Purification and characterization of an anti-(A+B) specific lectin from the mushroom Hygrophorus hypothejus

Purification and characterization of a synergistic bioactive lectin from Pleurotus flabellatus (PFL-L) with potent antibacterial and in-vitro radical scavenging activity

Lectin is a carbohydrate-binding protein, which exhibits a plethora of biological properties such as antimicrobial, antifungal, and anticancer activities. In the present study, lectin, with an antibacterial and antioxidant potential, was purified from the oyster mushroom Pleurotus flabellatus. The P. flabellatus Lectin (PFL-L) was purified by using a DEAE - cellulose anion exchange chromatography followed by gel-filtration chromatography. The PFL-L was characterized by CD, HPLC, and MALDI-TOF/MS. The purity of PFL-L increased to 62.40% with the recovery of hemagglutinating activity (HA) by 12.12%. On SDS - PAGE, the PFL-L gave a single band of 18 kDa. PFL-L, consisting of d-galactose, exhibits a strong hemagglutinating activity. It was stable at pH (6.0-7.5) and temperature (10-20 °C) in addition to having extensive hemagglutinating activity. PFL-L enhanced the HA with the use of different metal ions namely Mg²⁺, Ca^2+, and Fe²⁺. The study of bacterial growth inhibition led to the inference that the PFL-L was more potent against gram-negative bacteria. PFL-L showed the highest radical scavenging activity for the DPPH assay at 100 μg/mL (89.9 ± 2.53%). The highest antioxidant activities with IC₅₀ values (for DPPH assay) of 53.96 μg/mL were determined for PFL-L and the present study shows that lectin from P. flabellatus manifested distinctive character and potentially exploitable activities.

Lectins purified from medicinal and edible mushrooms: Insights into their antiviral activity against pathogenic viruses

For thousands of years, fungi have been a valuable and promising source of therapeutic agents for treatment of various diseases. Mushroom is a macrofungus which has been cultivated worldwide for its nutritional value and medicinal applications. Several bioactive molecules were extracted from mushroom such as polysaccharides, lectins and terpenoids. Lectins are carbohydrate-binding proteins with non-immunologic origin. Lectins were classified according to their structure, origin and sugar specificity. This protein has different binding specificity with surface glycan moiety which determines its activity and therapeutic applications. A wide range of medicinal activities such as antitumor, antiviral, antimicrobial, immunomodulatory and antidiabetic were reported from sugar-binding proteins. However, glycan-binding protein from mushroom is not well explored as antiviral agent. The discovery of novel antiviral agents is a public health emergency to overcome the current pandemic and be ready for the upcoming viral pandemics. The mechanism of action of lectin against viruses targets numerous steps in viral life cycle such as viral attachment, entry and replication. This review described the history, classification, purification techniques, structure-function relationship and different therapeutic applications of mushroom lectin. In addition, we focus on the antiviral activity, purification and physicochemical characteristics of some mushroom lectins.

Allelopathy of Wild Mushrooms—An Important Factor for Assessing Forest Ecosystems in Japan

Research Highlights: Some organisms such as plants and fungi release certain secondary metabolites, generally called allelochemicals, which can influence the organisms around them. Some of the secondary metabolites released by mushrooms may have certain effects on the growth and development of neighboring plants. Background Objectives: The purpose of the present study was to investigate the allelopathic potential of mushrooms in a forest ecosystem. To this end, 289 Japanese mushroom species were collected from the wild and tested using a modified sandwich method, which is a quick and effective bioassay technique. Materials and Methods: The collected specimens were prepared for bioassay as dried samples, and 10 mg/well (10 cm2) was added to a 6-well multidish according to the mycelia biomass, which was estimated at 700−900 kg ha−1 year−1 (7–9 mg 10 cm−2) in coniferous forests. Results: Of the screened mushroom species, 74% inhibited more than 50% of the radicle elongation in lettuce (Lactuca sativa var. Great Lakes 366) seedlings, while the average of all species was 41.1%. This result suggests that wild mushrooms have a significant regulatory effect on lettuce growth. According to our standard deviation variance analysis, 54 out of 289 species showed significant allelopathic activity. Among these species, Xeromphalina tenuipes, Cortinarius violaceus, and Clavaria miyabeana exhibited the strongest growth inhibitory activity, with radicle elongation of 5.1%, 4.3%, and 7.6% of the control, respectively. In contrast, Ischnoderma resinosum stimulated the length of radicle and hypocotyl growth by 30.6% and 42.0%, respectively. These results suggest that these species may play important roles in ecosystems. In addition, the wide range of allelopathic activities observed in mushrooms indicates that various amounts of diverse secondary metabolites from these species are involved in mushroom allelopathy. Conclusions: Our study reveals the importance of evaluating mushroom allelopathy to understand the wider ecological structures within complex ecosystems.

