Crude polysaccharides from Spirulina platensis (SP) were isolated by maceration with a hot alkali solution and further fractionated by DEAE-52 cellulose and Sephadex G-100 chromatography into two purified fractions PSP-1 and PSP-2. The monosaccharide composition analysis indicated that SP was mainly composed of rhamnose and glucose, while PSP-1 and PSP-2 were composed only of glucose. The composition analysis of PSP-1 and PSP-2 by HPLC, FT-IR, and NMR showed that PSP-1 and PSP-2 were branching dextran, and their structures were (1 → 4)-linked-α-D-Glcp as the main chain, and C-6 replaced the single α-D-Glcp as the linear structure of the branch chain. The glucans (SP/PSP-1/PSP-2) can significantly improve the phagocytic ability of macrophages, enhance iNOS activity, promote NO production, and increase IL-6 mRNA expression, so they may possess certain immunomodulatory activity.

Polyphenol-rich foods exhibit anti-allergic/-inflammatory properties. As major effector cells of allergies, mast cells undergo degranulation after activation and then initiate inflammatory responses. Key immune phenomena could be regulated by the production and metabolism of lipid mediators by mast cells. Here, we analyzed the antiallergic activities of two representative dietary polyphenols, curcumin and epigallocatechin gallate (EGCG), and traced their effects on cellular lipidome rewiring in the progression of degranulation. Both curcumin and EGCG significantly inhibited degranulation as they suppressed the release of β-hexosaminidase, interleukin-4, and tumor necrosis factor-α from the IgE/antigen-stimulated mast cell model. A comprehensive lipidomics study involving 957 identified lipid species revealed that although the lipidome remodeling patterns (lipid response and composition) of curcumin intervention were considerably similar to those of EGCG, lipid metabolism was more potently disturbed by curcumin. Seventy-eight percent of significant differential lipids upon IgE/antigen stimulation could be regulated by curcumin/EGCG. LPC-O 22:0 was defined as a potential biomarker for its sensitivity to IgE/antigen stimulation and curcumin/EGCG intervention. The key changes in diacylglycerols, fatty acids, and bismonoacylglycerophosphates provided clues that cell signaling disturbances could be associated with curcumin/EGCG intervention. Our work supplies a novel perspective for understanding curcumin/EGCG involvement in antianaphylaxis and helps guide future attempts to use dietary polyphenols.