Lectins from mushrooms

Purification and Biochemical Characterization of Novel Galectin from the Black Poplar Medicinal Mushroom Cyclocybe cylindracea (Agaricomycetes) Strain MEST42 from Algeria

In the present study, a new galectin designated Cyclocybe cylindracea lectin (CCL) was extracted from the fruiting bodies of the wild black popular mushroom C. cylindracea grown in Algeria. The protein was isolated using sepharose 4B as affinity chromatography matrix, and galactose as elutant. The purified galectin was composed of two subunits of 17.873 kDa each, with a total molecular mass of 35.6 kDa. Its agglutinant activity was impeded by galactose and its derivatives, as well as melibiose. Lactose showed the highest affinity, with a minimal inhibitory concentration of 0.0781 mM. CCL was sensitive to extreme pH conditions, and its binding function decreased when incubated with 10 mM EDTA, and it could be restored by metallic cations such as Ca2+, Mg2+, and Zn2+. CCL agglutinated human red blood cells, without any discernible specificity. Circular dichroism spectra demonstrated that its secondary structure contained β-sheet as dominant fold. In addition, bioinformatics investigation on their peptide fingerprint obtained after MALDI-TOF/TOF ionization using mascot software confirmed that CCL was not like any previous purified lectin from mushroom: instead, it possessed an amino acid composition with high similarity to that of the putative urea carboxylase of Emericella nidulans (strain FGSC A4/ATCC 38163/CBS 112.46/NRRL 194/M139) with 44% of similarity score.

Effects of Local Nasal Immunotherapy with FIP-fve Peptide and Denatured Tyrophagus putrescentiae for Storage Mite-Induced Airway Inflammation

Allergic diseases are affecting public health and have increased over the last decade. Sensitization to mite allergens is a considerable trigger for allergy development. Storage mite-Tyrophagus putrescentiae shows great significance of allergenic potential and clinical relevance. The fungal immunomodulatory peptide FIP-fve has been reported to possess immunomodulatory activity. We aimed to determine whether T. putrescentiae-induced sensitization and airway inflammation in mice could be downregulated by FIP-fve in conjunction with denatured T. putrescentiae (FIP-fve and DN-Tp). Immune responses and physiologic variations in immunoglobulins, leukocyte subpopulations, cytokine productions, pulmonary function, lung pathology, cytokines in CD4⁺ and Treg cells were evaluated after local nasal immunotherapy (LNIT). After the LNIT with FIP-fve and DN-Tp, levels of specific IgE, IgG1, and IgG2a in the sera and IgA in the bronchoalveolar lavage fluid (BALF) were significantly reduced. Infiltrations of inflammatory leukocytes (eosinophils, neutrophils, and lymphocytes) in the airway decreased significantly. Production of proinflammatory cytokines (IL-5, IL-13, IL-17F and IL-23) and chemokine (IL-8) were significantly reduced, and Th1-cytokine (IL-12) increased in the airway BALF after LNIT. Pulmonary functions of Penh values were significantly decreased after the methacholine challenge, which resulted in a reduction of airway hypersensitivity after LNIT. Bronchus pathology showed a reduction of inflammatory cell infiltration and epithelium damage after LNIT. The IL-4⁺/CD4⁺ T cells could be downregulated and the IFN-γ⁺/CD4⁺ T cells upregulated. The Treg-related immunity of IL-10 and Foxp3 expressions in CD4⁺CD25⁺ cells were both upregulated after LNIT. In conclusion, LNIT with FIP-fve and DN-Tp had an anti-inflammatory effect on mite-induced airway inflammations and possesses potential as an immunomodulatory therapy agent for allergic airway diseases.

Purification and structural characterization of lectin with antibacterial and anticancer properties from grubs of hide beetle, Dermestes frischii

