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1. (Article ID: 6181)
 
Hussain H, Mamadalieva NZ, Ali I, Elizbit, Green IR, Wang D, Zou L, Simal-Gandara J, Cao H, Xiao J
Fungal glycosides: Structure and biological function
Trends in Food Science and Technology 110 (2021) 611-651
 

Background: Natural products acquire vast and intriguing structural diversity and have been recognized as a tremendously diverse source of new lead compounds. Numerous bioactive secondary metabolites are present in the form of glycosylated molecules in which the sugar parts are normally associated with the interaction along with molecular recognition of the cellular target. Scope and approach: The presence of sugar entities are crucial as well as in some cases necessary, for therapeutic effects. Establishing novel and potent glycosylated secondary metabolites has formed a main goal in the natural product field from fungi and bacteria. These compounds possess a diverse range of sugar units. Key findings and conclusions: Fungi is considered one of the important sources for approved drugs with a diverse range of mode of action. The sugar part in numerous pharmacologically active natural products enhances bioavailability, biological potential, reduce toxicity, and improve stability. The vast majority of glyocosides showed antimicrobial effects, cytotoxic, antiviral and antiinflammatory effects. Notably, numerous fungal glycosides presented in this review illustrate significant antimicrobial effects towards various microorganisms especially against plant pathogens. The antimicrobial effects of these fungal glycosides indicate that these metabolites could be employed as natural preservatives in food in order to abolish or control the growth of pathogenic and spoilage microorganisms.

glycoside, antimicrobial, fungi, food preservative, secondary metabolites

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2. (Article ID: 6192)
 
Rüdiger H, Siebert H-C, Solis D, Jiménez-Barbero J, Romero A, von der Lieth C-W, Diaz-Mariño T, Gabius H-J
Medicinal chemistry based on the sugar code: fundamentals of lectinology and experimental strategies with lectins as targets
Current Medicinal Chemistry 7(4) (2000) 389-416
 

Theoretical calculations reveal that oligosaccharides are second to no other class of biochemical oligomery in terms of coding capacity. As integral part of cellular glycoconjugates they can serve as recognitive units for receptors (lectins). Having first been detected in plants, lectins are present ubiquitously. Remarkably for this field, they serve as bacterial and viral adhesins. Following a description of these branches of lectinology to illustrate history, current status and potential for medicinal chemistry, we document that lectins are involved in a wide variety of biochemical processes including intra- and intercellular glycoconjugate trafficking, initiation of signal transduction affecting e. g. growth regulation and cell adhesion in animals. It is thus justified to compare crucial carbohydrate epitopes with the postal code ensuring correct mail routing and delivery. In view of the functional relevance of lectins the design of high-affinity reagents to occupy their carbohydrate recognition domains offers the perspective for an attractive source of new drugs. Their applications can be supposed to encompass the use as cell-type-selective determinant for targeted drug delivery and as blocking devices in anti-adhesion therapy during infections and inflammatory disease. To master the task of devising custom-made glycans/glycomimetics for this purpose, the individual enthalpic and entropic contributions in the molecular rendezvous between the sugar receptor under scrutiny and its ligand in the presence of solvent molecules undergoing positional rearrangements need to be understood and rationally exploited. As remunerative means to this end, cleverly orchestrated deployment of a panel of methods is essential. Concerning the carbohydrate ligand, its topological parameters and flexibility are assessed by the combination of computer-assisted molecular-mechanics and molecular-dynamics calculations and NMR-spectroscopic measurements. In the presence of the receptor, the latter technique will provide insights into conformational aspects of the bound ligand and into spatial vicinity of the ligand to distinct side chains of amino acids establishing the binding site in solution. Also in solution, the hydrogen-bonding pattern in the complex can be mapped with monodeoxy and monofluoro derivatives of the oligosaccharide. Together with X-ray crystallographic and microcalorimetric studies the limits of a feasible affinity enhancement can be systematically probed. With galactoside-binding lectins as instructive mo del, recent progress in this area of drug design will be documented, emphasizing the general applicability of the outlined interdisciplinary approach.

