Maitake Medicinal Mushroom, Grifola frondosa (Agaricomycetes), and Its Neurotrophic Properties: A Mini-Review.

Neurodegeneration is one of the most common manifestations in an aging population. The occurrence of oxidative stress and neuroinflammation are the main contributors to the phenomenon. Neurologic conditions such as Alzheimer's disease (AD) and Parkinson's disease (PD) are challenging to treat due to their irreversible manner as well as the lack of effective treatment. Grifola frondosa (Dicks.: Fr.) S.F. Gray, or maitake mushroom, is believed to be a potential choice as a therapeutic agent for neurodegenerative diseases. G. frondosa is known to be a functional food that has a wide variety of medicinal purposes. Thus, this review emphasizes the neuroprotective effects and the chemical composition of G. frondosa. Various studies have described that G. frondosa can protect and proliferate neuronal cells through neurogenesis, antioxidative, anti-inflammatory, and anti-ß-amyloid activities. The mechanism of action behind these therapeutic findings in various in vitro and in vivo models has also been intensively studied. In this mini review, we also summarized the chemical composition of G. frondosa to provide a better understanding of the presence of nutritional compounds in G. frondosa.

Preparation and structural characterization of acid-extracted polysaccharide from Grifola frondosa and antitumor activity on S180 tumor-bearing mice.

In this study, an acid-extracted polysaccharide (GFP-A) was extracted from the fruiting bodies of G. frondosa with 1 % hydrochloric acid solution. Our study aimed to imitate the processes of digestion, absorption and antitumor activities of polysaccharides from G. frondosa under the acid environment of stomach in the body. The preliminary structural analysis resulted that GFP-A (about 1.10 × 106 Da) was a neutral polysaccharide composed of xylose, mannose, glucose (molar ratio: 0.12:1.00:6.98) with α-type glycosidic linkages. Additionally, antitumor activities on S180 tumor-bearing mice showed that GFP-A could effectively inhibit the growth of S180 tumor cells by protecting immune organs (thymus and spleen), activating immune cells (NK cells, lymphocytes and macrophages), upregulating the secretion of serum cytokines (TNF-α, IL-2 and IFN-γ) in vivo. H & E staining and cell cycle determination further demonstrated that GFP-A could induce S180 tumor cells apoptosis via arresting them in G1 phase. These results demonstrated that GFP-A could provide a theoretical basis for treatment of cancer.

Maitake α-glucan promotes differentiation of monocytic myeloid-derived suppressor cells into M1 macrophages.

AIMS: Myeloid-derived suppressor cells (MDSCs) are major components of the tumor microenvironment and systemically accumulate in tumor-bearing hosts and patients with cancer, facilitating cancer progression. Maitake macromolecular α-glucan YM-2A, isolated from Grifola frondosa, inhibits tumor growth by enhancing immune responses. The present study investigated the effects of YM-2A on the immunosuppressive potential of MDSCs. MAIN METHODS: YM-2A was orally administered to CT26 tumor-bearing mice, and the number of immune cells in the spleen and tumor was measured. Splenic MDSCs isolated from the CT26 tumor-bearing mice were treated with YM-2A and co-cultured with T cells to measure their inhibitory effect on T cell proliferation. For adoptive transfer of monocytic MDSCs (M-MDSCs), YM-2A-treated M-MDSCs mixed with CT26 cells were implanted subcutaneously in the mice to measure the tumor growth rate. KEY FINDINGS: YM-2A selectively reduced the accumulation of M-MDSCs but not that of polymorphonuclear MDSCs (PMN-MDSCs) in CT26 tumor-bearing mice. In tumor tissues, YM-2A treatment induced the polarity of immunostimulatory M1-phenotype; furthermore, it increased the infiltration of dendritic, natural killer, and CD4+ and CD8+ T cells. YM-2A treatment of purified M-MDSCs from CT-26 tumor-bearing mice induced dectin-1-dependent differentiation into M1 macrophages. YM-2A-treated M-MDSCs lost their inhibitory activity against proliferation and activation of CD8+ T cells. Furthermore, adoptive transfer of M-MDSCs treated with YM-2A inhibited CT26 tumor growth. SIGNIFICANCE: YM-2A promotes the differentiation of M-MDSCs into immunostimulatory M1 macrophages, thereby enhancing the efficacy of cancer immunotherapy.

