Study On Hypoglycemic Effect And Mechanisms Of Polyphenols From Castanea Mollissima Blume Burs

Spiny burs of Castanea mollissima Blume (Chinese chestnut) are usually discarded as industrial byproduct during post-harvesting processing which cause a great waste of resource. Therefore, the study on chemical composition and biological activity of Castanea mollissima spiny burs (CMPE) is significant for the potential utilities and systematic development of chestnut industry. Based on a early established procedure of extraction and isolation of tannins from chestnut burs, the objective of this study was to assess the potential antioxidant activity, hypoglycemic effect and mechanisms of tannins from chestnut burs. The main results and conclusion are as follows:1. After extraction and purification of tannins from chestnut burs, the DPPH and ABTS radical scavenging activities increased significantly in the result.2. In normal rats, no significant changes were observed in serum glucose and lipid profiles after orally administration of CMPE at dose of300mg/kg and150mg/kg. In STZ-induced diabetic rats, orally administration of CMPE caused significant decrease in serum glucose and improved blood lipid metabolism level of diabetes rats. However, dosage of300mg/kg caused a significant body weight lose in both normal and diabetic rats.3. Anti-chemical oxidative activities, cellular antioxidant activity (CAA) and a-glycosidase inhibite activity of diabetes rats and normal rats were measured to reveals hypoglycemic mechanisms of chestnut bars. Oral administration of CMPE could cause significant decrease in MDA and GSH levels in spleen and liver tissues, and significant increase in SOD concentrations in diabetic rats and normal rats’tissues. Meanwhile, CAA results indicated that CMPE could enter the cells and enhance the cellular antioxidant activity to protect cell from oxidative damage. Further research indicates that CMPE significantly inhibited the activities of yeast alpha glycosidase enzymes through a competitive mode with IC5o of0.33μg/ml and Ki of1.22μg/ml. The inhibitory activities of CMPE were stronger than specific alpha glycosidase enzymes inhibitors acarbose (IC50:200μg/ml). The oral glucose tolerance test (OGTT) revealed that oral-administration of CMPE significant reduced postprandial blood glucose in mice following sugar challenge. These findings suggest that CMPE may have hypoglycemic effects through a mechanism include the inhibition of a-glucosidases and antioxidant.Those results in this study would offer sufficient informations about hypoglycemic activities of CMPE, by means of enhance viscera antoxidative activities, strengthening cellular free radical scavenging activities, and inhibiting intestinal carbohydrate digestion and absorption. Therefore, this study is of great theoretical significance and practical value to clarify the hypoglycemic effect and hypoglycemic mechanism, thereby providing the potential utilities of chestnut burs.