Abstract
Identifying DPP-IV inhibitory peptides from dietary protein has attracted increased attention. In the present study, bovine α-lactalbumin hydrolysates were generated by alcalase for various hydrolysis times, and DPP-IV inhibitory activity of these hydrolysates was determined. The 4 h hydrolysates displayed the most potent DPP-IV inhibitory activity, with DPP-IV inhibition rate of 82.30 ± 1.39% at concentration of 1.0 mg/mL. DPP-IV inhibitory peptides were isolated from the 4 h-hydrolysates with gel filtration chromatography and reversed-phase high-performance liquid chromatography (RP-HPLC). Using liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI MS/MS), two DPP-IV inhibitory peptides were identified, and their amino acid sequences were Glu-Leu-Lys-Asp-Leu-Lys-Gly-Tyr (ELKDLKGY) and Ile-Leu-Asp-Lys-Val-Gly-Ile-Asn-Tyr (ILDKVGINY), respectively. Furthermore, molecular docking analysis showed that peptides ELKDLKGY and ILDKVGINY could form hydrogen bonds, pi-cation interactions, and salt bridges with DPP-IV. These findings indicated that bovine α-lactalbumin may be a potential source of natural DPP-IV inhibitor.
Highlights
Diabetes, which is a worldwide chronic disease, affects 463 million people in 2019, and this number is expected to reach 700 million by 2045 [1]
Molecular docking analysis showed that peptides ELKDLKGY and ILDKVGINY could form hydrogen bonds, pi-cation interactions, and salt bridges with dipeptidyl-peptidase IV (DPP-IV)
DPP-IV is a ubiquitous enzyme widely known for degradation of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), which contribute to 50–60% of insulin secretion in a glucose-dependent way [5,6]
Summary
Diabetes, which is a worldwide chronic disease, affects 463 million people in 2019, and this number is expected to reach 700 million by 2045 [1]. Type 2 diabetes is characterized by insufficient pancreatic insulin secretion and/or insulin resistance in peripheral tissues, and is associated with various complications such as retinopathy, nephropathy and neuropathy, resulting in serious harm to human health [2,3]. Dipeptidyl-peptidase IV (DPP-IV) inhibitors have become a novel therapeutic approach to manage type 2 diabetes [4]. Inhibition of DPP-IV could maintain the insulinotropic activity of GLP-1 and GIP, resulting in improved glucose homeostasis in type 2 diabetes [7]. There are several synthetic DPP-IV inhibitors in use, e.g., sitagliptin, vildagliptin, saxagliptin, linagliptin, and alogliptin, which have been demonstrated to display protective effects against type 2 diabetes [6,8,9,10,11]. Despite possessing a high hypoglycemic activity, these DPP-IV inhibitors have shown some adverse side effects, such as asthenia, headache, Molecules 2020, 25, 3009; doi:10.3390/molecules25133009 www.mdpi.com/journal/molecules
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