title: Synthesis and characterization of phosphorylated galactomannan: the effect of DS on solution conformation and antioxidant activities.
abstract: Phosphorylated derivatives of galactomannan from guar gum (GG) with the degree of substitution (DS) of 0.35-0.52 were synthesized using POCl3/pyridine. FT-IR, (13)C NMR and XPS results revealed that phosphorylation had occurred and C-6 substitution was predominant in phosphorylated guar gum (PGG). PGG showed an increase in Mw and more broad molar mass distribution in size exclusion chromatography (SEC) analysis. Higher reaction temperature (above 60 °C) resulted in a higher MW value in PGG. It might be due to the cross-linking of polysaccharide chains by POCl3 via di-ester which was also supported by monosaccharide composition result. Results of M(W) - (S(2))(z)(1/2) showed a decrease in fractal dimension (df) values. DS had greater influence on its conformation in aqueous solution. The introduction of -PO3H2 groups improved significantly the stiffness of the chains due to the electrostatic effect. Furthermore, antioxidant experiments revealed that high DS could enhance the scavenging activities of radicals of PGG in vitro.
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, People's Republic of China; Bioactive Products Engineering Research Center for Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, People's Republic of China. Electronic address: nuno-vai@163.com.
authors.forename: Junlong
authors.initials: J
authors.lastname: Wang
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, People's Republic of China; Bioactive Products Engineering Research Center for Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, People's Republic of China.
authors.forename: Ting
authors.initials: T
authors.lastname: Yang
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, People's Republic of China; Bioactive Products Engineering Research Center for Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, People's Republic of China.
authors.forename: Jia
authors.initials: J
authors.lastname: Tian
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, People's Republic of China; Bioactive Products Engineering Research Center for Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, People's Republic of China.
authors.forename: Tao
authors.initials: T
authors.lastname: Zeng
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, People's Republic of China; Bioactive Products Engineering Research Center for Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, People's Republic of China.
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Wang
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, People's Republic of China; Bioactive Products Engineering Research Center for Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, People's Republic of China.
authors.forename: Jian
authors.initials: J
authors.lastname: Yao
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, People's Republic of China; Bioactive Products Engineering Research Center for Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, People's Republic of China; Key Laboratory of Eco-Environment-Related Polymer Materials Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, People's Republic of China.
authors.forename: Ji
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Eco-Environment-Related Polymer Materials Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, People's Republic of China.
authors.forename: Ziqiang
authors.initials: Z
authors.lastname: Lei
mesh_terms: D000975:Antioxidants / Q000138:chemical synthesis* / Q000378:metabolism; D005690:Galactose / Q000031:analogs & derivatives; D008351:Mannans / Q000138:chemical synthesis* / Q000378:metabolism; D008968:Molecular Conformation; D010766:Phosphorylation / Q000502:physiology; D012996:Solutions / Q000138:chemical synthesis / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods
chemical_list: D000975:Antioxidants; D008351:Mannans; D012996:Solutions; C012990:galactomannan; D005690:Galactose
keywords: Antioxidant activities; Galactomannan; Guar gum; Phosphorylation; Solution conformation