| Selenium(Se)is a necessary trace element for human body.Selenylation polysaccharide(Se-PS)has both the functional properties of polysaccharide and Se,and is a new source of Se enriched supplements or functional foods in the future.However,the production cost of natural Se-PS is high,the loading capacity of Se is small and can’t be controlled effectively.The hydrothermal method for chemical synthesis has some disadvantages,such as long esterification reaction time and limited esterification ability of selenide reagent.Based on the above problems,three kinds of Chinese herbal polysaccharides(Astragalus,Codonopsis and Angelica)were selected as templates in this study.Based on nitric acid-sodium selenite system,the three kinds of polysaccharides were selenized by microwave-assisted method to obtain the best preparation technology.The physicochemical properties,antioxidant activity and Se release efficiency of Se-PS in gastroenteric fluid were further investigated.This study expanded the application fields of Astragalus,Codonopsis and Angelica polysaccharides,and provided a theoretical reference for the synthesis of Se-PS.The main work and conclusions are as follows:(1)The physicochemical properties of three Se-PS,namely Selenylation Astragalus polysaccharides(Se-APS),Selenylation Codonopsis polysaccharides(SeCPPS)and Selenylation Angelica polysaccharides(Se-CAP),were prepared and characterized by microwave-assisted method.Firstly,the optimal experimental conditions were screened.The results showed that the highest Se content of Se-APS,Se-CPPS and Se-CAP after microwave selenylation was 18.79 mg/g,21.71 mg/g and13.22 mg/g,respectively,and the selenylation time was only 90 min.The physicochemical properties(Infrared Spectroscopy,X-ray Photoelectron Spectroscopy,Scanning Electron Microscopy,Gel Permeation Chromatography,Dynamic Light Scattering and X-ray Diffraction analysis)of the obtained high-Se polysaccharide were further characterized.The consequence showed that the binding mode of Se and polysaccharide chain in Se-PS could be connected by O-Se-O bond and O-H···Se bond.The valence states of Se were both 0 and +4,and the particle surface was negative charge.(2)Antioxidant properties of three Se-PS were determined by using DPPH,ABTS and superoxide anion scavenging indexes.The results showed that Se-APS3 had the highest scavenging activity,and the IC50 values were 0.787 mg/m L,0.101 mg/m L and1.041 mg/m L,respectively.The experimental results of ABTS free radical and superoxide anion oxidation certified that the transformation of Se valence(+4→0)after microwave selenylation could enhance the scavenging ability of the system for two kinds of free radicals.Overall comparison of the antioxidant properties of three groups was as follows: Se-APS3>Se-CPPS9>Se-CAP3.(3)To evaluate the Se release kinetics and mechanism of three kinds of Se-PS in vitro simulated gastroenteric fluid environment.The results indicated that Se-APS3 had better controlled release of Se in intestinal environment,stable structure and higher bioavailability.Five kinetic equations were used to fit Se release rate,and it was found that three Se-PS had their own optimal Se release fitting models.However,in the Korsmeyer-Peppas model,the SGF stage of all three models belonged to Fickian release case I transport.Se-CPPS9(SIF)and Se-CAP3(SIF)showed non-fickian release;Se-APS3(SIF)followed Fickian release super case Ⅱ transport;A comparative analysis of the effects of polysaccharides on HT-29 cell activity before and after selenylation proved that the highest cell survival rate of the three Se-PS was Se-CPPS9,reaching 171.30 %,and the dose was 0.1 m M,which was the optimal concentration. |
PDF Full Text Request