An antioxidant hispidin from the mycelial cultures of Phellinus linteus

A Comprehensive Experimental and Theoretical Investigation of the Antioxidant Properties of Hispidin and Isohispidin

This study provides a comprehensive analysis of the antioxidant activity of hispidin (His) and its tautomer isohispidin (IsoH) using DFT calculations, corroborated by experimental data. Under physiological conditions, both tautomers demonstrated significant scavenging capacity for the HO• radical, with koverall ranging from 4.48 × 109 to 2.06 × 1010 M-1 s-1 in lipid media and 3.24 × 1010 M-1 s-1 in water. Mechanistic analysis revealed that the radical adduct formation (RAF) mechanism is dominant in lipid environments, whereas both RAF and single electron transfer (SET) operate nonselectively in water. Hispidin also exhibited strong scavenging capacity for the HOO• radical in water (koverall = 1.40 × 108 M-1 s-1), but its reactivity in lipid environments was comparatively lower, with koverall of 1.40 × 102 M-1 s-1 for His and 1.94 × 104 M-1 s-1 for IsoH. The f-HAT mechanism was identified as the predominant pathway in lipid media, while both f-HAT and SET contribute to HOO• scavenging in water. Additionally, hispidin demonstrated a strong ability to chelate copper(II) ions, effectively inhibiting HO• radical formation via the Fenton reaction. The theoretical results align well with the experimental data from the DPPH and ABTS assays, indicating that hispidin is a potent antioxidant under physiological conditions.

Cloning and Expression Analysis of Bioluminescence Genes in Omphalotus guepiniiformis Reveal Stress-Dependent Regulation of Bioluminescence

Bioluminescence is a type of chemiluminescence that arises from a luciferase-catalyzed oxidation reaction of luciferin. Molecular biology and comparative genomics have recently elucidated the genes involved in fungal bioluminescence and the evolutionary history of their clusters. However, most studies on fungal bioluminescence have been limited to observing the changes in light intensity under various conditions. To understand the molecular basis of bioluminescent responses in Omphalotus guepiniiformis under different environmental conditions, we cloned and sequenced the genes of hispidin synthase, hispidin-3-hydroxylase, and luciferase enzymes, which are pivotal in the fungal bioluminescence pathway. Each gene showed high sequence similarity to that of other luminous fungal species. Furthermore, we investigated their transcriptional changes in response to abiotic stresses. Wound stress enhanced the bioluminescence intensity by increasing the expression of bioluminescence pathway genes, while temperature stress suppressed the bioluminescence intensity via the non-transcriptional pathway. Our data suggested that O. guepiniiformis regulates bioluminescence to respond differentially to specific environmental stresses. To our knowledge, this is the first study on fungal bioluminescence at the gene expression level. Further studies are required to address the biological and ecological meaning of different bioluminescence responses in changing environments, and O. quepiniiformis could be a potential model species.

Hispidin-enriched Sanghuangporus sanghuang mycelia SS-MN4 ameliorate disuse atrophy while improving muscle endurance

BACKGROUND

Disuse atrophy is a frequent cause of muscle atrophy, which can occur in individuals of any age who have been inactive for a prolonged period or immobilization. Additionally, acute diseases such as COVID-19 can cause frequent sequelae and exacerbate muscle wasting, leading to additional fatigue symptoms. It is necessary to investigate potent functional nutrients for muscle reinforcement in both disuse atrophy and fatigue to ensure better physical performance.

METHODS

The effects of Sanghuangporus sanghuang SS-MN4 mycelia were tested on two groups of 6-week-old male mice-one with disuse atrophy and the other with fatigue. The disuse atrophy group was divided into three sub-groups: a control group, a group that underwent hind limb casting for 7 days and then recovered for 7 days and a group that was administered with SS-MN4 orally for 14 days, underwent hind limb casting for 7 days and then recovered for 7 days. The fatigue group was divided into two sub-groups: a control group that received no SS-MN4 intervention and an experimental group that was administered with SS-MN4 orally for 39 days and tested for exhaustive swimming and running on Day 31 and Day 33, respectively. RNA sequencing (RNA-seq) and western blot analysis were conducted on C2C12 cell lines to identify the therapeutic effects of SS-MN4 treatment.

RESULTS

In a disuse atrophy model induced by hind limb casting, supplementing with 250 mg/kg of SS-MN4 for 14 days led to 111.2% gastrocnemius muscle mass recovery and an 89.1% improvement in motor function on a treadmill (P < 0.05). In a fatigue animal model, equivalent SS-MN4 dosage improved swimming (178.7%) and running (162.4%) activities (P < 0.05) and reduced blood urea nitrogen levels by 18% (P < 0.05). SS-MN4 treatment also increased liver and muscle glycogen storage by 34.36% and 55.6%, respectively, suggesting a higher energy reserve for exercise. RNA-seq and western blot studies from the C2C12 myotube showed that SS-MN4 extract upregulates Myh4 and helps sustain myotube integrity against dexamethasone damage.

CONCLUSIONS

Supplementation of SS-MN4 (250-mg/kg body weight) with hispidin as active compound revealed a potential usage as a muscle nutritional supplement enhancing muscle recovery, fast-twitch fibre regrowth and fatigue resistance.

Heimionones A-E, New Sesquiterpenoids Produced by Heimiomyces sp., a Basidiomycete Collected in Africa

With heimionones A-E (1-5), five new terpenoids were isolated from submerged cultures of Heimiomyces sp. in addition to the previously described compounds hispidin, hypholomin B, and heimiomycins A and B. Planar structures of the metabolites were elucidated by 1D and 2D NMR in addition to HRESIMS data. While ROESY data assigned relative configurations, absolute configurations were determined by the synthesis of MTPA esters of 1, 3, and 5. The [6.3.0] undecane core structure of compounds 3-5 is of the asteriscane-type, however, the scaffold of 1 and 2 with their bicyclo [5.3.0] decane core and germinal methyl substitution is, to our knowledge, unprecedented. Together with several new compounds that were previously isolated from solid cultures of this strain, Heimiomyces sp. showed an exceptionally high chemical diversity of its secondary metabolite profile.

