Angiotensin I-converting enzyme inhibitory activity and antioxidant capacity of bioactive peptides derived from enzymatic hydrolysis of buffalo milk proteins

Abstract Buffaloes' milk, which is consumed in many parts of the world, is a little-explored source of bioactive peptides. The angiotensin converting enzyme (ACE)-inhibitory activity and the antioxidant capacity of peptides from buffaloes' milk were examined. A retentate from buffaloes' skimmed milk was hydrolysed using papain, pepsin or trypsin. The papain hydrolysate showed the highest ACE-inhibitory activity and radical scavenging capacity and was fractionated by size exclusion chromatography (SEC) and characterized by LC-MS analysis. A SEC-fraction with intermediate peptide size showed very high ACE-inhibitory activity, while two fractions with small peptides exhibited the strongest antioxidant activity. Peptide identification by ultra-performance liquid-chromatography-tandem mass spectrometry showed that these active fractions contained known bioactive sequences, in addition to novel peptides with supposed ACE-inhibitory (FPGPIPK, IPPK, IVPN, and QPPQ) and antioxidant (YPSG, HPFA and KFQ) activities. The results obtained showed the potential of buffaloes' milk proteins to release ACE-inhibitory and antioxidant peptides.