| Botanical polysaccharides derived from many plant species are a class of natural substances which exhibit diverse biological activities. Experimental and clinical studies have demonstrated that plant-derived polysaccharides exhibit a number of beneficial therapeutic properties, including immunostimulatory, anti-tumor, anti-inflammation, anti-viral, radioprotective, reducing the hypoglycemia and so on. Thus botanical polysaccharides play an important role in the organism, and it is the research hot sport of many subjects.It has been recognized that plant polysaccharides affect the immune system through many pathways. They can activate T lymphocytes and B lymphocytes, macrophage, NK cells. They can also activate complement system and stimulate the release of cytokines. Macrophage is a kind of most important member of immune system. Macrophages can function as antigen presenting cells and interact with T lymphocytes to modulate the adaptive immunity. The effects of botanical polysaccharides on the immune system are thought to be due to the modulation of innate immunity, especially, macrophage function. The primary effect of botanical polysaccharides is to enhance and/or activate macrophage immune responses, including increasing reactive oxygen species (ROS) production, and enhancing secretion of cytokines and chemokines.Asparagus officinalis.L is recognized as a traditional medical plant for its broad pharmacological activities. There are some chemical components in Asparagus officinalis.L which has many functions of anti-tumour, reducing blood fat, immunomodulatory, fighting against senium and so on. Polysaccharide is an immoportant component of Asparagus officinalis.L. Thus we isolated polysaccharide from Asparagus officinalis.L by means of hot-water extracting. The efficiency of extraction was 8.5%. Protein was removed by Sevage method, enzyme and Sevage method, and TCA respectively. And then we tested the function of it on macrophage cell line RAW264.7. The efficiency of extraction is 1.5%, 2.2%, 3.6% respectively. Three fractions were obtained respectively by the method of ethanol grading and the weight of E60 polysaccharide is 0.426g. Then E60 polysaccharide was purified with column chromatography on cellulose DEAE52, It was divided into two groups, named polysaccharide A, polysaccharide B. Then polysaccharide A was analyzed by infrared spectroscopy and atomic force microscope.By adding different concentration of polysaccharide into cultured macrophage in vitro, the influence of polysaccharide on the synthesis of nitrogen oxide (NO) was observed by Griess method. The results indicated that polysaccharide could significantly increase NO synthesis of macrophage RAW264.7 cultured with polysaccharide, and was in a dose-dependent manner. NO is related to the cytolytic function of macrophage against a variety of pathogens of fungi and bacteria, increased synthesis of NO can induce immunomodulatory activity in macrophages.To evaluate proliferation of macrophages treated by polysaccharide, cell viabilities of macrophages were evaluated by MTT test. The result implies that polysaccharides promote macrophage proliferation, and they did not cause significant cytotoxicity on macrophages.Then RT-PCR was performed to detecte the effects of asparagus polysaccharides on macrophage expression of iNOS gene. The result showed that the amounts of iNOS mRNA increased upon exposure to asparagus polysaccharide, therefore we speculate that asparagus polysaccharides can activate macrophages through the expression of iNOS and stimulate its release of NO. To examine the effects of asparagus polysaccharide on the expression of cytokines, RT-PCR was performed for the mRNAs of TNF-αand IL-6. The results showed that TNF-α, IL-6 transcripts were increased upon exposure to asparagus polysaccharides for 6 hours.
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