Characterization of tea catechins-loaded nanoparticles prepared from chitosan and an edible polypeptide

Tea catechins, the major polyphenolic compounds in green tea are potent antioxidant with numerous attributed health benefits. However, oral administration of the oxidation-sensitive compounds is limited by the harsh environment of the gastrointestinal tract (GIT) and become an important challenge. In this study, self-assembled nanoparticles composed of chitosan (CS) and an edible polypeptide, poly(γ-glutamic acid) (γ-PGA) were prepared for the delivery of tea catechins. The tea catechins-loaded nanoparticles were pH-responsive and demonstrated different tea catechins release profiles in simulated gastrointestinal tract (GI tract) media. Sustained free radical (DPPH and ABTS⁺) scavenging assays showed that the antioxidant activity of tea catechins was retained by the nanoparticles. The nanoparticles with a positive surface charge could transiently open the tight junctions between Caco-2 cells and thus increased the paracellular transport of tea catechins. These results demonstrate that CS/γ-PGA nanoparticles can be effective as a carrier for oral delivery of tea catechins with effective antioxidant activity.