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.