The optimal culture conditions of exopolysaccharides (EPS) production in submerged culture medium by Xylaria nigripes were determined using orthogonal matrix method. The optimal medium (per liter) EPS was 60.0 g L–1 maltose, 1.0 g L–1 peptone,
5 mmol L–1 KH2PO4, and initial pH 7.0 at 28 oC. In the optimal culture medium, the maximum EPS production was 11.967 g L–1 in shake flask. Two groups of EPSs (designated as Fr-I and Fr-II) were obtained from the culture filtrates by size exclusion chromatography
(SEC), and their molecular characteristics were examined by a multiangle laser-light scattering (MALLS) and refractive index (RI) detector system. The weight-average molar masses of Fr-I and Fr-II of EPS were determined to be 6.327104 and 1.478104 g mol–1, respectively. The SEC/MALLS analysis revealed that the molecular
formation of Fr-I is of nearly globular shape. Furthermore, the experiments in vitro indicated that X. nigripes EPS exhibited high antioxidative effects though its antitumour activity was limited