Characterization and immunological activity of polysaccharides from Ixeris polycephala

A water-soluble polysaccharide, named KMCP, was isolated and purified from edible plant Ixeris polycephala by using DEAE-52 cellulose chromatography. Its structure was determined by chemical analysis, methylation analysis, and NMR analysis, coupled with characterization by scanning electron spectroscopy (SEM). The resulting data indicated that KMCP was an arabinogalactan, with an average molecular weight of 1.95 × 106 Da, which was mainly composed of arabinose and galactose in a relative molar ratio of 28.1% and 70.3%, respectively. The structure of KMPC was characterized as 72.5% of (1 → 4)-β-Galp residues interspersed with 27.5% of (1 → 4,6)-β-Galp residues in the main chain, and the branches were composed of (1 → 5)-α-Araf moieties or α-Araf (1 → 5) α-Araf (1 → disaccharide moieties attached at O-6 of the (1 → 4,6)-β-Galp residues. KMCP was revealed to be capable of exhibiting macrophage-mediated innate immune responses via enhancing phagocytosis of macrophages and increasing production of NO, activating NF-κB signaling pathway and promoting the mice spleen cells proliferation in a dose-dependent manner within the test concentrations (10.0-200.0 μg/mL). These results suggested that KMCP could potentially be an effective and safe immunomodulator valuable to be utilized in pharmacological fields or in the development of functional foods.