title: Physicochemical properties, immunomodulation and antitumor activities of polysaccharide from Pavlova viridis.
abstract: OBJECTIVE
  Polysaccharides synthesized by microalgae can be used as the functional ingredients of food or drugs. Here, we investigated the physicochemical properties and bioactivities of the polysaccharide from microalgae Pavlova viridis, and indicated the structure-activity relationship.
  
  
  METHODS
  The polysaccharides (PPS0) were degraded with H2O2-vitamin C assisted by ultrasonic waves. The functional group content, monosaccharide composition, and average molecular weight (avg-MW) were detected by chemical or chromatographic method. The immunomodulatory activities were evaluated in vitro by detecting nitric oxide (NO) emission, neutral red uptake and macrophage proliferation. Antitumor activities of degraded fragments were detected using S180-tumor-bearing mouse model by intragastric administration.
  
  
  RESULTS
  Degraded polysaccharides PPS1 and PPS2 were obtained at avg-MW of 386.96 and 54.99 kDa. The sulfate group content of polysaccharide was 16%, and the uronic acid content was 5.88 and 8.48%. PPS mainly consisted of fructose, glucose and mannose. All the degraded PPSs could increase phagocytosis and proliferation of macrophages, and stimulated NO emission in a dose-dependently way. PPS2 in Low-MW fragments had the strongest immunoenhancing activities. Different doses of PPS all could inhibit the growth of implanted S180 tumor. At dose of 200 mg/kg/day, the tumor inhibition rate of PPS2 was 57.06%, about 23.6% less than that of CTX-treated group. Different-MW PPS significantly increased lymphocyte proliferation. At 200 mg/L, the proliferation index of PPS2 was 1.37, 2.03 times higher than that of CTX-treated group.
  
  
  CONCLUSIONS
  The polysaccharides of Pavlova viridis had potential antitumor activities by improving immune response. Moreover, the bioactivities depend on their molecular weight.
authors.affiliation: Department of Biological Engineering, College of Life Sciences, Yantai University, Shandong 264005, PR China. Electronic address: sliqin2005@163.com.
authors.forename: Liqin
authors.initials: L
authors.lastname: Sun
authors.affiliation: Department of Biological Engineering, College of Life Sciences, Yantai University, Shandong 264005, PR China.
authors.forename: Jinling
authors.initials: J
authors.lastname: Chu
authors.affiliation: Department of Biological Engineering, College of Life Sciences, Yantai University, Shandong 264005, PR China.
authors.forename: Zhongliang
authors.initials: Z
authors.lastname: Sun
authors.affiliation: Department of Biological Engineering, College of Life Sciences, Yantai University, Shandong 264005, PR China.
authors.forename: Lihong
authors.initials: L
authors.lastname: Chen
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects; D058087:Haptophyta / Q000737:chemistry*; D006801:Humans; D007155:Immunologic Factors / Q000494:pharmacology*; D008214:Lymphocytes / Q000187:drug effects; D008264:Macrophages / Q000187:drug effects; D051379:Mice; D008970:Molecular Weight; D009569:Nitric Oxide / Q000378:metabolism; D009929:Organ Size / Q000187:drug effects; D010587:Phagocytosis / Q000187:drug effects; D011134:Polysaccharides / Q000737:chemistry / Q000494:pharmacology*; D000067996:RAW 264.7 Cells / Q000187:drug effects / Q000378:metabolism; D012510:Sarcoma 180 / Q000188:drug therapy; D013431:Sulfates / Q000737:chemistry
chemical_list: D000970:Antineoplastic Agents; D007155:Immunologic Factors; D011134:Polysaccharides; D013431:Sulfates; D009569:Nitric Oxide
keywords: Bioactivities; Degradation; Molecular weight; Pavlova viridis; Polysaccharide