Lectins or haemagglutinins are diverse classes of non-immune proteins; they bind to carbohydrates and are abundant in nature. In the present study, a coleopteran lectin from grubs of hide beetle, Dermestes frischii called DFL, was purified by glutaraldehyde (fixative-agent) fixed hen erythrocytes and characterized further for its functional properties. The purified DFL was stable between pH range 5 to 9 and heat-stable up to 50C. It was insensitive to EDTA and did not require any divalent cations. DFL native molecular mass was approximately 69 kDa with three different polypeptide subunits of 33 (pI ~4.4), 22 (pI ~6) and 14 (pI ~4.4) kDa. Haemagglutinating activity of DFL was highly inhibited by N-acetyl-D-glucosamine. DFL partial peptide sequences obtained from peptide mass fingerprinting experiments matched with amino acid sequences of lectins from different organisms confirmed its nature. Biological properties of purified DFL namely antibacterial and bacterial agglutination experiments revealed that DFL have both the effects against laboratory cultures of Aeromonas hydrophila, Enterococcus faecalis, Escherichia coli and habitat bacterial isolates of Staphylococcus cohnii and Bacillus cereus. In addition, the DFL exhibited substantial anticancer properties against HeLa cells. These results concluded that purified DFL could serve as a potent therapeutic agent for various biomedical applications.

Biomolecules of mushroom: a recipe of human wellness

The Indian system of medicine - Ayurveda says "When diet is wrong, medicine is of no use. When diet is correct, medicine is of no use". In this context, mushroom constitutes one of the major resources for nutraceuticals. Biomolecules of mushrooms have attracted the attention of researchers around the globe due to their proven healthy attributes. They have a plenitude of health-giving properties and these range from immunomodulatory, antiviral, antibacterial, antifungal, antioxidant, anti-inflammatory, antitumor, anticancer, anti-HIV, antidiabetic, anticholesterolic to antiarthritic activities.Mushrooms contain both primary and secondary metabolites. The primary metabolites provide energy while the secondary metabolite exhibits medicinal properties. Hence, the mushroom can be a recipe for human wellness and will play a significant role in fighting COVID-19 pandemics and other infectious diseases.The key findings suggested in this paper refer to the exploration of health and the healing traits of biomolecules of mushrooms. This article reviews the current status of the medicinal attributes of mushrooms and their biomolecules in different diseases such as cardiovascular, diabetes, reproductive diseases, cancer, and neurodegenerative diseases. The global malnutrition-related morbidity and mortality among children under five and lactating women presents a frightening picture and also a black spot on the human face. Malnutrition is responsible for more ill-health than any other cause. Mushrooms as a rich source of bioactive compounds can be claimed as "Best from the Waste" since they grow on the most abundant organic wastes of the Earth, the lignocellulosic substrate, and 'Best of the Rest' because they are excellent nutraceutical resources.

Natural Products with Inhibitory Activity against Human Immunodeficiency Virus Type 1

Infections caused by human immunodeficiency virus (HIV) are considered one of the main public health problems worldwide. Antiretroviral therapy (ART) is the current modality of treatment for HIV-1 infection. It comprises the combined use of several drugs and can decrease the viral load and increase the CD4+ T cell count in patients with HIV-1 infection, thereby proving to be an effective modality. This therapy significantly decreases the rate of morbidity and mortality owing to acquired immunodeficiency syndrome (AIDS) and prolongs and improves the quality of life of infected patients. However, nonadherence to ART may increase viral resistance to antiretroviral drugs and transmission of drug-resistant strains of HIV. Therefore, it is necessary to continue research for compounds with anti-HIV-1 activity, exhibiting a potential for the development of an alternative or complementary therapy to ART with low cost and fewer side effects. Natural products and their derivatives represent an excellent option owing to their therapeutic potential against HIV. Currently, the derivatives of natural products available as anti-HIV-1 agents include zidovudine, an arabinonucleoside derivative of the Caribbean marine sponge (Tectitethya crypta), which inhibits the reverse transcriptase of the virus. This was the first antiviral agent approved for treatment of HIV infection. Additionally, bevirimat (isolated from Syzygium claviflorum) and calanolide A (isolated from Calophyllum sp.) are inhibitors of viral maturation and reverse transcription process, respectively. In the present review, we aimed to describe the wide repertoire of natural compounds exhibiting anti-HIV-1 activity that can be considered for designing new therapeutic strategies to curb the HIV pandemic.

Genetic sequence analysis and characterization of bioactive compounds in mushroom-forming fungi

Mushroom-forming fungi produce unique bioactive compounds that have potential applications as medicines, supplements, and agrochemicals. Thus, it is necessary to clarify the biosynthetic pathways of these compounds using genome and transcriptome analyses. This review introduces some of our research on bioactive compounds isolated from mushrooms, as well as genetic analysis with next-generation sequencing.

