Medicinal Potential of the Insoluble Extracted Fibers Isolated from the Fomes fomentarius (Agaricomycetes) Fruiting Bodies: A Review.

The tough, hoof-shaped fruiting bodies of the tinder conk mushroom, Fomes fomentarius (L.) Fr. (Polyporaceae, Agaricomycetes), were traditionally used all over the world as tinder to start fire, for ritual purposes, to make artworks like clothing, frames, ornaments, and also to cure various human diseases (wounds, gastro-intestinal disorders, liver-related problems, inflammations, various cancers, etc.). The first wave of scientific interest in F. fomentarius in Europe dates back to the early 1970s with the discovery of the red-brown pigments of the F. fomentarius external layer. Since then, a number of research papers and reviews have mentioned the history of use, taxonomy, composition and medicinal properties of some F. fomentarius preparations, e.g., soluble extracts and their fractions, isolated cell walls, mycelia and compounds purified from the culture broth. The present review is focused on the composition and benefits of the water-insoluble cell walls obtained from the F. fomentarius fruiting bodies. Isolated cell walls of the tinder mushroom reveal a fibrous hollow structure with an average diameter of 3-5 µm and a wall thickness of 0.2-1.5 µm. Naturally, the fibers are composed of 25-38% glucans, with a majority of ß-glucans, around 30% polyphenols, 6% chitin and less than 2% hemicellulose. The percentage of the main structural compounds can vary either slightly or considerably, depending on the extraction conditions. According to in vitro, in vivo, ex vivo as well as clinical studies, F. fomentarius fibers can modulate the immune system, contribute to intestinal health, accelerate wound healing, absorb heavy metals, organic dyes and radionuclides, normalize kidney and liver function, and provide antibacterial, antiviral, antifungal, anxiolytic, anti-inflammatory and analgesic effects. Multiple action of the insoluble cell walls purified from the F. fomentarius fruiting bodies is particularly effective in the treatment of chronic, recurring, complicated multifactorial diseases. It is certainly worth exploring the medicinal potential and the practical application of these preparations further.

Antioxidant activity and cytotoxicity of exopolysaccharide from mushroom Hericium coralloides in submerged fermentation.

Mushrooms of the genus Hericium spp. represent a series of delicious edible mushrooms with medicinal value. Here, for the first time, the species native to Iran, the mushroom Hericium coralloides, was collected in Mazandaran province, identified, and registered with the NCBI under accession number MW136052. The production of exopolysaccharides (EPS) in submerged culture was optimized using the response surface method. Among the physicochemical and culture medium conditions tested, rotation speed and concentration of maltose and peptone of soybean significantly affected the production of EPS. The proposed model predicts maximum EPS production (0.13 g/L) at 50 g/L maltose, 3 g/L soy peptone, and 1 g/L yeast extract, pH = 6.5, 200 rpm, inoculum at 5% v/v, and 22 °C. The molecular weight of the EPS chains was 413 and 1578 Da. EPS has antioxidant action (EC50 = 6.59 mg/mL) and cytotoxic activity against cancer cells. The viability of AGS and MKN-45 cancer cell lines declined to 20 and 30% after 48 h of the EPS treatment. H. coralloides EPS could be considered a natural dietary anti-cancer supplement. Further studies are necessary to understand the mechanism of the H. coralloides EPS activity on the cell cycle of cancer cells and to prove its action in vivo. Supplementary Information: The online version contains supplementary material available at 10.1007/s13399-022-03386-0.

In Vitro Cytotoxic Activity of an Aqueous Alkali Extract of the Tinder Conk Mushroom, Fomes fomentarius (Agaricomycetes), on Murine Fibroblasts, Human Colorectal Adenocarcinoma, and Cutaneous Melanoma Cells.

Bioactive complexes of medicinal mushrooms have become attractive as complementary anticancer remedies. Our in vitro study focused on the cytotoxicity of the polyphenol-reach and beta-glucan-containing aqueous alkali extract from Fomes fomentarius fruiting bodies (FFE) using murine fibroblasts (L929), human colon adenocarcinoma cells (Caco-2), and cutaneous melanoma cells (COLO-818). Dose-dependent FFE cytotoxicity with an half maximal inhibitory concentration of 0.44 mg/mL was observed for L929 cells upon analysis of the total number of adherent cells, degree of cell viability, cell morphology, and mitochondrial metabolic activity. Cytotoxic effects on cancer cells tested using cell impedance were dependent on FFE concentration, type of cells, and their density. As a routine in vitro model for predicting human intestinal absorption, Caco-2 cells did not react on FFE, which can indirectly support its safety for the human intestinal epithelium. Melanoma cells were affected in a dose-dependent manner, even at low FFE concentrations (0.01-0.05 mg/mL). The confluent cell layer, which resembles a fully formed tumor, was much more resistant than the incompletely formed, subconfluent cell layer, simulating tumor formation. FFE applied topically could be a promising candidate to prevent melanoma development in its early stages.