Fabrication And Application Of Oxidized Lotus Root Starch-based Delivery Systems

Lotus root is a fresh water aquatic plant,which has high nutritional and medical values.Starch is the most important nutritional component in lotus root.Currently,the studies of lotus root starch are mainly focused on its separation,purification and physicochemical properties.The applications of this starch in biomedicine and functional food have been rarely reported.These could be attributed to its low solubility and surface zero charge.To overcome these short comings,lotus root starch(LRS)was oxidized to obtain the OLRS in the present work.Luteolin(Lut)is an important dietary flavonoid,which has anti-inflammatory,antibacterial and antioxidant activities.However,the low solubility,poor stability,and easy degradation and biotransformation of luteolin extremely limited its pharmacological activity.Ulcerative colitis(UC)is a chronic recurrent disease mediated by immunity,which greatly affects people's healthy life.It has been reported that luteolin can effectively relieve the intestinal inflammation and reduce the risk of colorectal cancer.The present work investigated the encapsulation and release properties of luteolin by OLRS nanoparticles.The main experiment results are showed as follows:(1)Preparation and characterization of luteolin-oxidized lotus root starch nanoparticles(Lut-OLRS NPs)by antisolvent precipitation.Results showed that stable Lut-OLRS NPs was formed using Lut and OLRS(oxidization degree,15%)in the weight ratio of 3:1,as well as antisolvent and solvent in the volume ratio of 10:1.Under this condition,the particle size,polydispersity index and zeta-potential of Lut-OLRS NPs was 305 nm,0.173 and-20.8 m V,respectively.The analysis of transmission electron microscopy,X-ray diffractometer and Fourier transform infrared spectroscopy demonstrated that the Lut was successfully encapsulated in OLRS NPs,giving an encapsulation efficiency of 87.2%.The release characteristic and antioxidant activity of encapsulated Lut were further investigated.Results exhibited that the OLRS NPs enabled Lut to be stable in simulated gastric fluid and sustained release in simulated intestinal fluid,leading to the enhancement of antioxidant activity of Lut.(2)Fabrication and application of the Lut-contained OLRS delivery system with colon target property.The porous oxidized lotus root starch(POLRS)was prepared by enzymatic hydrolysis and oxidation.The POLRS was then used to encapsulate Lut.To fabricate the colon targeted delivery system(Lut-POLRS-CS-ES),chitosan(CS)and polymethacrylate Eudragit^?S 100(ES)were coated on the Lut-POLRS via layer-by-layer self-assembly technology.UC animal model was induced by administering DSS.C57BL/6 mice were randomly divided into seven groups:healthy group,DSS model group,positive control group,free Lut low dose group(Lut,20mg/kg.d),free Lut high dose group(Lut,50 mg/kg.d),Lut-POLRS-CS-ES low dose group(Lut,20 mg/kg.d),Lut-POLRS-CS-ES high dose group(Lut,50 mg/kg.d).The results of ex vivo imaging showed that Cy7-POLRS-CS-ES could accumulate in the site of colitis,exhibiting good inflammatory site targeting.In vivo experiments showed that all treatment groups have anti-inflammatory effects on UC mice.Moreover,among these groups,Lut-POLRS-CS-ES with high dose luteolin exhibited the best performance on reducing MPO activity and DAI score,maintaining the weight and colon length of mice,and repairing damaged colon tissue.