Molecular mechanics, Rhizobium meliloti, lectinology, lectins as targets, computer assisted, NMR spectoscopic, crystallographic elucidation, sugar code, chemioal tailoring, phosphodiester backbone, microheterogeneity of glycan, monomer variability, N acetylneuramicinic, transgenic pollen, nitrogen enriched nutrients, non agglutinating ricin, hydrophobic molecules, phytopathogenic fungus, phosphomannose mutase, B bearing individuals, anti adhesion therapy, NMR spectrum, parenchymal host cells

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3. (Article ID: 6934)
 
Boros C, Katz B, Mitchell S, Pearce C, Swinbank K, Taylor D
Emmyguyacins A and B: unusual glycolipids from a sterile fungus species that inhibit the low-pH conformational change of hemagglutinin A during replication of influenza virus
Journal of Natural Products 65 (2002) 108-114
 

Two novel glycolipids, emmyguyacin A (1a) and emmyguyacin B (1b), were isolated at concentrations of 1.51 g/L from a potato dextrose agar fermentation of a sterile fungus species. The compounds inhibit replication of influenza A virus (A/X31) in MDCK cells by inhibiting the pH-dependent conformational change of hemagglutinin A (IC50 9 μM). The structures were deduced using one- and two-dimensional NMR techniques and mass spectrometric analyses on both the parent compounds and a host of degradation products and derivatives. A novel and unusual oxalic acid ester of a monohydroxylated fatty acid (5, 17-oxalyloxydocosanoic acid) is reported. The first isolation and characterization of the fatty acid 17-hydroxydocosanoic acid (3) itself is also reported as a saponification product of 1.

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4. (Article ID: 7180)
 
Saito H, Yoshioka Y, Yokoi M, Yamada Y
Distinct gelation mechanism between linear and branched (1-3)-β-D-glucans as revealed by high-resolution solid-state 13C NMR
Biopolymers 29(14) (1990) 1689-1698
 

We have recorded high-resolution 13C-NMR spectra of linear (curdlan) and branched (lentinan, HA-β-glucan and its polyol and aldehyde derivatives) (1-3)-β-D-glucans in hydrate and gel states, in order to gain insight into their gelation mechanism. Network structure of curdlan turned out to be highly heterogeneous from its motional state, from liquid-like, through intermediate, to solid-like domains. They are studied by a variety of experiments, conventional high-resolution NMR by broad-band decoupling, high-power decoupling with magic angle spinning (MAS), and cross-polarization-magic-angle-spinning (CP-MAS). Nevertheless, we found that conformations of these distinct liquid-like and solid-like do- mains exhibit an identical single helix conformation with a small proportion of a triple helix form, supporting our previous view as to the gelation mechanism. In contrast, the network structure of branched (1-3)-β-D-glucans in the gel state arises mainly from the triple helix conformation. This means that gelation of branched (1-3)-β-D-glucan proceeds from partial association of the triple helical chains, previously proposed for gelation of a linear glucan. Furthermore, we found that conversion from the single chain to the single helix was not achieved readily by hydration of over 8h at 96% R. H. for branched glucan but the triple helix form is obtained when these samples are hydrated fully as in gel state.

conformation, 13C NMR, Curdlan, lentinan

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5. (Article ID: 7284)
 
Nazir M, Sultan M, Riaz N, Hafeez M, Hussain H, Ahmed I, Schulz B, Draeger S, Jabbar A, Krohn K, Ashraf M, Saleem M
Depsitinuside: a new depside galactoside from an endophytic fungus isolated from Viburnum tinus
Journal of Asian Natural Products Research 13(11) (2011) 1056-1060
 

Chromatographic purification of the extract of an endophytic fungal culture yielded depsitinuside (1), a new phenolic ester together with ergosterol (2) and (22E,24S)-24-methyl-5-α-cholesta-7,22-diene-3β,5,6β-triol (3). The structure of 1 was elucidated based on 1D, 2D NMR spectroscopy and high-resolution mass spectrometry, whereas the known compounds (2 and 3) were identified by (1)H NMR, mass spectrometry, and in comparison with the literature values. Compound 1 was evaluated for its enzyme inhibitory potential against acetylcholinesterase, butyrylcholinesterase and lipoxygenase, and was found inactive (10%-40% inhibition at a concentration of 2 mg/ml).

