Bioactive Peptides/Chitosan Nanoparticles Enhance Cellular Antioxidant Activity of (-)-Epigallocatechin-3-gallate

(-)-Epigallocatechin-3-gallate (EGCG), one representative of the well-studied chemopreventive phytochemicals but with low bioavailability, was encapsulated in monodispersed nanoparticles that were assembled from bioactive caseinophosphopeptide (CPP) and chitosan (CS). The encapsulation efficiency of EGCG in CS-CPP nanoparticles ranged from 70.5 to 81.7%; meanwhile, the in vitro release of EGCG from CS-CPP nanoparticles was in a controllable manner. The EGCG-loaded CS-CPP nanoparticles exerted stronger activity of scavenging free radical than the free EGCG (p < 0.01) in the cellular antioxidant activity assay. Furthermore, cellular uptake of the EGCG-loaded CS-CPP nanoparticles was confirmed by the green fluorescence inside the human hepatocellular caricinoma (HepG2) cells, which was considered to play an important role in the improvement of the antioxidant activity of the nanoencapsulated EGCG. The results suggested that encapsulation of EGCG using CS-CPP nanoparticles should be a potential approach to enhance its antioxidant activity in biological systems.