Calamene-Type Sesqui-, Mero-, and Bis-sesquiterpenoids from Cultures of Heimiomyces sp., a Basidiomycete Collected in Africa

New meroterpenoids bis-heimiomycins A-D (1-4) and heimiomycins D and E (5 and 6) were isolated from solid rice cultures of Heimiomyces sp., while new calamene-type sesquiterpenoids heimiocalamene A (7) and B (8) were isolated from shake cultures, respectively. Structures of the metabolites were elucidated by 1D and 2D NMR in addition to HRESIMS data. While relative configurations were assigned by ROESY data, absolute configurations were derived from the structurally related, previously described calamenes, which we herein name heimiocalamenes C-E (9-11). A plausible biosynthetic pathway was proposed for 1-6, with a radical reaction connecting their central para-benzoquinone building block to calamene-sesquiterpenoids. Based on the assumption of a common biosynthesis, we reviewed the structure of the known nitrogen-containing derivative 11, calling the validity of the originally proposed structure into question. Subsequently, the structure of 11 was revised by analysis of HMBC and ROESY NMR data. Only heimiomycin D (5) displayed cytotoxic effects against cell line KB3.1.

Hispidin in the Medicinal Fungus Protects Dopaminergic Neurons from JNK Activation-Regulated Mitochondrial-Dependent Apoptosis in an MPP+-Induced In Vitro Model of Parkinson's Disease

Degenerative diseases of the brain include Parkinson's disease (PD), which is associated with moveable signs and is still incurable. Hispidin belongs to polyphenol and originates primarily from the medicinal fungi Inonotus and Phellinus, with distinct biological effects. In the study, MES23.5 cells were induced by 1-methyl-4-phenylpyridinium (MPP⁺) to build a cell model of PD in order to detect the protective effect of hispdin and to specify the underlying mechanism. Pretreatment of MES23.5 cells with 1 h of hispdin at appropriate concentrations, followed by incubation of 24 h with 2 μmol/L MPP⁺ to induce cell damage. MPP⁺ resulted in reactive oxygen species production that diminished cell viability and dopamine content. Mitochondrial dysfunction in MS23.5 cells exposed to MPP⁺ was observed, indicated by inhibition of activity in the mitochondrial respiratory chain complex I, the collapse of potential in mitochondrial transmembrane, and the liberation of mitochondrial cytochrome c. Enabling C-Jun N-terminal kinase (JNK), reducing Bcl-2/Bax, and enhancing caspase-9/caspase-3/PARP cleavage were also seen by MPP⁺ induction associated with increased DNA fragmentation. All of the events mentioned above associated with MPP⁺-mediated mitochondrial-dependent caspases cascades were attenuated under cells pretreatment with hispidin (20 µmol/L); similar results were obtained during cell pretreatment with pan-JNK inhibitor JNK-IN-8 (1 µmol/L) or JNK3 inhibitor SR3576 (25 µmol/L). The findings show that hispidin has neuroprotection against MPP⁺-induced mitochondrial dysfunction and cellular apoptosis and suggest that hispidin can be seen as an assist in preventing PD.

RAGE Inhibitors for Targeted Therapy of Cancer: A Comprehensive Review

The receptor for advanced glycation end products (RAGE) is a member of the immunoglobulin family that is overexpressed in several cancers. RAGE is highly expressed in the lung, and its expression increases proportionally at the site of inflammation. This receptor can bind a variety of ligands, including advanced glycation end products, high mobility group box 1, S100 proteins, adhesion molecules, complement components, advanced lipoxidation end products, lipopolysaccharides, and other molecules that mediate cellular responses related to acute and chronic inflammation. RAGE serves as an important node for the initiation and stimulation of cell stress and growth signaling mechanisms that promote carcinogenesis, tumor propagation, and metastatic potential. In this review, we discuss different aspects of RAGE and its prominent ligands implicated in cancer pathogenesis and describe current findings that provide insights into the significant role played by RAGE in cancer. Cancer development can be hindered by inhibiting the interaction of RAGE with its ligands, and this could provide an effective strategy for cancer treatment.

Cultivation of Inonotus hispidus in Stirred Tank and Wave Bag Bioreactors to Produce the Natural Colorant Hispidin

Hispidin (6-(3,4-dihydroxystyrl)-4-hydroxy-2-pyrone) production in submerged cultured mycelia of the basidiomycete Inonotus hispidus was doubled in shake flasks through irradiation with white light. The daily addition of 1 mM hydrogen peroxide as a chemical stressor and a repeated supplementation of the shake flask cultures with 2 mM caffeic acid, a biogenetic precursor, further increased the hispidin synthesis. These cultivation conditions were combined and applied to parallel fermentation trials on the 4 L scale using a classical stirred tank bioreactor and a wave bag bioreactor. No significant differences in biomass yield and colorant production were observed. The hispidin concentration in both bioreactors reached 5.5 g·L−1, the highest ever published. Textile dyeing with hispidin was successful, but impeded by its limited light stability in comparison to industrial dyes. However, following the idea of sustainability and the flawless toxicity profile, applications in natural cosmetics, other daily implements, or even therapeutics appear promising.

Styrylpyrones from Phellinus linteus Mycelia Alleviate Non-Alcoholic Fatty Liver by Modulating Lipid and Glucose Metabolic Homeostasis in High-Fat and High-Fructose Diet-Fed Mice

Phellinus linteus (PL), an edible and medicinal mushroom containing a diversity of styrylpyrone-type polyphenols, has been shown to have a broad spectrum of bioactivities. In this study, the submerged liquid culture in a 1600-L working volume of fermentor was used for the large-scale production of PL mycelia. Whether PL mycelia extract is effective against nonalcoholic fatty liver disease (NAFLD) is still unclear. In the high fat/high fructose diet (HFD)-induced NAFLD C57BL/6 mice study, the dietary supplementation of ethyl acetate fraction from PL mycelia (PL-EA) for four weeks significantly attenuated an increase in body weight, hepatic lipid accumulation and fasting glucose levels. Mechanistically, PL-EA markedly upregulated the pgc-1α, sirt1 genes and adiponectin, downregulated gck and srebp-1c; upregulated proteins PPARγ, pAMPK, and PGC-1α, and downregulated SREBP-1 and NF-κB in the liver of HFD-fed mice. Furthermore, the major purified compounds of hispidin and hypholomine B in PL-EA significantly reduced the level of oleic and palmitic acids (O/P)-induced lipid accumulation through the inhibition of up-regulated lipogenesis and the energy-metabolism related genes, ampk and pgc-1α, in the HepG2 cells. Consequently, these findings suggest that the application of PL-EA is deserving of further investigation for treating NAFLD.

