Structural characterization of chia seed polysaccharides and evaluation of its immunomodulatory and antioxidant activities

This study aims to extract an active heteropolysaccharide Chia seed polysaccharide (CSP-A) and further purified by DEAE Sepharose Fast Flow and Sepharose CL-6B chromatographic column, characterize its structure, and evaluate its antioxidant and immunomodulatory activities. Structural analysis revealed that CSP-A was composed of d-mannose, d-glucuronic acid and d-xylose in a molar ratio of 1:3:4 with molecular weight of 1.688 × 105 Da, owning 4 sugar residues of β-d-Manp-(1→, →4)-α-d-GlcpA-(1→, →2,4)-β-d-Xylp-(1→, and → 4)-β-d-Manp-(1 →. Congo red assay and microscopic characteristics showed that CSP-A in its solution may possess a helical conformation. In vitro experiments showed that CSP-A had moderate DPPH· and OH· scavenging activities. CSP-A also enhanced the phagocytosis ability of RAW 264.7 cells and prompted the release of NO, TNF-α, IL-6 and IL-1β from RAW 264.7 cells, which indicated CSP-A had immune regulation effect. This experiment provides scientific basis for further utilization and development of chia seeds, a kind of functional food.