Structural Variation and Microrheological Properties of a Homogeneous Polysaccharide from Wheat Germ

A novel polysaccharide (WGP) was purified from crude wheat germ polysaccharide by Sephacryl S-500HRgel filtration. The molecular weight of WGP was determined as 4.89 × 10⁶ Da and consisted of arabinose, xylose, glucose, and galactose. Methylation analysis and 1D/2D nuclear magnetic resonance was used to analyze the structural characterization of WGP. WGP was mainly a backbone composed of (1 → 4)-linked-β-d-Xylp (19.01%) and (1 → 3, 4)-linked-β-d-Xylp (26.27%) residues, which was branched of (1 → 5)-linked α-l-Araf (28.09%) and (1 → 3,6)-linked β-d-Galp (12.11%) with β-d-Glcp (14.52%) as terminal unit. The calculated values of Turbiscan stability indexes suggested that WGP (0.1-0.5 mg/mL) is a stable system. Microrheology results showed that WGP can form gel behavior when the concentration of WGP ranges from 0.1 to 3 mg/mL. Results of in vitro assays showed that WGP could cause the proliferation of RAW264.7 macrophages, upregulating the release of TNF-α and IL-8 in the lymphocytes.