Bioactive Ingredients and Medicinal Values of Grifola frondosa (Maitake).

Grifola frondosa (G. frondosa), generally known as hen-of-the-woods or maitake in Japanese and hui-shu-hua in Chinese, is an edible mushroom with both nutritional and medicinal properties. This review provides an up-to-date and comprehensive summary of research findings on its bioactive constituents, potential health benefits and major structural characteristics. Since the discovery of the D-fraction more than three decades ago, many other polysaccharides, including ß-glucans and heteroglycans, have been extracted from the G. frondosa fruiting body and fungal mycelium, which have shown significant antitumor and immunomodulatory activities. Another class of bioactive macromolecules in G. frondosa is composed of proteins and glycoproteins, which have shown antitumor, immunomodulation, antioxidant and other activities. A number of small organic molecules such as sterols and phenolic compounds have also been isolated from the fungus and have shown various bioactivities. It can be concluded that the G. frondosa mushroom provides a diverse array of bioactive molecules that are potentially valuable for nutraceutical and pharmaceutical applications. More investigation is needed to establish the structure-bioactivity relationship of G. frondosa and to elucidate the mechanisms of action behind its various bioactive and pharmacological effects.

Anti-inflammation activity of exopolysaccharides produced by a medicinal fungus Cordyceps sinensis Cs-HK1 in cell and animal models.

This study was to assess the anti-inflammatory potential of exopolysaccharide (EPS) produced by a medicinal fungus Cordyceps sinensis Cs-HK1. The EPS was isolated from the Cs-HK1 mycelial fermentation broth by ethanol precipitation and purified by deproteinization and dialysis. The EPS had a total sugar content of 74.8% and a maximum average molecular weight (MW) over 107 Da, and consisted mainly of glucose and mannose, and a small amount of galactose and ribose. In THP-1 and RAW264.7 cell cultures, EPS significantly inhibited lipopolysaccharide (LPS)-induced inflammatory responses of the cells including the release of NF-κB and several pro-inflammatory factors such as NO, TNF-α and IL-1ß. In the murine model of LPS-induced acute intestinal injury, the oral administration of EPS to the animals effectively suppressed the expression of major inflammatory cytokines TNF-α, IL-1ß, IL-10 and iNOS and alleviated the intestinal injury. The results suggest that the Cs-HK1 EPS has notable anti-inflammatory activity and can be a potential candidate for further development of new anti-septic therapeutics. To the best of our knowledge, this is the first report on the anti-inflammation of an EPS from C. sinensis fungal fermentation.

Effects of exopolysaccharide fractions with different molecular weights and compositions on fecal microflora during in vitro fermentation.

This study was to investigate the potential prebiotic function of exopolysaccharide (EPS) from a medicinal fungus and the relationship to the molecular properties by in vitro human fecal fermentation. The EPS from Cordyceps sinensis Cs-HK1 mycelial fermentation was processed into three fractions with different monosaccharide contents, a higher molecular weight (MW) and a lower MW attained by two-step ethanol precipitation, and an intermediate MW by ultrasound-degradation of EPS. All the EPS fractions were well utilized during 24-48 h of fecal fermentation, leading to significant increases in the short chain fatty acid (SCFA) production. The consumption rate and production level of SCFAs varied slightly with the different EPS fractions. The EPS also influenced the composition and diversity of the fecal microflora, increasing the relative abundance of Firmicutes but suppressing that of Proteobacteria, which may be a beneficial effect for human health. Overall the results have shown that the Cs-HK1 EPS has significant prebiotic activity which is dependent on its molecular properties.

Protective effects of exopolysaccharide of a medicinal fungus on probiotic bacteria during cold storage and simulated gastrointestinal conditions.

The efficacy of probiotic health products depends on the capability of the constituent probiotic bacteria to survive through long period of cold storage and the gastrointestinal tract. This study was to evaluate the protective effects of a high-molecular weight (MW) exopolysaccharide (EPS) from a medicinal fungus Cs-HK1 on three different bifidobacteria. The EPS had a total dietary fiber content about 70% (w/w), which was close to its total carbohydrate content. It was resistant to artificial gastric acid (pH 2) with no more than 4% (w/w) hydrolysis in 6 h. EPS at 5 g/L significantly increased the survival rate of the probiotic bacteria during cold storage (4 °C) and in simulated gastric acid, reducing the death rate of different bacterial strains by 50% to 70%. The protective effect of EPS was weaker when the concentration was decreased to 3 g/L or when the MW of EPS was reduced by partial degradation with power ultrasound. EPS also showed significantly protective effect on the all bacterial strains in bile juice. The results have demonstrated the potential value of Cs-HK1 EPS as a novel prebiotic fiber for the formulation of synbiotic products with probiotic bacteria.

