Study On Structure And Antioxidant Activity Of Bupleurum Polysaccharide

Bupleurum was a perennial and herbaceous Umbelliferae. It has many functions, such as antipyretic, antivirus, anti-inflammatory, to improve immune function, to resist damage of the liver et al, so it has the important research and development value.Study on extraction, purification, physicochemical properties, structural analysis and Antioxidant Activity of bupleurum polysaccharide. The experimental results are summarized as follows:1. The bupleurum polysaccharide was extracted by water-extract and ultrasonic method, to obtain WAP and SAP respectively with the extraction rate were 2.35% and 1.73%.Through physical and chemical properties analysis, WAP and SAP contain sugar hyaluronic acid, but does not contain protein, nucleic acid and phenols. SEM figure shows, WAP appeared slice layer structure, and SAP appeared smaller slice layer structure even clastic shape. When to extract bupleurum polysaccharide with ultrasonic extraction, it has degradation of polysaccharides.2. To WAP and SAP on antioxidant activity analysis, the results showed that activity of SAP is higher than WAP in reduction ability, scavenging O2 and inhibiting lipid peroxidation. In clearing DPPH-, WAP and SAP have superior and approximate clearance; In clearing OH, WAP has higher removal ability than SAP. Therefore, on the whole, the antioxidant activity of SAP is higher than WAP.Although this can explain ultrasonic degradation of polysaccharides to a certain extent, it did not affect the activity of polysaccharide. But its activity increased. This may be due to the ultrasonic degradation of polysaccharide, that makes the active groups of structure released in the hidden.3.SAP1-2 and SAP3-1 were isolated by CTAB method and Sephadex G-150 gel column chromatography respectively from bupleurum polysaccharide SAP. Liquid chromatography determine the molecular weight of two polysaccharides.The polysaccharide functional groups were analyzed by fourier transform infrared spectroscopy (FTIR). The monosaccharide composition of polysaccharides was determined by gas chromatography (GC). The structure of polysaccharides was analyzed by environmental scanning electron microscope and atomic force microscopy (AFM). The results showed that,the two polysaccharides are homogeneous. The average molecular weight of SAP1-2 is 3.2x105, and the average molecular weight of SAP3-1 is 3.3xl05D. Both polysaccharides have distinct absorption peaks of polysaccharide, and its monosaccharide residues are the pyran-type; SAP 1-2 is composed of Rhamnose, arabinose, xylose, mannose, glucose and galactose, and the molar ratio of various monosaccharide is 1.96:1.09:2.60:1.00:1.10:1.84. SAP3-1 is composed of Rhamnose, xylose, mannose, glucose and galactose, and the molar ratio of various monosaccharide is 2.07:1.34:1:1.84:1.97. Environmental scanning electron microscopy analysis showed that Bupleurum polysaccharide SAP1-2 show sheet structure of different sizes, smooth surface and uniform distribution. The structure of bupleurum polysaccharide SAP3-1 appear like "mushroom", and its distribution is uniform. Atomic force microscopy analysis showed that, SAP1-2 has a highly branched structure, and the sugar chains form a ring structure through different connections, and the ring structure form network structure through further interaction. SAP3-1 also has a branch structure, and the formation of sugar chains wrapped is like "8" shape of the ring structure.4.From Congo red experiment, part acid hydrolysis, periodate oxidation, Smith degradation and methylation analysis results, it's known that SAP 1-2 does not have the triple helix conformation, it contains rhamnose, xylose, mannose and glucose in side chain of the polysaccharide.Xylose connects by 1→2 glycosidic bonds, and Connects with the main chain by a higher degree of polymerization. Part of the rhamnose connects by 1→6 glycosidic bonds. Glucose, mannose and part of the rhamnose are in non-reducing end; Arabinose and galactose form arabinogalactan in the main chain, in which arabinose links by 1→2,1→3 glycosidic bonds and galactose links by 1→2,1→6 glycosidic. The structure of SAP1-2 is very complex, and One possible structure of repeating units:Glc-(1→2)Xyl Rha-(1→2)Xyl 11↑↑66→1)-Gal-(2→1)Ara-(2→1)Gal-3 1 Rha-(3→1)Man...