Pleurotus Tuber-regium Research Articles

English

Pleurotus tuber-regium (Rumph. Ex Fr.) Singer (King tuber mushroom) was cultivated on sawdust; mixture of sawdust and waste paper and mixture of Telfairia occidentalis Hook.F. (Fluted pumpkin) stem and waste paper in order to examine growth of the mushroom on the test substrates. The spawn of the mushroom was used to inoculate the substrates. Mycelia ramification and sclerotia production were monitored on the substrates during the research. The sclerotia produced were analyzed for protein and crude fiber content. Mycelia ramification for paper mixed with fluted pumpkin stem treatment was significantly different from sawdust and sawdust mixed with paper at P=0.05. Fluted pumpkin stem and waste paper could serve as substrates for cultivation of P. tuber-regium. Key words: Fluted pumpkin stem, Pleurotus tuber-regium, sclerotia, waste paper

Mushroom Dietary Fiber from the Fruiting Body of Pleurotus tuber-regium: Fractionation and Structural Elucidation of Nondigestible Cell Wall Components

The cell wall of mushroom fruiting body is constituted of nondigestible macromolecules that are a rich source of dietary fiber with biological functions that are beneficial to human health. The cell wall components of an edible mushroom fruiting body from Pleurotus tuber-regium (PTR) were fractionated, and their chemical structures were investigated by chemical, physicochemical, and microscopic analyses. The present results suggest that the cell wall of the PTR mushroom fruiting body contains four main fractions: an outer fraction of polysaccharide and protein complex, which can be extracted using boiling water; a cold alkali-soluble fraction of heteropolysaccharides associated with a small amount of proteins; a hot alkali-soluble fraction of hyper-branched glucans; and an alkali-insoluble fraction of glucan-chitin complex with a normalized relative percentage of 3.6:21.9:55.7:18.8. The anomeric linkage of all the glucans was revealed by infrared spectroscopy to be β type. The structure of the major mushroom fruiting body cell wall polysaccharide (the hot alkali-soluble one, FHA-I) was elucidated by the methylation analysis to be composed of →1)-Glcp-(4→ linkages as the backbone with a 52% degree of branching consisting of →1)-Glcp-(6→ linkages in the side chains, whereas some →1)-Glcp-(3→ linkages might exist in the backbone or side chains. Size exclusion chromatography coupled with multiangle laser light scattering analysis revealed that FHA-I had a molecular weight of 4.224 × 10(6) g/mol and a root-mean-square radius of 30.4 nm. Both scanning electron and atomic force microscopy further showed the highly branched microstructure of FHA-I when dispersed in an aqueous sodium dodecyl sulfate solution.

Inhibitory effects of Pleurotus tuber-regium mycelia and bioactive constituents on LPS-treated RAW 264.7 cells

Pleurotus tuber-regium (PTR) is an edible and medicinal mushroom found mainly in tropical and subtropical countries. In this study, we investigated the anti-inflammatory effects of PTR mycelia on RAW 264.7 macrophages. Samples of PTR mycelia were prepared by submerged fermentation. An ethanolic extract of PTR mycelia (PTRA) inhibited the production of nitric oxide (NO), TNF-α, and IL-6 in LPS-treated RAW 264.7 cells. Two compounds were purified and identified as cerevisterol (CE) and ergosta-4,6,8(14),22-tetraen-3-one (EG). Both CE and EG inhibited the production of NO, TNF-α, and PGE2 in LPS-treated RAW 264.7 cells. The expression of the iNOS and COX2 proteins was inhibited by CE and EG in a dose-dependent manner. In addition, CE and EG repressed the expression of iNOS, COX2, TNF-α, and SOCS3 mRNAs. This study revealed that an ethanolic extract of PTR mycelia exhibited anti-inflammatory activity and that CE and EG might contribute to this activity.

Hepato- and nephroprotective activities of a Nigerian local king tuber oyster mushroom, Pleurotus tuberregium (higher Basidiomycetes), in chemically induced organ toxicities in rats.

