A glucose-containing polysaccharide from Lycii fructus: Structural characterization and immunomodulatory activities in vitro and in vivo.

The present work describes the isolation procedure and structural characterization of LFP-5, an immunomodulatory glucose-containing polysaccharide purified from Lycii fructus. Structural analysis revealed that LFP-5 consists of Rha:Ara:Xyl:Man:Glu:Gal with molar ratios of 2.01:7.32:6.30:10.03:60.14:14.21, and its primary structure consists of repeating units of 1,6-α-D-Glcp with multiple branching points in the branched chains at 1,4,6-α-D-Glcp,1,4,6-β-D-Manp, and 1,3,6-β-D-Galp. In vitro immunological assays revealed that LFP-5 stimulated the production of NO, IL-6, and TNF-α in RAW264.7 cells, an effect found to be mediated by the MAPK signaling pathway. LFP-5 counteracted the splenic functional impairment caused by cyclophosphamide in vivo, and its regulation of immune function in mice was linked to a favorable remodeling of the gut microbiota, evidenced by an increase in probiotics like Akkermansia muciniphila, Lactobacillus reuteri, and, L. intestinalis, and a decrease in harmful genera such as Alistipes and Desulfovibrio fairfieldensis. Collectively, these findings elucidate the structural basis and multifaceted immunomodulatory mechanisms of LFP-5, contributing to the understanding of bioactive polysaccharides from Lycii fructus.