Berry bioactive phenolics reduce DPP‐IV expression and increase insulin secretion from pancreatic beta cells in vitro (LB412)

Abstract

Berries are a rich source of bioactive phenolic compounds that are able to bind and inhibit the enzyme DPP‐IV, a current target for type‐2 diabetes therapy. The objective was to screen berry phenolic bioactive compounds to decrease DPP‐IV activity in vitro and determine the potential mechanism of action to increase insulin secretion. Blueberry extract reduced DPP‐IV activity in Caco‐2 cells by 31% after 8 h. Western blot analysis revealed a decrease in DPP‐IV protein expression of 78% ± 0.1 (p < 0.05) by this blueberry extract and of 44% ± 2.8 (p < 0.05) by anthocyanin (ANC) extracts from fermented blueberry‐blackberry beverages. ANC at 50 µM cyanidin‐3‐glucoside equivalents were also able to increase glucose‐stimulated insulin secretion from pancreatic iNS‐1E cells by 233 and 100 µIU insulin/mL directly and after epithelial transport, respectively. ANCs up‐regulated gene expression of incretin hormone GLP‐1 (fold‐change 2.4 ± 0.3), and genes in the insulin secretory pathway including iGF1R (1.6 ± 0.4), iGFBP1 (1.5 ± 0.2), iRS2 (1.4 ± 0.3) and iNS2 (1.3 ± 0.4). Also, PTP1B gene expression was down‐regulated (‐1.8 ± 0.1), a potential therapeutic target of type‐2 diabetes. In conclusion, bioactive compounds from berries have potential to reduce onset and progression of type‐2 diabetes through increased insulin secretion due to reduced DPP‐IV expression and up‐regulated insulin‐receptor associated proteins.Grant Funding Source: Supported by Vision 20/20