Hydrocolloids from the Mushroom Auricularia heimuer: Composition and Properties.

The ear- to shell-shaped fruiting bodies of the genus Auricularia are widely used as food and in traditional medicinal remedies. This study was primarily focused on the composition, properties and potential use of the gel-forming extract from Auricularia heimuer. The dried extract contained 50% soluble homo- and heteropolysaccharides, which were mainly composed of mannose and glucose, acetyl residues, glucuronic acid and a small amount of xylose, galactose, glucosamine, fucose, arabinose and rhamnose. The minerals observed in the extract included approximately 70% potassium followed by calcium. Among the fatty and amino acids, 60% unsaturated fatty acids and 35% essential amino acids could be calculated. At both acidic (pH 4) and alkaline (pH 10) conditions, the thickness of the 5 mg/mL extract did not change in a temperature range from -24 °C to room temperature, but decreased statistically significantly after storage at elevated temperature. At neutral pH, the studied extract demonstrated good thermal and storage stability, as well as a moisture retention capacity comparable to the high molecular weight sodium hyaluronate, a well-known moisturizer. Hydrocolloids that can be sustainably produced from Auricularia fruiting bodies offer great application potential in the food and cosmetic industries.

Fortifying a meal with oyster mushroom powder beneficially affects postprandial glucagon-like peptide-1, non-esterified free fatty acids and hunger sensation in adults with impaired glucose tolerance: a double-blind randomized controlled crossover trial.

PURPOSE: Impaired glucose tolerance (IGT) is a pathophysiological condition characterized by insulin resistance with known metabolic consequences such as postprandial hyperglycemia and hypertriglyceridemia. We hypothesized that fortifying a meal with mushrooms rich in ß-glucans may diminish glucose and triglyceride responses by improving postprandial gastrointestinal hormone release. METHODS: In a randomized controlled crossover study, 22 subjects with IGT ingested a meal either enriched with 20 g powder (8.1 g ß-glucans) of oven-dried Pleurotus ostreatus (enriched meal, EN) or without enrichment (control meal, CON). Blood was collected before and repeatedly within 4 h after the meal to determine AUC of glucose (primary outcome), insulin, triglycerides, non-esterified free fatty acids (NEFAs), glucagon-like peptide-1 (GLP-1), gastric inhibitory polypeptide (GIP) and ghrelin. Appetite sensations (hunger, satiety, fullness, and desire to eat) were assessed before and after meal consumption by visual analog scales. RESULTS: Postprandial glucose, insulin, triglycerides, GIP and ghrelin concentrations as well as the corresponding AUCs did not differ between EN and CON. NEFAs-AUC was 14% lower (P = 0.026) and GLP-1-AUC 17% higher (P = 0.001) after EN compared to CON. Appetite ratings did not differ between treatments, except for hunger (AUC 22% lower after EN vs. CON; P = 0.031). CONCLUSION: The observed immediate postprandial metabolic changes indicate that an easily manageable fortification of a single meal with powder from dried oyster mushrooms as ß-glucan source may improve postprandial metabolism. If the effect is preserved long term, this measure can diminish the risk for further development of overweight/obesity and type 2 diabetes in subjects with IGT. CLINICAL TRIAL REGISTRATION: German Clinical Trial Register on 09/08/2018; trial-ID: DRKS00015244.

Chemical Composition and Ultraviolet Absorption Activity of an Aqueous Alkali Extract from the Fruiting Bodies of the Tinder Conk Mushroom, Fomes fomentarius (Agaricomycetes).

White rot mushroom Fomes fomentarius is a medicinal fungus with great potential to be explored. This work focused on the chemical composition of a basic aqueous extract from F. fomentarius fruiting bodies. The extract was mostly composed of phenolics, carbohydrates, minerals, and crude fat with a low amount of proteins and chitin. One-third of the total carbohydrates were in the form of beta-glucans with minor amounts of alpha-glucans. The most valuable essential part of the extract was composed of an acid-resistant ultraviolet (UV)-absorbing mixture of phenolic compounds such as melanins, lignins, and humic acids. These compounds, also referred to as melanin-like pigments, provided for the high antioxidant activity of the extract measured in vitro. Moderate sun-protective capacity was observed with regard to UVB rays and also expected in the UVA range. Quantification of melanin-like pigments in the F. fomentarius extract was possible either gravimetrically as acid-insoluble residue or spectrophotometrically in the UV region. Melanin estimation, based on nitrogen measurements, offered misleading results due to the presence of nitrogen-free melanins along with other nitrogen-containing compounds such as proteins and chitin. F. fomentarius water-soluble basic extract, containing beta-glucans and rich in melanin-like substances, could be used, for example, for topical skin application to prevent cell damage caused by excessive UV exposure or cytotoxic free radicals. The bioactive potential, safety, and further applications of the F. fomentarius extract are currently being investigated.

The Birch Bracket Medicinal Mushroom, Fomitopsis betulina (Agaricomycetes) - Bioactive Source for Beta-Glucan Fraction with Tumor Cell Migration Blocking Ability.

