Regioselective sulfation of Artemisia sphaerocephala polysaccharide: Solution conformation and antioxidant activities in vitro

•Regioselective sulfation of Artemisia sphaerocephala polysaccharides was studied.•The current studies were focused on characterization of solution conformation.•The conformational transition and stiffness of the chains after sulfation was observed.•Substitution position could influence antioxidant...

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Bibliographic Details
Published in:Carbohydrate polymers 2016-01, Vol.136, p.527-536
Main Authors: Wang, Junlong, Yang, Wen, Tang, YinYing, Xu, Qing, Huang, Shengli, Yao, Jian, Zhang, Ji, Lei, Ziqiang
Format: Article
Language:English
Subjects:
Antioxidant activity
Antioxidants - chemistry
Artemisia - chemistry
Artemisia sphaerocephala
Carbohydrate Conformation
Oxidation-Reduction
Polysaccharides - chemistry
Regioselective synthesis
Solution conformation
Sulfated polysaccharide
Sulfates - chemistry
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Summary:•Regioselective sulfation of Artemisia sphaerocephala polysaccharides was studied.•The current studies were focused on characterization of solution conformation.•The conformational transition and stiffness of the chains after sulfation was observed.•Substitution position could influence antioxidant activities of sulfated polysaccharides. Regioselective modification is an effective approach to synthesize polysaccharides with different structure features and improved properties. In this study, regioselective sulfation of Artemisia sphaerocephala polysaccharide (SRSASP) was prepared by using triphenylchloromethane (TrCl) as protecting precursor. The decrease in fractal dimension (df) values (1.56–2.04) of SRSASP was observed in size-exclusion chromatography combined with multi angle laser light scattering (SEC-MALLS) analysis. Compared to sample substituted at C-6, SRSASP showed a more expanded conformation of random coil, which was attributed to the breakup of hydrogen bonds and elastic contributions. Circular dichroism (CD), methylene blue (MB) and congo red (CR) spectrophotometric method and atomic force microscopy (AFM) results confirmed the conformational transition and stiffness of the chains after sulfation. SRSASP exhibited enhanced antioxidant activities in the DPPH, superoxide and hydroxyl radical scavenging assay. Sulfation at C-2 or C-3 was favorable for the chelation which might prevent the generation of hydroxyl radicals. It concluded that the degree of substitution and substitution position were the factors influencing biological activities of sulfated polysaccharides.
ISSN:0144-8617
1879-1344
DOI:10.1016/j.carbpol.2015.09.073