Structural characterization of a purified polysaccharide from Chrysanthemum vestitum and its effects on acute lung injury in mice

Abstract

Background

Chrysanthemum vestitum, a perennial plant in the Compositae family and closely related to Chrysanthemum morifolium, has long been used as both food and medicine. To explore the structural characteristics and potential anti-inflammatory mechanisms of polysaccharides derived from C. vestitum, a homogeneous polysaccharide, CVP_C, was isolated from C. vestitum using hot water extraction and alcohol precipitation. The crude extract was then purified via DEAE-52 cellulose chromatography and gel filtration system. Structural characterization of CVP_C was performed by Fourier-transform infrared (FT-IR) spectroscopy, molecular weight determination, scanning electron microscopy (SEM), monosaccharide composition analysis, thermogravimetric analysis (TGA), nuclear magnetic resonance (NMR) spectroscopy, and methylation analysis. An LPS-induced ALI mouse model was established to assess the protective effects of CVP_C. Inflammatory cytokine levels (IL-6 and TNF-α) in lung tissues and bronchoalveolar lavage fluid (BALF) were quantified, and histopathological changes were evaluated. In addition, gut microbiota profiling was employed to study the underlying mechanisms.

Results

Structural analysis revealed that CVP_C is a xylan-type polysaccharide and has a molecular weight of 25.049 kDa. It is primarily composed of mannose (Man), galactose (Gal), glucosamine (GlcN), glucose (Glc), glucuronic acid (GlcA), xylose (Xyl), rhamnose (Rha), and arabinose (Ara). The backbone structure consisted of → 4)-β-D-Xylp-(1 → residues. In vivo, CVP_C significantly reduced total protein content in BALF and suppressed the expression levels of TNF-α and IL-6 in both BALF and lung tissues, effectively attenuating pulmonary inflammation in the murine model. Histopathological examination and lung injury score further demonstrated inhibition of inflammatory cell infiltration and alleviation of lung tissue injury following CVP_C treatment. Gut microbiota analysis revealed that CVP_C reversed LPS-induced dysbiosis by increasing the relative abundance of Firmicutes while decreasing that of Bacteroidota, thereby ameliorating ALI.

Conclusions

CVP_C is a novel acidic xylan polysaccharide that protects against ALI by reducing pro-inflammatory cytokine secretion and inhibiting inflammatory cell infiltration. Its therapeutic mechanism is likely linked to modulation of gut microbiota composition, promoting beneficial bacteria and suppressing pathogenic taxa. These findings indicate that CVP_C has potential for use as a natural anti-inflammatory agent and functional food ingredient for the promotion of respiratory and gastrointestinal health.

Graphical Abstract