Characterization of a polysaccharide from Polygala tenuifolia willd. with immune activity via activation MAPKs pathway

Polysaccharides from the Polygala tenuifolia Willd. have been shown multiple biological activities, however the structural feature and immunomodulatory activity are still rarely reported. In this study, a polysaccharide was obtained by purification, and its structural characteristics and immune activity were analyzed. The polysaccharide was a homogeneous macromolecular polysaccharide with smooth flat flakes surface structure and molecular weight of 2.34 × 105 Da, and composed of Rha, Ara, Xyl, Man, Glc, Gal. Methylation and NMR analyses confirmed that the repeating unit of polysaccharide was [→3)-α-Araf-(1 → 3)-α-Araf-(1 → 5)-α-Araf-(1 → 5)-α-Araf-(1 → 3)-α-Araf-(1 → ]n, and the side chain was α-Araf-(1 → 6)-β-Galp-(1 → 6)-β-Glcp-(1 → 6)-α-Manp-(1→, which was attached to the C3 of → 3,5)-α-Araf-(1 →. In vitro, the RAW 264.7 cells were co-cultivated with LPS and polysaccharide, and the results revealed that the polysaccharide can promote cell proliferation, activate effectors to release cytokines (TNF-α, IL-6, IL-1β), and then activate macrophages for immune activity. Therefore, we can infer that the polysaccharide might regard as a potential immunomodulator.