Fabrication of a curcumin-loaded polysaccharide delivery system based on pH- and biodegradation-dependent strategies: in vivo and in vitro characterization

Curcumin (Cur) is renowned for its antioxidant and anti-inflammatory properties; however, its application faces many challenges, including poor bioavailability and low solubility. Alginate (SA) gel system is a promising platform for the delivery of Cur, but its efficacy remains limited and requires further improvement. In this study, Cur/oil was encapsulated into water-in-oil nanoemulsions, which were subsequently incorporated into SA microparticles modified with chitosan (CS) or inulin (IN) to fabricate four types of microparticles: Cur/SA, Cur/SAIN, Cur/SACS, and Cur/Mix. Their characteristics were analyzed, including particle size and morphology, and their stability and release properties were assessed using in vitro models. It demonstrated that the incorporation of IN and CS slightly improved the encapsulation efficiency and stability of SA-based microparticles in simulated human upper digestive tract conditions. The in vitro results further indicated that the incorporation of IN and CS enhanced the release of Cur from SA microparticles in simulated intestinal conditions through pH- and biodegradation-dependent mechanisms. Moreover, Cur/Mix exhibited a longer residence time in the small intestine and colon compared to the other microparticles. The four microparticles exerted distinct effects on the composition of gut microbiota, with Cur/Mix enhancing microbiota richness and diversity. Furthermore, these microparticles altered microbiota metabolite profile, particularly amino acid metabolism, with Cur/Mix exhibiting a more pronounced effect on arginine biosynthesis. This study suggests that incorporating IN and CS into SA microparticles not only improves their physicochemical properties but also achieves a synergistic effect between Cur and polysaccharides.