Study On Preparation,structure Characterization And Anti-inflammatory Activity Of Burdock Polysaccharide-Pentacyclic Triterpene Nanoparticles

Burdock is a biennial herb of the Compositae family,which is homologous to medicine and food,and contains various active ingredients such as polysaccharides,pentacyclic triterpenes and polyphenols.Ursolic acid and oleanolic acid are a pair of pentacyclic triterpenoids that are isomers of each other,and have similar molecular structures and pharmacological activities.Both are often co-existed in natural plants,so the study of the synergistic effect between oleanolic acid and ursolic acid is helpful for the utilization of functional components.Oleanolic acid and ursolic acid have poor water solubility and low bioavailability,which greatly limit their application in the food and pharmaceutical industries.Therefore,this paper constructed a delivery of oleanolic acid and ursolic acid based on burdock polysaccharide as a carrier system to improve its water solubility and explore their synergistic anti-inflammatory activity between the two.The main findings are as follows:（1）Using copper sulfate-induced transgenic zebrafish as an anti-inflammatory experimental model,different ratios of oleanolic acid and ursolic acid（0:1,1:3,1:1,3:1,1:0）antiinflammatory activity evaluation was performed.The results showed that when the ratio of the two was 1:1,the anti-inflammatory effect was the best,and the number of macrophages decreased by 29.55%-51.14% compared with the model group,which was significantly different from the model group.（2）Nanoparticles were synthesized by anti-solvent precipitation method,and their encapsulation efficiency was measured and characterized by particle size,potential,FTIR,thermogravimetry,XRD,transmission electron microscopy,and scanning electron microscopy.The encapsulation efficiency of the obtained nanoparticles was 48.98%±3.77%,the loading was 0.96%±0.07%,the average particle size of burdock polysaccharide was178.2±1.3 nm,the particle size of ALP-OA/UA was 199.1±4.7 nm,the potential of burdock polysaccharide was-9.65±0.88 m V,The ALP-OA/UA potential was-7.15±1.17 m V.From the results of scanning electron microscopy and transmission electron microscopy,it can be seen that the prepared nanoparticles have a loose network structure.The thermogravimetric results showed that the thermal stability of polysaccharides and nanoparticles was not much different.Infrared spectroscopy showed that the encapsulation of oleanolic acid and ursolic acid by burdock polysaccharides mainly involved O-H bonds and C-O groups or O-C-O structures of hydroxyl groups.XRD showed that oleanolic acid and ursolic acid were encapsulated by polysaccharide and transformed from crystal structure to water-soluble amorphous structure.（3）The anti-inflammatory activities of polysaccharides and nanoparticles were evaluated using copper sulfate-induced transgenic zebrafish as the anti-inflammatory experimental model and lipopolysaccharide-induced RAW264.7 cell inflammation model.In the cellular inflammation model,different concentrations of polysaccharide solution can reduce the content of NO by 19.37%-48.66%,while different concentrations of nanoparticle solution can reduce the content of NO by 30.09%-64.58% compared with the model group,both of which have certain anti-inflammatory effects.Compared with the oleanolic acid-ursolic acid combination in the zebrafish inflammation model（the mass ratio was 1:1,the maximum reduction was 51.14% compared with the model group）,the maximum reduction of ALPOA/UA nanoparticles was 54.90% after the addition of nanoparticles.RT-PCR analysis showed that both polysaccharides and nanoparticles could achieve anti-inflammatory effects by down-regulating NF-κB2,TNF-α,IL-1β and IL-8 in the NF-κB signaling pathway.（4）The stability of nanoparticles under different pH,temperature and ion concentration conditions and the effect on zebrafish intestinal peristalsis were explored.It exhibited excellent stability under conditions such as 0-100 m M salt solution and storage for 30 days.Compared with the model group,the fluorescence intensity of the ALP-OA/UA group decreased by 49.08%,39.72% and 9.13%,respectively,and the burdock polysaccharide group decreased by 19.74%,40.57% and 33.46%,respectively,compared with the model group.