Pilot Study: Nutritional and Preclinical Safety Investigation of Fermented Hispidin-Enriched Sanghuangporus sanghuang Mycelia: A Promising Functional Food Material to Improve Sleep

Sleep disturbances have been the hallmark of the recent coronavirus disease 2019 pandemic. Studies have shown that once sleep is disrupted, it can lead to psychological and physical health issues which can, in turn, disrupt circadian rhythm and induce further sleep disruption. As consumers are trying to establish healthy routines, nutritional and preclinical safety investigation of fermented hispidin-enriched Sanghuangporus sanghuang mycelia (GKSS) as a novel food material for spontaneous sleep in Sprague-Dawley rats is conducted for the first time. Results showed that the nutritional analysis of GKSS including moisture, ash, crude lipid, crude protein, carbohydrate, and energy were found to be 2.4 ± 0.3%, 8.0 ± 2.5%, 1.7 ± 0.3%, 22.9 ± 1.2%, 65.1 ± 3.1%, and 367.1 ± 10.2 kcal/100 g respectively. In the 28-day repeated-dose oral toxicity study, only Sprague-Dawley male rats receiving 5 g/kg showed a slight decrease in feed consumption at week 3, but no associated clinical signs of toxicity or significant weight loss were observed. Although a significant reduction of the platelet count was found in mid- and high-dose GKSS treated male groups, such changes were noted to be within the normal range and were not correlated with relative spleen weight changes. Hence, the no observed adverse effect level (NOAEL) of GKSS was identified to be higher than 5 g/kg in rats. After the safety of GKSS is confirmed, the sleep-promoting effect of GKSS ethanolic extract enriched with hispidin was further assessed. Despite 75 mg/kg of GKSS ethanolic extract does not affect wakefulness, rapid eye movement (REM) sleep and non-REM (NREM) sleep, GKSS ethanolic extract at 150 mg/kg significantly decreased wakefulness and enhanced NREM and REM sleep. Interestingly, such effects seem to be mediated through anti-inflammatory activities via NF-E2-related factor-2 (Nrf2) signaling pathway. Taken together, these findings provide the preliminary evidence to studies support the claims suggesting that GKSS contained useful phytochemical hispidin could be considered as and is safe to use as a functional food agent or nutraceutical for relieving sleep problems mediated by Nrf2 pathway, which the results are useful for future clinical pilot study.

Hispidin, Harmaline, and Harmine as potent inhibitors of bovine xanthine oxidase: Gout treatment, in vitro, ADMET prediction, and SAR studies

Alkaloids and phenols are potent inhibitors family for many enzymes used in many therapies. We aim to evaluate in vitro and in silico, the inhibition effect of Hispidin, Harmaline, and Harmine as pure molecules to bovine milk xanthine oxidase (BXO), Molecular docking and SAR study with GOLD was done to explain the mechanism of action related to its inhibition, ADMET parameters were checked to confirm their pharmacokinetics (PK) using preADMET 2.0 server, we classified our inhibitors by applying five drug-likeness rules, the best-ranked inhibitors were chosen based on the approved ADMET properties, drug-likeness qualifications, and the best PLPchem score generated by GOLD. The in vitro results show important inhibition activity to BXO comparing to the control with an IC50 of 39.72 ± 3.60 µM, 51.00 ± 1.0 µM, and 48.52 ± 1.76 µM for Hispidin, Harmaline, and Harmine respectively. The in silico results show that Hispidin was the best inhibitor model with approved ADMET properties and qualification in all drug-likeness rules; Harmaline was saved second-best model to BXO with suitable ADMET properties and qualified in most drug-likeness rules. Eventually, Harmine was ranked third potent inhibitor model with acceptable ADMET properties, drug-likeness rules, and PLPchem score. The tested inhibitors could be significant in drug discovery, especially in treating gout disease; therefore, drug development, including clinical trials, should be done with promising results.

Therapeutic Potential of Hispidin-Fungal and Plant Polyketide

There is a large number of bioactive polyketides well-known for their anticancer, antibiotic, cholesterol-lowering, and other therapeutic functions, and hispidin is among them. It is a highly abundant secondary plant and fungal metabolite, which is investigated in research devoted to cancer, metabolic syndrome, cardiovascular, neurodegenerative, and viral diseases. This review summarizes over 20 years of hispidin studies of its antioxidant, anti-inflammatory, anti-apoptotic, antiviral, and anti-cancer cell activity.

A comprehensive review on phenolic compounds from edible mushrooms: Occurrence, biological activity, application and future prospective

Phenolic compounds are minor metabolites usually present in mushroom species. Because of their potential advantages for human health, such as antioxidant and other biological activities, these bioactive components have been gaining more interest as functional foods, nutraceutical agents for providing better health conditions. This review aims to comprehensively discuss the recent advances in mushroom phenolic compounds, including new sources, structural characteristics, biological activities, potential uses and its industrial applications as well as the future perspectives. Phenolic acids as well as flavonoids are considered the most common phenolics occurring in mushroom species. These are responsible for its bioactivities, including antioxidant, anti-inflammatory, antitumor, antihyperglycaemic, antiosteoporotic, anti-tyrosinase and antimicrobial activities. Several edible mushroom species with good phenolic content and show higher biological activity were highlighted, in a way for its futuristic applications. Trends on mushroom research highlighting new research areas, such as nanoformulation were discussed. Furthermore, the use of phenolic compounds as nutraceutical and cosmeceutical agents as well as the future perspectives and recommendations were made.

Screening for proteins related to the biosynthesis of hispidin and its derivatives in Phellinus igniarius using iTRAQ proteomic analysis

Background

Hispidin (HIP) and its derivatives, a class of natural fungal metabolites, possess complex chemical structures with extensive pharmacological activities. Phellinus igniarius, the most common source of HIP, can be used as both medicine and food. However, the biosynthetic pathway of HIP in P. igniarius remains unclear and we have a limited understanding of the regulatory mechanisms related to HIP. In this work, we sought to illustrate a biosynthesis system for hispidin and its derivatives at the protein level.

Results

We found that tricetolatone (TL) is a key biosynthetic precursor in the biosynthetic pathway of hispidin and that its addition led to increased production of hispidin and various hispidin derivatives. Based on the changes in the concentrations of precursors and intermediates, key timepoints in the biosynthetic process were identified. We used isobaric tags for relative and absolute quantification (iTRAQ) to study dynamic changes of related proteins in vitro. The 270 differentially expressed proteins were determined by GO enrichment analysis to be primarily related to energy metabolism, oxidative phosphorylation, and environmental stress responses after TL supplementation. The differentially expressed proteins were related to ATP synthase, NAD binding protein, oxidoreductase, and other elements associated with electron transfer and dehydrogenation reactions during the biosynthesis of hispidin and its derivatives. Multiple reaction monitoring (MRM) technology was used to selectively verify the iTRAQ results, leading us to screen 11 proteins that were predicted to be related to the biosynthesis pathways.

