Study On The Active Ingredients And The Hypoglycemic Activity

The flower of Edgeworthia gardneri belongs to genus edgeworthia in Thymelaeaceae family is peculiar in Tibet and the local residents usually drink tea made from the flower of Edgeworthia.for treatment of diabetes. Guided by ?-glucosidase and ?-amylase inhibition bioactivities, this article reports the bioactive compounds and chemical integrates of E. Gardneri. Research and development mainly include the following aspects:1. Edgeworthia gardneri was extracted with methyl alcohol, followed by using different polar reagents such as petroleum ether, ethyl acetate and n-butanol, respectively, three extracts of different polarity were obtained. A total of thirteen compounds including a new ones is isolated through various separation techniques and structurally identified on the basis of diverse spectroscopic methods(NMR, MS, IR, UV). There were ten coumarins, a flavonoid, a phenylpropanoid and a lignaniod.2. All isolates were evaluated for the inhibitory activity against α-glucosidase and ?-amylase.It turned out that compound 3 showed significant α-glucosidase inhibitory activity(IC50 = 12.02μM), and compound 8 showed significant α-amylase inhibitory activity(IC50= 18.7 μM).Compared to α-amylase, the coumarins from E. gardneri were more potent inhibitors ofα-glucosidase.3. To clarify the ?-glucosidase inhibition mode of compound 3, which was the most active among cumarins, Lineweaver-Burk plots were generated. The results indicated that compound 3exhibited a noncompetitive mode of inhibition. In additional, the value of the inhibition constant(Ki) was 53.82 ?M according to Michaelis-Menten kinetics. To further investigate the interaction between compound 3 and ?-glucosidase, fluorescence measurements were performed. The fluorescence spectrum indicated that the interaction between compound 3 and ?-glucosidase led to a microenvironment variation for Trp residues and a conformational change in ?-glucosidase. The values of the binding constant(Ka) and binding sites(n) were calculated by plotting lg[(F0-F)/F]against lg[Q] according to the Stern-Volmer equation. Furthermore, according to the Van’t Hoff equation, hydrophobic forces played a predominant role in the interaction between compound 3and ?-glucosidase and the interaction was a spontaneous process.4. To clarify the ?-amylase inhibition mode of compound 8, which was the most abundantcompound among the extracts, Lineweaver-Burk plots were generated. The results indicated that compound 8 was a noncompetitive mode of inhibitor. According to Michaelis-Menten kinetics, the inhibition constant(Ki) is 9.72 μM. Furthermore, the actual pharmacological potentials of compounds 8 is demonstrated by the reduction of postprandial blood glucose levels in normal Kunming mice. In vitro and in vivo experiments showed that the inhibition of ?-amylase is one of the mechanisms of antihyperglycemic activity of E. gardneri.