endophytic fungus, Viburnum tinus, depside, steroids, enzyme inhibition

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6. (Article ID: 7292)
 
Nimrichter L, Rodrigues ML
Fungal glucosylceramides: from structural components to biologically active targets of new antimicrobials
Frontiers in Microbiology 2 (2011) ID212
 

The first work reporting synthesis of glucosylceramide (cerebrin, GlcCer) by yeasts was published in 1930. During approximately 70-years members of this class of glycosphingolipids (GSL) were considered merely structural components of plasma membrane in fungi. However, in the last decade GlcCer was reported to be involved with fungal growth, differentiation, virulence, immunogenicity, and lipid raft architecture in at least two human pathogens. Fungal GlcCer are structurally distinct from their mammalian counterparts and enriched at the cell wall, which makes this molecule an effective target for antifungal activity of specific ligands (peptides and antibodies to GlcCer). Therefore, GSL are promising targets for new drugs to combat fungal diseases. This review discusses the most recent information on biosynthesis and role of GlcCer in fungal pathogens.

glucosylceramide, antifungal targets, fungal pathogens

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7. (Article ID: 7794)
 
Mandala SM, Thornton RA, Rosenbach M, Milligan J, Garcia-Calvo M, Bull HG, Kurtz MB
Khafrefungin, a novel inhibitor of sphingolipid synthesis
Journal of Biological Chemistry 272(51) (1997) 32709-32714
 

In the course of screening for antifungal agents we have discovered a novel compound isolated from an endophytic fungus that inhibits fungal sphingolipid synthesis. Khafrefungin, which is composed of aldonic acid linked via an ester to a C22 modified alkyl chain, has fungicidal activity against Candida albicans, Cryptococcus neoformans, and Saccharomyces cerevisiae. Sphingolipid synthesis is inhibited in these organisms at the step in which phosphoinositol is transferred to ceramide, resulting in accumulation of ceramide and loss of all of the complex sphingolipids. In vitro, khafrefungin inhibits the inositol phosphoceramide synthase of C. albicans with an IC50 of 0.6 nM. Khafrefungin does not inhibit the synthesis of mammalian sphingolipids thus making this the first reported compound that is specific for the fungal pathway.

antifungal activity, khafrefungin, sphingolipid synthesis inhibition

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8. (Article ID: 7795)
 
Mandala SM, Harris GH
Isolation and characterization of novel inhibitors of sphingolipid synthesis: australifungin, viridiofungins, rustmicin, and khafrefungin
Methods in Enzymology 311 (2000) 335-348
 

Sphingolipid synthesis is an essential process in yeast and the pathogenic fungi that cause life-threatening human infections such as candidiasis, aspergillosis, and cryptococcosis. Although many steps in the human and fungal sphingolipid biosynthetic pathway are similar, there are several enzymes found uniquely in fungi that are potential targets for the development of nontoxic therapeutic antifungals. In the screening program, it has been found that natural products are a rich source of structurally diverse inhibitors of sphingolipid synthesis. Natural product inhibitors to four different enzymes that affect sphingolipid synthesis have been discovered: sphingofungins, lipoxamycin, myriocin/ISP1, and viridiofungins inhibit serine palmitoyltransferase; fumonisin B1 and australifungin, inhibit ceramide synthase; aureobasidins, khafrefungin, and rustmicin inhibit inositol phosphoceramide synthase; and minimoidin inhibits the fatty acid elongation pathway. Most of these compounds have fungicidal activity against a broad spectrum of pathogenic fungi, but only the inhibitors of inositol phosphoceramide are fungal selective; compounds that inhibit early biosynthetic steps show comparable activity against orthologous mammalian enzymes. This chapter describes a method to identify sphingolipid inhibitors and detailed protocol for the isolation of australifungin. More abbreviated descriptions of the isolation of viridiofungins, khafrefungin, and rustmicin are also included.

antifungal activity, khafrefungin, sphingolipid synthesis inhibition

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9. (Article ID: 7826)
 
