Purification and identification of dipeptidyl peptidase (DPP) IV inhibitory peptides from the macroalga Palmaria palmata

Dipeptidyl peptidase (DPP)-IV inhibitory peptides were purified and identified from an aqueous Palmaria palmata protein extract hydrolysed with Corolase PP. The hydrolysate was fractionated by solid phase extraction (SPE) using a C18 matrix followed by semi-preparative reverse phase-high performance liquid chromatography (SP RP-HPLC). IC50 values of 1.47 ± 0.09, 0.54 ± 0.03 and 0.36 ± 0.03 mg/ml were obtained for the hydrolysate, the 25% – acetonitrile (ACN) SPE fraction and the most active SP RP-HPLC peptide fraction (SP RP-HPLC 25_F28), respectively. Thirteen peptide sequences were identified following UPLC–ESI MS/MS analysis of SP RP-HPLC 25_F28. Three novel DPP-IV inhibitory peptides, Ile-Leu-Ala-Pro, Leu-Leu-Ala-Pro and Met-Ala-Gly-Val-Asp-His-Ile, with IC50 values in the range 43–159 μM were identified. The results indicate that P. palmata derived peptides may have potential as functional food ingredients in the prevention and management of type 2 diabetes.