Characterisation, rheological properties and immunomodulatory efficiency of corn silk polysaccharides

Abstract

Corn silk polysaccharide (CSP) was isolated by heated 80 °C ethanol 70%. The extracted light (83.70 L*) with a yellowish (13.09 b*) reddish (1.98 a*) CSP had an ash content of 2.53 ± 0.03%. It is mainly composed of seven monosaccharides (xylose 23.64, glucose 16.65, ribose 17.35, galactose 13.64, rhamnose 11.93, arabinose 11.87 and mannose 4.85 mol%) and showed four peaks in 13C NMR correlated to the anomeric carbon of arabinose and/or xylose residues. The thermal characteristics exhibited the breakdown of CSP glycosidic bonds at 321.16 °C. The rheological properties showed that the raising of share rate (γ) caused a reduction in apparent viscosity for all tested concentrations, whilst the elastic G′ and viscous G″ storage moduli of CSP were enhanced by increasing the oscillation frequency. The immunomodulatory effects of CSP on RAW264.7 cells showed a significant (P < 0.05) increase in NO secretion up to a concentration of 80 μg mL−1 from CSP. Additionally, the phagocytosis index and acid phosphatase activity were enhanced (P < 0.05) in a dose-dependent manner by increasing CSP concentrations.