ABSTRACT
We previously reported that active Astragalus polysaccharides APS-Ⅱ generate strong immune activity. Here we establish the optimal method for APS-II acid degradation. After preliminary structural studies and separation and preparation of the degradation products, the oligosaccharide active center with the strongest immune activity was identified by in vitro immune cell culture experiments. The optimum acid degradation conditions for APS-II were determined by a single factor experiment and an orthogonal experiment. Astragalus oligosaccharides prepared under the optimal conditions were subjected to structural analysis by hydrophilic interaction chromatography - electrospray ionization source - high resolution time-of-flight mass spectrometry. The products were separated and oligosaccharide fragments with different degrees of polymerization were isolated by preparative purification chromatography. Finally, fragments of the immunologically active centers were identified by in vitro immune cell cultures from multiple perspectives. The results show that the optimal acid hydrolysis conditions for APS-Ⅱ are hydrolysis temperature 80 ℃, trifluoroacetic acid concentration 1.0 mol·L-1, hydrolysis time 1 h. The degradation conditions have good repeatability. The degradation product is a six-carbon aldehyde glycan structure with the main chain 1→4 connected. The immune activity screening experiment for six oligosaccharide fragments showed that larger molecular weight oligosaccharides have stronger immune-promoting effects. It is speculated that the immunologically active center of Astragalus oligosaccharide is located in the sugar chain of DP9-DP19. The animal welfare and the experimental process in this study follow the requirements of the Animal Ethics Committee of Shanxi University. This result suggests a foundation for the structural characterization and structure-activity relationship research of Astragalus oligosaccharides, and may promote the development of Astragalus oligosaccharide drugs.
ABSTRACT
italic>Astragalus polysaccharides are the main immunomodulatory substances in Astragali Radix. The structure of polysaccharides is difficult to accurately determine, which limits the in-depth study of the molecular mechanism of Astragalus polysaccharides in vivo. "Polysaccharide receptor theory" believes that there are one or more oligosaccharide fragment "active centers" in immunologically active polysaccharide molecules. Therefore, the degradation of Astragalus polysaccharides into oligosaccharides and the study of the active centers of polysaccharides at the oligosaccharide level provide new ideas in the study of the structure and mechanism of Astragalus polysaccharides. This article adopts endo-α-1,4-glucanase enzymatic hydrolysis, and determines the best degradation conditions through single factor test and orthogonal test to degrade the immunologically active polysaccharide APS-Ⅱ (10 kDa component) into oligomers with different degrees of polymerization. Then through the preparation of polyacrylamide gel chromatography and specific immune and non-specific immune cell tests, the immune activity screening of different oligosaccharide components is carried out. The animal welfare and the experimental process in this study follow the requirements of the Animal Ethics Committee of Shanxi University. The results showed that compared with the immunologically active polysaccharide APS-Ⅱ, different oligosaccharide components have obvious differences in different immunological activities. This paper studies the different immunological activities of Astragalus polysaccharides at the level of oligosaccharides, laying a foundation for further elucidating the structure and function of Astragalus polysaccharides, enriching the theory of polysaccharide receptors, and providing new ideas for the development of Astragalus polysaccharides.
ABSTRACT
Characterization of the polysaccharides and monosaccharides of Bupleurum chinense was undertaken to identify differences in the Bupleurum chinense's sugar profiles, so as to provide a basis for the identification of different varieties. High performance liquid chromatography (HPLC) was used to generate chromatograms of the total polysaccharides of Bupleurum using an Evaporation Light Detector (ELSD), and a monosaccharide chromatogram was generated using a UV-detector (UV) following polysaccharide derivatization. The data were analyzed using SIMCA software and SPSS software to distinguish different varieties of Bupleurum. The results show that the yield of polysaccharides from Bupleurum falcatum is the highest, while the yield of polysaccharides from Bupleurum chinense is the lowest. The polysaccharide spectrum shows that the molecular weights of the polysaccharides in different Bupleurum differ, and their percentages of the total peak area are also different. The four Bupleurum polysaccharides are composed of mannose, glucuronic acid, rhamnose, galacturonic acid, glucose, galactose, and arabinose, but differ in length. The ratio of glucose to arabinose in Bupleurum chinense, Bupleurum scorzonerifolium, Bupleurum falcatum and Bupleurum marginatum var. stenophyllum is: 3.0-4.0, 5.5-7.0, 12.0-17.0, 9.0-12.0. In this study, a sugar profile technique was developed to provide a new method for the identification of different varieties of Bupleurum.
ABSTRACT
Oligosaccharides play important roles in many biological processes and have great medicinal potential. The structure-activity study of oligosaccharides is complicated by the diversity and complexity of their structures. This review summarizes the state of oligosaccharide structural analysis in recent years. The ionization methods and dissociation rule of acid oligosaccharides, neutral oligosaccharides and glycopeptides in mass spectrometry are discussed and the methods of extraction and purification of oligosaccharides, the suitable mass spectrometry models for different types of oligosaccharides, and the advantages and disadvantages of different mass spectrometry models are introduced. We believe that this review will be helpful for the further investigation of these important biological substances.