Mushroom lectin overcomes hepatitis B virus tolerance via TLR6 signaling

Currently, chronic hepatitis B virus (HBV) infection remains a serious public health problem in the world. Recombinant HBV vaccine, as a preventive strategy against HBV infection, generates high antibody level, but it is not effective to activate innate and cellular immunity for chronic HBV infection therapy. Lectins from mushroom are natural and active proteins which have been shown important biological functions. However, little is known about the immunological mechanism engaged by mushroom lectins. Here we report that, lectin from Pleurotus ostreatus (POL) stimulated innate response by activating Toll-like receptor 6 signal pathway of dendritic cells. Subsequently POL enhanced HBV specific antibody level and follicular helper T cells response which overcame HBV tolerance in transgenic mice. This study suggests a novel mechanism for POL acting on immune response and a therapeutic approach to break HBV tolerance.

Lectins from Mycelia of Basidiomycetes

Lectins are proteins of a nonimmunoglobulin nature that are capable of specific recognition of and reversible binding to the carbohydrate moieties of complex carbohydrates, without altering the covalent structure of any of the recognized glycosyl ligands. They have a broad range of biological activities important for the functioning of the cell and the whole organism and, owing to the high specificity of reversible binding to carbohydrates, are valuable tools used widely in biology and medicine. Lectins can be produced by many living organisms, including basidiomycetes. Whereas lectins from the fruit bodies of basidiomycetes have been studied sufficiently well, mycelial lectins remain relatively unexplored. Here, we review and comparatively analyze what is currently known about lectins isolated from the vegetative mycelium of macrobasidiomycetes, including their localization, properties, and carbohydrate specificities. Particular attention is given to the physiological role of mycelial lectins in fungal growth and development.

Transcriptomic analysis of basidiocarp development in Ustilago maydis (DC) Cda

Previously, we demonstrated that when Ustilago maydis (DC) Cda., a phytopathogenic basidiomycete and the causal agent of corn smut, is grown in the vicinity of maize embryogenic calli in a medium supplemented with the herbicide Dicamba, it developed gastroid-like basidiocarps. To elucidate the molecular mechanisms involved in the basidiocarp development by the fungus, we proceeded to analyze the transcriptome of the process, identifying a total of 2002 and 1064 differentially expressed genes at two developmental stages, young and mature basidiocarps, respectively. Function of these genes was analyzed with the use of different databases. MIPS analysis revealed that in the stage of young basidiocarp, among the ca. two thousand differentially expressed genes, there were some previously described for basidiocarp development in other fungal species. Additional elements that operated at this stage included, among others, genes encoding the transcription factors FOXO3, MIG3, PRO1, TEC1, copper and MFS transporters, and cytochromes P450. During mature basidiocarp development, important up-regulated genes included those encoding hydrophobins, laccases, and ferric reductase (FRE/NOX). The demonstration that a mapkk mutant was unable to form basidiocarps, indicated the importance of the MAPK signaling pathway in this developmental process.

A Jacalin-Related Lectin Regulated the Formation of Aerial Mycelium and Fruiting Body in Flammulina velutipes

Flammulina velutipes, one of the most popular mushroom species in the world, has been recognized as a useful model system to study the biochemical and physiological aspects of the formation and elongation of fruit body. However, few reports have been published on the regulation of fruiting body formation in F. velutipes at the molecular level. In this study, a jacalin-related lectin gene from F. velutipes was characterized. The phylogenetic tree revealed that Fv-JRL1 clustered with other basidiomycete jacalin-like lectins. Moreover, the transcriptional pattern of the Fv-JRL1 gene in different developmental stages of F. velutipes implied that Fv-JRL1 could be important for formation of fruit body. Additionally, RNA interference (RNAi) and overexpression analyses provided powerful evidence that the lectin gene Fv-JRL1 from F. velutipes plays important roles in fruiting body formation.

