Structural characteristics and intestinal flora metabolism mediated immunoregulatory effects of Lactarius deliciosus...

Lactarius deliciosus, a widely appreciated mushroom with delightful tastes and texture, has exhibited immunomodulatory activity in vitro, while the effects on intestinal flora metabolisms in vivo are ambiguous. In this study, a L. deliciosus polysaccharide (LDP) was extracted and purified, and the structural characteristics were evaluated, as well as the immunological enhancement on tumor-bearing mice through regulating intestinal flora metabolisms. Results showed that LDP was a heteropolysaccharide (average molecular weight of 1.44 × 10⁷ Da) with a backbone of α-(1 → 6)-Manp and branches of α-(1 → 6)-Galp, α-(1 → 3)-Fucp, α-(1 → 6)-Glcp, α-(1 → 4)-Glcp. Animal experiments indicated that LDP could significantly protect immune organs of tumor-beraing mice and suppress solid tumors growth with inhibitory rate of 51.61 % (high-dose, 100 mg/kg), and improve the intestinal lactobacillus contents, promote adenine mediated zeatin biosynthesis, then competitively antagonize A2A receptor and enhance the activities of CD4⁺ T cells and CD8⁺ T cells, finally effectively facilitate the apoptosis and elimination of tumor cells. These results would provide powerful data supports for the further antitumor mechanisms development and practical applications of L. deliciosus polysaccharide in food and drug industries.