Identification of a NFκB inhibitory peptide from tryptic β-casein hydrolysate

Abstract

Several bioactive peptides are encrypted within the sequence of major milk proteins, requiring enzymatic proteolysis for release and activation. The present study aimed at the identification of potential anti-inflammatory activities in tryptic hydrolysates of bovine β-casein. Inflammatory processes involve in most cases an activation of Nuclear factor Kappa-light-chain enhancer of activated B cells (NFκB), which is a pro-inflammatory transcription factor of several genes. Hence, a NFκB reporter cell line was established, and TNF-α mediated activation of NFκB was used as a measurement. Bovine β-casein (β-CN) was hydrolysed by trypsin and fractionated by ultrafiltration. Total proteolysate as well as the fraction containing peptides between 1 and 5kDa showed an inhibitory effect in the cell-based assay, while the fraction containing molecules smaller than 1kDa did not. This anti-inflammatory effect was ascribed to a group of large, hydrophobic peptides, which were identified using LC–MS. The main peptide was synthesised and showed a significant anti-inflammatory effect in HEKnfkb-RE-cells. Thus, for the first time, a casein-derived peptide having an anti-inflammatory effect in vitro has been identified.