The structural characteristics of a pectic polysaccharide from Choerospondias axillaris fruit and its immunomodulatory effect on cyclophosphamide-induced immunosuppressed mice

This study aimed to elucidate the structure of a polysaccharide from Choerospondias axillaris fruit (CAP) and to evaluate the immunomodulatory effect against cyclophosphamide (CTX)-induced immunosuppression mice. The solution of CAP exhibited non-Newtonian pseudoplastic fluid behavior. The backbone of CAP was defined as →2)- α -L-Rha p -(1 → 4)- α -D-Gal p A-(1 → 4)- α -D-Gal p A-(1 → [4)- α -D-Gal p A-(1] 5 →, with side chains attached at the O -4 and O -3 positions, demonstrating that CAP is a pectic polysaccharide with partial methyl esterification. Administration of CAP improved immune organ indices, reduced levels of inflammation cytokines, and diminished oxidative stress of the immunosuppression mice. Furthermore, CAP significantly promoted the expression of intestinal barrier proteins (Claudin-1, Occludin and ZO-1). Additionally, CAP markedly up-regulated the phosphorylation levels of ERK1/2, p38, IκBα and p65 in the colon tissue, suggesting that CAP might alleviate intestinal inflammation by modulating MAPK/NF-κB signaling pathway. Moreover, CAP could restore the abundance of probiotic species ( Lactobacillus and Bacteroides ), while decreasing pathogenic species ( Oscillospira and Helicobacter ). These findings underscore the substantial immunomodulatory potential of CAP.