Chronic kidney disease, end-stage renal failure, and liver diseases are increasing worldwide and constitute a huge burden on health care costs, with attendant high morbidity and debility. Despite advances in modern medicine, there are still no licensed drugs that satisfactorily restore lost kidney or hepatic functions. In this study the chemoprotective effects of the hot aqueous extract of a local edible oyster mushroom, Pleurotus tuberregium (APTR), was evaluated in experimental liver and kidney toxicities. The effect of APTR on carbon tetrachloride (CCl4)- and paracetamol (PCM)-induced hepatotoxicity in rats was investigated by determining serum concentrations of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP). Short-term oral treatment with APTR (100 and 250 mg/kg) significantly reduced (P < 0.05) the increased concentrations of AST, ALT, and ALP induced in both PCM and CCl4 models of liver toxicity. APTR (100 and 250 mg/kg) decreased the mean serum AST concentrations by as much as 73.00% and 99.37%, respectively, in PCM-treated rats. Nephroprotection was assessed by determining the serum concentrations of creatinine and urea, as well as antioxidant enzymes, in kidney tissue homogenates after a repeated high dose of gentamicin. APTR (100 and 250 mg/kg) produced a significant decrease (P < 0.05) in the escalated serum concentrations of creatinine and urea by as much as 48.36% and 41.53%, respectively, compared to control. Similarly, levels of the antioxidant enzymes catalase, glutathione peroxidase, and superoxide dismutase in kidney tissue were increased in a dose-related manner in groups that received oral APTR supplementation. The results of this study suggest that the consumption of our local edible mushroom, P. tuberregium, could, in addition to its high nutritive value, protect the liver and kidneys from oxidative damage caused by drugs and toxicants such as CCl4 and high doses of gentamicin and PCM.

Regulation effect of polysaccharides from Pleurotus tuber-regium (Fr.) on the immune activity of mice macrophages

Pleurotus tuber-regium (Fr.) is widely consumed as a nutritious food due to its multiple health effects, especially immune function. This study was aimed at investigating its immune activity using the mice peritoneal macrophage model. Two polysaccharides, water and alkaline extraction of polysaccharides (W-PTR and A-PTR), from P. tuber-regium were used to test their immune functions and compare their possible activity differences. Results showed that both W-PTR and A-PTR showed a significant enhancement effect on the macrophage phagocytosis, and could activate the related enzymes, such as ATPases, lysozyme, and LDH, which are responsible for providing the maturation and proliferation process of macrophages with sufficient energy. In addition, levels of intracellular cytokines (IL-1, TNF-α, NO) were significantly increased after being treated with polysaccharides. A-PTR displayed a better performance than W-PTR in almost all tests. It is concluded that both polysaccharides could enhance the immune system by activating the macrophages and related enzymes, and induce the release of cytokines, indicating that polysaccharides are responsible for the immune function of Pleurotus tuber-regium (Fr.).

Biodegradation and Sugar Release from Canola Plant Biomass by Selected White Rot Fungi

Canola crop is rich in plant biomass. It is considered a major cash crop in North America and a potential source for biofuel. We evaluated six strains of white rot basidiomycetes under solid state fermentation (SSF) for their potentials to secrete oxidative and hydrolytic enzymes to biodegrade canola plant biomass (CPB), and release sugars. Fuscoporia gilva and Pleurotus tuberregium produced high amount of laccase (440.86 U/L and 480.63 U/L at day 7), as well as carboxylmethylcellulase (CMCase) (4.78 U/mL at day 21 and 3.13 U/mL at day 14) and xylanase (4.48 U/mL and 7.8 U/mL at day 21), respectively. Bjerkandera adusta showed high amount of MnP (50.4 U/L) and peroxidase (64.5 U/L), relative to the other strains. Loss of organic matter peaked after 21 days of incubation in all the tested strains; however, the best result (34.0%) was shown in P. tuberregium. The highest lignin loss was observed in Coriolopsis caperata strains. Among the sugar polymers, hemicellulose was highly degraded by P. tuberregium and P. pulmonarius (4.1% - 4.6%), while cellulose (3.3% - 4.3%) was mainly degraded by F. gilva and B. adusta. Glucose was the dominant sugar released by all the fungi tested, with the highest concentration of 1.25 mg/mL produced by B. adusta at day 14 of incubation. Results indicate that selected white rot fungi can achieve significant delignification of CPB within 14 days of solid state fermentation. Their importance in low cost pretreatment of lignocellulosic biomass prior to conversion into biofuels and bio-products of economic importance is discussed.

