Plant Antifungal Lectins: Mechanism of Action and Targets on Human Pathogenic Fungi

Lectins are proteins characterized by their ability to specifically bind different carbohydrate motifs. This feature is associated with their endogenous biological function as well as with multiple applications. Plants are important natural sources of these proteins; however, only a reduced group was shown to display antifungal activity. Although it is hypothesized that the target of lectins is the fungal cell wall, the mechanism through which they exert the antifungal action is poorly understood. This topic is relevant to improve treatment against pathogens of importance for human health. In this context, mechanisms pointing to essential attributes for virulence instead of the viability of the pathogen emerge as a promising approach. This review provides the current knowledge on the action mechanism of plant antifungal lectins and their putative use for the development of novel active principles against fungal infections.

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Spatial Distribution of a Porphyrin-Based Photosensitizer Reveals Mechanism of Photodynamic Inactivation of Candida albicans

Frontiers in Medicine ◽

10.3389/fmed.2021.641244 ◽

2021 ◽

Vol 8 ◽

Author(s):

Thomas Voit ◽

Fabian Cieplik ◽

Johannes Regensburger ◽

Karl-Anton Hiller ◽

Anita Gollmer ◽

...

Keyword(s):

Cell Wall ◽

Candida Albicans ◽

Fungal Infections ◽

Cell Envelope ◽

Antimicrobial Photodynamic Therapy ◽

Fungal Cell ◽

Before And After ◽

Antifungal Action ◽

Complete Cell ◽

Further Development

The antimicrobial photodynamic therapy (aPDT) is a promising approach for the control of microbial and especially fungal infections such as mucosal mycosis. TMPyP [5,10,15, 20-tetrakis(1-methylpyridinium-4-yl)-porphyrin tetra p-toluenesulfonate] is an effective photosensitizer (PS) that is commonly used in aPDT. The aim of this study was to examine the localization of TMPyP in Candida albicans before and after irradiation with visible light to get information about the cellular mechanism of antifungal action of the photodynamic process using this PS. Immediately after incubation of C. albicans with TMPyP, fluorescence microscopy revealed an accumulation of the PS in the cell envelope. After irradiation with blue light the complete cell showed red fluorescence, which indicates, that aPDT is leading to a damage in the cell wall with following influx of PS into the cytosol. Incubation of C. albicans with Wheat Germ Agglutinin (WGA) could confirm the cell wall as primary binding site of TMPyP. The finding that the porphyrin accumulates in the fungal cell wall and does not enter the interior of the cell before irradiation makes it unlikely that resistances can emerge upon aPDT. The results of this study may help in further development and modification of PS in order to increase efficacy against fungal infections such as those caused by C. albicans.

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Identification of a New Class of Antifungals Targeting the Synthesis of Fungal Sphingolipids

mBio ◽

10.1128/mbio.00647-15 ◽

2015 ◽

Vol 6 (3) ◽

Cited By ~ 64

Author(s):

Visesato Mor ◽

Antonella Rella ◽

Amir M. Farnoud ◽

Ashutosh Singh ◽

Mansa Munshi ◽

...

Keyword(s):

Cell Cycle Progression ◽

Fungal Infections ◽

Pathogenic Fungi ◽

Antifungal Drugs ◽

Sequencing Analysis ◽

Fungal Cell ◽

New Class ◽

Narrow Spectrum

ABSTRACT Recent estimates suggest that >300 million people are afflicted by serious fungal infections worldwide. Current antifungal drugs are static and toxic and/or have a narrow spectrum of activity. Thus, there is an urgent need for the development of new antifungal drugs. The fungal sphingolipid glucosylceramide (GlcCer) is critical in promoting virulence of a variety of human-pathogenic fungi. In this study, we screened a synthetic drug library for compounds that target the synthesis of fungal, but not mammalian, GlcCer and found two compounds [N′-(3-bromo-4-hydroxybenzylidene)-2-methylbenzohydrazide (BHBM) and its derivative, 3-bromo-N′-(3-bromo-4-hydroxybenzylidene) benzohydrazide (D0)] that were highly effective in vitro and in vivo against several pathogenic fungi. BHBM and D0 were well tolerated in animals and are highly synergistic or additive to current antifungals. BHBM and D0 significantly affected fungal cell morphology and resulted in the accumulation of intracellular vesicles. Deep-sequencing analysis of drug-resistant mutants revealed that four protein products, encoded by genes APL5, COS111, MKK1, and STE2, which are involved in vesicular transport and cell cycle progression, are targeted by BHBM. IMPORTANCE Fungal infections are a significant cause of morbidity and mortality worldwide. Current antifungal drugs suffer from various drawbacks, including toxicity, drug resistance, and narrow spectrum of activity. In this study, we have demonstrated that pharmaceutical inhibition of fungal glucosylceramide presents a new opportunity to treat cryptococcosis and various other fungal infections. In addition to being effective against pathogenic fungi, the compounds discovered in this study were well tolerated by animals and additive to current antifungals. These findings suggest that these drugs might pave the way for the development of a new class of antifungals.

