory activity against α-glucosidase. Compound 5, identified as the major constituent of the flower of E. gardneri, showed a significant α-glucosidase inhibitory activity and acted as a competitive inhibitor. The oral administration of compound 5 at a dose of 300 mg/kg significantly reduced the postprandial blood glucose levels of normal and streptozotocin (STZ)-induced diabetic mice. Furthermore, compound 5 significantly decreased the fasting blood glucose levels in STZ-induced diabetic mice.