Shao CL, Shao CL1, Guo ZY, Xia XK, Liu Y, Huang ZJ, She ZG, Lin YC, Zhou SN
Five nitro-phenyl compounds from the South China Sea mangrove fungus
Journal of Asian Natural Products Research 9(7) (2007) 643-648
 

A novel nitro-phenyl glucoside (1) was isolated from mangrove endophytic fungus (fungus B60), collected from the Shenzhen mangrove Acanthus ilicifolius linn. Four related nitro-phenyl compounds (2-5) were also obtained, which were isolated for the first time as natural products. Their structures were established on the basis of NMR spectroscopic, mass spectrometric data and some chemical transformations. In the preliminary bioassay, compound 1 had a slight inhibitory effect on α-glucosidase with an IC(50) of 160.3 μM.

cytotoxicity, fungus, α-glucosidase, nitro-phenyl

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10. (Article ID: 7872)
 
Yin H, Zhao Q, Sun FM, An T
Gentiopicrin-producing endophytic fungus isolated from Gentiana macrophylla
Phytomedicine 16(8) (2009) 793-797
 

Gentiana macrophylla is a traditional Chinese medicinal plant. Its dominant active constituents are secoiridoids, mainly gentiopicrin. The objective of this study was to determine whether endophytic fungi isolated from this plant produce the bioactive ingredient gentiopicrin. Primary screening was done by Dragendorff's reaction and the strain re-selection was done with thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) to identify the fermentation products of the selected strains. In this study, 20 strains of endophytic fungi were isolated from G. macrophylla, and the extracts from five strains had a positive Dragendorff's reaction. Two strains (QJ16 and QJ18) had a component with the same R(f) value in TLC as that of authentic gentiopicrin and one ingredient of the QJ18 extract had a retention time identical with that of authentic gentiopicrin in HPLC. Therefore, the fungus appears to produce the bioactive ingredient gentiopicrin, as does its host plant, and could be used for the production of gentiopicrin by fermentation.

endophytic fungus, Gentiana macrophylla, gentiopicrin, secoiridoid, medicinal plant

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11. (Article ID: 7878)
 
Zeng YB, Wang H, Zuo WJ, Zheng B, Yang T, Dai HF, Mei WL
A fatty acid glycoside from a marine-derived fungus isolated from mangrove plant Scyphiphora hydrophyllacea
Marine Drugs 10(3) (2012) 598-603
 

To study the antimicrobial components from the endophytic fungus A1 of mangrove plant Scyphiphora hydrophyllacea Gaertn. F., a new fatty acid glucoside was isolated by column chromatography from the broth of A1, and its structure was identified as R-3-hydroxyundecanoic acid methylester-3-O-α-L-rhamnopyranoside (1) by spectroscopic methods including 1D and 2D NMR (HMQC, 1H-1H COSY and HMBC) and chemical methods. Antimicrobial assay showed compound 1 possessed modest inhibitory effect on Saphylococcus aureus and methicillin-resistant S. aureus (MRSA) using the filter paper disc agar diffusion method.

secondary metabolite, R-3-hydroxyundecanoic acid methylester-3-O-α-L-rhamnopyranoside, Scyphiphora hydrophyllacea, marine endophyte

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12. (Article ID: 7902)
 
Free SJ
Fungal cell wall organization and biosynthesis
Advances in Genetics 81 (2013) 33-82
 

The composition and organization of the cell walls from Saccharomyces cerevisiae, Candida albicans, Aspergillus fumigatus, Schizosaccharomyces pombe, Neurospora crassa, and Cryptococcus neoformans are compared and contrasted. These cell walls contain chitin, chitosan, β-1,3-glucan, β-1,6-glucan, mixed β-1,3-/β-1,4-glucan, α-1,3-glucan, melanin, and glycoproteins as major constituents. A comparison of these cell walls shows that there is a great deal of variability in fungal cell wall composition and organization. However, in all cases, the cell wall components are cross-linked together to generate a cell wall matrix. The biosynthesis and properties of each of the major cell wall components are discussed. The chitin and glucans are synthesized and extruded into the cell wall space by plasma membrane-associated chitin synthases and glucan synthases. The glycoproteins are synthesized by ER-associated ribosomes and pass through the canonical secretory pathway. Over half of the major cell wall proteins are modified by the addition of a glycosylphosphatidylinositol anchor. The cell wall glycoproteins are also modified by the addition of O-linked oligosaccharides, and their N-linked oligosaccharides are extensively modified during their passage through the secretory pathway. These cell wall glycoprotein posttranslational modifications are essential for cross-linking the proteins into the cell wall matrix. Cross-linking the cell wall components together is essential for cell wall integrity. The activities of four groups of cross-linking enzymes are discussed. Cell wall proteins function as cross-linking enzymes, structural elements, adhesins, and environmental stress sensors and protect the cell from environmental changes.

