Study On The Preparation And Derivatization Of Lentinan

Lentinun edodes is nutrient-rich, abundant.It contains 18 kinds of basic amino acids and all of 8 kinds of amino acids required for human body. Lentinun edodes is a top one in edible fungi.Lentinan is an important nutrient composition in Lentinun edodes.Lentinan has many biological activities, such as anticancer, antitumor, antivirus, and anti-infective. It can also enhance the function of immune system. It has low adverse reaction and toxic and side effect. Sulfated Lentinan has anti-HIV activity.It is important to find specific drugs of AIDS which were seriously threated to human health. And there are relations between the inhibitory effects on HIV and sulfate group contents. As the contents of sulfate group increased, the effects on HIV growed stronger. Without sulfate group, there are no effects on HIV. Now more and more attention has been paid to study on Lentinan.The dissertation was focus on the process of enzymatic extraction of Lentinan. Then Lentinan was purified by DEAE-Sepharose Fast Flow, and morphology was observed by scanning electron microscope. In order to prepare highly immunity active chemical modified polysaccharide, the process of sulfated Lentinan modified by SO3- pyridine complex was studied. It was to replace the widely used chlorosulfonic acid-pyridine method. And the antioxidant activity of lentinan was evaluated. The results show that:1. When Lentinan was extracted by papain, the optimal experimental parameters were pH 9, extraction temperature 60℃, enzyme addition 0.75%, and extraction time 1.5h. And pH is an important factor in the experiment, followed by temperature, enzyme addition and time. When Lentinan was extracted by cellulase, the optimal experimental parameters were pH 7, extraction temperature 40℃, enzyme addition 1.25%, and extraction time 2.5h. And pH is an important factor in the experiment, followed by temperature, time and enzyme addition. The use of papain and cellulose can significantly improve the extraction rate of Lentinan. And the extraction rate of Lentinan extracted by papain is much higher than the extraction rate of Lentinan extracted by the cellulose. The extraction rate of Lentinan extracted by papain is 19.23%, and the extraction rate of Lentinan extracted by the cellulose is 15.21%. They are 3.1, 2.4 times more than the extraction rate of Lentinan extracted by traditional water extraction method, respectively.2. Lentinan was purified by DEAE-Sepharose Fast Flow. Lentinan was eluted with water and different concentrations of NaCl solution. Five pure Lentinan were obtained. The first peak was LNT-Ⅰ, and it was water-phase.The next was LNT-Ⅱ-1 and it was salt-phase. The third to fifth peaks are salt-phase, these peaks were relatively small, therefore it had no more studies.SephadexG-200 atlas illustrated that LNT-Ⅰand LNT-Ⅱ-1 were showed a single symmetrical peak, They are relatively pure components.3. Scanning electron micrographs photographs of Lentinan indicated as follows: Part of LNT-Ⅰwas fibrous. Some may be due to a lot of molecules or molecular groups gathered into bundle of different styles.But another part of LNT-Ⅰwas the irregular geometric shape with holes in the fold structure, and its surface was uneven. It was indicated that there were mutual repulsion between the Lentinan molecules, and intermolecular attraction was relatively weak.Part of LNT-Ⅱ-1 was platelike or clastic accumulation, and its surface morphology was smooth. But another part of LNT-Ⅱ-1 was platelike, and the surface was unevenness. Lentinan can not completely congregate, because of small gap between crystals. It was indicated that there were mutual repulsion between the Lentinan molecules, and intermolecular attraction was relatively weak.4. Study of sulfated Lentinan shows the material ratio is an important factor, followed by the temperature and time. The optimal experimental parameters were material ratio 1:2.5, temperature 95℃, reaction time 2h.5. In this experiment, antioxidant activity of Lentinan was evaluated by vitro experiment. Antioxidant activity of Lentinan was studied by reduction ability and the inhibition effect of Lentinan on lipid peroxidation of yolk protein. With the concentration of Lentinan increased, the reduction ability of Lentinan gradually growed stronger. It showed good dose-effect relationship. Lentinan could inhibit peroxidation of unsaturated fatty acids of yolk proteins, and the effect growed stronger with concentration of Lentinan increased.