Cosmetic and Skincare Benefits of Cultivated Mycelia from the Chinese Caterpillar Mushroom, Ophiocordyceps sinensis (Ascomycetes).

Mushrooms are potential sources of novel natural cosmeceutical ingredients. This study was conducted to evaluate the cosmetic (skincare) benefits of the valuable medicinal species Ophiocordyceps sinensis (=Cordyceps sinensis). The mycelial extracts of 2 O. sinensis strains, Cs-HK1 and Cs-4, prepared sequentially with ethyl acetate, ethanol, and hot water were tested with in vitro assays for tyrosinase-, collagenase-, and elastase-inhibitory activity. The ethyl acetate extracts of both fungal strains showed potent antityrosinase and antielastase activity, with low half-maximal inhibitory concentrations (0.14-0.47 mg/mL) comparable to those of the respective reference compounds (arbutin and epigallocatechin gallate). All mycelial extracts exhibited moderate or significant anticollagenase activity; most extracts showed a significant photoprotective effect with a sun protection factor up to 25. The results from this study show the potential use of O. sinensis as a source of cosmetic ingredients for skincare applications.

Bifidogenic effects of Cordyceps sinensis fungal exopolysaccharide and konjac glucomannan after ultrasound and acid degradation.

The bifidogenic effects of exopolysaccharide (EPS) of a medicinal fungus (Cordyceps sinensis) and a well-known food polysaccharide konjac glucomannan (KGM) with different molecular weight (MW) ranges were evaluated through in vitro experiments in liquid cultures of Bifidobacteria. Native EPS and KGM were partially degraded with power ultrasound (US) to improve the water solubility, and further hydrolysed with trifluoroacetic acid to much lower MW. The acid-hydrolysed fractions (EPS-AH and KGM-AH) supported the growth of all five tested bifidobacterial species, while the US-degraded high MW fractions, EPS-US and KGM-US, could only slightly support the growth of some species. All EPS fractions increased the acetic acid production of most bifidobacterial species. Most remarkably, the high MW EPS-US, EPS-AH and KGM-US fractions significantly enhanced the cell viability with much higher colony forming unit (CFU) counts, suggesting a protective effect of these high MW polysaccharides for the bacterial survival. The results have shown that MW was a significant factor on the bifidogenic properties of partially degraded EPS and KGM.

Antifatigue Functions and Mechanisms of Edible and Medicinal Mushrooms.

Fatigue is the symptom of tiredness caused by physical and/or psychological stresses. As fatigue is becoming a serious problem in the modern society affecting human health, work efficiency, and quality of life, effective antifatigue remedies other than pharmacological drugs or therapies are highly needed. Mushrooms have been widely used as health foods, because of their various bioactive constituents such as polysaccharides, proteins, vitamins, minerals, and dietary fiber. This paper reviews the major findings from previous studies on the antifatigue effects, the active components of mushrooms, and the possible mechanisms. Many studies have demonstrated the antifatigue effects of edible and medicinal mushrooms. These mushrooms probably mitigate human fatigue through effects on the functional systems, including the muscular, cardiovascular, hormone, and immune system. The bioactive constituents that contribute to the antifatigue effects of mushrooms may include polysaccharides, peptides, nucleosides, phenolic compounds, and triterpenoids. Further research is still needed to identify the active ingredients and to investigate their mechanism of action on the antifatigue effects. Since most previous studies have been carried out in animal models, more human trials should be performed to verify the antifatigue function of edible and medicinal mushrooms.

Formation and Physiochemical Properties of Silver Nanoparticles with Various Exopolysaccharides of a Medicinal Fungus in Aqueous Solution.

