Effect of in vitro dynamic gastrointestinal digestion on antioxidant activity and bioaccessibility of vitexin nanoencapsulated in vaterite calcium carbonate

Poor aqueous solubility and poor intestinal absorption of vitexin, a plant antioxidant flavonoid, limits its putative health benefits and its application in functional foods. In this study, vitexin was encapsulated in CaCO3 nano -particles using co-precipitation method to improve its bioaccessibility. The effects of synthesis parameters, re-action temperature and homogenization speed, on the properties of vitexin-loaded CaCO3 nanoparticles were studied. Under the optimal condition (temperature of 40 degrees C and homogenization speed of 25,000 rpm), encapsulation efficiency of 90.45% and loading capacity of 28.64% were obtained. The optimized nanoparticles mainly consisted of vaterite crystals of 99.89% with an average particle size of 78.10 nm and a low PDI of 0.119. In vitro dynamic gastrointestinal digestion study showed 62.15% dissolution of and 78.69% cumulative vitexin release. The enhanced solubilization of the nanoencapsulated vitexin resulted in a 4.2 and 5.8 fold increase in the DPPH center dot and ABTS center dot+ scavenging activities, respectively, and a 6.8 fold increase in the bioaccessibility compared to those of the free vitexin. Therefore, this research provides a detailed strategy using the benefits of nanotech-nology for enhancement of the in vitro bioaccessibility of vitexin for functional food applications.