| Lentinan is paid much more closer attentions due to many kinds of biological activities such as antitumor, antivirus, immune regulation and so on. In this thesis, lentianus edodes is used as raw material, gel permeation chromatogram method was set up to determine the molecular weight and content of lentinan simultaneously, and the technologies of preparation, structural characteristics and bioactivities of lentinan were studied. Several experimental results were given as follows:1. Gel permeation chromatogram (GPC) method was set up to determine the molecular weight and content of lentinan. This method showed a good accuracy, precision, specification and durablibity, the limit of detection and quantitation were 0.468μg and 1.6μg, respectively. There was a good linearity between 3.75μg and 120μg, and the range for determination was 1.6μg~360μg.2. Lentinan was extracted by water as a ratio of 1:20 at 95℃~100℃, for 2h each time and extracted for 3 times in all, and the yield ratios were 15.73%,3.22% and 0.56%,respectively.3. The alcohol precipitation regularity and the distribution of the molecular weight of lentinan gained were studied. The time of ethanol precipitation showed little influence on the yields of lentinan gained by ethanol stepwise precipitation, and the rate of ethanol precipitation were lower and lower as time went by. For step ethanol precipitation, yield of lentinan was highest when the ethanol concentration was 30%(V/V). For sub-grade ethanol precipitation, yields of lentinan were increased with the increase of ethanol volume percentage. Peak molecular weights (Mp) of lentinan were 22,671Da, 18,649Da and 6,011Da when volume concentration of ethanol were 30%, 50% and 80%.4. The methods and the regularity for decoloration of lentinan were investigated. Methods of decolorization with resins and H2O2 were studied, respectively. The most optimal conditions for H2O2 decolorization were the time was 2 hours, the temperature was 55℃, the pH value was 7.0 and the mass fraction of hydrogen peroxide was 8.5%, under this condition, the decoloration efficiency was 76.8%, and the retention percentage of lentinan was 78.4%. Little effect was found on the molecular weight of lentinan by H2O2 at a certain decoloration time.5. Sevage method to remove protein was investigated, the results were V trichlormethane: Vn-butanol = 5:1, Vsevage:Vlentinan solution =0.3:1, it needed 5 times to deproteinize, and under this condition, the deproteiniation efficiency was 54.7%, and the retention percentage of lentinan was 65.3%.6. The technologies of separation and purification of lentinan were studied. The molecular weights of lentinans gained by DEAE-cellulose column chromatography washing off with water, 0.2M NaCl and 0.4M NaCl solution were 33,038Da, 20,261Da and 8,587Da, respectively. The molecular weight of lentinan gained by DEAE-cellulose and then sephadex G-200 column chromatography washing off with water as eluents was 35,064Da. The membrane separation for one time was of higher efficiency only when to gain crude lentinan.7. The structural characteristics of lentinan were researched. The results shown that lentinan did not contain protein, reducing sugar and starch, and was one kind ofβ- glucofuranose. The monosaccharide compositions of lentinan were manmose, glucose and galactose, and their molar ratios were 1:0.633:0.745.8. The bioactivities of lentinan were preliminarily inspected. The chemical oxidation methods demonstrated that all lentinans from different places of production with differernt molecular weights processed the abilities of scavenging DPPH and hydroxy radical. And the MTT tests indicated lentinan with high molecular weight could obviously inhibit proliferation of colon cancer cells. However, lentinan with low molecular weight showed little effect on inhibition.
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