No abstract

BACKGROUND: Type 2 diabetes mellitus (T2DM) is a serious threat to human health. Owing to the action of dipeptidyl peptidase-IV (DPP-IV), the half-life of entero-insulin hormone after secretion is extremely short, causing insufficient insulin secretion in diabetic patients. Dipeptidyl peptidase-IV inhibitors can be used as a new treatment for T2DM. In this study, the proteins of eel (Anguilla rostrata) scraps hydrolyzed using Protamex protease (EPHs) were found to have strong DPP-IV inhibitory activity. The study also provided research ideas for the development and utilization of A. rostrata scraps. RESULTS:The median inhibition concentration (IC 50 ) value of EPHs was 5.455 ± 0.24 mg mL −1 . The peptide fractions with the highest DPP-IV inhibitory activity were sequentially separated by ultrafiltration, gel filtration chromatography (GFC), and reversed-phase high performance liquid chromatography (RP-HPLC) in a continuous hierarchical manner and analyzed using matrix-assisted laser desorption/ionization time-of-flight/ time-of-flight mass spectrometry/mass spectrometry (MALDI-TOF/ TOF MS/MS). Three peptides that revealed significant inhibitory activity were screened among the identified sequences, with sequences of Phe-Pro-Arg (IC 50 = 62.14 ± 1.47 ∼M), Tyr-Pro-Pro-Ser-Phe-Ser (IC 50 = 102.65 ± 4.57 ∼M), and Tyr-Pro-Tyr-Pro-Ala-Ser (IC 50 = 68.30 ± 3.85 ∼M). Molecular docking simulations revealed that their inhibitory effect was mainly due to the formation of hydrogen bonds with amino acid residues in the active sites of DPP-IV. Analysis of the inhibition patterns of the synthetic peptides displayed that Phe-Pro-Arg and Tyr-Pro-Pro-Ser-Phe-Ser displayed competitive inhibition, whereas Tyr-Pro-Tyr-Pro-Ala-Ser showed mixed competitive/non-competitive inhibition.CONCLUSIONS: The protein hydrolysates isolated from eel scraps are potential functional food ingredients for the treatment of T2DM.

No abstract

No abstract