Conclution

These findings help to clarify the molecular mechanism of biosynthesis of hispidin and its derivatives and may serve as a foundation for future strategies to identify new hispidin derivatives.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02134-0.

Natural Products Targeting Amyloid Beta in Alzheimer's Disease

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by severe brain damage and dementia. There are currently few therapeutics to treat this disease, and they can only temporarily alleviate some of the symptoms. The pathogenesis of AD is mainly preceded by accumulation of abnormal amyloid beta (Aβ) aggregates, which are toxic to neurons. Therefore, modulation of the formation of these abnormal aggregates is strongly suggested as the most effective approach to treat AD. In particular, numerous studies on natural products associated with AD, aiming to downregulate Aβ peptides and suppress the formation of abnormal Aβ aggregates, thus reducing neural cell death, are being conducted. Generation of Aβ peptides can be prevented by targeting the secretases involved in Aβ-peptide formation (secretase-dependent). Additionally, blocking the intra- and intermolecular interactions of Aβ peptides can induce conformational changes in abnormal Aβ aggregates, whereby the toxicity can be ameliorated (structure-dependent). In this review, AD-associated natural products which can reduce the accumulation of Aβ peptides via secretase- or structure-dependent pathways, and the current clinical trial states of these products are discussed.

The phytochemistry and pharmacology of medicinal fungi of the genus Phellinus: a review

Phellinus Quél is one of the largest genera of Hymenochaetaceae, which is comprised of about 220 species. Most Phellinus macro-fungi are perennial lignicolous mushrooms, which are widely distributed on Earth. Some Phellinus fungi are historically recorded as traditional medicines used to treat various diseases in eastern Asian countries, especially China, Japan and Korean. Previous phytochemical studies have revealed that Phellinus fungi produce diverse secondary metabolites, which mainly contain polysaccharides, flavones, coumarins, terpenes, steroids, and styrylpyranones. Pharmacological documents have demonstrated that Phellinus mushrooms and their compounds have a variety of bioactivities, such as anti-tumor, immunomodulation, anti-oxidative and anti-inflammation, anti-diabetes, neuro-protection, and anti-viral effects. This review surveys the literature reporting the isolation, characterization, and bioactivities of secondary metabolites from the fungi of the genus Phellinus, focusing on studies published in the literature up to April 2020. Herein, a total of more than 300 compounds from 13 Phellinus species and their isolation, characterization, chemistry, pharmacological activities, and relevant molecular mechanisms are comprehensively summarized.

Role and Mechanisms of RAGE-Ligand Complexes and RAGE-Inhibitors in Cancer Progression

Interactions of the receptor for advanced glycation end product (RAGE) and its ligands in the context of their role in diabetes mellitus, inflammation, and carcinogenesis have been extensively investigated. This review focuses on the role of RAGE-ligands and anti-RAGE drugs capable of controlling cancer progression. Different studies have demonstrated interaction of RAGE with a diverse range of acidic (negatively charged) ligands such as advanced glycation end products (AGEs), high-mobility group box1 (HMGB1), and S100s, and their importance to cancer progression. Some RAGE-ligands displayed effects on anti- and pro-apoptotic proteins through upregulation of the phosphatidylinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR), mitogen-activated protein kinases (MAPKs), matrix metalloproteinases (MMPs), vascular endothelial growth factor (VEGF), and nuclear factor kappa B (NF-κB) pathways, while downregulating p53 in cancer progression. In addition, RAGE may undergo ligand-driven multimodal dimerization or oligomerization mediated through self-association of some of its subunits. We conclude our review by proposing possible future lines of study that could result in control of cancer progression through RAGE inhibition.

Optimized production and safety evaluation of hispidin-enriched Sanghuangporus sanghuang mycelia

Phellinus linteus, also known as the sanghuang mushroom, is a medicinal mushroom that has been recognized as beneficial to health for more thousands of years. Among its diverse valuable secondary metabolites, the yellow-brown styrylpyrone pigment hispidin has garnered significant attention due to its various pharmacological effects. However, recently after detailed morphological and molecular phylogenetic studies, the correct scientific name of the true sanghuang strains was shown not to be P. linteus but Sanghuangporus sanghuang. As the incorrect binomial name P. linteus has long been misleadingly referred, there is a need to evaluate the safety of S. sanghuang. Moreover, the growing conditions can impact the secondary metabolite profile of the fungi. Hence, this study is the first to optimize hispidin production and to investigate the genotoxic and oral toxic effects of hispidin-enriched S. sanghuang mycelia. In order to induce the biosynthesis of hispidin, 15 different culture media consisting of five carbon sources, five nitrogen sources, and five initial pH conditions were screened. Glucose and yeast extract at an initial pH of 5 were found to be the most suitable carbon and nitrogen sources, respectively, for the optimal growth and production of hispidin. Moreover, the production of hispidin was 3 mg/g in a 20-ton bioreactor under optimal conditions. Furthermore, the ames test, in vitro chromosome aberration test, acute oral toxicity test, and bone marrow micronucleus test were used to detect toxicological properties of 3 mg/g hispidin-enriched S. sanghuang mycelia. In all tests, there was no statistically significant difference between the mycelia and the negative control. Based on the results obtained, the present study demonstrates that 3 mg/g hispidin-enriched S. sanghuang mycelia has a very low order of toxicity, which supports its safety for human consumption.

