Astraeus Hygrometricus Research Articles

Bioactive potential of the wild mushroom Astraeus hygrometricus in South-west India

ABSTRACTThe wild mushroom Astraeus hygrometricus is a traditional delicacy during the monsoon season in South-western India. Bioactive principles and antioxidant potential of uncooked and pressure-cooked tender mushroom have been evaluated. Seven bioactive principles of mushroom (tannins, flavonoids, vitamin C, phytic acid, lycopene, β-carotene and trypsin inhibition) were significantly higher, while total phenolics content was significantly lower in uncooked than in cooked samples. Mushroom was devoid of L-DOPA, whereas only uncooked samples showed haemagglutinin activity against A+ blood group. The principal component analysis of uncooked mushroom showed only two bioactive principles clustered with two antioxidant properties, while in cooked mushroom five bioactive principles clustered with three antioxidant properties depicting the nutraceutical potential of cooked mushroom. Future studies should focus on appropriate thermal treatment, which retain maximum bioactive and antioxidant potential to combat health- and lifestyle-related ailments. The A. hygrometricus is ectomycorrhizal, conservation of its host tree species is utmost importance in improvement and expansion of its yield to sustain food security and economic gains of local tribals.

Successful Therapy of Murine Visceral Leishmaniasis with Astrakurkurone, a Triterpene Isolated from the Mushroom Astraeus hygrometricus, Involves the Induction of Protective Cell-Mediated Immunity and TLR9.

In our previous report, we showed that astrakurkurone, a triterpene isolated from the Indian mushroom Astraeus hygrometricus (Pers.) Morgan, induced reactive oxygen species, leading to apoptosis in Leishmania donovani promastigotes, and also was effective in inhibiting intracellular amastigotes at the 50% inhibitory concentration of 2.5 μg/ml. The aim of the present study is to characterize the associated immunomodulatory potentials and cellular activation provided by astrakurkurone, leading to effective antileishmanial activity in vitro and in vivo Astrakurkurone-mediated antileishmanial activity was evaluated by real-time PCR and flow cytometry. The involvement of Toll-like receptor 9 (TLR9) was studied by in vitro assay in the presence of a TLR9 agonist and antagonist and by in silico modeling of a three-dimensional structure of the ectodomain of TLR9 and its interaction with astrakurkurone. Astrakurkurone caused a significant increase in TLR9 expression of L. donovani-infected macrophages along with the activation of proinflammatory responses. The involvement of TLR9 in astrakurkurone-mediated amastigote killing has been evidenced from the fact that a TLR9 agonist (CpG, ODN 1826) in combination with astrakurkurone enhanced the amastigote killing, while a TLR9 antagonist (bafilomycin A1) alone or in combination with astrakurkurone curbed the amastigote killing, which could be further justified by in silico evidence of docking between mouse TLR9 and astrakurkurone. Astrakurkurone was found to reduce the parasite burden in vivo by inducing protective cytokines, gamma interferon and interleukin 17. Moreover, astrakurkurone was nontoxic toward peripheral blood mononuclear cells of immunocompromised patients with visceral leishmaniasis. Astrakurkurone, a nontoxic antileishmanial, enhances the immune efficiency of host cells, leading to parasite clearance in vitro and in vivo.

Observations on the Astraeus spp. of Southwestern India

Astraeus is a widespread genus of gasteromycete in tropical, sub-tropical and temperate regions. During mycological survey, two distinct species of Astraeus were recovered from the Southwestern India. Astraeus hygrometricus was frequent in forests of foothill region of the Western Ghats. In fire affected scrub jungles of the west coast, Astraeus odoratus was common and represents second report from the Indian Subcontinent. Astraeus spp. recovered were ectomycorrhizal in a variety of native and exotic tree species growing in sandy loam/gravel/pebblerich lateritic soils. Tender A. hygrometricus occurring in forests of foothill region of the Western Ghats serve as traditional nutritional delicacy and sold in local markets during rainy season.

