Abstract
Recent investigations have focused on food-derived peptides as novel natural inhibitors of dipeptidyl peptidase IV (DPP-IV), a new target for diabetes. This study aimed to optimize fast, sensitive, and cost-effective DPP-IV assays in situ on human intestinal Caco-2 cells and ex vivo on human serum. Both assays were applied to investigate the inhibitory activity of soy and lupin peptides. The best conditions for in situ DPP-IV activity in Caco-2 cells were obtained using 2-day cells and 50 µM Gly-Pro-AMC. Sitagliptin, used as reference inhibitor, showed a dose-dependent response with a 50% inhibition concentration (IC50) of 0.6 µM. A lower IC50 (0.2 µM) was obtained for sitagliptin on human serum incubated with the substrate for 24 h. Both assays were applied to assess the activity of Lup1 (LTFPGSAED) and Soy1 (IAVPTGVA) on DPP-IV. Lup1 and Soy1 inhibited DPP-IV in situ, with IC50 values of of 207.5 and 223.2 µM, respectively, and maintained their inhibitory activity ex vivo on circulating DPP-IV with a slightly lower potency. These assays can be used to characterize the DPP-IV inhibitory activity of food-derived molecules more accurately than in vitro biochemical tests. This combined approach also considers their effects on the circulating form of DPP-IV, correlated to metabolic diseases.
Highlights
Dipeptidyl peptidase IV (DPP-IV)/CD26 is a cell surface ectoenzyme (EC 3.4.14.5) that cleaves dipeptides from the N-terminus of polypeptides in which proline is at the penultimate position
The importance of DPP-IV as a promising therapeutic target for glycemic control has recently emerged [4]. It plays a major role in glucose metabolism by N-terminal truncation and inactivation of the incretins glucagon-like peptide (GLP-1) and gastrointestinal insulinotropic peptide (GIP)
DPP-IV is an enzyme expressed by non-differentiated Caco-2 cells, it increases during culture differentiation [16,17]
Summary
Dipeptidyl peptidase IV (DPP-IV)/CD26 is a cell surface ectoenzyme (EC 3.4.14.5) that cleaves dipeptides from the N-terminus of polypeptides in which proline is at the penultimate position.DPP-IV, originally characterized as a T-cell differentiation antigen, was later reported to be ubiquitously expressed on the surface of various cell types, such as renal proximal tubules, intestinal epithelial cells, vascular endothelium, biliary caniliculi, alveolar pneumocytes, and skin fibroblasts [1]. Dipeptidyl peptidase IV (DPP-IV)/CD26 is a cell surface ectoenzyme (EC 3.4.14.5) that cleaves dipeptides from the N-terminus of polypeptides in which proline is at the penultimate position. Enhanced soluble DPP-IV levels and/or activity have been suggested to be a novel regulator of many metabolic diseases, such as type 2 diabetes (T2DM), obesity, cardiovascular disease, and non-alcoholic fatty liver disease [2,3]. The importance of DPP-IV as a promising therapeutic target for glycemic control has recently emerged [4]. It plays a major role in glucose metabolism by N-terminal truncation and inactivation of the incretins glucagon-like peptide (GLP-1) and gastrointestinal insulinotropic peptide (GIP). GIP and GLP-1 stimulate insulin biosynthesis at the pancreatic level and are responsible for up to 70% of insulin secretion
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