The Protective Effect of Hispidin against Hydrogen Peroxide-Induced Oxidative Stress in ARPE-19 Cells via Nrf2 Signaling Pathway

Hispidin, a polyphenol compound isolated from Phellinus linteus, has been reported to possess antioxidant activities. In this study, we aimed to investigate the mechanisms underlying the protective effect of hispidin against hydrogen peroxide (H₂O₂)-induced oxidative stress on Adult Retinal Pigment Epithelial cell line-19 (ARPE-19) cells. Hispidin was not cytotoxic to ARPE-19 cells at concentrations of less than 50 μM. The levels of intracellular reactive oxygen species (ROS) were analyzed by dichlorofluorescin diacetate (DCFDA) staining. Hispidin significantly restored H₂O₂-induced cell death and reduced the levels of intracellular ROS. The expression levels of antioxidant enzymes, such as NAD(P)H:Quinine oxidoreductase-1 (NQO-1), heme oxygenase-1 (HO-1), glutamate-cysteine ligase catalytic subunit (GCLC), and glutamate-cysteine ligase modifier subunit (GCLM) were examined using real-time PCR and Western blotting. Our results showed that hispidin markedly enhanced the expression of nuclear factor erythroid 2-related factor 2 (Nrf2), HO-1, NQO-1, GCLM, and GCLC in a dose-dependent manner. Furthermore, knockdown experiments revealed that transfection with Nrf2 siRNA successfully suppresses the hispidin activated Nrf2 signaling in ARPE-19 cells. Moreover, activation of the c-Jun N-terminal kinase (JNK) pathway is involved in mediating the protective effects of hispidin on the ARPE-19 cells. Thus, the present study demonstrated that hispidin provides protection against H₂O₂-induced damage in ARPE-19 cells via activation of Nrf2 signaling and up-regulation of its downstream targets, including Phase II enzymes, which might be associated with the activation of the JNK pathway.

Structural characterization of two endopolysaccharides from Phellinus sp. and their immunologic effects by intragastric administration in a healthy mammalian model

Two purified endopolysaccharides derived from cultured Phellinus sp., individually named SHIP-1 and 2, were structurally characterized, along with an evaluation of their in vivo influential immunomodulatory activity in a healthy mammalian model. The structure of SHIP-1 was mainly composed of →4)-α-d-Fucp-(1→, →3,6)-α-d-Araf-(1→ and →2,4)-β-d-Galp-(→, with four residuals of α-d-Manp-(1→ and one α-d-Glcp-(1→ as sidegroups, while the planar structure and the heteronuclear multiple-bond correlation of SHIP-2 were not able to be analyzed. Biochemical analysis in the healthy mice model demonstrated that SHIP-1 increased the concentrations of the detected cytokines in a dosage-dependent manner but not in a time-dependent way. SHIP-2 exerted a positive effect in a dose-dependent manner over time for interferon gamma (IFN-γ) and interleukin (IL)-2 cytokine production at elevated dosages of 200, or 350 mg kg^-1 d^-1, while IFN-alpha(α) and IL-4 production was observed only in a dosage-dependent manner even at high dosages. Thus, SHIP-1 and 2 significantly improved the immune response through the intragastric administration of the tested high dosages by increasing the production of cytokines in the healthy mice, and these polysaccharides could possibly be used as an immunopotentiator in health foods or dietary supplements.

Protective Effects and Possible Mechanisms of Ergothioneine and Hispidin against Methylglyoxal-Induced Injuries in Rat Pheochromocytoma Cells

Diabetic encephalopathy (DE) is often a complication in patients with Alzheimer's disease due to high blood sugar induced by diabetic mellitus. Ergothioneine (EGT) and hispidin (HIP) are antioxidants present in Phellinus linteus. Methylglyoxal (MGO), a toxic precursor of advanced glycated end products (AGEs), is responsible for protein glycation. We investigated whether a combination EGT and HIP (EGT + HIP) protects against MGO-induced neuronal cell damage. Rat pheochromocytoma (PC12) cells were preincubated with EGT (2 μM), HIP (2 μM), or EGT + HIP, then challenged with MGO under high-glucose condition (30 μM MGO + 30 mM glucose; GLU + MGO) for 24–96 h. GLU + MGO markedly increased protein carbonyls and reactive oxygen species in PC12 cells; both of these levels were strongly reduced by EGT or HIP with effects comparable to those of 100 nM aminoguanidine (an AGE inhibitor) but stronger than those of 10 μM epalrestat (an aldose reductase inhibitor). GLU + MGO significantly increased the levels of AGE and AGE receptor (RAGE) protein expression of nuclear factor kappa-B (NF-κB) in the cytosol, but treatment with EGT, HIP, or EGT + HIP significantly attenuated these levels. These results suggest that EGT and HIP protect against hyperglycemic damage in PC12 cells by inhibiting the NF-κB transcription pathway through antioxidant activities.

Traditional uses, fermentation, phytochemistry and pharmacology of Phellinus linteus: A review

Medicinal mushroom Phellinus linteus ("Sanghuang" in Chinese, ) is a famous fungus which is widely used in China, Korea, and other Asian countries. As a traditional Chinese medicine with a 2000-year long history, medicinal applications of Phellinus linteus mainly include treating hemorrhage, hemostasis and diseases related to female menstruation according to Chinese clinical empirical practice. A number of studies reported Phellinus linteus possessed good therapeutic effects on various ailments including tumor, diabetes, inflammation, obesity, etc. The present paper comprehensively reviewed the traditional uses, fermentation, constituent and pharmacology of Phellinus linteus based on scientific literature as well as critical analysis of the research. This review aimed to provide latest information and new foundations and directions for further investigations on Phellinus linteus. All available information about Phellinus linteus was supplied by library database and electronic search (CNKI, Google Scholar, ScienceDirect, Web of Science, PubMed, etc.). Some local and ancient books as well as brilliant scholars were also important information resources. Improvement of fermentation techniques promoted the production of Phellinus linteus. Studies of constituents showed the main chemical composition of Phellinus linteus included polysaccharides, flavones, triterpenes, aromatic acids, amino acids, etc. and polysaccharides were found to account for the largest proportion. Pharmacological researches revealed Phellinus linteus possessed a variety of biological activities including anti-cancer, immuno-regulation, anti-diabetes, anti-oxidation and anti-inflammation. Based on these summarized information, this review was presented to provide helpful references and beneficial directions for future studies of Phellinus linteus.

Structural characterization and anti-aging activity of a novel extracellular polysaccharide from fungus Phellinus sp. in a mammalian system

Little is known about the chemical structure of purified extracellular polysaccharides from Phellinus sp., a fungal species with known medicinal properties. A combination of IR spectroscopy, methylation analysis and NMR were performed for the structural analysis of a purified extracellular polysaccharide derived from Phellinus sp. culture, denoted as SHP-1, along with an evaluation of the anti-aging effect in vivo of the polysaccharide supplementation. The structure of SHP-1 was established, with a backbone composed of →2,4)-α-d-glucopyranose-(1→ and →2)-β-d-mannopyranose-(1→ and two terminal glucopyranose branches. Biochemical analysis from mammalian animal experiments demonstrated that SHP-1 possesses the ability to enhance antioxidant enzyme activities, such as catalase (CAT) and superoxide dismutase (SOD) activities, Trolox equivalent antioxidant capacity (TEAC) in serum of d-galactose-aged mice, while reducing lipofuscin levels, another indicator of cell aging, indicating a potential association with anti-aging activities in a dose dependent manner. This compound had a favourable influence on immune organ indices, and a marked amelioration ability of histopathological hepatic lesions such as necrosis, karyolysis and reduced inflammation and apoptosis in mouse hepatocytes. These results suggest that SHP-1 has strong antioxidant activities and a significant protective effect against oxidative stress or hepatotoxicity induced by d-galactose in mice and it could be developed as a food ingredient or a pharmaceutical to prevent many age-associated diseases such as major depressive disorder and hepatotoxicity. To our knowledge, this is the first report on the antioxidant effects of a novel purified exopolysaccharide derived from Phellinus sp.

