title: Studies on the chemical structure and antitumor activity of an exopolysaccharide from Rhizobium sp. N613.
abstract: The molecular structure of the rhizobium exopolysaccharide (REPS) was analyzed by enzymolysis, periodate oxidation, and Smith degradation, and by IR and NMR spectroscopy. The results indicated that REPS was a beta-glucan with a backbone of beta-D-(1-->4)-linked glucose residues and branches of beta-D-(1-->6)-linked glucose residues. The branch was attached to the main chain at the 6-O-position. The molar ratio of 1-->4 and 1-->6 was 2:1. The terminal C3 of the (1-->6)-Glc branch had an O-acetyl group. The molecular weight was estimated to be 35 kDa by Sephadex G-100 column chromatography. The antitumor activity of REPS was evaluated in mice bearing sarcoma 180, hepatoma 22, and Ehrlich ascites carcinoma tumor, respectively. At doses of 10-60 mg/kg, it was observed that tumor formation decreased significantly (P <0.01), but the relative spleen and thymus weight, the phagocytic function of monocytes, lymphocyte proliferation, and serum hemolysis antibody increased significantly (P <0.05). Results of these studies demonstrated that the REPS polysaccharide possessed antitumor activity.
authors.affiliation: Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Shanxi University, Taiyuan 030006, China. liangqi@sxu.edu.cn
authors.forename: Liangqi
authors.initials: L
authors.lastname: Zhao
authors.forename: Yanli
authors.initials: Y
authors.lastname: Chen
authors.forename: Sheng
authors.initials: S
authors.lastname: Ren
authors.forename: Yong
authors.initials: Y
authors.lastname: Han
authors.forename: Hongbing
authors.initials: H
authors.lastname: Cheng
mesh_terms: D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000188:drug therapy*; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy*; D049109:Cell Proliferation / Q000187:drug effects*; D005260:Female; D006461:Hemolysis / Q000187:drug effects; D006968:Hypersensitivity, Delayed; D008114:Liver Neoplasms, Experimental / Q000188:drug therapy*; D008214:Lymphocytes / Q000187:drug effects; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D051379:Mice; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism; D010084:Oxidation-Reduction; D010504:Periodic Acid / Q000737:chemistry; D010587:Phagocytosis; D011134:Polysaccharides / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D012231:Rhizobium / Q000737:chemistry*; D012510:Sarcoma 180 / Q000188:drug therapy*; D013154:Spleen / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D011134:Polysaccharides; D010504:Periodic Acid; C009288:metaperiodate