Evaluation of Selenomethionine Entrapped in Nanoparticles for Oral Supplementation Using In Vitro, Ex Vivo and In Vivo Models

Selenium methionine (Se Met) is an essential micronutrient required for normal body function and is associated with additional health benefits. However, oral administration of Se Met can be challenging due to its purported narrow therapeutic index, low oral bioavailability, and high susceptibility to oxidation. To address these issues, Se Met was entrapped in z e i n-coated nanoparticles made from chitosan using an ionic gelation formulation. The high stability of both the Se Met and s e l e n o methionine nanoparticles (Se Met-NPs) was established using cultured human intestinal and liver epithelial cells, rat liver homogenates, and rat intestinal homogenates and lumen washes. Minimal cytotoxicity to Caco-2 and HepG2 cells was observed for Se Met and Se Met-NPs. Antioxidant properties of Se Met were revealed using a Reactive Oxygen Species (ROS) assay, based on the observation of a concentration-dependent reduction in the build-up of peroxides, hydroxides and hydroxyl radicals in Caco-2 cells exposed to Se Met (6.25–100 M). The basal apparent permeability coefficient (Papp) of Se Met across isolated rat jejunal mucosae mounted in U s s i n g chambers was low, but the Papp was increased when presented in NP. Se Met had minimal effects on the electrogenic ion secretion of rat jejunal and colonic mucosae in U s s i n g chambers. Intra-jejunal injections of Se Met-NPs to rats yielded increased plasma levels of Se Met after 3 h for the Se Met-NPs compared to free Se Met. Overall, there is potential to further develop Se Met-NPs for oral supplementation due to the increased intestinal permeability, versus free Se Met, and the low potential for toxicity.