Natural polysaccharides are the most widely used biopolymers for green synthesis of eco-friendly silver nanoparticles (AgNPs). In a previous study, a high molecular weight (MW) fraction of exopolysaccharides (EPS) produced by a medicinal fungus Cs-HK1 has been shown useful for green and facile synthesis of AgNPs in water. This study was to further evaluate the effects of molecular properties of EPS on the formation, stability and properties of AgNPs with different EPS fractions at various pH conditions. Three EPS fractions (P0.5, P2.0 and P5.0: MW high to low and protein content low to high) were reacted with silver nitrate at various pH 3.0-8.0 in water. The most favorable pH range was 5.5-8.0 for the formation and stable dispersion of AgNPs. At a given pH, the maximum amount of AgNPs was produced with P5.0, and the minimum with P0.5. The shape, size and physiochemical properties of AgNPs were strongly affected by the molecular characteristics of EPS (MW and conformation). The results may be helpful for understanding the factors and mechanisms for formation of stable AgNPs with natural polysaccharides and the interactions between AgNPs and the polysaccharide hydrocolloids in water.

Molecular properties and antioxidant activities of polysaccharides isolated from alkaline extract of wild Armillaria ostoyae mushrooms.

This study aims to discover novel and bioactive polysaccharides (PS) from wild Armillaria ostoyae, a honey mushroom species. Two PS designated AkPS1V-1 (66.6 kDa) and AkPS1V-2 (15.3 kDa) were isolated and fractionated by anion ion exchange (IEC) and size exclusion chromatography (SEC) from the alkaline extract of A. ostoyae mushrooms. AkPS1V-1 was a glucan composed of solely glucose residues and AkPS1V-2 a heteropolysaccharide composed of glucose and galactose at 6:1 molar ratio. AkPS1V-2 exhibited higher antioxidant activities than AkPS1V-1 based on reducing power, radical scavenging and metal chelating assays. The structure of AkPS1V-2 was further analyzed and elucidated as a branched galactoglucan with a backbone composed of (1→6)-ß-D-glucopyranosyl, (1→3)-ß-D-glucopyranosyl, (1→3)-α-D-galactopyranosyl and (1→3,6)-ß-D-glucopyranosyl residues at 3:1:1:1 ratio, and side chain of (1→3)-ß-D-glucopyranosyl residue. This is the first report on a pure PS structure and its antioxidant activities from this mushroom species.

Effects of pH and temperature on colloidal properties and molecular characteristics of Konjac glucomannan.

The hydrocolloidal characteristics of Konjac glucomannan (KGM) are important for its application as a thickening and gelling agent for liquid foods. In this study, the rheological behavior and molecular properties such as molar mass, hydrodynamic radius and chain conformation of KGM in water were determined at various pH levels (4.0-10.0) during heating from 20 to 80 °C. Acidic and neutral conditions (pH 4.0-7.0) promoted the dispersion of KGM, and alkaline condition at pH 10 favored its aggregation in water, while KGM maintained a random coil conformation in the whole pH range. Associated with the pH effects were changes in the rheological behavior during heating from 20 to 80 °C. The significant differences in the colloidal and rheological characteristics were mainly attributed to alteration of intermolecular interaction (attractive or repulsive) rather than deacetylation at various pH levels. Deacetylation occurred in both acidic and alkaline condition. The second virial value was positive in acidic and negative in alkaline condition. The results showed that hydrocolloidal characteristics of KGM in water were significantly affected by pH.

Isolation and structure characterization of an antioxidative glycopeptide from mycelial culture broth of a medicinal fungus.

A novel glycopeptide (Cs-GP1) with an average molecular weight (Mw) of 6.0 kDa was isolated and purified by column chromatography from the lower Mw fraction of exopolysaccharide (EPS) produced by a medicinal fungus Cordyceps sinensis Cs-HK1. Its carbohydrate moiety was mainly composed of glucose and mannose at 3.2:1.0 mole ratio, indicating an O-linked glycopeptide. The peptide chain contained relatively high mole ratios of aspartic acid, glutamic acid and glycine (3.3-3.5 relative to arginine) but relatively low ratios of tyrosine and histidine. The peptide chain sequence analyzed after trypsin digestion by LC-MS was KNGIFQFGEDCAAGSISHELGGFREFREFLKQAGLE. Cs-GP1 exhibited remarkable antioxidant capacity with a Trolox equivalent antioxidant capacity of 1183.8 µmol/g and a ferric reducing ability of 611.1 µmol Fe(II)/g, and significant protective effect against H2O2-induced PC12 cell injury at a minimum dose of 10 µg/mL. This is the first report on the structure and bioactivity of an extracellular glycopeptide from the Cordyceps species.

An antioxidative galactomannan-protein complex isolated from fermentation broth of a medicinal fungus Cs-HK1.