Transcriptome Analysis Revealed Highly Expressed Genes Encoding Secondary Metabolite Pathways and Small Cysteine-Rich Proteins in the Sclerotium of Lignosus rhinocerotis

Lignosus rhinocerotis (Cooke) Ryvarden (tiger milk mushroom) has long been known for its nutritional and medicinal benefits among the local communities in Southeast Asia. However, the molecular and genetic basis of its medicinal and nutraceutical properties at transcriptional level have not been investigated. In this study, the transcriptome of L. rhinocerotis sclerotium, the part with medicinal value, was analyzed using high-throughput Illumina HiSeq^TM platform with good sequencing quality and alignment results. A total of 3,673, 117, and 59,649 events of alternative splicing, novel transcripts, and SNP variation were found to enrich its current genome database. A large number of transcripts were expressed and involved in the processing of gene information and carbohydrate metabolism. A few highly expressed genes encoding the cysteine-rich cerato-platanin, hydrophobins, and sugar-binding lectins were identified and their possible roles in L. rhinocerotis were discussed. Genes encoding enzymes involved in the biosynthesis of glucans, six gene clusters encoding four terpene synthases and one each of non-ribosomal peptide synthetase and polyketide synthase, and 109 transcribed cytochrome P450 sequences were also identified in the transcriptome. The data from this study forms a valuable foundation for future research in the exploitation of this mushroom in pharmacological and industrial applications.

Xylaria hypoxylon Lectin as Adjuvant Elicited Tfh Cell Responses

Foot-and-mouth disease (FMD) caused by FMD virus (FMDV) is a major health and economic problem in the farming industry. Vaccination of livestock against this highly infectious viral disease is crucial, and inactivated FMD vaccine has been effective at controlling infection. However, accumulated data show that the inactivated vaccine generates weak immune responses and that the oil formulation results in undesirable side effects. Mushroom lectins have recently been shown to display adjuvant effects when incorporated into DNA vaccines. In this study, to enhance the cellular immune response of FMDV antigen (146S), C57BL/6 mice were immunized with 146S combined with Xylaria hypoxylon lectin (XHL). The oil formulation (146S/Oil) was served as control group. Strong humoral immune responses were elicited in mice immunized with 146S/XHL as shown by high 146S antigen-specific IgG levels, and also in 146S/Oil group. Interestingly, XHL in conjunction with inactivated FMD vaccine activated strong Th1 and Tc1 cell responses, especially Tfh cell responses, in immunized mice. XHL stimulated dendritic cell maturation by upregulating expression of major histocompatibility complex II (MHCII) molecules and co-stimulatory molecules CD40 and CD86 in immunized mice. No XHL-specific IgG or inflammatory factors were detected indicating the safety of XHL as an adjuvant. Taken together, these results suggest the effectiveness of XHL at inducing cellular immune responses and therefore confirm its suitability as an adjuvant for inactivated FMD vaccine.

Hitting the sweet spot-glycans as targets of fungal defense effector proteins

Organisms which rely solely on innate defense systems must combat a large number of antagonists with a comparably low number of defense effector molecules. As one solution of this problem, these organisms have evolved effector molecules targeting epitopes that are conserved between different antagonists of a specific taxon or, if possible, even of different taxa. In order to restrict the activity of the defense effector molecules to physiologically relevant taxa, these target epitopes should, on the other hand, be taxon-specific and easily accessible. Glycans fulfill all these requirements and are therefore a preferred target of defense effector molecules, in particular defense proteins. Here, we review this defense strategy using the example of the defense system of multicellular (filamentous) fungi against microbial competitors and animal predators.

Mushroom lectins: specificity, structure and bioactivity relevant to human disease

Lectins are non-immunoglobulin proteins that bind diverse sugar structures with a high degree of selectivity. Lectins play crucial role in various biological processes such as cellular signaling, scavenging of glycoproteins from the circulatory system, cell-cell interactions in the immune system, differentiation and protein targeting to cellular compartments, as well as in host defence mechanisms, inflammation, and cancer. Among all the sources of lectins, plants have been most extensively studied. However, more recently fungal lectins have attracted considerable attention due to their antitumor, antiproliferative and immunomodulatory activities. Given that only 10% of mushroom species are known and have been taxonomically classified, mushrooms represent an enormous unexplored source of potentially useful and novel lectins. In this review we provide an up-to-date summary on the biochemical, molecular and structural properties of mushroom lectins, as well as their versatile applications specifically focusing on mushroom lectin bioactivity.

