Chemical Modification of Botryosphaeran: Structural Characterization and Anticoagulant Activity of a Water-Soluble Sulfonated (1 -> 3)(1 -> 6)-beta-D-Glucan

Abstract

The exopolysaccharide botryosphaeran (EPS(GLC); a (1 -> 3)(1 -> 6)-beta-D-glucan from Botryosphaeria rhodina MAMB-05) was sulfonated to produce a water-soluble fraction (EPS(GLC)-S) using pyridine and chlorosulfonic acid in formamid. This procedure was then repeated twice to produce another fraction (EPS(GLC)-RS) with a higher degree of substitution (DS, 1.64). The purity of each botryosphaeran sample (unsulfonated and sulfonated) was assessed by gel filtration chromatography (Sepharose CL-4B), where each polysaccharide was eluted as a single symmetrical peak. The structures of the sulfonated and re-sulfonated botryosphaerans were investigated using ultraviolet-visible (UV-Vis), Fourier-transform infrared (FT-IR), and (13)C nuclear magnetic resonance ((13)C NMR) spectroscopies. EPS(GLC) and EPS(GLC)-RS were also assayed for anticoagulation activity, and EPS(GLC)-RS was identified as an anticoagulant.