Cell wall structure of mushroom sclerotium (Pleurotus tuber-regium): Part 2. Fine structure of a novel alkali-soluble hyper-branched cell wall polysaccharide

The fine molecular structure of a novel alkali-soluble polysaccharide (SCA-I) from the mushroom sclerotial cell wall of Pleurotus tuber-regium was elucidated by 1-D and 2-D NMR spectroscopy as a hyper-branched glucan having a 64.9% degree of branching at O-6 and consisting a main chain with →1)-Glcp-(4→ linkages and short side chains having either →1)-Glcp-(3→ or →1)-Glcp-(6→ linkages. This partial structure of SCA-I was consistent with that obtained from methylation analysis. The molecular conformation of SDS-treated SCA-I was visualized for the first time by TEM and AFM. Microscopic images confirmed the highly branched structure of SCA-I as well as its multiple chain conformation when its compact structure was opened up by SDS treatment. This unique hyper-branched polysaccharide has the potential application in the design of carbohydrate-based nano-particles and drug delivery systems.

In vitro antioxidant activities of the polysaccharides from Pleurotus tuber-regium (Fr.) Sing.

The antioxidant activities of two homogeneous polysaccharides, water extraction of polysaccharide (W-PTR) and alkali extraction of polysaccharide (A-PTR) from Pleurotus tuber-regium (Fr.) Sing. were evaluated. Results showed that W-PTR was stronger than A-PTR in O2- scavenging activity, while A-PTR was stronger than W-PTR in the scavenging activities to OH, DPPH, inhibition effects on liver lipid peroxidation, liver mitochondria swelling, and red blood cell (RBC) hemolysis. At concentration of 0.3g/L, the O2- scavenging activity of W-PTR and A-PTR were 85.7% and 71.7%. At concentration of 0.25g/L, the OH scavenging activity of W-PTR and A-PTR were 64.20% and 74.97%. At the concentration of 0.3g/L, the lipid peroxidation inhibition effects of A-PTR were 79.37%. At concentration of 0.8g/L, the hemolysis inhibition rate of A-PTR was 77.16%. The polysaccharides of P. tuber-regium had strong antioxidant potency and might be exploited as effective natural antioxidant to alleviate oxidative stress.

Cell wall structure of mushroom sclerotium (Pleurotus tuber regium): Part 1. Fractionation and characterization of soluble cell wall polysaccharides

The cell wall structure of mushroom sclerotium was investigated by a fractionation of its soluble cell wall polysaccharides followed by chemical, physico-chemical and microscopic analyses. The present results suggest that cell wall structure of Pleurotus tuber regium sclerotium contains three main layers: an outer layer of glycoproteins, a middle layer of hyper-branched glucans and an inner layer of complex between hyper-branched glucan and chitin. The structure of the hyper-branched glucans were elucidated by the methylation analysis to be composed of →1)-Glcp-(4→ linkages as the backbone with some →1)-Glcp-(6→ linkages existed in the side chains, while some →1)-Glcp-(3→ linkages might exist in the backbone or side chains. SEC-MALLS analysis revealed that hyper-branched β-glucans had a Mw ranging from 1.4 to 5.2 × 106 g/mol and R.M.S. radius ranging from 26 nm to 38.5 nm. SEM and AFM further showed that hyper-branched β-glucans were spherical in shape when dispersed in water.

