The Isolation And Identification Of Exopolysaccharide From Marine Fungus Spicaria Elegans

Marine microorganisms are one of the important resources from which many antitumor drugs have been discovered. The secondary metabolites isolated from the fermented liquid of marine-derived fungus Spicaria elegans, which was selected from the sediment samples collected from Chian's Jiaozhou Bay, showed lethal activity to marine shrimp and cytotoxic activity to mammalian tsFT210 cells. The exopolysaccharides (EPS) were observed in the fermented liquid in a large amount. So after purification, chemical structure and bioactivity of EPS were studied in this thesis.Lipids and pigments were removed from the fermented liquid. After concentration the crude exopolysaccharide in supernatant were precipitated with ethanol. Then the crude exopolysaccharides were purified by ultrafiltration and gel permeation chromatography consequently, and EPS was obtained. The molecular weight of EPS was analyzed by the high performance gel permeation chromatography (HPGPC). The result was 88 kD. The primary structure of EPS has been investigated by the thin layer ghromatography (TLC), gas chromatography (GC), infra-red spectrometry (IR), nuclear magnetic resonance spectrometry (NMR), gas chromatography-mass spectrometry (GC/MS), periodate oxidation and Smith degradation. TLC and GC were used to analyse the makeup of EPS. It showed that only mannose was involved in EPS. IR and 1H NMR showed that EPS only contained ofα-Man. The results of GC/MS, periodate oxidation and Smith degradation analysis showed that EPS was a branched molecule which possessed a backbone of 1→2 linked Man and side chains of 1→4 and 1→6 linked Man. Between the side chains and backbone it was 1→6 linking and 1→3 linking, with a few 1→4 linking.