title: Structure and antioxidant activities of sulfated guar gum: homogeneous reaction using DMAP/DCC catalyst.
abstract: It was essential to understand the chemical structure of polysaccharides for further research and biochemical or medical application of this natural biopolymer. In the present study, sulfated derivatives of guar gum with high degree of sulfation (DS) were synthesized using 4-dimethylaminopyridine (DMAP)/dimethylcyclohexylcarbodiimide (DCC) as catalyst in homogeneous conditions. The effects of the ratio of chlorosulfuric acid to pyridine, the content of catalyst and reaction temperature were investigated. Results of FT-IR, (1)H and (13)C NMR indicated that C-6 substitution was predominant in sulfated polysaccharide. In the sulfation reaction, a sharp decrease in M(W) was observed. The enhanced antioxidant activities of sulfated polysaccharides were not a function of a single factor but a combination of high DS and low molecule weight.
authors.affiliation: Bioactive Products Engineering Research Center For Gansu Distinctive Plants, Northwest Normal University, Lanzhou, China. nuno-vai@163.com
authors.forename: Junlong
authors.initials: J
authors.lastname: Wang
authors.forename: Baotang
authors.initials: B
authors.lastname: Zhao
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Wang
authors.forename: Jian
authors.initials: J
authors.lastname: Yao
authors.forename: Ji
authors.initials: J
authors.lastname: Zhang
mesh_terms: D015761:4-Aminopyridine / Q000031:analogs & derivatives / Q000737:chemistry; D000975:Antioxidants / Q000494:pharmacology*; D002384:Catalysis; D005685:Galactans / Q000737:chemistry* / Q000494:pharmacology*; D008351:Mannans / Q000737:chemistry* / Q000494:pharmacology*; D008970:Molecular Weight; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction / Q000187:drug effects; D053149:Plant Gums / Q000737:chemistry* / Q000494:pharmacology*; D017550:Spectroscopy, Fourier Transform Infrared; D013431:Sulfates / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D005685:Galactans; D008351:Mannans; D053149:Plant Gums; D013431:Sulfates; D015761:4-Aminopyridine; C007894:guar gum; C003885:4-dimethylaminopyridine