Moderation of hematological and plasma biochemical indices of sub-chronic salt-loaded rats by aqueous extract of the sclerotia of Pleurotus tuberregium (Fr) Sing's: Implications for the reduction of cardiovascular risk

Ethnopharmacological relevanceThe sclerotia of Pleurotus tuberregium are used in Southern Nigeria for the management of diabetes and hypertension, yet there is scarcity of information in the literature regarding the evaluation of the biochemical basis of its antihypertensive property, as well as the biochemical impact of its administration to the hypertensive. Thus, in this study, the ability of an aqueous extract of the sclerotia of Pleurotus tuberregium to moderate biochemical and hematological indices was investigated in normal and sub-chronic salt-loaded rats. Materials and methodsThe normal and treatment control groups received a diet consisting 100% of the commercial feed, while the test control, reference and test treatment groups received an 8% salt-loaded diet. The extract was orally administered daily at 100 and 200mg/kg body weight; while the moduretics was administered at 1mg/kg. The normal and test control groups received appropriate volumes of water by the same route. ResultsOn gas chromatographic analysis of the crude aqueous extract, 29 known flavonoids (mainly 47.71% kaempferol and 37.36% quercetin), four saponins (mainly 72.93% avenacin B1 and 26.80% avenacin A1), six hydroxycinnamic acid derivatives (mainly 57.57% p-coumaric and 42.10% caffeic acid), ten carotenoids (mainly 58.44% carotene and 28.16% lycopene) and seven phytosterols (mainly 98.16% sitosterol) were detected. Also detected were nine benzoic acid derivatives (mainly 44.19% ferulic acid and 25.92% rosmarinic acid), six lignans (mainly 70.88% galgravin and 22.69% retusin), three allicins (mainly 71.92% diallyl thiosulphinate and 23.68% methyl allyl thiosulphinate), seven glycosides (mainly 84.86% arbutin and 12.01% ouabain), 31 alkaloids (mainly 48.82% lupanine, 32.26% augustamine) and 24 terpenes (mainly 60.66% limonene and 6.52% geranyl acetate). Compared to test control, the treatment significantly, dose-dependently lowered (P<0.05) the mean cell volume, atherogenic indices (cardiac risk ratio, atherogenic coefficient and atherogenic index of plasma), plasma alanine and aspartate transaminase activities, mean cell hemoglobin, sodium, bicarbonate, urea, blood urea nitrogen, triglyceride, total-, non-high density lipoprotein-, low density lipoprotein- and very low density lipoprotein cholesterol concentrations, and neutrophils, monocytes and platelets counts of the treated animals. However, it significantly, dose-dependently increased (P<0.05) the hemoglobin concentration, mean cell hemoglobin, red cells and lymphocytes counts, plasma high density lipoprotein cholesterol, calcium, potassium, chloride, creatinine, albumin and total protein concentrations of the treated animals. ConclusionsAll these results support the use of the plant in traditional health care, for the management of hypertension, and highlight the cardio-protective potential of the sclerotia, whilst suggesting that its antihypertensive activity may be mediated through alteration of plasma levels of sodium and potassium, or increases in muscle tone brought about by changes in plasma calcium levels.

Effects of different substrates on the yield and nutritional value of Pleurotus tuberregium (FR.) sing

Two experiments were conducted to study the effects of different substrates on the yield and nutritional content of Pleurotus tuberregium (Fr.) Sing. Seven different substrates were used in both experiments to grow the mushrooms and sclerotia, respectively. The experiments were carried out using a completely randomized design (CRD). Fresh and dry weights of the harvested mushrooms and sclerotia were recorded and the proximate analysis of the mushrooms conducted using Association of Official Analytical Chemists (AOAC’s) methods. Analysis of variance (ANOVA) was used for data analysis and test of significance carried out by the Duncan’s multiple range test. Results of the mushroom cultivation experiment showed that mean dry weights varied from 0.22 g for mixture of topsoil and fermented sawdust substrate (M5) to 3.34 g for mixture of river sand and fermented sawdust substrate (M7), while the mean fresh weights varied from 1.42 g for M5 to 13.76 g for M7. The mean fresh weights of M2, M3 and M7 were not significantly different from one another but were significantly different from those of M4 and M5. Furthermore, percentage carbohydrate content ranged from 59.03% in M1 to 65.41% in M2 while that of crude protein varied from 14.88% in M3 to 17.78% in M1. For the second experiment, the rate of substrate colonization differed significantly (P≤ 0.05) for the treatments. The mean colonization rate varied from 0.0 day in S2, S3 to 31.2 days in S5, S4 and S6, which were not significantly different from each other but were significantly different from S1, S5 and S7 and from S2 and S3. The mean dry weight yield varied from 46.26 g in S5 to 127.48 g in S1. The biological efficiency of sclerotia harvested from S1, S6 and S7 were not significantly different from one another but were significantly different from those of S4 and S5 substrates. Considering all the parameters investigated; a mixture of river sand and fermented sawdust substrate (M7) is recommended as the best substrate for the cultivation of P. tuberregium mushrooms while a mixture of corn waste and fermented sawdust substrate (S6) is recommended for sclerotial cultivation. Mushrooms grown on topsoil substrate (M1) are recommended as the best for nutritional supplement.

