Construction Of Juglans Regia L. Shells Polyphenols Microgeland Its Protective Effect On Ultraviolet Radiation Damage

Long term exposure to ultraviolet radiation can induce the body to produce excessive reactive oxygen species oxidative(ROS)free radicals,and then trigger oxidative stress response,resulting in various diseases.Studies found that the polyphenolic compounds isolated from plants had been demonstrated to possess the excellent UV radioprotective activities.They can exert their anti-UV radiation effect through absorption of UV radiation and scavenging active oxygen free radicals generated by UV radiation.This project was designed to construct p H-responsive Juglans regia L.shells polyphenol(JRP)microgel nano-delivery system(JRP-Microgel)by self-assembly technology,investigate its gastrointestinal digestion characteristics in vitro,and systematically evaluate its UV radioprotective activities during the processes of gastrointestinal digestion.The specific results are as follows:In this study,JRP separated and purified from Juglans regia L.shells was mainly composed of quercetin and its derivatives,which were identified by HPLC-MS/MS.The self-assembly technology was used to construct and characterize the structural characteristics of p H-responsive JRP-Microgel.The results showed that JRP-Microgel,with the encapsulation efficiency of 80% and average particle size of 647 nm,possessed a subspherical pore structure and good photothermal stability.Meanwhile,it can increase the adsorption of mucin to prolong the residence time in the gastrointestinal tract.The gastrointestinal digestion model was established in vitro,and the release characteristics of JRP-Microgel were studied.The results showed that the nano-delivery system could significantly reduce the exposure of JRP to gastric juice and target release in small intestine that effectively prevented the degradation of JRP during gastric-juice digestion,thereby improving its bioavailability.Through establishment of UVB irradiated damage model in vitro,the radioprotective effects of JRP-Microgel on HMVEC cells were measured during gastrointestinal digestion.The results indicated that compared with unencapsulated JRP,JRP-Microgel possessed the significant protect effects on HMVEC cells against the damages induced by UVB radiation by promoting cell proliferation,reducing the accumulation of cellular ROS,enhancing the antioxidant defense system,as well as inhibiting cell cycle arrest at G0/G1.This paper used self-assembly technology to construct JRP-Microgel,which exhibited the sustained release effects during gastrointestinal digestion process in vitro.After gastrointestinal digestion,JRP-Microgel exhibited the stronger radiation protective effect than unencapsulated JRP.This study shows that the construction of JRP-Microgel can effectively solve the problem of low bioavailability of JRP during gastrointestinal digestion process,and provides a theoretical reference for nano-delivery system construction of other polyphenol compounds.