Structural characterization and anti-inflammatory activity of a novel neutral polysaccharide isolated from Smilax glabra Roxb.

Crude polysaccharides isolated from Smilax glabra were screened for anti-inflammatory activity using mice ear swelling animal experiments, during which the neutral polysaccharide S1 was identified. The structural characteristics and anti-inflammatory effects of the anti-inflammatory S1 polysaccharide were then investigated. The results showed that S1 was mainly composed of rhamnose, arabinose, galactose, glucose, xylose, and mannose. The structure of the main chain consisted of →6)-α-Galp-(1 → 6)-β-Galp-(1 → 4)-α-Xylp-(1 → 6)-β-Galp-(1→, with branched chains comprising α-Araf-(1 → 4)-α → Manp-(1 → and β-Rhap-(1 → 4)-α-Glcp-(1 → units. Furthermore, S1 did not have a triple helix conformation. S1 could inhibit NO secretion, reduce the levels of pro-inflammatory factors (IL-6 and TNF-α), and significantly reduce LPS-stimulated inflammatory damage in RAW 264.7 cells by inhibiting activation of the NF-κB (p65) pathway. These results shed light on the possibility of S1 to be developed as a novel anti-inflammatory drug for therapeutic purposes.