Therapeutic potential of culinary-medicinal mushrooms for the management of neurodegenerative diseases: diversity, metabolite, and mechanism

Mushrooms have long been used not only as food but also for the treatment of various ailments. Although at its infancy, accumulated evidence suggested that culinary-medicinal mushrooms may play an important role in the prevention of many age-associated neurological dysfunctions, including Alzheimer's and Parkinson's diseases. Therefore, efforts have been devoted to a search for more mushroom species that may improve memory and cognition functions. Such mushrooms include Hericium erinaceus, Ganoderma lucidum, Sarcodon spp., Antrodia camphorata, Pleurotus giganteus, Lignosus rhinocerotis, Grifola frondosa, and many more. Here, we review over 20 different brain-improving culinary-medicinal mushrooms and at least 80 different bioactive secondary metabolites isolated from them. The mushrooms (either extracts from basidiocarps/mycelia or isolated compounds) reduced beta amyloid-induced neurotoxicity and had anti-acetylcholinesterase, neurite outgrowth stimulation, nerve growth factor (NGF) synthesis, neuroprotective, antioxidant, and anti-(neuro)inflammatory effects. The in vitro and in vivo studies on the molecular mechanisms responsible for the bioactive effects of mushrooms are also discussed. Mushrooms can be considered as useful therapeutic agents in the management and/or treatment of neurodegeneration diseases. However, this review focuses on in vitro evidence and clinical trials with humans are needed.

Anti-inflammatory activity of mushroom-derived hispidin through blocking of NF-κB activation

BACKGROUND

Hispidin, a polyphenol compound mainly derived from the valuable medicinal mushroom Phellinus species, has been found to possess distinct biological effects. However, the anti-inflammatory potential of hispidin still remains uncharacterized.

RESULTS

In this study, the effects of hispidin on activation of nuclear factor kappa B (NF-κB) and the subsequent production of inducible nitric oxide synthase (iNOS) were determined in the lipopolysaccharide (LPS)-induced macrophage RAW 264.7 cells. Our data indicated that hispidin inhibits transcriptional activity of NF-κB in a dose-dependent manner. Hispidin also attenuated LPS-induced NF-κB nuclear translocation and associated inhibitor of kappa B (IκB-α) degradation. Furthermore, hispidin deceased iNOS protein expression and the generation of reactive oxygen species (ROS) in the LPS-induced cells, but did not affect phosphorylation of mitogen-activated protein kinases.

CONCLUSION

These findings suggest that hispidin exhibits anti-inflammatory activity through suppressing ROS mediated NF-κB pathway in mouse macrophage cells.

Cytoprotective effect of hispidin against palmitate-induced lipotoxicity in C2C12 myotubes

It is well known that Phellinus linteus, which produces hispidin and its derivatives, possesses antioxidant activities. In this study, we investigated whether hispidin has protective effects on palmitate-induced oxidative stress in C2C12 skeletal muscle cells. Our results showed that palmitate treatment in C2C12 myotubes increased ROS generation and cell death as compared with the control. However, pretreatment of hispidin for 8 h improved the survival of C2C12 myotubes against palmitate-induced oxidative stress via inhibition of intracellular ROS production. Hispidin also inhibited palmitate-induced apoptotic nuclear condensation in C2C12 myotubes. In addition, we found that hispidin can suppress cleavage of caspase-3, expression of Bax, and NF-κB translocation. Therefore, these results suggest that hispidin is capable of protecting C2C12 myotubes against palmitate-induced oxidative stress.

Separation and purification of the antioxidant compound hispidin from mushrooms by molecularly imprinted polymer

A new molecularly imprinted polymer (MIP), prepared by hispidin as the template molecule, was synthesized and applied as an adsorbent phase for solid phase extraction (SPE) to isolate and enrich hispidin from eight species of mushrooms. The optimization of synthesis and the adsorption behaviors of the MIPs were investigated in detail. In comparison with C18-SPE, MIP-SPE displayed high selectivity and good affinity for hispidin for extract of Phellinus igniarius. The antioxidant activity of the extracts after using the MIPs was evaluated by free radical scavenging activity, and inhibition of erythrocyte hemolysis, and lipid peroxidation. This developed method provided a rapid, selective, and effective approach for separation and enrichment of active compounds from the natural products.

Correlation of nitric oxide produced by an inducible nitric oxide synthase-like protein with enhanced expression of the phenylpropanoid pathway in Inonotus obliquus cocultured with Phellinus morii

Fungal interspecific interactions enhance biosynthesis of phenylpropanoid metabolites (PM), and production of nitric oxide (NO) is known to be involved in this process. However, it remains unknown which signaling pathway(s) or regulator(s) mediate fungal PM biosynthesis. In this study, we cocultured two white-rot fungi, Inonotus obliquus and Phellinus morii, to examine NO production, expression of the genes involved in phenylpropanoid metabolism and accumulation of phenylpropanoid-derived polyphenols by I. obliquus. Coculture of the two fungi caused an enhanced NO biosynthesis followed by increased transcription of the genes encoding phenylalanine ammonia lyase (PAL) and 4-coumarate CoA ligase (4CL), as well as an upregulated biosynthesis of styrylpyrone polyphenols in I. obliquus. Addition of the NO synthase (NOS) selective inhibitor aminoguanidine (AG) inhibited NO production by more than 90% followed by cease in transcription of PAL and 4Cl. Treatment of guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one did not affect NO production but suppressed transcription of PAL and 4CL and reduced accumulation of total phenolic constituents. Genome-wide analysis of I. obliquus revealed two genes encoding a constitutive and an inducible NOS-like protein, respectively (cNOSL and iNOSL). Coculture of the two fungi did not increase the expression of the cNOSL gene but triggered expression of the iNOSL gene. Cloned iNOSL from Escherichia coli shows higher activity in transferring L-arginine to NO, and this activity is lost upon AG addition. Thus, iNOSL is more responsible for NO production in I. obliquus and may act as an important regulator governing PM production during fungal interspecific interactions.

