Chemical Characterization and Biological Functions of Hot Alkali-Soluble Crude Polysaccharide from the Water-Insoluble Residue of Macrocybe lobayensis (Agaricomycetes) Fruit Bodies

The treasured giants: a current overview on agricultural, nutritional, bioactive, and economic potential of Macrocybe Species (Agaricales, Basidiomycota)

Macrocybe is a well-studied genus in the family Callistosporiaceae (Basidiomycota). Currently, the genus comprises eight species with worldwide distribution. All species in this genus are relatively large compared to other edible mushrooms and are commonly consumed by locals. Cultivation methodologies have been developed for several species of the genus, including M. gigantea, M. crassa, M. titans, and M. lobayensis. These mushrooms can be cultivated in lignocellulosic wastes such as sawdust, straw, and other agro-industrial wastes. The nutritional compositions have been identified for M. gigantea, M. crassa, and M. lobayensis, revealing that they are rich in fibers, proteins, and various vitamins. Although these mushrooms are of culinary significance, precautions should be taken when consuming them due to their potential cyanic toxicity. In addition to being rich in different nutrients, Macrocybe species possess medicinal properties such as antimicrobial, antioxidant, immunomodulatory, anticancer, anti-inflammatory, hepatoprotective, and several other beneficial effects. Several species are commercially available in countries like China and Thailand, and the commercial potential is high due to the large size, taste, and long shelf life of these mushrooms. There is significant potential for cultivating species of this genus and introducing their artificial cultivation practices to various counties worldwide. Diverse value-added products can also be produced using Macrocybe species.

Extraction of chitin-glucan complex from shiitake (Lentinula edodes) fruiting bodies using natural deep eutectic solvents and its prebiotic potential

Chitin-glucan complex (CGC) is an emerging novel prebiotic with numerous physiological activities in amelioration of clinical manifestations. In the present work, natural deep eutectic solvent (NADES), ultrasonication, and submerged fermentation using probiotic microorganisms were deployed for the extraction of CGC from Shiitake fruiting bodies. CGC obtained through non-ultrasonication assisted fermentation employing Lactiplantibacillus plantarum exhibited maximum polysaccharide yield (27.86 ± 0.82 % w/w). However, based on antioxidant potential, NADES combination of urea: glycerol (1:1 M ratio) was selected for further characterization. The rheological behavior of CGC under optimized conditions showed shear thinning property in both 0.1 M NaCl and salt-free solution. FTIR, 1H-(1D), and 2D 1H1H Homonuclear NMR spectra displayed distinctive patterns associated with β-glycosidic linkage and β-d-glucopyranose sugar moiety. XRD profiles of CGC exhibited characteristic peaks at 2θ = 23°, 25°, and 28° with corresponding hkl values of (220), (101), and (130) lattice planes, respectively. Enhanced radical scavenging activities were noticed due to the triple helical structure and anionic nature of CGC. CGC exhibited potential prebiotic activity (prebiotic score 118-134 %) and short chain fatty acids liberation (maximum 9.99 ± 0.41 mM by Lactobacillus delbrueckii). Simulated static in-vitro digestion demonstrated that CGC withstands acidic environment of gastric phase, which indicated its suitability for use as a prebiotic in nutraceutical-enriched food products.

Cold Alkali-Extractable Antioxidative Polysaccharide from Russula pseudocyanoxantha (Agaricomycetes), a Novel Mushroom, Stimulates Immune Responses in RAW264.7 Cells by Regulating the TLR/NF-κB Pathway

In our previous study, we have established Russula pseudocyanoxantha as a unique species, playing a crucial role in indigenous diets through ages. The research also brought attention to bioactive potential of polysaccharide fraction extracted from the unexplored food using hot water. However, residue of the conventional process still contains therapeutic biopolymers that could further be utilized for pharmacological purposes instead of being discarded. Therefore, the current study aims to valorize the solid remnants, contributing to a deeper understanding of the novel taxon. Subsequently, the leftover was treated with cold alkali, leading to the preparation of a high-yield fraction (RP-CAP). Chemical characterization through FT-IR, GC-MS, HPTLC, and spectroscopy demonstrated presence of several monomers in the carbohydrate backbone, predominantly composed of β-glucan. Furthermore, GPC chromatogram indicated presence of a homogeneous polymer with molecular weight of ~ 129.28 kDa. Subsequently, potent antioxidant activity was noted in terms of radical scavenging (O2·-, OH·, DPPH· and ABTS·+), chelating ability, reducing power and total antioxidant activity where EC50 values ranged from 472-3600 μg/mL. Strong immune-boosting effect was also evident, as the biopolymers stimulated murine macrophage cell proliferation, phagocytic activity, pseudopod formation, and NO as well as ROS synthesis particularly at the concentration of 100 μg/mL. In-depth analysis through RT-PCR revealed that the fraction stimulated synthesis of several inflammatory mediators, elucidating the mode of action through TLR/ NF-κB pathway. Therefore, the findings collectively suggest that RP-CAP possesses great potential to serve as a healthimproving component in functional food and pharmaceutical sectors.