Isolation and characterization of a novel lectin from the edible mushroom Stropharia rugosoannulata

To date, only a few steroids have been isolated from the mushroom Stropharia rugosoannulata which can be cultivated. In this paper, a novel lectin (SRL) with a molecular weight of 38 kDa, and a unique IKSGVYRIVSWQGALGPEAR N-terminal sequence was isolated from S. rugosoannulata, which represents the first protein isolated from the mushroom. The purification methods included (NH₄)₂SO₄ precipitation, ion exchange chromatography on CM-cellulose, Q-Sepharose, and SP-Sepharose, and gel- filtration on Superdex-75. The lectin was adsorbed on all three types of ion exchangers and was purified more than 450-fold. The lectin was stable below 70 °C (with half of the activity preserved at 80 °C), and in the presence of NaOH and HCl solutions up to a concentration of 12.5 mM and 25 mM, respectively. The hemagglutinating activity of SRL was inhibited by inulin. Cd²⁺ and Hg²⁺ ions strongly reduced the hemagglutinating activity at concentrations from 1.25 mM to 10 mM. SRL exhibited anti-proliferative activity toward both hepatoma Hep G2 cells and leukemia L1210 cells, with an IC₅₀ of 7 μM and 19 μM, respectively. The activity of HIV-1 reverse transcriptase could also be inhibited by SRL, with an IC₅₀ of 10 μM.

Penetration through the peritrophic matrix is a key to lectin toxicity against Tribolium castaneum

In the last decades lectins have received a lot of attention as potential tools in pest control. Despite substantial progress in the field not all the factors determining insecticidal potency and selectivity of these proteins have been described. Recently, three lectins, RSA (Rhizoctonia solani agglutinin), SNA-I and SNA-II (Sambucus nigra agglutinin I and II) have been shown to be toxic to aphids and caterpillars. In this project we investigated if these lectins are also toxic against larvae and a cell line of the red flour beetle, Tribolium castaneum, a model organism and important pest of stored products. Furthermore, we analyzed the stability of the lectins in the larval gut and used confocal microscopy to compare their efficiency in passing through the peritrophic matrix (PM). We observed that all three lectins were toxic against the T. castaneum cell line and their effectiveness in vitro was in decreasing order SNA-II>SNA-I>RSA with the respective EC50 being 0.1, 0.5 and 3.6 μg/ml. Larvae feeding for 16 day on diets containing 2% RSA, 2% SNA-II and 2% SNA-I weighed 0.14 ± 0.07 mg, 0.67 ± 0.44 mg and 1.89 ± 0.38 mg, corresponding to approximately 7%, 36% and 80% of control larvae, respectively. As a consequence, RSA increased the time to adult emergence by over 3-fold, SNA-II by 1.9-fold and SNA-I by 1.2-fold. RSA and SNA-II were stable in the larval gut, while SNA-I was digested and excreted with the feces. Finally, confocal microscopy confirmed that RSA passed through the PM more efficiently than SNA-II. In conclusion, our data suggest that the lectin ability to pass through the PM, governed by molecule dimensions, charge and size of PM pores, is one of the features that determine the toxicity of these insecticidal proteins.

Characterization of polysaccharides with antioxidant and hepatoprotective activities from the wild edible mushroom Russula vinosa Lindblad

The aim of the present study was to investigate the antioxidant and hepatoprotective effects of water-soluble polysaccharides (RVLWP) and alkali-soluble polysaccharides (RVLAP) from Russula vinosa on carbon tetrachloride (CCl4)-induced acute liver damage in mice. For the in vitro antioxidant activities, RVLWP and RVLAP exhibited potent 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (IC50 = 1.55 ± 0.04 and 3.37 ± 0.21 mg/mL, respectively), hydrogen peroxide scavenging activity (IC50 = 6.07 ± 0.24 and 9.23 ± 0.54 mg/mL, respectively), lipid peroxidation inhibitory effect (IC50 = 0.52 ± 0.095 and 0.86 ± 0.043 mg/mL, respectively), and moderate reducing power and Fe(2+) chelating activity (IC50 = 1.86 ± 0.0036 and 0.22 ± 0.0057 mg/mL, respectively). Ascorbic acid was employed as the standard antioxidant in the present study. For the in vivo hepatoprotective activity, administration of RVLWP and RVLAP (200 mg/kg) significantly prevented the elevation in serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in acute liver damage induced by CCl4 and suppressed hepatic malondialdehyde (MDA) formation. Mice treated with RVLWP and RVLAP demonstrated a better profile of antioxidants with augmented activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in the liver. The results suggest that RVLWP and RVLAP protect the liver from CCl4-induced hepatic damage via antioxidant mechanisms.

