Effect of the degree of sulfation on the physicochemical and biological properties of Pleurotus eryngii polysaccharides

Polysaccharides extracted from Pleurotus eryngii were chemically modified by sulfation and the effects on the structural and biological properties of the polysaccharides were investigated as a function of the degree of sulfation. 13C NMR spectroscopy demonstrated that polysaccharides from P. eryngii were mainly composed of β-(1 → 3)-glucans with β-(1 → 6) branches. The structure of the sulfated polysaccharides was confirmed by FT-IR and their degree of substitution (DS) was determined to be 0.12–0.92. When P. eryngii polysaccharides were sulfated they were shown to be effective in inhibiting cancer cell growth in a dose-dependent way. Furthermore, their DPPH radical quenching effects were improved with increasing degree of sulfation. Thus, it seemed that the chemical modification of P. eryngii polysaccharides by sulfation effectively enhanced their potential biological properties.