Characterization of water and alkali-soluble polysaccharides from Pleurotus tuber-regium sclerotia

Pleurotus tuber-regium sclerotia, an edible and medicinal mushroom, is a rich source of polysaccharides used as a functional food to promote health and longevity. The crude polysaccharides were isolated from the P. tuber-regium by hot aqueous and alkali extraction and then further purified by DEAE-52 cellulose chromatography and Sephadex G-100 chromatography. Two polysaccharides, water and alkaline extraction of polysaccharides (W-PTR and A-PTR), were obtained and their extraction process were optimized through orthogonal array design. Structure characteristics (physicochemical property analysis, molecular weight, monosaccharide composition, sulfate and uronic acid contents, triple helical structures, ultraviolet spectrum and infrared spectroscopy) of the two polysaccharides were investigated. Results showed that the main difference between the two polysaccharides is reflected in color, solubility, molecular weight and monosaccharide composition. Conformational analysis showed that both W-PTP and A-PTP had triple-helix conformation. The 3D structure of the two polysaccharides and their structure–function relationship will be challenge in the future.

Contractile Effect of Aqueous Pleurotus tuberregium Extract on the Isolated Bovine Iris

ABSTRACTBackground: Aqueous extract of Pleurotus tuberregium (PT) has been shown to reduce intraocular pressure (IOP) but the underlying mechanism has not been explained.Purpose: To investigate the effect of PT on the bovine iris in vitro in comparison with acetylcholine (ACh).Method: Strips of the iris were mounted in 10 ml organ baths and exposed to increasing concentrations of PT, ACh and a combination of both agents. The effect of atropine on the responses to the agents was also investigated.Results: PT and ACh separately caused contractile responses on the iris, but their effect reduced with higher concentrations. Combination of PT and ACh did not significantly alter the reduced responses seen with high concentrations of either agent. Atropine completely abolished the contractile responses of the agents.Conclusion: The contractile effect of PT on muscarinic receptor-containing iris muscle may explain its IOP reducing property.

Major and trace elements in sclerotium of Pleurotus tuber-regium (Ósū) mushroom—Dietary intake and risk in southeastern Nigeria

This paper presents the results of the determination of Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, P, Pb, Rb, Sr and Zn in 30 specimens of the sclerotia of Pleurotus tuber-regium mushroom from two markets in southeastern Nigeria. The elements were determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The K and Mg contents ranged from 500 to 10,000μg/g (dry weight), followed by Ca and Na ranging from 19 to 1700μg/g. The median concentrations of Fe, Zn, Al, and Mn were generally >10μg/g, followed by Rb, Cu, Sr, Ba, and P with median between 1.1 and 11μg/g, while Cr, Ni, Ag, Co, and Cd were <1μg/g. The Hg concentrations were between 0.0033 and 0.15μg/g. The Pb (0.05–2.2μg/g) and Cd (0.0027–0.16μg/g) contents were below EU limits for these metals in fungi, and thus safe for human consumption. Principal component analysis (PCA) showed that the concentrations of Ba, Ca, Mg, P, Rb and Sr in sclerotia did not vary considerably, depending on the sampling location, as did Cd, Cu, and Mn. PCA also revealed that the Hg and Pb in sclerotia could be related to anthropogenic sources.