A novel hemagglutinin with antiproliferative activity against tumor cells from the hallucinogenic mushroom Boletus speciosus

Little was known about bioactive compounds from the hallucinogenic mushroom Boletus speciosus. In the present study, a hemagglutinin (BSH, B. speciosus hemagglutinin) was isolated from its fruiting bodies and enzymatic properties were also tested. The chromatographic procedure utilized comprised anion exchange chromatography on Q-Sepharose, cation exchange chromatography on CM-Cellulose, cation exchange chromatography on SP-Sepharose, and gel filtration by FPLC on Superdex 75. The hemagglutinin was a homodimer which was estimated to be approximately 31 kDa in size. The activity of BSH was stable up to 60°C, while there was a precipitous drop in activity when the temperature was elevated to 70°C. BSH retained 25% hemagglutinating activity when exposed to 100 mM NaOH and 25 mM HCl. The activity was potently inhibited by 1.25 mM Hg²⁺ and slightly inhibited by Fe²⁺, Ca²⁺, and Pb²⁺. None of the sugars tested showed inhibition towards BSH. Its hemagglutinating activity towards human erythrocytes type A, type B, and type AB was higher than type O. The hemagglutinin showed antiproliferative activity towards hepatoma Hep G2 cells and mouse lymphocytic leukemia cells (L1210) in vitro, with IC₅₀ of 4.7 μM and 7.0 μM, respectively. It also exhibited HIV-1 reverse transcriptase inhibitory activity with an IC₅₀ of 7.1 μM.

Chemical composition and cellular toxicity of ethnobotanical-based hot and cold aqueous preparations of the tiger's milk mushroom (Lignosus rhinocerotis)

ETHNOPHARMACOLOGICAL RELEVANCE

The sclerotium of the "tiger's milk mushroom" (Lignosus rhinocerotis) is used as tonic and folk medicine for the treatment of cancer, fever, cough and asthma by the local and indigenous communities. It is traditionally prepared by either boiling or maceration-like methods; however, there is no attempt to understand how different processing methods might affect their efficacies as anticancer agents.

AIM OF THE STUDY

This investigation was undertaken to evaluate the cytotoxicity of the hot and cold aqueous extracts of Lignosus rhinocerotis and to deduce the nature of the chemical component(s) that might be responsible for differential cellular toxicity of the extracts.

MATERIALS AND METHODS

The hot (LR-HA) and cold (LR-CA) aqueous extracts of the sclerotium of Lignosus rhinocerotis were prepared. The levels of bioactive components in the extracts were determined and chemical profiling was performed using UPLC-ESI-MS, SDS-PAGE and SELDI-TOF MS. Cytotoxicity of LR-HA and LR-CA against a panel of human cancer and normal cell lines was assessed by the MTT and trypan blue exclusion assays. Changes in cell morphology upon treatment with the extracts were observed. The chemical composition and bioactivities data were correlated to explain the nature of the cytotoxic component(s).

RESULTS

LR-HA and LR-CA were particularly abundant in polar components. Both extracts exhibited varying degree of cytotoxicity against the cancer cell lines with LR-CA showed significantly stronger cytotoxicity (IC50: 37-355 µg/ml) than LR-HA (IC50>500 µg/ml); however, LR-CA lacked selectivity in that it also has cytotoxic effect on the normal cell lines. Based on the results of protein profiling of heat-treated LR-CA (40-100°C) coupled to the MTT assay, the cytotoxic component(s) in LR-CA were deduced to be thermo-labile, water-soluble protein/peptide(s).

CONCLUSION

Our findings have shown that the use of different preparation methods (hot and cold aqueous extraction) for Lignosus rhinocerotis has resulted in extracts with distinctively different cellular toxicity in which the cytotoxic constituents were present only in LR-CA.