Anti-obesity effects of hispidin and Alpinia zerumbet bioactives in 3T3-L1 adipocytes

Obesity and its related disorders have become leading metabolic diseases. In the present study, we used 3T3-L1 adipocytes to investigate the anti-obesity activity of hispidin and two related compounds that were isolated from Alpinia zerumbet (alpinia) rhizomes. The results showed that hispidin, dihydro-5,6-dehydrokawain (DDK), and 5,6-dehydrokawain (DK) have promising anti-obesity properties. In particular, all three compounds significantly increased intracellular cyclic adenosine monophosphate (cAMP) concentrations by 81.2% ± 0.06%, 67.0% ± 1.62%, and 56.9% ± 0.19%, respectively. Hispidin also stimulated glycerol release by 276.4% ± 0.8% and inhibited lipid accumulation by 47.8% ± 0.16%. Hispidin and DDK decreased intracellular triglyceride content by 79.5% ± 1.37% and 70.2% ± 1.4%, respectively, and all three compounds inhibited glycerol-3-phosphate dehydrogenase (GPDH) and pancreatic lipase, with hispidin and DDK being the most potent inhibitors. Finally, none of the three compounds reduced 3T3-L1 adipocyte viability. These results highlight the potential for developing hispidin and its derivatives as anti-obesity compounds.

Progress on understanding the anticancer mechanisms of medicinal mushroom: inonotus obliquus

Cancer is a leading cause of death worldwide. Recently, the demand for more effective and safer therapeutic agents for the chemoprevention of human cancer has increased. As a white rot fungus, Inonotus obliquus is valued as an edible and medicinal resource. Chemical investigations have shown that I. obliquus produces a diverse range of secondary metabolites, including phenolic compounds, melanins, and lanostane-type triterpenoids. Among these are active components for antioxidant, antitumoral, and antiviral activities and for improving human immunity against infection of pathogenic microbes. Importantly, their anticancer activities have become a hot recently, but with relatively little knowledge of their modes of action. Some compounds extracted from I. obliquus arrest cancer cells in the G0/G1 phase and then induce cell apoptosis or differentiation, whereas some examples directly participate in the cell apoptosis pathway. In other cases, polysaccharides from I. obliquus can indirectly be involved in anticancer processes mainly via stimulating the immune system. Furthermore, the antioxidative ability of I. obliquus extracts can prevent generation of cancer cells. In this review, we highlight recent findings regarding mechanisms underlying the anticancer influence of I. obliquus, to provide a comprehensive landscape view of the actions of this mushroom in preventing cancer.

Chemical analysis and antioxidant activity of polysaccharides extracted from Inonotus obliquus sclerotia

Three water-soluble polysaccharide fractions (IOP40, IOP60 and IOP80) were isolated by using different concentrations of alcohol precipitation from Inonotus obliquus sclerotia. Their physicochemical properties, including total sugar content, protein content, monosaccharide composition and percentage were analyzed. And their in vitro antioxidant capacities were investigated in terms of reducing power assay and scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals, hydroxyl radicals, superoxide anion radicals and hydrogen peroxide (H2O2). In general, three polysaccharide fractions exhibited increasing antioxidant activity with increasing concentration at the ranges of tested dosage. The orders of reducing power, DPPH-scavenging capacity, H2O2-scavenging capacity, and hydroxyl-scavenging activity were all IOP60>IOP40>IOP80. These findings demonstrated that three polysaccharide fractions extracted from I. obliquus, especially IOP60, could be employed as natural ingredients in functional food and pharmaceutical industry to alleviate the oxidative stress.

Phaeolschidins A-E, five hispidin derivatives with antioxidant activity from the fruiting body of Phaeolus schweinitzii collected in the Tibetan Plateau

Five new hispidin derivatives, phaeolschidins A-E (1-5), as well as two known natural products, pinillidine (6) and hispidin (7), were isolated from the fruiting bodies of Phaeolus schweinitzii collected in the Tibetan Plateau. The structures of the new compounds were elucidated by spectroscopic methods. Phaeolschidins A-D (1-4) are new bishispidins. Phaeolschidin E (5) is a new class of hispidin derivative in which one pyrrolidin-2-one moiety was linked to C-3 of hispidin. The antioxidant activity of 1-7 was evaluated using three methods: the DPPH scavenging assay, the total antioxidant capacity assay, and the lipid peroxidation assay. Hispidin showed the strongest antioxidant activity of all tested compounds. This is the first report of secondary metabolites from the fungus P. schweinitzii.

Phellinus linteus mushroom protects against tacrine-induced mitochondrial impairment and oxidative stress in HepG2 cells

Tacrine (THA) was the first drug licensed for the treatment of Alzheimer's disease. Unfortunately, reversible hepatotoxicity is evident in about 30% of patients and limits its clinical use. The intracellular mechanisms have not yet been elucidated. Phellinus linteus (PL) is a mushroom that has long been used as a folk medicine. In our previous study, we found that PL could decrease the reactive oxygen species (ROS) formation in HepG2 cells. Presently, protective effects of PL on tacrine-induced ROS formation and mitochondria dysfunction were evaluated. The results showed that PL significantly reduced tacrine-induced ROS production, disruption of ΔΨm, 8-OHdG formation in mitochondrial DNA, and cytotoxicity in HepG2 cells. These data suggest that PL could attenuate the cytotoxicity and mitochondria dysfunction induced by tacrine in HepG2 cells. The protection is probably mediated by an antioxidant protective mechanism. Consumption of PL may be a plausible way to prevent tacrine-induced hepatotoxicity.

Influence of rutin, FeSO4, Tween 80, aspartate and complex vitamins on synthesis of fungal exopolysaccharide

The influence of several components on exopolysaccharide (EPS) production and antioxidative activity (TEAC, Trolox-Equivalent Antioxidant Capacity) as well as their effects on the morphological development and cell viability of Phellinus sp. P0988 was determined. Rutin, FeSO(4), Tween 80 and complex vitamins were found to impose a stronger influence on EPS production and TEAC compared to their effects on the mycelia growth of Phellinus sp. P0988. The relative effects of these components on EPS activity were found to be different from that on EPS yield. Rutin and aspartate significantly affected EPS TEAC (P<0.05), while FeSO(4) and Tween 80 significantly influenced EPS production (P<0.05). These results yielded the optimum culture medium composition, with an EPS yield and TEAC of 6.2±0.2 g/L and 5.5±0.1 mM, respectively.