Probiotics-Fermented Grifola frondosa Total Active Components: Better Antioxidation and Microflora Regulation for Alleviating Alcoholic Liver Damage in Mice.

Alcoholic liver damage is caused by long-term drinking, and it further develops into alcoholic liver diseases. In this study, we prepared a probiotic fermentation product of Grifola frondosa total active components (PFGF) by fermentation with Lactobacillus acidophilus, Lactobacillus rhamnosus, and Pediococcus acidilactici. After fermentation, the total sugar and protein content in the PFGF significantly decreased, while the lactic acid level and antioxidant activity of the PFGF increased. Afterward, we investigated the alleviating effect of PFGF on alcoholic liver injury in alcohol-fed mice. The results showed that the PFGF intervention reduced the necrosis of the liver cells, attenuated the inflammation of the liver and intestines, restored the liver function, increased the antioxidant factors of the liver, and maintained the cecum tissue barrier. Additionally, the results of the 16S rRNA sequencing analysis indicated that the PFGF intervention increased the relative abundance of beneficial bacteria, such as Lactobacillus, Ruminococcaceae, Parabacteroids, Parasutterella, and Alistipes, to attenuate intestinal inflammation. These results demonstrate that PFGF can potentially alleviate alcoholic liver damage by restoring the intestinal barrier and regulating the intestinal microflora.

Anti-Aging and Neuroprotective Properties of Grifola frondosa and Hericium erinaceus Extracts.

Nutrition has relevant consequences for human health and increasing pieces of evidence indicate that medicinal mushrooms have several beneficial effects. One of the main issues in Western countries is represented by the challenges of aging and age-related diseases, such as neurodegenerative disorders. Among these, Parkinson's disease (PD) affects 10 million people worldwide and is associated with α-synuclein misfolding, also found in other pathologies collectively called synucleinopathies. Here, we show that aqueous extracts of two edible mushrooms, Grifola frondosa and Hericium erinaceus, represent a valuable source of ß-glucans and exert anti-aging effects in yeast. Their beneficial effects are mediated through the inhibition of the Ras/PKA pathway, with increased expression of heat shock proteins, along with a consistent increase of both mean and maximal lifespans. These fungal extracts also reduce the toxicity of α-synuclein heterologously expressed in yeast cells, resulting in reduced ROS levels, lower α-synuclein membrane localization, and protein aggregation. The neuroprotective activity of G. frondosa extract was also confirmed in a PD model of Drosophila melanogaster. Taken together, our data suggest the use of G. frondosa and H. erinaceus as functional food to prevent aging and age-related disorders, further supporting the neuro-healthy properties of these medicinal mushroom extracts.

Effect of Maitake D-fraction in advanced laryngeal and pharyngeal cancers during concurrent chemoradiotherapy: A randomized clinical trial.

BACKGROUND: Concurrent chemo-radiotherapy (CCRT) is an ideal treatment for advanced head and neck squamous cell carcinoma (HNSCC). The performance of CCRT induces severe toxicities in HNSCC patients and decreases the quality of life (QOL). Maitake D-Fraction is proteoglycan which has anti-tumor function associated with its immunomodulatory capacity. The polysaccharides of Maitake also have anti-radiation effect in radiation therapy during cancer treatment. This research aimed to illustrate Maitake D-Fraction effects on CCRT-associated adverse events and QOL. METHODS: During CCRT, Maitake capsules were taken orally 3 times a day, each time 4 capsules, one hour before meals. QOL were analyzed by EORTC QLQ-C30-Chinese version and EORTC QLQ-HandN-35-Chinese version. 141 patients were recruited and divided into an intervention group and a placebo group. RESULTS: Frequencies of severe CCRT-associated adverse events in intervention group were less than in placebo group. Global QOL score in intervention group was higher than in placebo group 5 weeks post treatment. The proportion of patients returning to baseline global QOL score at 6-month was increased by Maitake D-Fraction administration. CONCLUSION: In conclusion, this randomized clinical trial demonstrated that in advanced laryngeal and pharyngeal cancer patients, the oral administration of Maitake D-Fraction alleviated CCRT-related adverse events and deterioration in QOL.

