Inhibition of Dipeptidyl Peptidase (DPP)-IV and α‑Glucosidase Activities by Pepsin-Treated Whey Proteins

Inhibitors of the enzymes dipeptidyl peptidase (DPP)-IV and α-glucosidase are two classes of pharmacotherapeutic agents used for the treatment of type 2 diabetes. In the present study, whey protein isolate (WPI), α-lactalbumin, β-lactoglobulin, serum albumin, and lactoferrin hydrolysates obtained by peptic digestion were investigated for their potential to serve as natural sources of DPP-IV and α-glucosidase inhibitors. Although inhibition of DPP-IV activity was observed in all pepsin-treated whey proteins studied, the α-lactalbumin hydrolysate showed the greatest potency with an IC50 value of 0.036 mg/mL. Conversely, only WPI, β-lactoglobulin, and α-lactalbumin hydrolysates displayed some inhibitory activity against α-glucosidase. This study suggests that peptides generated from whey proteins may have dual beneficial effects on glycemia regulation and could be used as functional food ingredients for the management of type 2 diabetes.