pH-sensitive chitosan/sodium alginate/calcium chloride hydrogel beads for potential oral delivery of rice bran bioactive peptides

Although rice bran active peptide (RBAP) has potent antioxidant properties, its practical applications have been limited by its low bioavailability. In this study, we hypothesized that pH-responsive hydrogels prepared from the ionic gelation between chitosan and alginate could be a promising delivery system of short-chain peptides, like RBAP, for protecting them from chemical degradation during digestion and improving their functionality. The hydrogel beads retained RBAP in the gastric environment due to strong interactions between two biopolymers and RBAP, followed by a sustained release of more than 70 % peptide in the intestinal condition, thus improving its gastrointestinal stability. The RBAP-loaded hydrogel beads not only significantly enhanced free radical scavenging ability by 3-7 times during digestion but also protected human umbilical vein endothelial cells from H2O2-induced oxidative stress after digestion. This study presents a novel hydrogel platform for enhancing the gastrointestinal stability and functional efficacy of RBAP and other water-soluble peptides.