Extraction, structural characterization, chemical modification and anti-inflammatory activity of polysaccharides from Ceratocarpus arenarius L.

The extraction process for crude polysaccharides from <i>Ceratocarpus arenarius</i> L. was optimized using response surface methodology (RSM). A major polysaccharide fraction with high purity, designated CAP, was isolated from the crude polysaccharides using DEAE-650 M and Sephadex G-75 column chromatography. Its structure was comprehensively characterized using FT-IR, partial acid hydrolysis, peroxide oxidation, Smith degradation, methylation analysis, and NMR analysis. Subsequently, carboxymethylated (CAP-C), acetylated (CAP-A), sulfated (CAP-S), and phosphorylated (CAP-P) derivatives of CAP were prepared. Their structures were characterized using techniques, including HPSEC, GC, UV, FT-IR, Congo red assay, SEM, XRD, and thermal stability analysis. The results of the RSM optimization indicated that the optimal extraction conditions were as follows: time 43 min, ultrasonic power 310 W, liquid-solid ratio 21:1 mL/g, temperature 62 °C. The crude polysaccharide yield obtained under these conditions was 19.09 ± 0.12%. CAP is primarily composed of pyranose rings linked by α-glycosidic bonds. Its backbone primarily consists of →3)-Xyl<i>p</i>-(1→, →3)-Gal<i>p</i>-(1→, Gal<i>p</i>-(1→, and →2,4)-Gal<i>p</i>-(1→ glycosidic bonds, while the terminal residues of the side chains are mainly T-Xyl<i>p</i> and T-Rha<i>p</i>. Structural modification significantly altered the monosaccharide molar ratio, molecular weight, viscosity, solubility, surface morphology, crystalline characteristics, and thermodynamic properties of CAP and its derivatives. Anti-inflammatory activity studies revealed that different modification methods differentially enhanced the polysaccharide bioactivity. However, all derivatives could effectively suppress LPS-induced inflammatory responses by regulating the production of nitric oxide (NO), prostaglandin E2 (PGE₂), interleukin-6 (IL-6), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α). These findings suggest that CAP and its derivatives have potential applications in the functional food and pharmaceutical industries.