Structural characterization of an acid-extracted polysaccharide from Suillus luteus and the regulatory effects on intestinal flora metabolism in tumor-bearing mice.

Suillus luteus is an excellent edible fungus that has been applied in soil remediation and environmental pollution control, while the development of bioactive polysaccharide component including structural performance and intestinal flora regulation is still insufficient. In this study, a S. luteus acid-extracted polysaccharide (SLAP) was prepared under room temperature, then the structural characteristics and regulatory effects on gut microbiota metabolism in tumor-bearing mice were investigated. Results showed that SLAP was a kind of gulcomannan (average molecular weight of 1.76 × 10 Da) comprised of Xyl, Man, Glc, Gal (molar ratio of 0.19:1.00:0.72:0.53), which took β-(1 → 4)-Manp and β-(1 → 4)-Glcp as the backbone with β-(1 → 6)-Glcp and α-(1 → 6)-Galp as branches. The animal experiment results demonstrated that SLAP could effectively enhance the immunoregulatory activities of CD4 and CD8 T cells in tumor-bearing mice via improving intestinal lactobacillaceae contents and promoting primary bile acids biosynthesis, finally leading to the suppression of solid tumors growth with an inhibitory rate of 61.14 % (100 mg/kg·d). These results would provide certain data support and research basis for further applications of SLAP as an immunomodulatory adjuvant in food and medicine fields.