Extraction Optimization and Characterization of Antioxidant Polysaccharides From Suillus bovinus

A three-variable, three-level Box–Behnken design combined with response surface methodology (BBD-RSM), based on single-factor experiments, was employed to optimize the extraction parameters of crude polysaccharides (SubPs) from Suillus bovinus. SubPs were purified using a DEAE-52 cellulose column and a Sephadex G-100 chromatography column, yielding four homogeneous fractions (S-1, S-2, Y-1, Y-2) with molecular weights from 47.34 to 97.07 kDa. Among these fractions, Y-1 exhibited superior antioxidant activity, demonstrating a 34.73% ± 1.31% reduction in reactive oxygen species (ROS) levels at 50 μg/mL compared to the tert-butyl hydroperoxide (t-BHP)-treated model group in HepG2 cells, along with enhanced activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), as well as reduced malondialdehyde (MDA) content. The chemical structure of Y-1 was further characterized through monosaccharide composition analysis, methylation analysis, and nuclear magnetic resonance (NMR) spectroscopy. These findings provide structural insights into Y-1 and highlight its potential as a natural antioxidant.