Mechanistic insights into cholesterol and micellar components insolubilisation by cowpea bioactive peptides in a model system

Cowpea beans are widely recognised for their hypocholesterolemic potential, which is largely attributed to their high protein content and derived bioactive peptides. This study explored the mechanistic effects of hydrolysed cowpea proteins and sequence-defined synthetic peptides on cholesterol micelle structure and solubilisation in vitro. Synthetic peptides consistently reduced micelle size by at least 6 nm, whereas the ≤ 3 kDa hydrolysate fraction induced a threefold increase in micelle radius. This hydrolysate fraction also decreased cholesterol solubility and phosphatidylcholine content in a dose-dependent manner, forming insoluble aggregates through 50–60% complexation with phosphatidylcholine and thereby disrupting micellar organisation. The three synthetic peptides reduced cholesterol solubility by 10–20% relative to untreated micelles, effects attributed to altered bile acid and phosphatidylcholine composition, as well as potential direct peptide–cholesterol interactions. These findings indicate that micellar competition between peptides and non-cholesterol constituents is a central mechanism modulating cholesterol solubilisation. By examining both complex hydrolysate fractions and precise peptide sequences, this study provides detailed mechanistic insight into cowpea protein activity. These results not only enhance our understanding of peptide–micelle interactions but also establish an in vitro foundation for future validation studies, informing potential dietary or therapeutic strategies aimed at modulating cholesterol absorption.