Purification, Structural Characterization, and Immunomodulatory Activity of Polysaccharides from Cinnamomum cassia

In this manuscript, we report the successful purification of two polysaccharide fractions (F1 and F2) from Cinnamomum cassia (C. cassia). Their chemical composition analysis revealed carbohydrates (54.8–61.1%), sulfates (8.1–9.5%), proteins (4.8–8.0%), and uronic acids (3.7–3.9%), with molecular weights ranging from 46.1 to 2919.1 kDa. Methylation analysis indicated that the highly active F2 fraction possesses a main chain of (1 → 4)-linked glucose, with minor side chains of (1 → 3)- and (1 → 5)-linked arabinose or (1 → 6)-linked glucose, and terminal glucose/arabinose residues. In vitro experiments demonstrated that F2 significantly enhanced nitric oxide and cytokine (TNF-α, IL-1β, IL-6, IL-10) production in RAW264.7 macrophages through activation of NF-κB and MAPK signaling pathways, exhibiting stronger immunomodulatory activity than F1. These results provide evidence that C. cassia polysaccharides, particularly F2, possess promising potential as natural immunostimulants for functional food or therapeutic applications.