Structure Characterization And Activity Studies Of A Novel Polysaccharide Isolated From Ginkgo Biloba

In this thesis, the extraction, isolation, purification and structure analysis of the water-soluble polysaccharides from Ginkgo biloba were extensively studied.The crude polysaccharides of the Ginkgo biloba were extracted by hot water and precipitated by ethanol. The crude polysaccharide was divided into eight fraction GBP50S1, GBP50S2, GBP70S1, GBP70S2, GBP70S3, GBP70S4, GBPBW1 and GBPBS1. The crude polysaccharide purified by ion chromatograph DEAE-Cellulose, and gel permeation chromatograph Sephacryl S-300. The gel permeation Chromatography, UV spectrum and specific rotation proved that the four fractions are homogenous with high purity. The carbohydrate content of the GBP50S2, GBP70S1, GBP70S2 were 94%,95.5%,84.6%. The average Mw of the GBP50S2, GBP70S1, GBP70S2 were 2.30×103 KDa,7.38×103 KDa and 3.54×103 KDa respectively by gel permeation chromatograph. Ion-chromatography detection indicated that GBP50S2 was composed of L-Rhamnose, D-Mannose, D-Galactose in the molar rario of 4.2:1:3.8; GBP70S1 was composed of L-Rhamnose, L-arabinose, D-Galactose, D-Mannose in the molar tario of 2.2:3.4:3.8:1.3; GBP70S2 was composed of L-arabinose, D-glucose, D-xylcose in the molar rario of 1.33:1.05:1.15. Structural features of GBP50S2, GBP70S1, GBP70S2 were investigated by a combination of instrumental and chemical analyses, including methylation analysis, total hydrolysis, partial acid hydrolysis, periodate oxidation and Smith degradation and the instrument analysis including HPAEC-PAD,gas chromatography-mass spectrometry analysis,UV,FT-IR,NMR spectroscopy. The main chain of GBP50S2 was made of (1→3,4)-a-D-Man, and the side chain was composed of (1→4)-α-D-Gal and (1→3,4)-α-D-Man, terminated withβ-L-Rha. The main chain of GBP70S1 was made of (1→5)-α-L-Ara, (1→3,6)-β-D-Gal, (1→3,4)-α-D-Man, and the side chain was composed of (1→5)-α-L-Ara, (1→4)-α-D-Gal, (1→6)-α-D-Gal, terminated withβ-L-Rha. The main chain of GBP70S2 was made of (1→2,5)-α-L-Ara, (1→3)-α-D-Glu, and the side chain was composed ofβ-D-Xyl.