Study on the Polysaccharide Structure and Antitumor Mechanism of Russula adusta

Abstract

A previously undescribed polysaccharide was isolated from the edible mushroom Russula adusta. Structural analysis showed that Russula adusta polysaccharide (RA‑P) has a molecular mass of 20,576 Da and main chain consists of (1→4,6)-Glcp, (1→4)-D-Glcp, (1→4)-D-Galp and (1→6)-Galp remnants, with side chain →1)-Galp and a glucose/galactose ratio of 6:4. RA‑P (10 μg/mL) markedly enhanced RAW264.7 macrophage proliferation (68.47% enhancement) and stimulated release of IL‑1β and TNF‑α. At 20 μg/mL, RA‑P inhibited MFC gastric cancer cell proliferation by 64.35%, accompanied by severe fragmentation of F‑actin filaments and disruption of the cytoskeletal. Transcriptome analysis revealed that RA‑P up‑regulated ubiquitin-fold modifier 1 (Ufm1) and down‑regulated 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (Pfkfb3) and RGD motif, leucine rich repeats, tropomodulin domain and proline-rich containing protein (Rltpr), affecting glycolysis and cytoskeletal stability. Moreover, RA‑P reduced the expression of forkhead box O1 (Foxo1), forkhead box O3 (Foxo3), forkhead box O4 (Foxo4) and SMAD family member 3 (Smad3) in the FoxO pathway, impairing energy metabolism and cell motility. Our in vitro findings indicate that RA-P exhibits immunomodulatory and antitumor activities in RAW264.7 macrophages and MFC cancer cells, but these data are preliminary and require further safety, mechanistic, and in vivo validation before any functional food application can be considered.