Grifola frondosa Extract Containing Bioactive Components Blocks Skin Fibroblastic Inflammation and Cytotoxicity Caused by Endocrine Disrupting Chemical, Bisphenol A.

Grifola frondosa (GF), a species of Basidiomycotina, is widely distributed across Asia and has been used as an immunomodulatory, anti-bacterial, and anti-cancer agent. In the present study, the pharmacological activity of the GF extract against an ecotoxicological industrial chemical, bisphenol A (BPA) in normal human dermal fibroblasts (NHDFs), was investigated. GF extract containing naringin, hesperidin, chlorogenic acid, and kaempferol showed an inhibitory effect on cell death and inflammation induced by BPA in the NHDFs. For the cell death caused by BPA, GF extract inhibited the production of reactive oxygen species responsible for the unique activation of the extracellular signal-regulated kinase. In addition, GF extract attenuated the expression of apoptosis-related proteins (Bax, Bcl-2, and cleaved caspase-3) and the pro-inflammatory cytokine IL-1ß by the suppression of the redox-sensitive transcription factor, nuclear factor-kappa B (NF-κB) in BPA-treated NHDFs. For the inflammation triggered by BPA, GF extract blocked the inflammasome-mediated caspase-1 activation that leads to the secretion of IL-1ß protein. These results indicate that the GF extract is a functional antioxidant that prevents skin fibroblastic pyroptosis induced by BPA.

CD3Ɛ immune restorative ability induced by Maitake Pro4x in immunosupressed BALBc mice.

OBJECTIVES: The aim of this research was to determine if the rich beta glucan compound called Maitake Pro4X can recover the T cell/NK population depleted by Dexamethasone treatment in lymph nodes from cancer-free BALBc female mice. A CD3Ɛ molecular FITC labelled marker was used to measure the effect of Maitake D-Fraction Pro4X (5 mg/kg) on T cell/NK cells populations employing flow cytometry from immunosuppressed female BALBc mice in lymph nodes. There were employed other molecular markers such as CD19, CD105, Ly6G. RESULTS: Maitake Pro4X (5 mg/kg) was able to recover 42.97% of the depleted CD3Ɛ FITC cell population level in Lymph nodes from immunosuppressed female BALBc mice from 4.328 ± 6.229 to 22.646 ± 12.393 (p < 0.01) using Flow Cytometry. Maitake was also able to significantly increase the Ly6G PE cell population with p < 0.05 in lymph nodes.

Effect of low-intensity magnetic field on the growth and metabolite of Grifola frondosa in submerged fermentation and its possible mechanisms.

This study aimed to investigate the effects of low intensity alternating magnetic field on the submerged fermentation of Grifola frondosa, and its possible mechanism was also explored. Under the optimal shaking flask conditions, amino acids in mycelium with magnetic field treatment significantly increased, and the morphology of mycelium obviously changed. During the scale-up magnetic field-assisted fermentation, Mycelium biomass increased by 12%. The yield of polysaccharides and relative dissolved oxygen in the fermentation broth was higher than in the control group. Transcriptome sequencing results showed that the expression of genes related to amino acid metabolism increased significantly after magnetic treatment. In addition, magnetic field stimulation enhanced the mycelium biomass by upregulation the expression of genes related to cell repair and stress response. This study suggested that applying a magnetic field in submerged fermentation of G frondosa is an innovative approach to produce metabolites.

Assessment of Cosmetic Properties and Safety of Use of Model Washing Gels with Reishi, Maitake and Lion's Mane Extracts.