Wild-grown fruiting bodies of the basidiomycete Fomitopsis betulina (Agaricomycetes, birch bracket mushroom, = Piptoporus betulinus) in different growing stages were collected and analyzed for their beta-glucan content. It could be shown that no significant difference in beta-glucan content regarding size or location of the collected fruiting bodies could be determined, but all samples displayed high values of beta-glucan in comparison to other well-known culinary or medicinal mushroom species. Furthermore, F. betulina fruiting bodies extracted with cold sodium chloride were separated into several fractions by cross flow ultrafiltration, and glucan and protein content were analyzed. The fractions showed varying amounts of beta-glucan and very low protein contents were detected. Also, bioactivity of the fractionated extract was analyzed. None of the mushroom extract fractions induced significant cytotoxicity after 48 h of incubation at a concentration up to 1 mg/mL. Interestingly, in a scratch wound assay, the extract FbS 1, an ultrafiltrated fraction > 300 kDa, was able to block tumor cell migration by 38% compared to solvent control after 48 h of incubation at a concentration of 0.33 mg/mL. In conclusion, our results have high potential for identifying novel antitumor activities based on F. betulina.

Characterization of selenium speciation in selenium-enriched button mushrooms (Agaricus bisporus) and selenized yeasts (dietary supplement) using X-ray absorption near-edge structure (XANES) spectroscopy.

Selenium is an essential trace element for which dietary intake is not sufficient in many parts of the world such as in Europe. Yeast and mushrooms may accumulate considerable amounts of selenium, but the chemical form in mushrooms has not been elucidated yet. Thus, we determined the selenium speciation of selenium-enriched button mushrooms in comparison to that of selenized yeast via Se K-edge XANES spectroscopy. Quantitative analysis of the XANES spectra revealed that the selenium in selenized yeast is mainly present as seleno-methionine but that in selenium-enriched button mushrooms, it is present predominantly as Se-methyl-l-selenocysteine. As this form is highly bioavailable and directly enters the selenium metabolic pool, selenium-enriched mushrooms may be a good food choice to improve selenium intake.

Cross-Flow Ultrafiltration Fractions of a Cold Aqueous Extract of the Shiitake Culinary-Medicinal Mushroom, Lentinus edodes (Agaricomycetes), Exhibit Apoptosis in Tumor Cells.

Lentinus edodes (shiitake) ranks among the most well-known medicinal mushrooms worldwide. Immune-modulating effects of shiitake extracts have been widely demonstrated in animals and humans. Apart from providing highly purified compounds such as lentinan, crude mushroom extracts also show antitumor activities. The direct cytotoxicity of crude preparations still requires investigation. The focus of our study lies in the molecular weight cutoff distribution of ß-glucans and proteins in a cold aqueous extract from L. edodes. We applied cross-flow ultrafiltration to obtain 6 fractions with different molecular sizes. ß-glucan and protein contents were quantified. We were able to show that only small amounts of ß-glucans were extracted and that protein content decreases with fraction size. The cytotoxic potential of the cold aqueous preparation was demonstrated by analyzing inhibition of the growth of non-small cell lung cancer and triple-negative breast cancer cells.

Screening of beta-glucan contents in commercially cultivated and wild growing mushrooms.

Mushrooms have unique sensory properties and nutritional values as well as health benefits due to their bioactive compounds, especially beta-glucans. Well-known edible and medicinal mushroom species as well as uncommon or unknown species representing interesting sources of bioactive beta-glucans have been widely studied. Commercially cultivated and wild growing mushrooms were analysed for their beta-glucan contents. Enzymatic determinations of all glucans, alpha-glucans and beta-glucans in 39 mushrooms species were performed, leading to very remarkable results. Many wild growing species present high beta-glucan contents, especially Bracket fungi. The well-known cultivated species Agaricus bisporus, Lentinula edodes and Cantharellus cibarius as well as most screened wild growing species show higher glucan contents in their stipes than caps.

Characterization of Cross-Flow Ultrafiltration Fractions from Maitake Medicinal Mushroom, Grifoia frondosa (Agaricomycetes), Reveals Distinct Cytotoxicity in Tumor Cells.

ß-glucans from Basidiomycetes like Grifola frondosa (the maitake mushroom) are well known for their health benefits. Polysaccharide preparations from medicinal mushrooms such as G. frondosa have been successfully tested in a vast number of studies. Many mushroom extracts have been developed and today are merchandized for use medicinally and commercially. Studies could show that, in particular, chemical structural features such as the molecular size of ß-glucans significantly influence their bioactivity. Thus it is highly important to explore the composition and structural properties of ß-glucans extracted from medicinal mushrooms and their effects on human tumor cell viability. Our study focuses on the molecular weight cutoff distribution of ß-glucans in hot water-based extracts from maitake mushrooms. Cross-flow ultrafiltration was applied to obtain 5 fractions of different molecular size. ß-glucan content was quantified using an enzyme-based test kit, specialized to 1,3-1,6-ß-glucans. Here we show that only small amounts of ß-glucans with a high molecular weight (>100 kDa) could be detected from an aqueous extract of G. frondosa. The main compounds encompass substances with a low molecular weight (<5 kDa), composing about 35% of the whole extract. In addition, tumor cell viability studies demonstrate significant cytotoxic potential in 2 different solid cancer cell types for the fraction with a high molecular weight (>100 kDa) and for 1 fraction with a low molecular weight (5-10 kDa). In summary, our experiments prove that cross-flow ultrafiltration serves as a quick and easy method for dividing crude aqueous mushroom extracts into different molecular-weight fractions that inhibit tumor cell viability in vitro.