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Surface Glycans of Candida albicans and Other Pathogenic Fungi: Physiological Roles, Clinical Uses, and Experimental Challenges

Clinical Microbiology Reviews ◽

10.1128/cmr.17.2.281-310.2004 ◽

2004 ◽

Vol 17 (2) ◽

pp. 281-310 ◽

Cited By ~ 118

Author(s):

James Masuoka

Keyword(s):

Fungal Infections ◽

Pathogenic Fungi ◽

Host Cells ◽

Composition Analysis ◽

Fungal Cell ◽

Whole Cells ◽

Host Interaction ◽

Rapid Characterization ◽

Cell Fractions

SUMMARY Although fungi have always been with us as commensals and pathogens, fungal infections have been increasing in frequency over the past few decades. There is a growing body of literature describing the involvement of carbohydrate groups in various aspects of fungal disease. Carbohydrates comprising the cell wall or capsule, or as a component of glycoproteins, are the fungal cell surface entities most likely to be exposed to the surrounding environment. Thus, the fungus-host interaction is likely to involve carbohydrates before DNA, RNA, or even protein. The interaction between fungal and host cells is also complex, and early studies using whole cells or crude cell fractions often produced seemingly conflicting results. What was needed, and what has been developing, is the ability to identify specific glycan structures and determine how they interact with immune system components. Carbohydrate analysis is complicated by the complexity of glycan structures and by the challenges of separating and detecting carbohydrates experimentally. Advances in carbohydrate chemistry have enabled us to move from the foundation of composition analysis to more rapid characterization of specific structures. This, in turn, will lead to a greater understanding of how fungi coexist with their hosts as commensals or exist in conflict as pathogens.

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Hitting the Caspofungin Salvage Pathway of Human-Pathogenic Fungi with the Novel Lasso Peptide Humidimycin (MDN-0010)

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00683-15 ◽

2015 ◽

Vol 59 (9) ◽

pp. 5145-5153 ◽

Cited By ~ 23

Author(s):

Vito Valiante ◽

Maria Cândida Monteiro ◽

Jesús Martín ◽

Robert Altwasser ◽

Noureddine El Aouad ◽

...

Keyword(s):

Fungal Infections ◽

Pathogenic Fungi ◽

Major Effect ◽

Strong Increase ◽

The Novel ◽

Salvage Pathway ◽

Fungal Cell ◽

Content Type ◽

High Osmolarity Glycerol ◽

Microbial Extracts

ABSTRACTFungal infections have increased dramatically in the last 2 decades, and fighting infectious diseases requires innovative approaches such as the combination of two drugs acting on different targets or even targeting a salvage pathway of one of the drugs. The fungal cell wall biosynthesis is inhibited by the clinically used antifungal drug caspofungin. This antifungal activity has been found to be potentiated by humidimycin, a new natural product identified from the screening of a collection of 20,000 microbial extracts, which has no major effect when used alone. An analysis of transcriptomes and selectedAspergillus fumigatusmutants indicated that humidimycin affects the high osmolarity glycerol response pathway. By combining humidimycin and caspofungin, a strong increase in caspofungin efficacy was achieved, demonstrating that targeting different signaling pathways provides an excellent basis to develop novel anti-infective strategies.

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Overview of the Interplay Between Cell Wall Integrity Signaling Pathways and Membrane Lipid Biosynthesis in Fungi: Perspectives forAspergillus fumigatus

Current Protein and Peptide Science ◽

10.2174/1389203720666190705164203 ◽

2020 ◽

Vol 21 (3) ◽

pp. 265-283 ◽

Cited By ~ 1

Author(s):

João Henrique T.M. Fabri ◽

Marina C. Rocha ◽

Iran Malavazi

Keyword(s):

