Ex vivo degradation of β-Casomorphin-7 by human plasma peptidases: Potential implications for peptide systemic effects

[Display omitted] •Ex vivo stability of synthetic β-casomorphins-7 in blood specimen was studied.•Fourteen peptide degradation products were identified and quantified.•Results proved that β-casomorphins-7 is rapidly degraded in the human blood.•Measured half-time seems not compatible with β-casomorphins-7 systemic effects. Susceptibility to proteolytic activity is a critical limitation for food-derived peptides possibly influencing human physiological processes. This study explores the ex vivo stability and degradation kinetics of the milk-derived opioid peptide β-casomorphin-7 (BCM7) in human blood. Blood specimens collected from three healthy volunteers were individually spiked with synthetic BCM7 and sampled at seven time points over 2 h. Liquid chromatography-electrospray-high resolution tandem mass spectrometry was used to monitor the stability of BCM7 and the formation of its hydrolytic fragments. Human plasma peptidases rapidly hydrolyzed BCM7 generating inactive peptides with similar sharp degradation kinetics across the blood of different individuals. The estimated plasma half-life (t1/2) value of BCM7 ranged from 35 to 40 min. The peptide degradation pattern pointed to prolyl oligopeptidase, prolidase, and dipeptidyl peptidase as the primary enzyme candidates responsible for BCM7 hydrolysis. Overall, the findings of this study suggest that BCM7 cannot exert systemic effects in humans.