Topological structure, rheological characteristics and biological activities of exopolysaccharides produced by Saccharomyces cerevisiae ADT.

Saccharomyces cerevisiae ADT is an edible fungus, with limited research on its exopolysaccharides (EPS). Three types of exopolysaccharides (EPS60, EPS80, and EPS100) were obtained through multiple purification steps using varying concentrations of ethanol in this study. The topological structure, rheological properties, and biological characteristics of EPS were investigated. High performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR) analyses indicated that the three EPS are primarily made up of mannose with a small amount of glucose. Acetyl groups were also found, along with the presence of α-type pyranose and β-type pyranose. The Congo Red test and X-ray diffraction results reflected the absence of a triple helix structure and crystal properties. Atomic force microscopy (AFM) revealed the self-assembly of three exopolysaccharides into various topological structures under different concentration gradients, and a clear network structure of entangled chains was observed. EPS60, EPS80 and EPS100 displayed pseudoplasticity, weak gel behavior and thermal stability. Significantly, EPS exhibited antioxidant activity in a dose-dependent manner and showed no acute cytotoxicity to RAW264.7 and HEK293T cells. Therefore, EPS in this study is anticipated to be utilized in natural antioxidants, medications, and functional materials.