In vitro digestion and intestinal absorption of curcumin-loaded zein nanoparticles

Colloidal delivery systems improve the oral bioavailability of lipid-soluble bioactives, providing protection throughout the gastrointestinal tract. In this study, the fate of a model bioactive, curcumin, was followed during in vitro digestion and absorption, using state of the art INFOGEST in vitro models. Curcumin was loaded in zein nanoparticles, prepared by antisolvent precipitation, with or without sodium caseinate (Cur-Z-C and Cur-Z, respectively). The bioefficacy of the digesta were evaluated using Caco-2 cells. In addition, the absorption of curcumin was evaluated using a co-culture of Caco-2/HT29-MTX cells, which are mucus producing. Ultra-high-performance quadrupole time-of-flight mass spectrometry and cellular bioassays were utilized to assess the presence of bioaccessible material, and any residual curcumin after absorption. Zein nanoparticles were fully digested during gastrointestinal transit. A comparison between aqueous curcumin and digested Cur-Z and Cur-Z-C showed that Cur-Z-C decreased the proliferation of Caco-2 cells by ∼55%. This finding points out the importance of matrix effect on the efficacy of delivery systems.