Peptide identification from a Porphyra dioica protein hydrolysate with antioxidant, angiotensin converting enzyme and dipeptidyl peptidase IV inhibitory activities

• Published in: Food & function 2019-06, Vol.10 (6), p.3421-3429
• Main Authors: Cermeño, Maria, Stack, Julianne, Tobin, Paul R, O'Keeffe, Martina B, Harnedy, Pádraigín A, Stengel, Dagmar B, FitzGerald, Richard J
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Angiotensin; Angiotensin-Converting Enzyme Inhibitors - chemistry; Angiotensin-Converting Enzyme Inhibitors - isolation & purification; Antioxidants; Antioxidants - chemistry; Antioxidants - isolation & purification; Biological activity; Chromatography; Conversion; Digestive system; Dipeptidyl Peptidase 4 - chemistry; Dipeptidyl-peptidase IV; Dipeptidyl-Peptidase IV Inhibitors - chemistry; Dipeptidyl-Peptidase IV Inhibitors - isolation & purification; Enzymes; Gastrointestinal tract; Liquid chromatography; Mass spectrometry; Mass spectroscopy; Peptidase; Peptides; Peptides - chemistry; Peptides - isolation & purification; Peptidyl-dipeptidase A; Peptidyl-Dipeptidase A - chemistry; Porphyra; Porphyra - chemistry; Porphyra dioica; Protein Hydrolysates - chemistry; Proteins; Reactive oxygen species; Vitamin E
• ISSN: 2042-6496; 2042-650X
• DOI: 10.1039/c9fo00680j

A Porphyra dioica protein extract was enzymatically hydrolysed and then fractionated using semi-preparative reverse-phase high performance chromatography. The hydrolysate and its fractions were tested for their oxygen radical absorbance capacity (ORAC) along with their angiotensin converting enzyme (ACE) and dipeptidyl peptidase IV (DPP-IV) inhibitory activities. The most potent fraction was analysed by liquid chromatography mass spectrometry. Eight peptide sequences were selected for synthesis based on their structure-activity criteria for bioactivity. Asp-Tyr-Tyr-Lys-Arg showed the highest ORAC activity (4.27 ± 0.15 μmol Trolox equivalent per μM). Thr-Tyr-Ile-Ala had the highest ACE inhibitory activity (IC50: 89.7 ± 7.10 μM). Tyr-Leu-Val-Ala was the only peptide showing DPP-IV inhibitory activity (IC50: 439 ± 44 μM). Apart from Asp-Tyr-Tyr-Lys-Arg and Thr-Tyr-Ile-Ala, which displayed increased ORAC activity, the bioactivities of the peptides were either maintained or decreased following in vitro simulated gastrointestinal digestion. The results indicate that P. dioica-derived peptides may have potential applications as health enhancing ingredients.