Study on Properties of Quercetin-loaded Enzymatic Glycosylated Casein Composite Nanoparticles

Objective: To prepare quercetin loaded casein nanoparticles (_n-Cas-Que) and transglutaminase glycosylated casein nanoparticles (_n-Cas-Cos-Que), and explore their storage stability, in vitro anti digestibilitiy, bioaccessibility, anti-oxidation and inhibitory effect on human prostate cancer PC-3 cells. The results showed that when stored in 4 ℃ avoid light, 25 ℃ avoid light and 25 ℃ natural light for 60 days, the retention rates of quercetin in _n-Cas-Que and _n-Cas-Cos-Que were 80.78%, 91.30%, 66.87%, 79.25%, 22.18%, 34.33%, respectively, which indicated that _n-Cas-Cos-Que nanoparticles could protect quercetin better.The results of anti-digestion pointed out that _n-Cas-Cos-Que had better anti-digestibility and higher bioavailability than _n-Cas-Que. After 180 min of simulated digestion in vitro, the bioaccessibility of quercetin aqueous solution, _n-Cas-Que and _n-Cas-Cos-Que were 10.13%, 27.65% and 48.91%, respectively. DPPH method and ABTS method were used to investigate the antioxidant activity of the two nanoparticles. The scavenging rates of _n-Cas-Cos-Que and _n-Cas-Que on DPPH and ABTS were 58.71%, 53.82% and 56.98% and 48.34%, respectively, which indicated that _n-Cas-Cos-Que had better antioxidant activity than _n-Cas-Que. The inhibition of human prostate cancer PC-3 cells expressed that with the increase of quercetin concentration, the inhibitory effects of Que, _n-Cas-Que and _n-Cas-Cos-Que on PC-3 cells were gradually enhanced. When the concentration of quercetin reached 80 μg/mL, the survival rates of PC-3 cells treated with Que, _n-Cas-Que and _n-Cas-Cos-Que were 73.25%, 56.84% and 49.88% respectively, and there were significant differences among these survival rates (P<0.05). Compared with Que and _n-Cas-Que, _n-Cas-Cos-Que nanoparticles had better inhibitory effect on PC-3 cells. The results showed that casein nanoparticles can protect quercetin well, and enzymatic glycosylation can improve its protective effect on quercetin, and raise its anti digestion and biological accessibility, as well as antioxidant and anti-cancer activity.