Structural characterization of a bioactive water-soluble heteropolysaccharide from Nostoc sphaeroids kutz

A water soluble Nostoc sphaeroids kutz polysaccharide (NSKP) was extracted and purified by precipitating hot-water extract from Nostoc sphaeroids kutz with 40% (v/v) ethanol. The yield was 40.10% (w/w), and weight average molecular weight (M-w) was determined as 1.31x10(5) g/mol. Cell culture study showed that NSKP could stimulate the NO release from RAW264.7 macrophages. The. value (R-g/R-h) of NSKP was calculated as 1.50, indicating flexible random coils conformation of NSKP in aqueous solution. According to methylation analysis, and 1D & 2D NMR spectra, the molecular structure of polysaccharide NSKP was deduced as below: [GRAPHICS] .