Preparation Of EGCG-Loaded CS-PAA Nanoparticles And Of Its Bioactivity

The instability of EGCG which easily affected by the light, oxygen, temperature, pH, metal ions and other external factors limit its commercial applications. On the basis of the reported studies, chitosan nano-vehicle could increase the instability of EGCG and improve its bioavailability.In the present study, EGCG was loaded in chitosan nanoparticles for the preservation of antioxidant activity and stability, which prepared by ionic crosslinking between chitosan and ploy-aspartic acid. The conditions of self-assembling nanoparticles by chitosan (CS) and aspartic acid (PAA) were investigated. When the following conditions were employed, i.e. the weight ratio of CS to PAA at1, pH at3.5, the reaction time at1hour, the molecular weight of CS with3-5KDa the molecular weight of PAA with30-50KDa, satisfied nanoparticles were obtained according to the particle size, Zetal potential, the EGCG loading efficiency (344.1mg/kg) and the entrapped efficiency (25%) of EGCG in particles. The EGCG-loaded nanoparticles were pH-responsive and showed different EGCG release profiles in simulated gastrointestinal tract media. The EGCG nanoparticles were proved to have the protection of the EGCG antioxidant based on the analysis by FRAP and DPPH methods. Meanwhile, EGCG nanoparticles were found to be a better protection than EGCG against high temperature, alkaline and other harsh environments. The stability of EGCG in nanoparticles during in vitro digestion was studied, which was carried out in SGF and SIF separately. Moreover, the EGCG nanoparticles exhibited better stability in stimulated gastric fluid (SGF) and stimulated intestinal fluid conditions than EGCG alone.The EGCG nanoparticles showed high safety in the cytotoxicity test and acute toxicity experiment in vitro. The acute toxicity test showed that the dose of60mL/kg of EGCG nanoparicles was safe for mice. Oral EGCG-CS-PAA nanoparticles by rabbits showed16.9±5.8%of average ratio (%) of lipid deposit area which was close to those of oral simvastatin (15.6±4.1%), while those of oral EGCG and the blank nanoparticles gave65.3±10.8%and42.1±4.0%of average ratio of lipid deposit area, respectively. The bioavailability of EGCG against rabbit atherosclerosis was significantly improved by the nano-formulation EGCG.These above results were helpful to utilize chitosan nanoparticles as a protective vehicle for EGCG and other active material in medicine and food.