Purification, characterization and bioactivity of an extracellular polysaccharide produced from Phellinus igniarius

An extracellular polysaccharide (EPS) from Phellinus igniarius was purified and characterized and its production investigated. The preferred culture conditions for EPS production were pH 6, temperature 28 degrees C, with sucrose (35.40 g/L) and soy extract (2.58 g/L) as best carbon and nitrogen sources, respectively. The maximum EPS concentration was 1.549 g/L. Pure EPS was obtained from culture filtrates by size exclusion chromatography, and its molecular characteristics were examined using a multiangle laser-light scattering and refractive index detector system. The weight-average molar masses of the EPS was determined to be 3.430 x 10(5) g/mol. The molecular conformation of the EPS in aqueous solution was random coil. Furthermore, P. igniarius EPS could scavenge superoxide anion and hydroxyl radicals. The antitumor activity of EPS reached 6.79% at an EPS concentration of 200 mu g/mL. These results show the great potential for EPS to be used in the pharmacological industry in place of synthetic compounds.