Candida albicans, Aspergillus fumigatus, Saccharomyces cerevisiae, fungal cell wall, Schizosaccharomyces pombe, Neurospora crassa, cell wall biogenesis, glucan; chitin, Cryptococcus neoformas

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13. (Article ID: 7917)
 
Dahmen JL, Stacey G, Hunt HK
Current and emerging analytical technologies for analyzing chitin-protein binding interactions
Reviews in Analytical Chemistry 32(1) (2013) 35-53
 

Chitin, a small organic molecule commonly found in fungal cell walls and insect exoskeletons, has the ability to elicit an immune response in plants by binding to specific membrane-bound receptors. Understanding how plants detect and fend off deleterious fungi and insects will enable improved defense strategies against these pathogens. A wide array of techniques, including affinity binding studies, isothermal calorimetry, structural analysis, and molecular genomic methods have been used to identify and characterize chitin-binding receptors as well as the kinetic parameters of chitin-receptor interactions. There are a number of newly developed analytical technologies in mechanical, electrochemical, and optical biosensing that have great potential to further elucidate the interactions between chitin and its binding partners. In this review, we provide a detailed examination of the methods currently used to characterize chitin-binding interactions, along with emerging analytical techniques that have the potential to transform this area of study.

biosensors, N-acetyl-chitooligosaccharides, pathogen-associated molecular patterns

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14. (Article ID: 7923)
 
Adrangi S, Faramarzi MA
From bacteria to human: a journey into the world of chitinases
Biotechnology Advances 31(8) (2013) 1786-1795
 

Chitinases, the enzymes responsible for the biological degradation of chitin, are found in a wide range of organisms from bacteria to higher plants and animals. They participate in numerous physiological processes such as nutrition, parasitism, morphogenesis and immunity. Many organisms, in addition to chitinases, produce inactive chitinase-like lectins that despite lacking enzymatic activity are involved in several regulatory functions. Most known chitinases belong to families 18 and 19 of glycosyl hydrolases, however a fewchitinases that belong to families 23 and 48 have also been identified in recent years. In this review, different aspects of chitinases and chi-lectins from bacteria, fungi, insects, plants and mammals are discussed.

Biomarker, chitinase, chi-lectin, gene evolution, biocontrol

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15. (Article ID: 8092)
 
Abbott DW, Martens EC, Gilbert HJ, Cuskin F, Lowe EC
Coevolution of yeast mannan digestion: Convergence of the civilized human diet, distal gut microbiome, and host immunity
Gut Microbes 6(5) (2015) 334-339
 

The complex carbohydrates accessible to the distal gut microbiota (DGM) are key drivers in determining the structure of this ecosystem. Typically, plant cell wall polysaccharides and recalcitrant starch (i.e. dietary fiber), in addition to host glycans are considered the primary nutrients for the DGM; however, we recently demonstrated that α-mannans, highly branched polysaccharides that decorate the surface of yeast, are also nutrients for several members of Bacteroides spp. This relationship suggests that the advent of yeast in contemporary food technologies and the colonization of the intestine by endogenous fungi have roles in microbiome structure and function. Here we discuss the process of yeast mannan metabolism, and the interparagraph between various sources of intestinal fungi and their roles in recognition by the host innate immune system.

polysaccharide, symbiosis, evolution, mannooligosaccharide, fungal cell wall, carbohydrate active enzyme, catabolism, distal gut microbiota, yeast mannan

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