Structural characterization and immunomodulatory activity of exopolysaccharide from Aureobasidium pullulans CGMCC 23063

Exopolysaccharide (EPS-1) was isolated from Aureobasidium pullulans CGMCC 23063 and purified with DEAE 650M and Sephadex G-100 column chromatography. The structural characteristics and immunomodulatory activity of EPS-1 were investigated. The results showed EPS-1 (294.9 KDa) was β-glucan consisting of the backbone (1→3)-linked β-Glcp and β-(1,6)-branches by Ion chromatography, gas chromatography-mass spectrometry, and 1D/2D NMR spectroscopy. The SEM and AFM showed that EPS-1 composed spheres joined by triple-helix conformation into chains and circles. In vitro cell experiments, EPS-1 displayed immunological activity on the RAW264.7 cells. After being treated with EPS-1 (400 μg/mL), the concentration of NO, TNF-α, and IL-6 could reach 17.05 μM, 448.46 pg/mL, and 15.18 pg/mL, respectively. In addition, the cytokines mRNA levels also demonstrated the above results at the molecular level. The western-blot results demonstrated that the expression of phosphorylated p65 and p-erk associated with cytokine release, was increased with the dose of EPS-1.