Natural cosmetics are becoming more and more popular every day. For this reason, this work investigates the properties of mushroom extracts, which are not as widely used in the cosmetics industry as plant ingredients. Water extracts of Grifolafrondosa (Maitake), Hericiumerinaceus (Lion's Mane) and Ganoderma lucidum (Reishi) were tested for their antioxidant properties, bioactive substances content, skin cell toxicity, ability to limit TEWL, effect on skin hydration and pH, and skin irritation. Our research showed that Maitake extract contained the highest amount of flavonoids and phenols, and also showed the most effective scavenging of DPPH and ABTS radicals as well as Chelation of Fe2+ and FRAP radicals, which were 39.84% and 82.12% in a concentration of 1000 µg/mL, respectively. All tested extracts did not increase the amount of ROS in fibroblasts and keratinocytes. The addition of mushroom extracts to washing gels reduced the irritating effect on skin, and reduced the intracellular production of free radicals, compared with the cosmetic base. Moreover, it was shown that the analyzedcosmetics had a positive effect on the pH and hydration of the skin, and reduced TEWL.

The anti-obesity effects of a water-soluble glucan from Grifola frondosa via the modulation of chronic inflammation.

Polysaccharides from Grifola frondosa (G. frondosa) have anti-obesity and anti-inflammatory activities. In this study, the major type, molecular weight, homogeneity and structure of a polysaccharide purified from G. frondosa (denoted GFPA) were determined. In high-fat diet (HFD)-treated mice, 8 weeks of GFPA administration efficiently decreased body weight and blood glucose concentration and counteracted hyperlipidemia. GFPA efficiently decreased adipocyte size and ameliorated inflammatory infiltration in the three types of white adipose tissue and alleviated steatosis, fat accumulation and inflammatory infiltration in the livers of HFD-fed mice. GFPA also decreased the concentrations of aspartate aminotransferase, alanine aminotransferase and pro-inflammatory factors in the sera and livers of HFD-treated mice. Furthermore, GFPA was found to regulate lipid metabolism via the inhibition of ceramide levels in HFD-treated mice. GFPA exhibited strong anti-obesity effects via the modulation of chronic inflammation through Toll-like receptor 4/nuclear factor kappa-B signaling, which supports the use of GFPA for the treatment of obesity.

Structural characterization of mushroom polysaccharides by cyclic ion mobility-mass spectrometry.

Polysaccharides are biopolymers known to possess various bioactivities. Because of their molecular complexity, the structural characterization of polysaccharides remains challenging, and difficult to be completed with a single analytical method. In this study, a novel approach for the characterization of linkages and anomeric configuration of polysaccharides was proposed. Based on ion mobility-mass spectrometry (IM-MS), a database containing 5 glucotriose standards was set up. Information about the arrival time distribution and fragmentation patterns of these standards were included. The method was validated by three commercially available purified polysaccharides, namely laminarin, dextrin, and dextran, each having distinct connectivity and configuration of the glycosidic bonds. Lastly, the method was successfully applied to analyze polysaccharides prepared from three medicinal mushrooms, namely Xylaria nigripes, Grifola frondosa, and Laetiporus sulphureus. The results showed that water-soluble non-digestible polysaccharides of X. nigripes and G. frondosa were mainly composed of (1→3)-ß-glucan, while that of L. sulphureus was composed of (1→3)-ɑ-glucan. The present method has the advantages of being simple in sample preparation and short analysis time.

A cold-water polysaccharide-protein complex from Grifola frondosa exhibited antiproliferative activity via mitochondrial apoptotic and Fas/FasL pathways in HepG2 cells.