Pharmacological activities of selected wild mushrooms in South Waziristan (FATA), Pakistan

This study investigates the pharmacological importance of selected wild mushrooms viz., Morchella esculenta (common morel), Calvatia gigantea (Giant puffball) and Astraeus hygrometricus (False earthstar) collected from South Waziristan Agency, Federally Administered Tribal Areas (FATA), Pakistan. The selected mushrooms were collected from Tehsil Makeen, Wana and Birmal of South Waziristan Agency during a sampling survey conducted in April–May 2010. The dry fruiting bodies of mushrooms were methanol extracted and evaluated for total phenolic, protein, antioxidant activity, cytotoxicity and their effects on radish seed growth. The results revealed that methanol crude extracts prepared from fruiting bodies of A. hygrometricus and C. gigantea have higher phenolic content and total antioxidant activity as well as greater brine shrimp cytotoxicity. On the other hand, M. esculenta has a high level of protein content and promoted seedling growth in radish. Antioxidant activity for A. hygrometricus, C. gigantea and M. esculenta at IC50 values were: 9.3±0.3μg/ml, 22.2±0.3μg/ml and 18.0±0.1μg/ml, respectively. Methanolic extract of C. gigantea (10mg/ml) reduced the seed germination and shoot length of radish by 16%. In contrast, the methanolic extract (10mg/ml) of M. esculenta and C. gigantea enhanced the shoot length, root length and root/shoot ratio of radish. Higher LC50 value was recorded for methanolic extract of A. hygrometricus (19.0±0.3μg/ml) followed by M. esculenta (17±0.19μg/ml), whereas methanolic extract of C. gigantea showed lower LC50 value (16±0.23μg/ml). It is inferred from the present investigation that mushrooms collected from South Waziristan could be potential source of compounds with beneficial biological activities.

Tribal Relation to Spatio-Temporal Variation of Wild Mushrooms in Eastern Lateritic Part of India

Mushroom is one of the most significant biodiversity components for both ecological and economic point of view. It deserves not only the good sources of nutrients, medicine but also has key function in nutrient recycling and niche for several animal resources. Eastern lateritic part of India with its distinct seasonality and undulated topography, harbours mosaic macro fungal resources on the forest floors with distinct spatio-temporal variation. Among 18 species related to tribal use, the most usable species were Astraeus hygrometricus Amanita vaginata var. alba , Amanita banangiana , Russula Nigerians , Termitomyces eurhizus , Termitomyces microcarpus etc. During monsoon and post monsoon period, second half of August is the optimum time for 11 wild edible mushrooms. Out of total production 47.2% production was taken place at that time. These regions with its tribal population, especially the Santals in the forest fringes, were very potential for traditional knowledge related to mushrooms. This paper deals with ethnic pattern of utilization in relation to spatio-temporal distribution of macro fungal diversity, its habitat and traditional tribal knowledge in ecology, use and others.

Growth characteristics of ectomycorrhizal seedlings of Quercus glauca, Quercus salicina, and Castanopsis cuspidata planted on acidic soil

Seedlings of three Fagaceae species planted on acidic, infertile colluvial soil showed accelerated growth when inoculated with ectomycorrhizal fungi. We conducted a study with seedlings of Fagaceae species inoculated with ectomycorrhizal fungi to estimate their utility for growth in acidic soil conditions. We selected Quercus glauca, Quercus salicina and Castanopsis cuspidata as typical evergreen, broad-leaved, woody species of southwestern Japan. Seedlings were inoculated with Astraeus hygrometricus or Scleroderma citrinum, and planted in acidic, infertile colluvial soil collected from an abandoned site. Six months after planting, seedlings of the three species inoculated with A. hygrometricus were growing well, especially, Q. salicina. The growth of seedlings inoculated with S. citrinum was inferior to seedlings inoculated with A. hygrometricus. In contrast, seedlings without ectomycorrhizal fungi did not grow well. Differences in growth among the three types of seedlings were related to differences in the levels of nutrient acquisition. We concluded that Fagaceae seedlings inoculated with A. hygrometricus were best suited for acidic, infertile environments.

