An untold story of a novel mushroom from tribal cuisine: an ethno-medicinal, taxonomic and pharmacological approach.

India showcases an array of fascinating and rare mushrooms that grow exclusively in the wilderness of West Bengal. Thus, the state has always been our prime choice to document myco-diversity and associated indigenous knowledge. Fortuitously, a recent expedition gifted us a violet-coloured Russuloid macrofungus, called "Jam Patra", that plays an integral part in the food security of local ethnic groups. However, the species has not received the much-needed attention among city dwellers and remains abandoned, motivating us to carry a thorough investigation. To our surprise, extensive analyses on morphological features and nrITS based phylogenetic estimation pointed the novelty of the taxon, as justified herein. Extending this research, a water-soluble polysaccharide-rich fraction was isolated to determine therapeutic prospects. Chemical characterization revealed that the backbone of the polymers, organized in triple-helical form, predominantly consisted of β-glucan accompanied by a lower extent of galactose, mannose and xylose. Subsequently, the effective antioxidant activity was noted in terms of radical scavenging, reducing power and chelating ability with EC of 305-2726 μg ml. Further, the macromolecules triggered murine macrophages to proliferate, phagocytose, release NO, produce intracellular ROS and change morphodynamics. A significant alleviation in the expression of TLR-2, TLR-4, NF-κB, COX-2, TNF-α, Iκ-Bα, IFN-γ, IL-10 and iNOS was also observed explaining the definite immune-stimulatory activity and supporting traditional consumption of "Jam Patra" as a health-promoting food. Altogether, the study introduces a species in the world's myco-diversity and tribal food list opening doors of various opportunities in functional food and nature-based drug development arenas, which are currently in trend.