Isolation, Purification, Characterization, and Immunomodulatory Activity Analysis of α-Glucans from Spirulina platensis

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-alpha-D-Glcp as the main chain, and C-6 replaced the single alpha-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.

Automated summary

Crude polysaccharides from Spirulina platensis were isolated and fractionated into two purified fractions PSP-1 and PSP-2, which were found to be branching dextran composed mainly of glucose. These glucans can enhance macrophages' phagocytic ability, iNOS activity, NO production, and IL-6 mRNA expression, indicating potential immunomodulatory activity.