Purification and characterization of a glucosamine-binding antifungal lectin from Phaseolus vulgaris cv. Chinese pinto beans with antiproliferative activity towards nasopharyngeal carcinoma cells

A lectin has successfully been isolated from Phaseolus vulgaris cv. Chinese pinto bean using affinity chromatography, ion exchange chromatography, and gel filtration in succession, with a 15.4-fold purification. Investigation of its characteristics revealed that Chinese pinto bean lectin (CPBL) was a 58-kDa dimeric glucosamine-binding protein. Its Mg(2+)-dependent hemagglutinating activity was stable at pH 7-8 and at or below 60 °C. When the purified lectin was tested against six fungal species including Phyllosticta citriasiana, Magnaporthe grisea, Bipolans maydis, Valsa mali, Mycosphaerella arachidicola, and Setosphaeria turcica, only the mycelial growth of V. mali was reduced by 30.6 % by the lectin at 30 μM. The lectin did not exert any discernible antiproliferative effects on breast cancer MCF-7 cells, but was able to suppress proliferation of nasopharyngeal carcinoma HONE-1 cells, with an IC50 of 17.3 μM, as revealed by the MTT assay. Since few plant lectins demonstrate antifungal activity against V. mali, and not many others have inhibitory effects on HONE-1 cells, CPBL is a distinctive lectin which may be exploited for development into an agent against V. mali and HONE-1 cells.

ROS-dependent mitochondria molecular mechanisms underlying antitumor activity of Pleurotus abalonus acidic polysaccharides in human breast cancer MCF-7 cells

Background

A greater reduction in cancer risk associated with mushroom diet rich in fungus polysaccharides is generally accepted. Meanwhile, edible Pleurotus abalonus as a member of Abalone mushroom family is a popular nutritional supplement that purportedly prevents cancer occurrence. However, these anecdotal claims are supported by limited studies describing tumor-inhibitory responses to the promising polysaccharides, and the molecular mechanisms underlying these properties have not yet been elucidated.

Methodology/Principal Findings

We here fractionated the crude polysaccharide preparation from the fruiting bodies of P. abalonus into three fractions, namely PAP-1, PAP-2 and PAP-3, and tested these fractions for antiproliferative activity in human breast cancer MCF-7 cells. The largest PAP-3, an acidic polysaccharide fraction with a molecular mass of 3.68×10⁵ Da, was the most active in inhibiting MCF-7 cancer cells with an IC₅₀ of 193 µg/mL. The changes in cell normal morphology were observed by DAPI staining and the PAP-3-induced apoptosis was confirmed by annexin V/propidium iodide staining. The apoptosis was involved in mitochondria-mediated pathway including the loss of mitochondrial membrane potential (Δψm), the increase of Bax/Bcl-2 ratio, caspase-9/3 activation, and poly(ADP-ribose) polymerase (PARP) degradation, as well as intracellular ROS production. PAP-3 also induced up-regulation of p53, and cell cycle arrest at the S phase. The incubation of MCF-7 cells with antioxidant superoxide dismutase (SOD) and N-acetylcysteine (NAC) significantly attenuated the ROS generation and apoptosis caused by PAP-3, indicating that intracellular ROS plays a pivotal role in cell death.

Conclusions/Significance

These findings suggest that the polysaccharides, especially acidic PAP-3, are very important nutritional ingredients responsible for, at least in part, the anticancer health benefits of P. abalonus via ROS-mediated mitochondrial apoptotic pathway. It is a major breakthrough bringing new insight of the potential use of the polysaccharides as health-care food or medicine to provide significant natural defense against human cancer.

Isolation and identification of a novel polysaccharide–peptide complex with antioxidant, anti-proliferative and hypoglycaemic activities from the abalone mushroom

A novel antioxidant polysaccharide–peptide complex LB-1b from the fruiting bodies of the edible abalone mushroom (Pleurotus abalonus) was purified and identified. The structural characteristic of LB-1b was identified by FTIR (Fourier-transform IR), 13C NMR and 1H NMR spectroscopy. LB-1b is a polysaccharide–peptide complex that contains glucose, rhamnose, glucuronic acid and galactose in the molar ratio of 22.4:1:1.7:1.6 and the N-terminal sequence of its peptide moiety has also been determined. The N-terminal amino acid sequence of LB-1b, IPKERKEFQQAQHLK, showed some resemblance to antioxidant enzymes. LB-1b exhibited high antioxidant activity in erythrocyte haemolysis in vitro and the anti-proliferative activity towards hepatoma HepG2 cells and breast cancer MCF7 cells with an IC50 of 24 and 14 μM respectively. LB-1b also demonstrated hypoglycaemic activity in drug-induced diabetic mice and anti-HIV-1 RT (reverse transcriptase) with an IC50 value of 12.5 μM.

