Dipeptidyl peptidase IV (DPP-IV) inhibitory properties of a camel whey protein enriched hydrolysate preparation

Camel milk proteins contain dipeptidyl peptidase IV (DPP-IV) inhibitory peptides. A camel whey protein concentrate (WPC, 44.7 ± 3.4% (w/w) protein) was prepared and subsequently hydrolysed with trypsin at different temperatures, enzyme to substrate (E:S) ratios and hydrolysis times yielding fifteen hydrolysates (H1-H15). Their DPP-IV half maximal inhibitory concentrations (IC₅₀) ranged from 0.55 ± 0.05 to 1.52 ± 0.16 mg L^-1 for H8 and H6, respectively. E:S was the only factor having a significant effect on the DPP-IV IC₅₀ value (p < 0.05). Relatively potent α-lactalbumin-derived DPP-IV inhibitory peptides (LAHKPL and ILDKEGIDY) were detected in selected hydrolysates. Additionally, three potent β-CN-derived peptides, VPV, YPI and VPF having DPP-IV IC₅₀ values of 6.6 ± 0.5, 35.0 ± 2.0 and 55.1 ± 5.8 µM, respectively, were identified. After IPI, VPV is the second most potent DPP-IV inhibitory peptide identified to date, which supports the role of camel milk as an antidiabetic agent.