Grifola frondosa (G. frondosa) is widely known for its anti-tumor potential, which has been demonstrated by numerous scientific researches. In this study, two water soluble polysaccharide-protein complexes were extracted from G. frondosa at 4 °C (GFG-4) and 100 °C (GFG-100) and purified. Compared with GFG-100, GFG-4 had a higher protein content and molecular weight. The main monosaccharides of GFG-4 and GFG-100 were rhamnose, glucose, and galactose, with an approximate ratio of 3.00: 1.00: 0.86 and 2.85: 1.00: 0.94, respectively. The Fourier transform infrared spectra indicated that the two polysaccharide-protein complexes displayed characteristic functional groups of polysaccharides and proteins, and mainly contain pyranose ring with α-glycosidic linkage. Atomic force microscope images showed that both GFG-4 and GFG-100 exhibited straight chains, and GFG-4 possessed a relatively abundant fraction of branched chains. Intriguingly, GFG-4 showed a stronger antiproliferative activity against HepG2 cells than GFG-100. The mechanisms were further investigated by quantitative real-time PCR and western blot, it found that GFG-4 inhibited the proliferation of HepG2 cells mainly through the intrinsic activation of mitochondrial pathway and the Fas/FasL-mediated Caspase-8/-3 pathway. Conclusively, G. frondosa cold-water extracted polysaccharide-protein complexes could be used as a functional food for preventing or treating hepatocellular carcinoma.

Current Advancements in Antitumor Properties and Mechanisms of Medicinal Components in Edible Mushrooms.

Edible and medicinal fungi, a group of eukaryotic organisms with numerous varieties, including Coriolus versicolor, Ganoderma lucidum, Cordyceps sinensis, Pleurotus ostreatus, and Grifola frondosa, have been demonstrated to possess a board range of pharmaceutical properties, including anti-virus, anti-inflammation, and neuroprotection. Moreover, edible and medicinal fungi have been traditionally consumed as food to provide multiple nutrients and as drugs owing to having the activities of invigorating blood circulation, reinforcing the healthy qi, clearing away heat, and eliminating stasis for thousands of years in China. Malignant tumors, well-known as the second leading cause of death globally, accounted for nearly 10 million deaths in 2020. Thus, in-depth exploration of strategies to prevent and treat cancer is extremely urgent. A variety of studies have reported that the main bioactive components of edible and medicinal fungi, mainly polysaccharides and triterpenoids, exhibit diverse anticancer activities via multiple mechanisms, including inhibition of cell proliferation and metastasis, induction of apoptosis and autophagy, reversing multidrug resistance, and regulation of immune responses, thus suggesting their substantial potential in the prevention and treatment of cancer. Our review summarizes the research progress on the anticancer properties of edible and medicinal fungi and the underlying molecular mechanism, which may offer a better understanding of this field. Additionally, few studies have reported the safety and efficacy of extracts from edible and medicinal fungi, which may limit their clinical application. In summary, there is a need to continue to explore the use of those extracts and to further validate their safety and efficacy.

Grifola frondosa Polysaccharide Ameliorates Early Diabetic Nephropathy by Suppressing the TLR4/NF-κB Pathway.

Grifola frondosa is a medicinal macro-fungus with a wide range of biological activities. Polysaccharides from Grifola frondosa (PGF) play a positive role in regulating blood glucose and alleviating kidney injury. Here, we investigated the exact mechanism of action by which PGF ameliorates diabetic nephropathy. Our results showed that PGF effectively improved glucose tolerance and insulin sensitivity in streptozocin (STZ)-induced DN mice. Additionally, administration of PGF also ameliorated renal function and inflammatory response in STZ-induced DN mice. Consistent with the in vitro results, the high glucose-induced inflammatory response and apoptosis of renal tubular epithelial cells were decreased by PGF treatment. Furthermore, PGF not only suppressed the expression of TLR4, but also more effectively protected the kidney and reduced the inflammatory response when TLR4 was inhibited. All these data revealed that PGF alleviates diabetic nephropathy by blocking the TLR4/NF-κB pathway.

Polysaccharides of Grifola frondosa ameliorate oxidative stress and hypercholesterolaemia in hamsters fed a high-fat, high-cholesterol diet.

