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ACE-inhibitory and radical-scavenging activity of peptides derived from β-lactoglobulin f(19-25). Interactions with ascorbic acid

Abstract:

In this work, the angiotensin-converting enzyme (ACE)-inhibitory and radical-scavenging activities of the β-lactoglobulin (β-Lg)-derived peptides WY f(19-20), WYS f(19-21), WYSL f(19-22), WYSLA f(19-23), WYSLAM f(19-24), and WYSLAMA f(19-25) have been determined. The ACE-inhibitory activity (IC50) varied from 38.3 to 90.4 μM, with the exception of WYS (>500 μM). All β-Lg-derived peptides also exhibited radical-scavenging activity (oxygen radical absorbance capacity (ORAC) values ranged from 4.45 to 7.67 μmol Trolox equivalents/μmol of peptide). The presence and position of amino acids Trp, Tyr, and Met were proposed to be responsible for the antioxidant activity. The equimolar amino acid mixtures of all the peptides showed ORAC values lower than those of the corresponding peptides, indicating that the peptidic bond or the structural conformation had a positive influence on this activity. Finally, positive antioxidant effects of WYS, WYSL, and WYLA with ascorbic acid were observed, whereas WY and WYSLAM showed negative effects, both cases for different molar ratio mixtures. These results should be taken into account in the development of new food ingbkp_redients on the basis of peptides from β-Lg. © 2007 American Chemical Society.