Hispidin produced from Phellinus linteus protects against peroxynitrite-mediated DNA damage and hydroxyl radical generation

Oxidative stress plays an important role in the progression of many chronic diseases including cardiovascular diseases, diabetes, cancer and neurodegenerative disorders. One such mediator of oxidative stress is peroxynitrite, which is highly toxic to cultured neurons and astrocytes, and has been reported to be involved in the pathogenesis of various types of neuronal diseases. Therefore, searching for natural compounds with peroxynitrite-scavenging activity might be an effective therapy for peroxynitrite-mediated cytotoxicity. Hispidin, a phenolic compound from Phellinus linteus (a medicinal mushroom), has been shown to possess strong antioxidant, anticancer, and antidiabetic properties. However, the astrocyte protective efficacy of hispidin has been not examined. This study was undertaken to investigate whether the astrocyte protective effect of hispidin is associated with inhibition of peroxynitrite-induced DNA damage, a critical event leading to peroxynitrite-mediated cytotoxicity. Our results showed that peroxynitrite can cause DNA damage in φX-174 plasmid DNA and rat primary astrocytes. The presence of hispidin (10-20 μg/ml) was found to significantly inhibit peroxynitrite-induced DNA damage and cytotoxicity. EPR spectroscopy demonstrated that the formation of DMPO-hydroxyl radical adduct (DMPO-OH) from peroxynitrite, and that hispidin potently diminished the adduct signal in a concentration-dependent manner. Taken together, these results demonstrate for the first time that hispidin can protect against peroxynitrite-mediated cytotoxicity, DNA damage and hydroxyl radical formation.

Ficus hispida Linn.: A review of its pharmacognostic and ethnomedicinal properties

Ficus hispida (FH) Linn. is a moderate sized tree found throughout the year and is grown wild or cultivated for its edible fruits and folklore value. Traditionally, different parts of the plant have been used in the treatment of ulcers, psoriasis, anemia, piles jaundice, vitiligo, hemorrhage, diabetes, convulsion, hepatitis, dysentery, biliousness, and as lactagogue and purgative. FH contains wide varieties of bioactives from different phytochemical groups like alkaloids, carbohydrates, proteins and amino acids, sterols, phenols, flavonoids, gums and mucilage, glycosides, saponins, and terpenes. Various scientific works have been published to establish the scientific basis of traditional medicinal values attributed to FH. Furthermore, newer pharmacological activities like antineoplastic, cardioprotective, neuroprotective and anti-inflammatory effects were also reported recently. Till now, no work has been published to elaborate the pharmacognostic features of FH Linn. The present review is, therefore, an effort to give a detailed account on its pharmacognosy and phytochemistry, and an extensive survey on its pharmacological activities. Moreover, we are trying to establish the mechanism of action behind its earlier reported pharmacology. The review also looks at the future formulation based delivery approaches of its lipophilic bioactives, which is done to enhance its dissolution so as to increase its bioavailability, and thus the associated pharmacological action.

Filtrate of Phellinus linteus Broth Culture Reduces Infarct Size Significantly in a Rat Model of Permanent Focal Cerebral Ischemia

Phellinus linteus, a natural growing mushroom, has been known to exhibit anti-tumor, anti-inflammatory, anti-allergic and anti-oxidant effects. Aiming to exploit the neuroprotective effects of P. linteus, we evaluated its effects on infarct volume reduction in a rat model of focal cerebral ischemia. Male Sprague-Dawley rats were subjected to right middle cerebral artery occlusion. Filtrate of P. linteus broth culture (various doses), fractionated filtrate (based on molecular weight) or control medium was administered intraperitoneally to rats before or after ischemia induction. Rats were killed at 24 h after the stroke surgery. Cortical and caudoputaminal infarct volumes were determined separately using an image analysis program following staining with 2,3,5-triphenyltetrazolium chloride. Significant cortical infarct volume reductions were found in the pre-treatment groups (30 and 60 minutes before onset of cerebral ischemia) compared with the control group, showing dose dependence. Posttreatment (30 minutes after ischemic onset) also significantly reduced cortical infarct volume. Furthermore, the higher molecular weight (≥12 000) fraction of the culture filtrate was more effective compared with the lower molecular weight fraction. The present findings suggest that P. linteus may be a new promising approach for the treatment of focal cerebral ischemia, with the additional benefit of a wide therapeutic time window since significant infarct volume reduction is obtained by administration even after the ischemic event. Our finding that the higher molecular weight fraction of the P. linteus culture filtrate demonstrated more prominent effect may provide a clue to identify the neuroprotective substances and mechanisms.

Styrylpyrone-class compounds from medicinal fungi Phellinus and Inonotus spp., and their medicinal importance

Members of the genera Phellinus and Inonotus, including P. linteus, P. igniarius, P. ribis, I. obliquus and I. xeranticus are well-known medicinal fungi (mushrooms) and have been used in treatment of cancer, diabetes, bacterial and viral infections and ulcer. Adverse effects of these medicinal mushrooms have not yet been reported, indicating the safe nature of these mushrooms. Polysaccharides, particularly β-glucan, are considered the compounds responsible for the biological activity of medicinal mushrooms. However, there is only a limited amount of evidence to indicate that polysaccharides are in fact responsible for the biological effects of these medicinal mushrooms. Recently, many research groups have begun identification of active low-MW compounds in medicinal mushrooms, with a focus on the yellow polyphenol pigments, which are composed of a styrylpyrone class of compounds. Interestingly, a representative group of medicinal fungi, including P. linteus, P. igniarius, P. ribis, I. obliquus and I. xeranticus were shown to produce a large and diverse range of styrylpyrone-type polyphenol pigments that exhibited various biological activities, including anti-oxidative, anti-inflammatory, cytotoxic, anti-platelet aggregation, anti-diabetic, anti-dementia and anti-viral effects. Styrylpyrone pigments in mushrooms are thought to have a role similar to that of flavonoids in plants. The unique and unprecedented carbon skeleton of fused styrylpyrone might be an attractive molecular scaffold for pharmacological applications. In this review, the structural diversity, biological effects and biogenesis of styrylpyrone-class polyphenols from medicinal fungi are described.