Structural characteristics of polysaccharides extracted from Cladophora glomerata Kützing affecting nitric oxide releasing capacity of RAW 264.7 cells

•Sulfated polysaccharide (F1) was purified from Cladophora glomerata Kützing.•The effect of structure of NF1 were investigated on the immunomodulating activity.•NF1 was not able to stimulate the RAW264.7 cells without sulfate group.•Oversulfation of NF1 slightly increased NO releasing capacity.

The effect of molecular structures of sulfated polysaccharide (NF1) isolated from Cladophora glomerata Kützing on the NO releasing capacity was investigated. It was possible to obtain the NF1 derivatives having various amounts of proteins (2.55-8.50%) and sulfates (6.88-13.1%) as well as different Mw (141-610 × 103 g/mol), which enabled to investigate the effects of various proteins, sulfates and Mw of NF1 on the NO releasing capacity from RAW 264.7 cells. The activity was lost after desulfation of the polysaccharides and moreover slightly increased NO releasing capacity after oversulfation of NF1 polysaccharides with the degree of sulfation (DS, 3.70). Suggesting that the sulfate groups were essential to activate NF1 polysaccharides are key factors to regulate the immunomodulatory activities.

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