Macrofungal diversity and habitat specificity: a case study

The diversity of macrofungi in the lateritic region of West Bengal was explored and 120 species, one subgenus and a variety, having eight ecological functions, were found to grow among three types of habitats, i.e. natural forests, plantation forests and villages. Yate’s corrected chi-square (χ2) test statistic was performed upon the 2 × 2 table (contingency table) and testing the null hypotheses of independence of observed cell frequencies of the presence/absence of a species in a given habitat type. Various degrees of specificities of macrofungi to their habitats were observed, i.e. Amanita vaginata, Astraeus hygrometricus, Laccaria laccata, Lactarius zonarius, Porphyrellus malaccensis, Russula brevipes, Russula delica, Russula emetica and Russula laurocerasi were absolutely specific for natural forests; Pisolithus arhizus and Ramaria fumigata were absolutely specific for plantation forests; Auricularia auricula, Schizophyllum commune and Termitomyces clypeatus (only association coefficient 100%) were found to absolutely specific for village habitat. MS Excel-based formulas for calculation of association/specificity of species to habitat and species to species as well as other diversity indices are provided. Local and tribal populations used 19 species of macrofungi during their fruiting period, of which 17 had culinary values and four were locally considered medicinal. This study is a first of its kind, and has various applications to allied disciplines in understanding diversity, ecology and biological prospects of the macrofungal realm.

Nucleotide Sequencing and Identification of Some Wild Mushrooms

The rDNA-ITS (Ribosomal DNA Internal Transcribed Spacers) fragment of the genomic DNA of 8 wild edible mushrooms (collected from Eastern Chota Nagpur Plateau of West Bengal, India) was amplified using ITS1 (Internal Transcribed Spacers 1) and ITS2 primers and subjected to nucleotide sequence determination for identification of mushrooms as mentioned. The sequences were aligned using ClustalW software program. The aligned sequences revealed identity (homology percentage from GenBank data base) of Amanita hemibapha [CN (Chota Nagpur) 1, % identity 99 (JX844716.1)], Amanita sp. [CN 2, % identity 98 (JX844763.1)], Astraeus hygrometricus [CN 3, % identity 87 (FJ536664.1)], Termitomyces sp. [CN 4, % identity 90 (JF746992.1)], Termitomyces sp. [CN 5, % identity 99 (GU001667.1)], T. microcarpus [CN 6, % identity 82 (EF421077.1)], Termitomyces sp. [CN 7, % identity 76 (JF746993.1)], and Volvariella volvacea [CN 8, % identity 100 (JN086680.1)]. Although out of 8 mushrooms 4 could be identified up to species level, the nucleotide sequences of the rest may be relevant to further characterization. A phylogenetic tree is constructed using Neighbor-Joining method showing interrelationship between/among the mushrooms. The determined nucleotide sequences of the mushrooms may provide additional information enriching GenBank database aiding to molecular taxonomy and facilitating its domestication and characterization for human benefits.

Ectomycorrhizal‐fungal colonization induces physio‐morphological changes in Quercus serrata leaves and roots

AbstractTo determine how colonization by different ectomycorrhizal (ECM)‐fungal species affects the physiology and morphology of Quercus serrata seedlings, we assessed the net photosynthetic rate, the respiration rate of the lateral roots, leaf and root nitrogen (N) concentrations, specific leaf area, and specific root length in 9‐month‐old Q. serrata seedlings inoculated with Pisolithus tinctorius, Scleroderma citrinum, Laccaria amethystea, and Astraeus hygrometricus. While uninoculated control plants showed no colonization, the percentage of ECM colonization of root tips attained 35% with P. tinctorius and about 86% with the other three ECM species. Similar to ECM root colonization, the photosynthetic as well as the root‐respiration rates were higher in seedlings with S. citrinum, L. amethystea, and A. hygrometricus than that in the control and those with P. tinctorius. Both the photosynthetic and root‐respiration rates were positively correlated with ECM‐fungal colonization. Similar trends were observed for the N concentration, specific leaf area, and specific root length, which differed significantly among ECM‐fungal species and were related with ECM‐fungal colonization. The results suggest that both physiological and morphological traits are specific to ECM‐fungal species. As Q. serrata seedlings with high colonization can exhibit better resource‐acquisition ability, the identification of strongly colonizing ECM‐fungal species is essential. Comparisons with high‐ and low‐colonizing ECM‐fungal species improve our understanding of source–sink relationships in carbon allocation of forest tree species.

