Structural and Biochemical Characterization of a Polysaccharide Isolated From Vaccinium uliginosum L

A novel polysaccharide (VUP-1) from Vaccinium uliginosum L. fruits is isolated using polyamide resin and Sephadex G-100 column chromatography. VUP-1 is a heteropolysaccharide, which is composed of mannose, galacturonic acid, galactose, glucose, and arabinose at a molar ratio of 1.00:3.35:7.99:8.38:11.89 with a molecular weight of 4.98 x 10(4) kDa. The glycosyl linkages of (1 -> 5)-alpha-L-Arabinose, (1 -> 4)-beta-D-Galactose, (1 -> 6)-alpha-D-Galactose, (1 -> 6)-alpha-D-Glucose, and (1 -> 4)-beta-D-Mannose are confirmed by nuclear magnetic resonance. Based on scanning electron microscopy and Congo red assays, VUP-1 shows flake-like structures, but no triple helix structure. VUP-1 presents high antioxidant activities (DPPH center dot, OH center dot, and reducing power) and moderate alpha-amylase inhibitory activity. Scavenging rate of VUP-1 on DPPH center dot and OH center dot are 93.86 +/- 0.59% and 48.58 +/- 0.64%, respectively. Reducing power of VUP-1 reached 1.14 +/- 0.05. Inhibition rate of alpha-amylase is 37.23 +/- 0.45% when VUP-1 concentration is 4.0 mg mL(-1). In addition, VUP-1 shows obvious inhibitory activities on the formation of dicarbonyl compounds (42.10 +/- 0.61%) and improved glycation end products (45.93 +/- 1.27%) compared to that of Amadori products (29.91 +/- 0.78%). This study concludes that polysaccharides from Vaccinium uliginosum L. have potential to be used as oral hypoglycemic agents.