OBJECTIVES: This study was to evaluate the antioxidant and anti-hypercholesterolaemia activities of Grifola frondosa in hamsters fed a high-fat, high-cholesterol (HFHC) diet. METHODS: G. frondosa, including fruiting bodies (FGF), fermented mycelia (MGF) and polysaccharides extracted from fruiting bodies (FPS), fermented mycelia (MIP) and fermented broth (BEP) were received intragastrically. Lipid profile and antioxidant status in the blood and liver of hamsters were assessed. KEY FINDINGS: FGF decreased weight gain, serum triglycerides and cholesterol and increased hepatic mRNA expression of cholesterol-7α-hydroxylase expression. FGF, MGF, FPS and MIP decreased the HFHC diet-increased area under the curve (AUC) of serum cholesterol. FGF and FPS further decreased AUC of serum triglycerides. When evaluating the redox status of erythrocytes, FPS and MIP increased non-protein sulfhydryl (NP-SH) groups, reduced glutathione (GSH) and catalase activity and FPS further increased GSH peroxidase activity. In the liver, MGF increased NP-SH groups and GSH and decreased triglycerides content. FPS, MIP and BEP decreased oxidized GSH and triglycerides content. Moreover, all treatments alleviated HFHC diet-increased LDL oxidation. CONCLUSIONS: Fruiting bodies of G. frondosa may improve hypercholesterolaemia via increased bile acid synthesis. Additionally, fermented biomass and polysaccharides of G. frondosa may have the potential to prevent hepatic lipid accumulation.

Fermentability of Maitake polysaccharides processed by various hydrothermal conditions and fermented with probiotic (Lactobacillus).

Maitake polysaccharides, after hydrothermal processing, were fermented with Lactobacillus acidophilus CCFM202 (L.A.) and Lactobacillus plantarum CCFM6392 (L.P.). The degradation of molecular weight of polysaccharides by hydrothermal processing under acidic conditions was obviously enhanced, which turned part of the water-insoluble-polysaccharides (WIP) into water-soluble-polysaccharides (WSPs). The pH value of water-soluble-polysaccharides (WSPs) and water-insoluble-polysaccharides (WIPs) were intensely dropped (4- 5) after 24 h fermentation. The optical density (O.D.) was increased (1.4- 2.3) due to bacterial growth, and short-chain fatty acids also followed this trend. LA-WSP predominantly produced acetic acid, 3- 4 folds to lactic acid, while LP-WIP groups produced dominant butyric acid (15- 17 folds). Hydrothermal processing induced the growth of L.A. and L.P., where the highest abundance was 2.5 × 104. From the Venn diagram, WSP-1 produced the most elevated metabolites (874). Therefore, experimental results show a significant impact on making WSPs fragments, whereas temperature and pH influence the WSPs degradation, withstand to higher fermentation efficacy.

Effects of alkaloid-rich extracts obtained from Grifola frondosa on gut microbiota and glucose homeostasis in rats.

Grifola frondosa (GF), also known as maitake (a type of mushroom), has been widely used as a food item and it exhibits various health-beneficial hypoglycemic activities. Rats fed with a fat/high-sucrose-based diet were used to determine the hypoglycemic activity of 95% and 55% GF ethanol extracts (labeled as GF95 and GF55, respectively). The activity was determined by monitoring the fasting blood glucose level. Oral glucose tolerance tests were conducted, and the levels of alanine aminotransferase and aspartate aminotransferase were studied to study the hypoglycemic activity. The HPLC-ESI-TOF-MS technique was used to analyze the samples, and the results revealed that alkaloids were present in abundance in GF95 and GF55. It was also observed that GF55 contained some organic acids and GF95 contained extra small amounts of phenoloid. The levels of intestinal microbiota were analyzed, and the results from transcriptome analysis indicated that GF55 reduced the relative abundance of Romboutsia and affected RT-Db1, thereby improving the extent of glucose metabolism achieved. GF95 downregulated the mRNA level of Socs1 by increasing the levels of Oscillibacter, Butyricimonas, Barnesiella, Turicibacter, Methanosphaera, Asaccharobacter, Globicatella, Bifidobacterium, Allobaculum, and Romboutsia. The expression of Pik3rl was upregulated when the levels of Ruminococcus and Saccharibacteria increased. The hypoglycemic activity was induced under these conditions. The obtained data indicated that the efficiency of GF95 to control glucose levels was higher than the efficiency of GF55. This suggested that GF95 can be potentially used to protect against hyperglycemia.