Two-Dimensional Gel Electrophoresis Analysis of Mycelial Cells Treated with Tween 80: Differentially Expressed Protein Related to Enhanced Metabolite Production

Two-dimensional gel electrophoresis identified 40 differentially expressed proteins which explained the mechanisms underlying the stimulatory effect of Tween 80 for exopolysaccharide production in the mycelium of an edible mushroom Pleurotus tuber-regium. The up-regulation of fatty acid synthase alpha subunit FasA might promote the synthesis of long-chain fatty acids and their incorporation into the mycelial cell membranes, increasing the membrane permeability. A down-regulation of Phospholipase D1 and an up-regulation of Hypothetical protein PGUG_02954 might mediate signal transduction between the mycelial cells and the extracellular stimulus (Tween 80). The down-regulated ATP-binding cassette transporter protein might function as pumps to extrude exopolysaccharide out of the cells that lead to a significant increase in its production. The present results explained how stimulatory agents like Tween 80 can increase mycelial cell membrane permeability to enhance the production of useful extracellular metabolites by submerged fermentation.

Uses of mushrooms in bioremediation: A review

One of the major environmental problems facing the world today is the contamination of soil, water and air by toxic chemicals as a result of industrialization and extensive use of pesticides in agriculture. Incineration is currently the most effective and common remediation practice but is costly in terms of money and energy used. A rapid cost effective and ecologically responsible method of clean-up is “bioremediation” which utilizes micro-organisms to degrade toxic pollutants in an efficient economical approach. Toxic chemicals are degraded to less harmful forms. Although, bioremediation by bacteria agents has received attention of workers, the role of fungi has been inadequately studied. The ability of fungi to transform a wide variety of hazardous chemicals has aroused interest in using them for bioremediation. Mushroom forming fungi (mostly basidiomycetes), are amongst nature’s most powerful decomposers, secreting strong extra cellular enzymes due to their aggressive growth and biomass production. These enzymes include lignin peroxidases (LiP), manganese peroxidase (MnP) and laccase, etc. Thus, carbon sources such as sawdust, straw and corn cob can be used to enhance degradation rates by these organisms at polluted sites. White rot fungi have been used for biotransformation of pesticides, degradation of petroleum hydrocarbons and lignocellulolytic wastes in the pulp and paper industry. Phanerochaete chrysosporium,Agaricus bisporus, Trametes versicolor and Pleurotus ostreatus amongst many mushrooms have been reported in the decontamination of polluted sites. In Nigeria, Lentinus squarrosulus,Pleurotus tuber-regium, P. ostreatus and P. pulmonarius have been employed in bioremediation of contaminated soils both in-situ and ex-situ. This paper highlights the use of fungal mycelia in bioremediation (myco-remediation) and studies on the uses of mushrooms for bioremediation. Key words: Bioremediation, mushrooms, polluted soils.

Effect of different sizes of planting material on the growth and yield components of edible mushroom &lt;i&gt;Pleurotus tuberregium&lt;/i&gt;

An experiment was conducted in 2004 and 2005 at the University of Uyo Teaching and Research Farm to assess the effect of different weights of planting materials on the performance and yield components of ediblemushroom Pleurotus tuberregium. The experiment was laid out in Randomized complete block design with three weights (20g, 40g and 60g) as treatments and replicated five times. Each plot size measured 1m x 1m with a total of 16 polybags per plot. Parameters studied were percent emergence, cap diameter, stipe height and girth as well as number of shoots. Results obtained showed no significance (P&lt;0.05) in percent emergence amongst the weights of planting materials. However, a significant (P&lt;0.05) effect was recorded in cap diameter (3.68cm) from the 20g weight planting material. Stipe height and girth did not show any significant difference amongst the treatments. The 60g planting material weight recorded more shoots than the 20g and 40g planting material sizes. The 60g planting material weight is recommended to farmers for the purpose of multiplication of Pleurotus tuberregium for better economicreturns.

