Structural elucidation of an Astragalus acidic polysaccharide and its anti-colon cancer activity through modulation of JNK/MAPK and NLRP3/IL-1β signaling pathways

Astragalus polysaccharide, a bioactive substance with significant immunomodulatory functions, has not yet had its specific configuration–function relationship fully elucidated. In the present study, four Astragalus polysaccharide fractions with different polarities were successfully obtained through DE52 anion exchange column separation technology, and their pharmacological activities were screened. Homogeneous Astragalus polysaccharide was isolated and purified using DE52 polarity separation columns and gel column purification techniques. The types of glycosidic bonds in Astragalus polysaccharide were identified through monosaccharide composition analysis, infrared spectroscopy, molecular weight determination, and polysaccharide methylation analysis. The probable disaccharide repeating unit structure of AMPS-0.2A polysaccharide was determined to be α-(1,2)-l-Rha-α-(1,4)-d-GalA. Astragalus polysaccharide was found to induce the polarization of macrophages from the M2 phenotype to the M1 phenotype. This effect was primarily mediated through the regulation of the JNK/MAPK signaling pathway and the NLRP3/IL-1β signaling pathway, thereby promoting the polarization of M1 macrophages.