Polysaccharides from Pleurotus eryngii: sequential extraction and structural characterization

Polysaccharides, a primary component from <i>Pleurotus eryngii</i> (<i>P. eryngii</i>), have diverse biological activities. To systematically investigate structural features of these polysaccharides, we have developed a sequential extraction strategy with gradient-enhanced solvent-oriented purification that includes cold and hot water, enzymes assisted, dilute and concentrated alkali. Five polysaccharides CWP (0.19%), HWP (0.1%), EAP (0.14%), DAP (0.65%), CAP (0.34%) were obtained. The sequential extraction strategy developed here is practical, significantly improving the total extraction yield compared to single methods. After purification, we obtained eight homogeneous polysaccharides. Using several characterization techniques, we discovered that <i>P. eryngii</i> polysaccharides contained five structural types, including β-1,3-D-glucan, β-1,6-D-glucan, α-1,6-D-galactan, α-1,3-D-mannan, and a novel polysaccharide α-1,2-D-mannan, with ratios of 20:7:4.3:1.6:1. This study provides valuable insights into the structural diversity and relative abundance of polysaccharides in <i>P. eryngii</i>. Our findings provide a foundation for further investigation into their structure-activity relationships and potential applications.