Structural Analysis and Immunoenhancing Activity of Polysaccharides Derived From <i>Imperatae rhizoma</i>

In order to enhance the high-value utilization of Imperata cylindrica (L.) P. Beauv. and help control its ecological impact as an invasive species, Imperatae rhizoma polysaccharide (IRcp-2) was successfully extracted from the roots of Imperata cylindrica (L.) P. Beauv. The total sugar and protein contents of IRcp-2 were 91.36% and 1.50%, respectively. Its monosaccharide composition was predominantly galactose, arabinose, xylose, and glucose, with a molar ratio of 44.8:34.4:13.8:7.0. Its average molecular weight was 29 964 Da. Methylation combined with nuclear magnetic resonance analysis showed that IRcp-2 mainly included 1,3,6-β-Galp, 1-β-Araf, and a small amount of 1-β-Galp, 1,3-β-Galp, 1,4-β-Galp, 1,6-β-Galp, 1-β-Glcp, 1,2-β-Glcp, 1,3-β-Glcp, 1,4-β-Glcp, 1,3,4-β-Glcp, 1,6-β-Glcp, 1,2,5-β-Araf, 1,5-β-Araf, 1-α-Xylp, 1,2-α-Xylp, and 1,4-α-Xylp. Cell experiments demonstrated that IRcp-2 at concentrations of 5-200 µg/mL significantly promoted the proliferation of macrophages and increased the production of tumor necrosis factor-α and nitric oxide in macrophages, suggesting that IRcp-2 may possess immunoenhancing effects.