Intrapolysaccharides from Amazonian Panus lecomtei induce pro-inflammatory responses and adhere to macrophage surfaces.

Panus lecomtei, an edible mushroom native to tropical regions, is recognized for its nutritional and bioactive compounds, particularly polysaccharides known for their immunomodulatory properties. In this study, an Amazonian strain of P. lecomtei was cultivated via submerged fermentation. The resulting mycelial biomass was subjected to intrapolysaccharide (IPS) extraction using sequential water and potassium hydroxide at 80 °C. The chemical, physicochemical, and rheological properties of the soluble fractions were analyzed using gas chromatography–mass spectrometry (GC-MS), nuclear magnetic resonance (NMR), and dynamic light scattering (DLS). Immunostimulatory activity was assessed on macrophages by measuring cytokine release and evaluating cell adhesion to IPS-coated microbeads manipulated with optical tweezers. Fraction analysis revealed that hot-alkali extraction yielded the highest IPS recovery (0.85%) and total carbohydrate content (70%). Monosaccharide composition varied according to the extraction method. NMR analysis suggests the presence of β-glucans, α-(1→4)- and β-(1→6)-linked glucans in the hot-water fraction. The hot-alkali fraction was predominantly composed of a β-D-glucan with a (1→3)-linked main chain, substituted at O-6 by β-D-Glcp non-reducing ends or (1→6)-linked β-D-Glcp side chains. Both fractions exhibited thermal stability, low resistance to shear stress, and variable elasticity. The hot-water fraction stimulated the secretion of IL-6 and TNF-α, whereas the hot-alkali fraction induced TNF-α only. Furthermore, IPS-coated microbeads adhered to macrophage surfaces within approximately 14 s, whereas uncoated control beads required about 60 s. These findings expand current knowledge of P. lecomtei strain 1466 and support the relevance of Amazonian mushroom biodiversity as a source of bioactive macromolecules.