Changes in antioxidant activity of Alcalase-hydrolyzed soybean hydrolysate under simulated gastrointestinal digestion and transepithelial transport

•Alcalase-hydrolyzed soybean hydrolysate displayed chemical antioxidant activities.•SPH decreased ROS levels in Caco-2 cells under both normal and stress conditions.•In vitro GI digestion enhanced the antioxidant activities of SPH in general.•Transepithelial transport of SPH was studied and absorbed peptides were identified. Peptides from Alcalase-hydrolyzed soybean protein hydrolysate (SPH) may hold the potential as natural antioxidants. In addition, the effect of human gastrointestinal (GI) tract on peptide bioavailability needs to be explored. In this study, the impact of simulated GI digestion and transepithelial transport on various antioxidant properties of SPH were investigated. SPH displayed DPPH radical scavenging (IC50 = 4.22 mg/mL), ABTS+ radical scavenging (IC50 = 2.93 mg/mL), reducing power and metal ion-chelating activities (IC50 = 0.67 mg/mL). Furthermore, SPH significantly (P