Figure 5.

The role of peptide II and sitagliptin as dipeptidyl peptidase-IV (DPP-IV) inhibitors. Glucagon-like peptide-1 (GLP-1) is released from the enteroendocrine cells in the gastrointestinal tract, then diffuses into the capillaries where degradation by DPP-IV and circulating in the plasma begins. Further degradation occurs during passage through the liver, as well as on the way to pancreatic islet. The intake of peptide II and sitagliptin inhibits the activity of DPP-IV and remains in the concentration of GLP-1 in plasma. The GLP-1 receptor activation in the pancreatic beta-cells leads to insulin secretion via the stimulation of incretin/cAMP pathways and recruits signaling mechanisms, leading to cell survival. The figure is reproduced from [40,41,42].