Structural characterization and immunomodulatory activity of polysaccharides from the lateral roots of Aconitum carmichaelii

Two polysaccharides, named FPS1-1 and FPS1-2, were separated from the neutral polysaccharides of the lateral roots of Aconitum carmichaelii, a widely used traditional Chinese medicine (Fuzi in Chinese). The monosaccharide composition analysis indicated that both FPS1-1 and FPS1-2 were glucans. However, further physicochemical analysis of FPS1-1 and FPS1-2 revealed distinct properties between the two glucans. FPS1-1 had a molecular weight (Mw) of 106.23 kDa with a spherical conformation, while FPS1-2 had a lower Mw of 19.23 kDa with a random coil conformation. The structure of FPS1-2 was further determined as a glucan whose backbone structure was composed of-*4)-alpha-D-Glcp-(1-*. The immunological activities of two polysaccharides were evaluated by a cyclophosphamide (CTX)-induced immunodeficiency model in mice. The result showed that FPS1-2 could restore CTX-induced immunosuppression by modulating CD4+ T cells differentiation and promoting cytokine secretion. Notably, FPS1-2 could modulate the colonic short-chain fatty acid (SCFA) levels and reverse the gut microbial dysbiosis induced by CTX. These findings reveal the potential benefits of Fuzi polysaccharides and provide evidences for developing immunologically functional products from Fuzi polysaccharides.