A protein-containing polysaccharide, EPS2BW, was fractionated from the exopolysaccharide (EPS) produced by a medicinal fungus Cordyceps sinensis (Cs-HK1). EPS2BW was mainly composed of galactomannan with about 16% (w/w) protein and 50 kDa average molecular weight. The galactomannan part consisted of mannose and galactose at 1.7:1.0 molar ratio, and the protein segments were composed of sixteen amino acids with 12.5% proline and 16.6% threonine (mol%) being the most abundant. Based on analytical results from NMR, methylation analysis, partial acid hydrolysis and GC-MS, the galactomannan structure was elucidated as a (1 → 2)-α-D-mannopyranosyl (Manp) backbone with O-6-linked galactopyranosyl (Galp) branches. EPS2BW exhibited a high antioxidant capacity in both chemical and cell culture assays, with a Trolox equivalent radical scavenging activity of 44.7 µmol Trolox/mg, a Fe(3+) reducing power of 38.9 µmol Fe(2+)/mg, and significant cytoprotective effect against H2O2-induced PC12 cell death at 50-250 µg/mL.

Structure and properties of a (1→3)-ß-D-glucan from ultrasound-degraded exopolysaccharides of a medicinal fungus.

A high molecular weight (MW) exopolysaccaride (EPS) fraction EPS1 was isolated from the fermentation broth of a medicinal fungus Cordyceps sinensis Cs-HK1 and partially degraded by high-intensity ultrasound (US) into a lower MW fraction EPS1U. EPS1U exhibited a single, symmetric peak on size exclusion chromatography with an average MW of 730kDa by light scattering analysis. It had a much lower intrinsic viscosity (1.7 versus 15.6dL/g) but a much higher solubility in water (77.5 versus 5.1g/L) than EPS1. Based on methylation analysis and NMR spectrometry, the structure of EPS1U was deduced as a (1→3)-ß-d-glucan with glucose side chains attached to O-6 position at the branching points. EPS1U showed a high moisture absorption capability comparable to chitosan and urea, suggesting its potential as a moisturizing agent for food and cosmeceutical application. This is the first report on a high MW (1→3)-ß-d-glucan isolated from EPS produced by Cordyceps sinensis.

Structure and antioxidant activity of a novel poly-N-acetylhexosamine produced by a medicinal fungus.

A novel poly-N-acetylhexosamine (polyhexNAc) about 6 kDa average molecular weight (MW) was isolated from the low-MW fraction of exopolysaccharide produced by liquid fermentation of a medicinal fungus Cordyceps sinensis Cs-HK1. The composition and linkage of sugar residues were determined by mass spectrometry and methylation analysis, and the anomeric configuration and chain linkage were confirmed by NMR. From the analytical results, the molecular structure was elucidated as a [-4-ß-D-ManNAc-(1→3)-ß-D-GalNAc-(1→] disaccharide repeating unit in the main chain with a Gal branch occurring randomly at the 3-position of ManNAc. This polyhexNAc showed notable antioxidant activities with a Trolox equivalent antioxidant capacity of 330 µmol Trolox/g, a ferric reducing ability of plasma of 45.7 µmol Fe(II)/g, and significant cytoprotective effect against H2O2-induced PC12 cell injury. This is the first report on the structure and bioactivity of an extracellular amino-polysaccharide from the Cordyceps species.

Involvement of anion channels in mediating elicitor-induced ATP efflux in Salvia miltiorrhiza hairy roots.

This study examines the roles of anion channels and ATP binding cassette (ABC) protein transporters in mediating elicitor-induced ATP release in Salvia miltiorrhiza hairy root cultures. The elicitor-induced ATP release was effectively blocked by two putative membrane anion channel blockers, niflumic acid and Zn(2+), but not by a specific Cl(-) channel blocker, phenylanthranilic acid. The elicitor-induced ATP release was also significantly suppressed by two ABC inhibitors, glibenclamide and ethacrynic acid. Notable ATP release from the hairy roots was also induced by verapamil (2mM), an ABC activator in animal cells. The verapamil-induced ATP release was effectively blocked by niflumic acid, but only slightly inhibited by the ABC inhibitors. Another notable effect of verapamil was the induction of exocytosis, the secretion of vesicle-like particles to the root surface. The verapamil-induced exocytosis was not inhibited by nifulumic acid and YE did not induce the exocytosis. Overall, the results suggest a significant role of anion channels, a possible involvement of ABC proteins and no significant involvement of exocytosis in mediating the ATP efflux in hairy root cells.