A comparative assessment of brush border membrane vesicles from porcine jejunum and small intestine powders from rat to study (poly)phenol hydrolysis and bioaccessibility.

Dietary (poly)phenols are predominantly present as sugar-conjugates, and the nature of the sugar influences their metabolic fate and biological activity. These compounds generally escape luminal digestion and undergo hydrolysis by intestinal brush-border α- and β-glycosidases, particularly by lactase-phloridzin hydrolase (LPH). This process is often overlooked in in vitro digestion models, limiting their physiological relevance for predicting the gastrointestinal fate of dietary (poly)phenols. In this study, brush-border membrane vesicles (BBMV) were isolated and purified from porcine jejunum and characterized for carbohydrate hydrolyzing activity. A crude commercial rat small intestinal extract (RSIE) was also evaluated for comparison. Then, a whole-apple phenolic extract was profiled and subjected to simulated upper gastrointestinal digestion (INFOGEST 2.0) with or without the mucosal enzymatic systems (BBMV or RSIE) standardized to 15 U*mL-1 maltase activity, corresponding to that reported for the human epithelium. The extract contained 45 (poly)phenols, including 24 sugar-conjugated derivatives comprising α- and β-O-glycosides and glycosyl esters. The effects of BBMV and RSIE on enzymatic hydrolysis and non-catalytic interactions were structure-dependent, varying according to (poly)phenol subclass, linkage pattern, and sugar identity. RSIE markedly decreased the bioaccessibility of all (poly)phenol subclasses relative to BBMV, with concomitant aglycone release from HCA, flavonol, and dihydrochalcone sugar-conjugates. In contrast, BBMV resulted in a more moderate decrease in (poly)phenol bioaccessibility and generated aglycones only from β-O-glycosides (e.g. dihydrochalcone glycosides), consistent with the specific β-glycosidase activity of LPH. By comparison, BBMV minimized non-catalytic interactions between (poly)phenols and brush-border systems while providing a β-O-glycosidase-specific environment with negligible residual cytosolic or microbial enzyme activities.