Microwave Extraction of New Polysaccharides From Inonotus obliquus , Structural Characterization, and Antioxidant Activity

To address the low extraction yield and structural degradation issues of conventional methods, this study optimized microwave-assisted extraction (61°C, 64 min, 30:1 mL/g ratio) to obtain Inonotus obliquus polysaccharides (IOP), followed by DEAE-52 and Sephadex G-100 purification to isolate two fractions: neutral IOP-1 (12.67 kDa) and acidic IOP-2 (26.13 kDa). Monosaccharide analysis revealed both as heteropolysaccharides containing mannose, glucose, and galactose with distinct compositional ratios. Structural characterization showed IOP-1 primarily contains 1,4-Glcp, 1,3,6-Glcp, and 1,3-Manp linkages, while IOP-2 features 1,3-Glcp, 1,4-Glcp, 1,4,6-Glcp, and 1,4-Galp linkages. Multiple antioxidant assays demonstrated superior free radical scavenging capacity in both polysaccharides, with IOP-1 exhibiting exceptional activity exceeding typical polysaccharides performance. These findings highlight IOP-1's potential as a novel natural antioxidant for pharmaceutical and food applications.