Prized edible Asian mushrooms: ecology, conservation and sustainability

Mushrooms can be found in forests worldwide and have long been exploited as resources in developed economies because of their important agro-industrial, medicinal and commercial uses. For less developed countries, such as those within the Greater Mekong Subregion, wild harvesting and mushroom cultivation provides a much-needed alternative source of income for rural households. However, this has led to over-harvesting and ultimately environmental degradation in certain areas, thus management guidelines allowing for a more sustained approach to the use of wild mushrooms is required. This article addresses a selection of the most popular and highly sought after edible mushrooms from Greater Mekong Subregion: Astraeus hygrometricus, Boletus edulis, Morchella conica, Ophiocordyceps sinensis, Phlebopus portentosus, Pleurotus giganteus, Termitomyces eurhizus, Thelephora ganbajun, Tricholoma matsuake, and Tuber indicum in terms of value, ecology and conservation. The greatest threat to these and many other mushroom species is that of habitat loss and over-harvesting of wild stocks, thus, by creating awareness of these issues we wish to enable a more sustainable use of these natural products. Thus our paper provides baseline data for these fungi so that future monitoring can establish the effects of continued harvesting on mushroom populations and the related host species.

Leishmanicidal and Anticandidal Activity of Constituents of Indian Edible Mushroom Astraeus hygrometricus

Two new lanostane-type triterpenes, 1 and 2, were isolated from Astraeus hygrometricus. The structures were established by IR, (1)H- and (13)C-NMR, MS, and X-ray crystallographic experiments. The triterpenes exhibited excellent in vitro toxicities against Candida albicans, comparable to standard antifungal antibiotics. The triterpene 2 significantly inhibited the growth of Leishmania donovani promastigotes in vitro. The triterpene skeleton may be considered a template structure in search for new compounds with anticandidal and leishmanicidal activity.

Activation of RAW 264.7 cells byAstraeus hygrometricus-derived heteroglucan through MAP kinase pathway

Mushroom-derived polysaccharides like β-glucan are being investigated for therapeutic properties for a long time, but their mode of action of immunomodulatory properties is not well established. In the present study, a heteroglucan from Astraeus hygrometricus designated as AE2 is investigated for its macrophage stimulatory properties using RAW 264.7 cell line. An augmentation of nitric oxide production is observed in the presence of AE2 in a dose-dependent manner due to up-regulation of iNOS (inducible NO synthase) expression; hence NF κB (nuclear factor κB) pathway is investigated. RAW 264.7 cells endured phosphorylation of Ikk (IκB kinase) and subsequently NF κB is translocated to the nucleus. Further, the PKC (protein kinase C) level of the cells enhanced significantly. We also found that AE2 could induce the phosphorylation of p38 MAPK (mitogen-activated protein kinase), ERK1/2 (extracellular-signal-regulated kinase 1/2), MEK (MAPK/ERK kinase) and JNK (c-Jun N-terminal kinase), whereas it failed to induce phosphorylation of JAK2 (Janus kinase 2) and STAT1. These results indicated that the macrophage activation by AE2 might be exerted, at least in part, via MAPKs (mitogen-activated protein kinases) pathway of signal transduction.

Identification of Japanese Astraeus, based on morphological and phylogenetic analyses

To clarify the diversity of Astraeus in Japan, 35 collections of Astraeus basidiomata from Japan and Thailand were examined for their morphological characteristics and the nucleotide sequences of the rDNA ITS region and compared with several worldwide Astraeus species. Japanese Astraeus specimens were separated into two groups based on basidiome size, shape of exoperidium, and ornamentation and size of basidiospores. The phylogenetic tree analyses supported the separation, and the morphological groups belonged to different clades. The Japanese Astraeus group 1, morphologically matched to Astraeus hygromerticus var. koreanus, showed the closest phylogenetic relationship with Astraeus hygrometricus from North American and Mediterranean regions, suggesting that the Astraeus group 1 can be indentified as A. hygrometricus var. koreanus. Another Astraeus group, group 2, morphologically matched to A. hygrometricus s.l., showed a distinct monophyletic clade that was separated from A. hygrometricus complexes, indicating an undescribed species.

