Cyanidin-3-Glucoside-Rich Extract from Chinese Bayberry Fruit Protects Pancreatic β Cells and Ameliorates Hyperglycemia in Streptozotocin-Induced Diabetic Mice

Chinese bayberry fruit is a rich source of anthocyanins, especially cyanidin-3-glucoside (C3G). The present study investigated the protective effects of C3G-rich bayberry fruit extract (CRBFE) against pancreatic beta cells against oxidative stress-induced injury as well as its hypoglycemic effect in diabetic mice. Bayberry extract from Biqi'' was used for both in vitro and in vivo testing because of its high C3G content and high antioxidant capacity. Pretreatment of beta cells with CRBFE (containing 0.5 mu mol/L C3G) prevented cell death, increased cellular viability, and decreased mitochondrial reactive oxygen species production and cell necrosis induced by 800 or 1200 mu mol/L H2O2. CRBFE dose-dependently up-regulated pancreatic duodenal homeobox 1 gene expression, contributing to increased insulin-like growth factor II gene transcript levels and insulin protein in INS-1 cells. In addition, administration of CRBFE (150 mu g of C3G/10 g of body weight twice per day) significantly reduced blood glucose in streptozotocin-induced diabetic ICR mice and increased the glucose tolerance in an oral glucose tolerance test (P <.05). Such results indicated that CRBFE might be useful in prevention and control of diabetes mellitus and diabetes-associated complications.