Bioactive sesquiterpenoids from the solid culture of the edible mushroom Flammulina velutipes growing on cooked rice

The edible mushroom Flammulina velutipes was cultivated on cooked rice. Six new cuparene sesquiterpenes, enokipodins E-J (1-6), and two new sterpurane sesquiterpenes, sterpurols A (10) and B (11), with four known sesquiterpenes, 2,5-cuparadiene-1,4-dione (7), enokipodins B (8) and D (9), and sterpuric acid (12), were isolated from the solid culture of F. velutipes. The structures of new metabolites were elucidated by NMR experiments. The absolute configurations in new compounds were assigned by X-ray crystallographic analysis, the modified Mosher method, and CD data analysis. Bioactivity screening indicated that compounds 5-9 displayed weak antibacterial activity against Bacillus subtilis; 2, 3, and 5 showed weak antifungal activity against Aspergilus fumigatus; 6-9 showed both moderate cytotoxicity against the human tumor cell lines (HepG2, MCF-7, SGC7901, and A549) and antioxidant activity in DPPH scavenging assay. These results suggest that the solid culture of F. velutipes on cooked rice could be a good functional food.

Purification of a new fungal mannose-specific lectin from Penicillium chrysogenum and its aphicidal properties

Several Ascomycetes fungi are commonly used in bio-industries and provide available industrial residues for lectin extraction to be valuable. A lectin from Penicillium chrysogenum, named PeCL, was purified from a fungal culture using gel-filtration chromatography column. PeCL was found to be a mannose-specific lectin by haemagglutination activity towards rabbit erythrocyte cells and was visualised on SDS-PAGE gel. Purified PeCL fraction was delivered via artificial diet to Myzus persicae aphid and was demonstrated to be aphicidal at 0.1 % with higher toxic efficiency than a known mannose-binding lectin Concanavalin A (ConA). A fast and efficient way to purify PeCL and a potential use in pest control is described.

N-acetyl-D-galactosamine-specific lectin isolated from the seeds of Carica papaya

N-Acetyl-D-galactosamine (GalNAc)-specific lectins are of great interest because they have been reported to detect tumor-associated antigens of malignant cells. We isolated a novel lectin from Carica papaya seeds, named C. papaya lectin (CPL). Purification of the lectin involved ammonium sulfate fractionation and DEAE anion exchange and repeated gel filtration chromatography. Inhibition of CPL causing hemagglutination on human erythrocytes showed that the lectin shows specificity to GalNAc and lactose. Surface plasmon resonance further revealed that the lectin possesses high specificity toward GalNAc with a dissociation constant of 5.5 × 10(-9) M. The lectin is composed of 38- and 40-kDa subunits with a molecular mass of ∼804 kDa estimated by size-exclusion high-performance liquid chromatography. Incubation of CPL with Jurkat T cells showed significant induction of IL-2 cytokine, which suggests that CPL has potent immunomodulatory effects on immune cells.

A lectin-mediated resistance of higher fungi against predators and parasites

Fruiting body lectins are ubiquitous in higher fungi and characterized by being synthesized in the cytoplasm and up-regulated during sexual development. The function of these lectins is unclear. A lack of phenotype in sexual development upon inactivation of the respective genes argues against a function in this process. We tested a series of characterized fruiting body lectins from different fungi for toxicity towards the nematode Caenorhabditis elegans, the mosquito Aedes aegypti and the amoeba Acanthamoeba castellanii. Most of the fungal lectins were found to be toxic towards at least one of the three target organisms. By altering either the fungal lectin or the glycans of the target organisms, or by including soluble carbohydrate ligands as competitors, we demonstrate that the observed toxicity is dependent on the interaction between the fungal lectins and specific glycans in the target organisms. The toxicity was found to be dose-dependent such that low levels of lectin were no longer toxic but still led to food avoidance by C. elegans. Finally, we show, in an ecologically more relevant scenario, that challenging the vegetative mycelium of Coprinopsis cinerea with the fungal-feeding nematode Aphelenchus avenae induces the expression of the nematotoxic fruiting body lectins CGL1 and CGL2. Based on these findings, we propose that filamentous fungi possess an inducible resistance against predators and parasites mediated by lectins that are specific for glycans of these antagonists.