Immunostimulatory Properties of a Polysaccharide Isolated fromAstraeus hygrometricus

Mushrooms have been used as food and for therapeutic purpose for decades, and various compounds derived from these have potential biological activities. Application of such agents of natural origin is vital with relevance to an increase in diseases involving immune dysfunction, cancer, and autoimmune conditions in recent years. These compounds belong mainly to polysaccharides, especially beta-D-glucan, glycopeptide/protein complexes, proteoglycans, proteins, and triterpenoids. Among these compounds, polysaccharides and their peptide/protein derivates have extremely important roles in immunomodulating activities. The present study aims to explore the immunomodulatory properties of polysaccharide isolated from the mushroom Astraeus hygrometricus. The polysaccharide isolated by hot alkaline extraction and chromatography was designated as AE2 and studied for its immunostimulatory potential in vivo in a murine model. Macrophages from treated mice showed higher production of nitric oxide and interleukin-1 and also exhibited an increased phagocytic potential. It also enhanced natural killer cell activation and proliferation of splenocytes with an increase in the T-helper (Th) 1 cytokine level of splenocyte culture supernatant. The cytokine level in serum also indicated a Th1 skew. The observed activities were associated with no general toxicity to the organism. The findings will be helpful in considering A. hygrometricus as a potential source of an immunomodulator and in designing further studies to understand its mode of action on immune system.

Antitumor properties of a heteroglucan isolated from Astraeus hygrometricus on Dalton’s lymphoma bearing mouse

Polysaccharides such as glucans are the best known and most potent mushroom-derived substances with antitumor and immunomodulating properties. However, a vast variety of mushroom species remain unexplored. The present study aims at exploring the possible role of a heteroglucan designated as AE2, isolated from Astraeus hygrometricus, on tumor bearing host. AE2 mediated tumor regression through the reversal of tumor induced immunosupression. Tumor-associated macrophages from AE2 administered tumor bearing host have been demonstrated to possess augmented surface expression of co-stimulatory molecules and MHC-II, representing essentially elevated state of macrophage activation. NK cell activity has also been found to be elevated with the AE2 treatment while the Th1 cytokine in the tumor micro-environment increases with the treatment, the Th2 cytokine levels concomitantly decreases. Further, following the immunoactivation, Daltons lymphoma (DL) cells has undergone apoptosis, thereby resulting in reduction of tumor growth and increased survival rate of the tumor bearing host. The present study sheds light on the potent antitumor property of the heteroglucan AE2 isolated from A. hygrometricus, and can be extended further to develop therapeutic protocols for treatment of cancer or disease resulting in immunosuppression.

In vitro mycorrhization of edible Astraeus mushrooms and their morphological characterization

Astraeus is the most popular and the most expensive edible ectomycorrhizal mushroom group consumed in Thailand, although it is not commonly consumed in other countries. The purpose of this work was to test the ability of Astraeus to form ectomycorrhizae with seedlings of Pinus densiflora in vitro. A single 1-week-old P. densiflora seedling was transplanted into a glass bottle containing autoclaved forest soil, and suspensions of more than 106 basidiospores of Astraeus odoratus or Astraeus hygrometricus were inoculated onto the seedling. Cultured mycelium was also inoculated onto an axenic pine seedling planted on sterilized vermiculite–sphagnum moss mixture in a glass bottle. Mycorrhization of A. hygrometricus was observed a few months after inoculation in both treatments. Fungal species identity of both the inoculum and ectomycorrhizae was assessed by PCR–RFLP analysis of the ITS region of rDNA. At 5–6 months after inoculation, A. hygrometricus ectomycorrhizae developed a sheath, rhizomorphs, and Hartig net on pine lateral roots. No ectomycorrhizal formation was found after A. odoratus inoculation. These results suggest that A. hygrometricus can form mycorrhizae on pine seedlings. The external morphological characteristics of A. hygrometricus ectomycorrhizae were distinct from those of other Boletales ectomycorrhizae. This article provides the first morphological and anatomical description of A. hygrometricus ectomycorrhizae.

