Comparison of Extraction, Isolation, Purification, Structural Characterization and Immunomodulatory Activity of Polysaccharides from Two Species of Cistanche

This study focuses on polysaccharides from <i>Cistanche deserticola</i> and <i>Cistanche tubulosa</i>, medicinal plants renowned for their health benefits. The "water extraction and alcohol precipitation" method was used to obtain the crude polysaccharides of the wine-making residues of <i>C. deserticola</i> (CDP) and <i>C. tubulosa</i> (CTP), respectively. Then, ultrafiltration membrane (UFM), DEAE-52, and Sephadex-G75 or Smartdex-G100 gel chromatography were used to separate and purify the crude polysaccharides, yielding the homogeneous fractions <b>CDP1-5-1</b>, <b>CDP2-2-2</b>, <b>CDP2-3-2</b>, <b>CTP1-5-1</b>, and <b>CTP1-5-3</b>. Structural analysis was conducted by using Fourier-transform infrared spectroscopy (FT-IR), high-performance anion-exchange chromatography coupled with multi-angle laser light scattering and refractive index detection (HPAEC-MALLS-RID), gas chromatography-mass spectrometry (GC-MS), nuclear magnetic resonance (NMR), congo red, and scanning electron microscopy (SEM). <b>CDP1-5-1</b> was found to be an arabinan, while <b>CDP2-2-2</b> and <b>CDP2-3-2</b> were agavin-like fructans with different molecular weights. <b>CTP1-5-1</b> and <b>CTP1-5-3</b> were identified as a heteropolysaccharide and a galacturonan, respectively. Immunological evaluation using RAW264.7 macrophages showed that they all significantly enhanced nitric oxide (NO) production, with <b>CDP1-5-1</b> exhibiting the most potent activity. The structural-activity relationship is summarized as follows: the arabinose was a key active unit with NO stimulatory effects. This research provides foundational data on the structure and immune-enhancing potential of <i>Cistanche</i> polysaccharides, supporting their further development and application.