Proteomic insights into the stimulatory effect of Tween 80 on mycelial growth and exopolysaccharide production of an edible mushroom Pleurotus tuber-regium

Proteomic analysis was applied to investigate the mechanism of the stimulatory effect of Tween 80 on the mycelial growth and exopolysaccharide production by an edible mushroom Pleurotus tuber-regium. 32 differentially expressed proteins were identified by one-dimension gel electrophoresis. Combined with our previous findings, the up-regulation of heat shock proteins might help to maintain cellular viability under environmental stress. The up-regulation of ATP:citrate lyase isoform 2 could suppress the activity of tricarboxylic acid cycle and, consequently, stimulate exopolysaccharide production. The present results provide important insight to the mechanism by which stimulatory agents (Tween 80) can increase the production of useful fungal metabolites and also fill the gap of our knowledge on the under-developed mushroom proteomics.

Comparative Proteomic Analysis of Mushroom Cell Wall Proteins among the Different Developmental Stages of Pleurotus tuber-regium

Cell wall proteins (CWPs) play a vital role in the development of the different morphological stages including mycelium, fruiting body, and sclerotium in mushrooms which are important human food sources. Using fractionation by detergents and reducing agents, mushroom cell wall fractions from the different developmental stages of Pleurotus tuber-regium (PTR) were prepared. Using one-dimensional gel electrophoresis coupled with LC-MS, there were 103, 91, and 48 noncovalently linked CWPs identified in the cell wall fractions of the PTR mycelium, fruiting body, and sclerotium, respectively. Comparing the CWPs in these cell wall fractions, 19 of them were in common, among which 17 belonged to the functional categories of translation, ribosomal structure, and biogenesis. This is the first study to provide important biochemical insights into the different developmental stages of PTR mediated by CWPs, and the identified CWPs helped to explain the morphological changes of PTR mushrooms during cultivation.

Abstract 5643A: Pleurotus pulmonarius extract suppresses liver cancer development and progression through VEGF-mediated autocrine regulation of PI3K/AKT pathway

Abstract Hepatocellular Carcinoma (HCC) is one of the leading causes of cancer-related deaths. However, the conventional chemotherapies are not only limited by late diagnosis, locally advanced and metastasis, but also by various unexpected side effects. Because of the diverse pharmacological characteristics including non-toxicity, potent biological activity and solubility, natural phytochemicals are receiving more and more attention in the implication of chemoprevention and chemotherapy recently. Our previous studies have reported the anticancer effects of several mushroom polysaccharides including the Poria cocos and Pleurotus tuber-regium. Interestingly, an active polysaccharide and protein complex isolated from mushroom Pleurotus pulmonarius, coded as PP, was screened out based on the antioxidant activity study of the mushroom species collection in our lab. However, whether PP has anti-cancer effects in liver cancer cells and the underlying molecular mechanisms remain to be elucidated. This study aims to explore the anticancer effect of PP, and to investigate the signaling pathways responsible for its suppressing effect. Our results indicated that the exposure of liver cancer cells to PP not only reduced the cancer cell proliferation and invasion but also enhanced the drug-sensitivity to conventional chemotherapeutic drugs cisplatin. More importantly, both oral administration and intraperitoneal injection of PP significantly inhibited the tumor growth of liver cancer cells in nude mice. Furthermore, treatment of PP triggered a marked suppression of the PI3K/AKT signaling pathway in liver cancer cells in vitro and in vivo, and overexpression of the constitutively active form of AKT, Myr-AKT, abrogated this effect and the inhibited proliferation and invasion by PP, suggesting the involvement of PI3K/AKT pathway in the function of PP in liver cancer cells. Interestingly, the data from western blot and ELISA (Enzyme-linked immunosorbent assay) demonstrated that treatment of liver cancer cells with PP reduced expression and secretion of vascular endothelial growth factor (VEGF), and addition of recombinant human VEGF attenuated the suppressive effects of PP on PI3K/AKT pathway and the cancer phenotypes. Taken together, our results indicated that PP, the active extract from Pleurotus pulmonarius, suppressed the proliferation, invasion, and drug-resistance of liver cancer cells in vitro and in vivo, and these effects are mediated by reduced expression and secretion of VEGF and the subsequent inhibited autocrine VEGF-induced activation of PI3K/AKT pathway. This study suggests potential therapeutic implication of PP in the treatment of liver cancer. The effects of PP on liver cancer stem cells and its chemopreventive effects in human liver cancer warrants further investigation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5643A. doi:1538-7445.AM2012-5643A