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Structural characterization and inhibition on α-d-glucosidase activity of non-starch polysaccharides from Fagopyrum tartaricum

Wang, Xiao-Ting, Zhu, Zhen-Yuan, Zhao, Liang, Sun, Hui-Qing, Meng, Meng, Zhang, Jin-Yu, Zhang, Yong-min
Carbohydrate polymers 2016 v.153 pp. 679-685
Fagopyrum, acarbose, arabinose, chemical composition, galactose, gas chromatography, glucose, methylation, molecular weight, nuclear magnetic resonance spectroscopy, polysaccharides, xylose
In the present study, the crude polysaccharide was extracted from Fagopyrum tartaricum and purified by Sephadex G-25 and G-75 column to produce a polysaccharide fraction termed TBP-II. Its average molecular weight was 26kDa. The structural characterization of TBP-II was investigated by gas chromatography, periodate oxidation-Smith degradation, Methylation and NMR. Congo red was applied to explore its advanced structures. The results revealed that chemical composition and structural characteristic of TBP-II was mainly consisted of galactose, arabinose, xylose and glucose with a molar ratio of 0.7:1:6.3:74.2. The backbone of TBP-II was composed of (1→4)-linked α-d-glucopyranosyl (Glcp), while the branches comprised of (1→3)-linked α-d-glucopyranosyl (Glcp), (1→6)-linked α-d-galactopyranosyl (Galp) and (1→2,4)-linked α-d-rhamnopyranosyl (Rhap). The structure of TBP-II was 1,3 and 1,6-branched-galactorhamnoglucan that had a linear backbone of (1→4)-linked α-d-glucopyranose (Glcp). Using Congo red assay showed that it was absent of triple helix structure. The α-d-glucosidase inhibitory activity of TBP-II was determined using acarbose as positive control. The result showed that the inhibition rate depended on the concentration of polysaccharides.