Purification and characterization of Se-enriched Grifola frondosa glycoprotein, and evaluating its amelioration effect on As3+ -induced immune toxicity.

BACKGROUND: Selenium (Se)-enriched glycoproteins have been a research highlight for the role of both Se and glycoproteins in immunoregulation. Arsenic (As) is a toxicant that is potentially toxic to the immune function and consequently to human health. Several reports suggested that Se could reduce the toxicity of heavy metals. Moreover, more and more nutrients in food had been applied to relieve As-induced toxicity. Hence glycoproteins were isolated and purified from Se-enriched Grifola frondosa, and their preliminary characteristics as well as amelioration effect and mechanism on As3+ -induced immune toxicity were evaluated. RESULTS: Four factions, namely Se-GPr11 (electrophoresis analysis exhibited one band: 14.32 kDa), Se-GPr22 (two bands: 20.57 and 31.12 kDa), Se-GPr33 (three bands: 15.08, 20.57 and 32.78 kDa) and Se-GPr44 (three bands: 16.73, 32.78 and 42.46 kDa), were obtained from Se-enriched G. frondosa via DEAE-52 and Sephacryl S-400 column. In addition, Se-GPr11 and Se-GPr44 are ideal proteins that contain high amounts of almost all essential amino acids. Thereafter, the RAW264.7 macrophage model was adopted to estimate the effect of Se-GPr11 and Se-GPr44 on As3+ -induced immune toxicity. The results showed that the pre-intervention method was the best consequent and the potential mechanisms were, first, by improving the oxidative stress state (enhancing the activity of superoxide dismutase and glutathione peroxidase, decreasing the levels of reactive oxygen species and malondialdehyde); secondly, through nuclear factor-κB and mitogen-activated protein kinase-mediated upregulation cytokines (interleukin-2 and interferon-γ) secretion induced by As3+ . CONCLUSION: The results suggested Se-enriched G. frondosa may be a feasible supplement to improve health level of the As3+ pollution population. © 2021 Society of Chemical Industry.

The ß-1,3-glucan synthase gene GFGLS2 plays major roles in mycelial growth and polysaccharide synthesis in Grifola frondosa.

ß-1,3-Glucans are well-known biological and health-promoting compounds in edible fungi. Our previous results characterized a glucan synthase gene (GFGLS) of Grifola frondosa for the first time to understand its role in mycelial growth and glucan biosynthesis. In the present study, we identified and functionally reannotated another glucan synthase gene, GFGLS2, based on our previous results. GFGLS2 had a full sequence of 5944 bp including 11 introns and 12 exons and a coding information for 1713 amino acids of a lower molecular weight (195.2 kDa) protein with different conserved domain sites than GFGLS (5927 bp with also 11 introns and a coding information for 1781 aa). Three dual-promoter RNA-silencing vectors, pAN7-iGFGLS-dual, pAN7-iGFGLS2-dual, and pAN7-CiGFGLS-dual, were constructed to downregulate GFGLS, GFGLS2, and GFGLS/GFGLS2 expression by targeting their unique exon sequence or conserved functional sequences. Silencing GFGLS2 resulted in higher downregulation efficiency than silencing GFGLS. Cosilencing GFGLS and GFGLS2 had a synergistic downregulation effect, with slower mycelial growth and glucan production by G. frondosa. These findings indicated that GFGLS2 plays major roles in mycelial growth and polysaccharide synthesis and provides a reference to understand the biosynthesis pathway of mushroom polysaccharides. KEY POINTS: • The 5944-bp glucan synthase gene GFGLS2 of G. frondosa was cloned and reannotated • GFGLS2 showed identity and significant differences with the previously identified GFGLS • GFGLS2 played a major role in fermentation and glucan biosynthesis.