Structural determination, immunomodulatory activity, and antitumor activity of a low-molecular-weight polysaccharide extracted from Lepista sordida

In this study, the isolation and purification of Lepista sordida polysaccharides (LS-P) were conducted, followed by an in-depth investigation of structural features and biological functions. The findings demonstrated that the backbone of LS-P comprised (1 → 6)-Glcp, (1 → 4)-D-Galp, (1 → 4)-D-Glcp, (1 → 6)-Galp, and (1 → 4,6)-Glcp, with the side chains primarily composed of terminal →2)-α-D-Glcp. The ratio of glucose to galactose was 8: 5. LS-P's weight-average molecular weight (Mw) was 13,135 Da, and it possessed a pyranose structure. In vitro immunomodulatory activity results demonstrated that LS-P could promote the proliferation of lymphocytes (B-Raji, T-Jurkat) and macrophages (RAW264.7). Additionally, LS-P significantly increased the levels of IL-1β and TNF-α produced by RAW264.7 cells. In vitro antitumor activity results indicate that LS-P could inhibit gastric cancer cell (MFC) proliferation, cause F-actin breakage, and disrupt MFC cells' backbone structure. The key findings of this study demonstrate that LS-P exhibits low molecular weight and excellent water solubility. The (1 → 4)- and (1 → 6)-linked glycosidic bonds were confirmed as the structural basis for LS-P's immunomodulatory and antitumor activities. Based on these characteristics, developing LS-P-based medications or functional foods could enhance the bioavailability and nutritional value of polysaccharides. Overall, these results provide valuable scientific evidence for developing and applying polysaccharide resources from L. sordida.