Structural characterization and immunomodulatory activity of a polysaccharide from Salvia miltiorrhiza and its sulfated derivative

A polysaccharide (PSMP2) was isolated from Salvia miltiorrhiza, and its sulfated derivative (PSMP2-S) was synthesized. The chemical structures of PSMP2 and PSMP2-S were analyzed by various chemical analysis methods and instrumental analysis methods. The ultrastructures and thermal stability were further investigated. In addition, PSMP2 and PSMP2-S had strong immunomodulatory activity and could regulate cytokines (interleukin-2, interleukin-6 and tumor necrosis factor-α), increased the content of short chain fatty acids and effectively reduced the relative abundance of Bacteroides and increased the relative abundance of Firmicutes, significantly increase Muribaculaceae and Lactobacillaceae, and inhibit Lachnospiraceae and Ruminococcaceae, improve the composition of gut microbiota. This study showed that PSMP2 and PSMP2-S might be used as potential natural immune regulators and gut microbiota regulators, and had great development value in the field of food and medicine.