Identification of Japanese <i>Astraeus</i>, based on morphological and phylogenetic analyses

To clarify the diversity of Astraeus in Japan, 35 collections of Astraeus basidiomata from Japan and Thailand were examined for their morphological characteristics and the nucleotide sequences of the rDNA ITS region and compared with several worldwide Astraeus species. Japanese Astraeus specimens were separated into two groups based on basidiome size, shape of exoperidium, and ornamentation and size of basidiospores. The phylogenetic tree analyses supported the separation, and the morphological groups belonged to different clades. The Japanese Astraeus group 1, morphologically matched to Astraeus hygromerticus var. koreanus, showed the closest phylogenetic relationship with Astraeus hygrometricus from North American and Mediterranean regions, suggesting that the Astraeus group 1 can be indentified as A. hygrometricus var. koreanus. Another Astraeus group, group 2, morphologically matched to A. hygrometricus s.l., showed a distinct monophyletic clade that was separated from A. hygrometricus complexes, indicating an undescribed species.

In vitro mycorrhization of edible <i>Astraeus</i> mushrooms and their morphological characterization

Astraeus is the most popular and the most expensive edible ectomycorrhizal mushroom group consumed in Thailand, although it is not commonly consumed in other countries. The purpose of this work was to test the ability of Astraeus to form ectomycorrhizae with seedlings of Pinus densiflora in vitro. A single 1-week-old P. densiflora seedling was transplanted into a glass bottle containing autoclaved forest soil, and suspensions of more than 106 basidiospores of Astraeus odoratus or Astraeus hygrometricus were inoculated onto the seedling. Cultured mycelium was also inoculated onto an axenic pine seedling planted on sterilized vermiculite–sphagnum moss mixture in a glass bottle. Mycorrhization of A. hygrometricus was observed a few months after inoculation in both treatments. Fungal species identity of both the inoculum and ectomycorrhizae was assessed by PCR–RFLP analysis of the ITS region of rDNA. At 5–6 months after inoculation, A. hygrometricus ectomycorrhizae developed a sheath, rhizomorphs, and Hartig net on pine lateral roots. No ectomycorrhizal formation was found after A. odoratus inoculation. These results suggest that A. hygrometricus can form mycorrhizae on pine seedlings. The external morphological characteristics of A. hygrometricus ectomycorrhizae were distinct from those of other Boletales ectomycorrhizae. This article provides the first morphological and anatomical description of A. hygrometricus ectomycorrhizae.

Antiproliferative and immunostimulatory protein fraction from edible mushrooms

Fruit bodies and mycelia of various higher Basidiomycetes were studied in search of biological effector molecules. In this study, we evaluated the antiproliferative and immunomodulatory properties of a protein fraction designated as Cibacron blue affinity eluted protein (CBAEP) isolated from five different species of edible mushrooms ( Termitomyces clypeatus, Pleurotus florida, Calocybe indica, Astraeus hygrometricus, and Volvariella volvacea). This protein fraction (10–100 μg/ml) mediated antiproliferative activity on several tumor cell lines through the induction of apoptosis. Also the isolated protein fraction from all five mushrooms had a stimulatory effect on splenocytes, thymocytes and bone marrow cells. Further it enhanced mouse natural killer (NK) cell cytotoxicity and stimulated macrophages to produce nitric oxide (NO). The highest immunostimulatory activity was determined in the CBAEP from T. clypeatus and the highest antiproliferative activity from C. indica.

Isolation and characterization of a heteroglycan from the fruits of Astraeus hygrometricus

A water-soluble polysaccharide was isolated from an alkaline extract of the fruits of the ectomycorrhizal fungus, Astraeus hygrometricus. It was found to contain d-mannose, d-glucose, and l-fucose in a molar ratio of 1:2:1. On the basis of total hydrolysis, methylation analysis, periodate oxidation, Smith degradation, and NMR studies ( 1H, 13C, DQF-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC) the structure of the repeating unit of the polysaccharide was established as [Display omitted]