Purification and characterization of angiotensin-Ⅰ-converting enzyme inhibitory peptides isolated from whey proteins of milk fermented with Lactobacillus plantarum QS670

摘要

An angiotensin-converting enzyme inhibitory (ACEI)peptide with a median inhibitory concentration (IC50)of 1.26 mg/mL was purified from whey proteins resultingfrom a fermentation using Lactobacillus plantarumQS670. The peptide was subsequently derived from anαS1-casein, κ-casein, β-lactoglobulin, or serum albuminfraction. Analysis via liquid chromatography tandemmass spectrometry indicated that it had an amino acidsequence of Gly-Ala (GA). The GA dipeptide was alsosynthesized using an Fmoc solid-phase method. TheGA dipeptide exhibited an IC_(50) of 1.22 mg/mL andwas shown to be stable across both temperature (20 to60°C) and pH (2 to 12). Digestive enzymes includingpepsin, trypsin, and chymotrypsin had negligible effectson activity. The whey exerted hypotensive effectswhen fed to spontaneously hypertensive rats (SHR),which exhibited a blood pressure drop of 2.33 kPa. A4-wk gavage treatment resulted in greater decreasesof 7.46 kPa. Results of this study indicate that milkfermented using Lb. plantarum QS306 has potential tobe used as a functional food to help prevent or reducehypertension-associated diseases.