Use of lectins in immunohematology

Lectins are carbohydrate binding proteins present in seeds of many plants, especially corals and beans, in fungi and bacteria, and in animals. Apart from their hemagglutinating property, a wide range of functions have been attributed to them. Their importance in the area of immunohematology is immense. They are used to detect specific red cell antigens, to activate different types of lymphocytes, in order to resolve problems related to polyagglutination and so on. The introduction of advanced biotechnological tools generates new opportunities to exploit the properties of lectins, which were not used earlier. Stem cell research is a very important area in transplant medicine. Certain lectins detect surface markers of stem cell. Hence, they are used to understand the developmental biology of stem cells. The role of various lectins in the areas of transfusion and transplant medicine is discussed in detail in this review.

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.

Mushroom lectins: current status and future perspectives

Lectins are nonimmune proteins or glycoproteins that bind specifically to cell surface carbohydrates, culminating in cell agglutination. These are known to play key roles in host defense system and also in metastasis. Many new sources have been explored for the occurrence of lectins during the last few years. Numerous novel lectins with unique specificities and exploitable properties have been discovered. Mushrooms have attracted a number of researchers in food and pharmaceuticals. Many species have long been used in traditional Chinese medicines or functional foods in Japan and other Asian countries. A number of bioactive constituents have been isolated from mushrooms including polysaccharides, polysaccharopeptides, polysaccharide-protein complexes, proteases, ribonucleases, ribosome inactivating proteins, antifungal proteins, immunomodulatory proteins, enzymes, lectins, etc. Mushroom lectins are endowed with mitogenic, antiproliferative, antitumor, antiviral, and immune stimulating potential. In this review, an attempt has been made to collate the information on mushroom lectins, their blood group and sugar specificities, with an emphasis on their biomedical potential and future perspectives.

Development of an all-in-one technology for glycan profiling targeting formalin-embedded tissue sections

An ultra-sensitive method for glycan analysis targeting small tissue sections (1.5mm in diameter) is described as an application of a recently-established lectin microarray technology. The developed system achieved a high level of detection of a tissue section consisting of approximately 500 cells for differential profiling, where both N- and O-glycans attached to a pool of glycoproteins are subjected to multiplex analysis with 43 lectins. By using an optimized protocol for differential glycan analysis, sections of adenocarcinoma (n=28) and normal epithelia (n=12) of the colon were analyzed in an all-in-one manner. As a result, Wisteria floribunda agglutinin (WFA) was found to clearly differentiate cancerous from normal epithelia with P<0.0001. The obtained results correlated well with the subsequent histochemical study using biotinylated WFA. Thus, the developed technology proved to be valid for expanding the lectin microarray applications to tissue-based glycomics, and hence, should accelerate a discovery phase of glycan-related biomarkers.

Purification and characterization of an N-acetyl-D-galactosamine-specific lectin from the edible mushroom Schizophyllum commune

An N-acetyl-D-galactosamine (GalNAc)-specific lectin was purified from the edible mushroom, Schizophyllum commune, using affinity chromatography on a porcine stomach mucin (PSM)-Sepharose 4B column. Under reducing and non-reducing conditions, SDS-polyacrylamide gel electrophoresis gave a major band of 31.5 kDa. The Schizophyllum commune lectin (SCL) showed high affinity toward rat erythrocytes and the sugar inhibition assay exhibited its sugar specificity highly toward lactose and N-acetyl-D-galactosamine. It was stable at 55 degrees C for 30 min and at pH 3-10 for 18-h test. The lectin was shown to be a glycoprotein with cytotoxic activity against human epidermoid carcinoma cells. The N-terminus of SCL was blocked but amino acid sequences of internal tryptic peptides showed moderately sequence similarities with some other fungal and plant lectins. Crystals of SCL were obtained by the sitting drop vapour-diffusion method using polyethylene glycol 8000 as the precipitant, and gave an X-ray diffraction pattern to approximately 3.8 angstroms resolution.

Peptides and proteins from fungi

The peptides and proteins secreted by fungi are reviewed in this article. They include ribosome inactivating peptides and proteins, antifungal peptides and proteins, lectins, ubiquitin-like peptides and proteins, peptides and proteins with nucleolytic activity, proteases, xylanases, cellulases, sugar oxidoreductases, laccases, invertases, trehalose phosphorylases, and various enzymes with applications in food industry, chemical production and the medical sector.

The Gal/GalNAc-specific lectin from the plant pathogenic basidiomycete Rhizoctonia solani is a member of the ricin-B family

The lectin isolated from the phytopathogenic basidiomycete Rhizoctonia solani (RSA) is a homodimer of two noncovalently associated monomers of 15.5 kDa. RSA is a basic protein (pI > 9) which consists mainly of beta-sheets. A presumed relationship with ricin-B is supported by the sequence similarity between the N-terminus of RSA and the N-terminal subdomain of ricin-B. Hydrophobic cluster analysis confirms that the N-terminus of both proteins has a comparable folding. RSA exhibits specificity towards Gal/GalNAc whereby the hydroxyls at the C3', C4', and C6' positions of the pyranose ring play a key role in the interaction with simple sugars. The carbohydrate-binding site of RSA apparently accommodates only a single sugar unit. Our results demonstrate an obvious evolutionary relationship between some fungal and plant lectins, but also provide evidence for the occurrence of a lectin consisting of subunits corresponding to a single subdomain of ricin-B.