Cell Wall ◽

Plasma Membrane ◽

Signaling Pathways ◽

Fungal Infections ◽

Invasive Pulmonary Aspergillosis ◽

Pathogenic Fungi ◽

Cell Wall Integrity ◽

Immune Recognition ◽

Fungal Cell ◽

Low Efficiency

:The cell wall (CW) and plasma membrane are fundamental structures that define cell shape and support different cellular functions. In pathogenic fungi, such as Aspegillus fumigatus, they not only play structural roles but are also important for virulence and immune recognition. Both the CW and the plasma membrane remain as attractive drug targets to treat fungal infections, such as the Invasive Pulmonary Aspergillosis (IPA), a disease associated with high morbimortality in immunocompromised individuals. The low efficiency of echinocandins that target the fungal CW biosynthesis, the occurrence of environmental isolates resistant to azoles such as voriconazole and the known drawbacks associated with amphotericin toxicity foster the urgent need for fungal-specific drugable targets and/or more efficient combinatorial therapeutic strategies. Reverse genetic approaches in fungi unveil that perturbations of the CW also render cells with increased susceptibility to membrane disrupting agents and vice-versa. However, how the fungal cells simultaneously cope with perturbation in CW polysaccharides and cell membrane proteins to allow morphogenesis is scarcely known. Here, we focus on current information on how the main signaling pathways that maintain fungal cell wall integrity, such as the Cell Wall Integrity and the High Osmolarity Glycerol pathways, in different species often cross-talk to regulate the synthesis of molecules that comprise the plasma membrane, especially sphingolipids, ergosterol and phospholipids to promote functioning of both structures concomitantly and thus, cell viability. We propose that the conclusions drawn from other organisms are the foundations to point out experimental lines that can be endeavored in A. fumigatus.

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Antifungal action of chlorogenic acid against pathogenic fungi, mediated by membrane disruption

Pure and Applied Chemistry ◽

10.1351/pac-con-09-01-08 ◽

2010 ◽

Vol 82 (1) ◽

pp. 219-226 ◽

Cited By ~ 68

Author(s):

Woo Sang Sung ◽

Dong Gun Lee

Keyword(s):

Antifungal Activity ◽

Chlorogenic Acid ◽

Mode Of Action ◽

Fungal Infections ◽

Pathogenic Fungi ◽

Membrane Dynamics ◽

Independent Manner ◽

Antifungal Action ◽

In Vitro Antifungal Activity

Chlorogenic acid is a polyphenol compound, derived from several fruit and plants. The aim of this study was to assess the in vitro antifungal activity of chlorogenic acid and its mode of action. The results indicate that chlorogenic acid exhibits antifungal activities against certain pathogenic fungi in an energy-independent manner, without any hemolytic effect on human erythrocytes. To elucidate the antifungal mode of action of chlorogenic acid, flow cytometry analysis by using DiBAC4(3) and changes in membrane dynamics using 1,6-diphenyl-1,3,5-hexatriene (DPH) were performed with Candida albicans. The results suggest that chlorogenic acid may exert antifungal activity by disrupting the structure of the cell membrane. It is demonstrated that chlorogenic acid is a valid lead compound for the development of bioactive alternatives for treatment of fungal infections.

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Carrier-Mediated Drug Uptake in Fungal Pathogens

Genes ◽

10.3390/genes11111324 ◽

2020 ◽

Vol 11 (11) ◽

pp. 1324

Author(s):

Mónica Galocha ◽

Inês Vieira Costa ◽

Miguel Cacho Teixeira

Keyword(s):

Drug Resistance ◽

Fungal Pathogens ◽

Fungal Infections ◽

Current Knowledge ◽

Pathogenic Fungi ◽

Resistance Mechanisms ◽

Antifungal Drugs ◽

Major Facilitator Superfamily ◽

Drug Uptake ◽

Human Pathogens

Candida, Aspergillus, and Cryptococcus species are the most frequent cause of severe human fungal infections. Clinically relevant antifungal drugs are scarce, and their effectiveness are hampered by the ability of fungal cells to develop drug resistance mechanisms. Drug effectiveness and drug resistance in human pathogens is very often affected by their “transportome”. Many studies have covered a panoply of drug resistance mechanisms that depend on drug efflux pumps belonging to the ATP-Binding Cassette and Major Facilitator Superfamily. However, the study of drug uptake mechanisms has been, to some extent, overlooked in pathogenic fungi. This review focuses on discussing current knowledge on drug uptake systems in fungal pathogens, highlighting the need for further studies on this topic of great importance. The following subjects are covered: (i) drugs imported by known transporter(s) in pathogenic fungi; and (ii) drugs imported by known transporter(s) in the model yeast Saccharomyces cerevisiae or in human parasites, aimed at the identification of their homologs in pathogenic fungi. Besides its contribution to increase the understanding of drug-pathogen interactions, the practical implications of identifying drug importers in human pathogens are discussed, particularly focusing on drug development strategies.

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Preliminary Characterisation of NP339, a Novel Polyarginine Peptide with Broad Antifungal Activity

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02345-20 ◽

2021 ◽

Author(s):

Vanessa Duncan ◽

Daniel Smith ◽

Laura Simpson ◽

Emma Lovie ◽

Laura Katvars ◽

...

Keyword(s):

Antifungal Agents ◽

Fungal Infections ◽

Pathogenic Fungi ◽

Drug Resistant ◽

Murine Models ◽

Therapeutic Application ◽

Fungal Cell ◽

Pathogenic Microbes ◽

A Charge

Fungi cause disease in nearly one billion individuals worldwide. Only three classes of antifungal agents are currently available in mainstream clinical use. Emerging and drug resistant fungi, toxicity, and drug–drug interactions compromise their efficacy and applicability. Consequently, new and improved antifungal therapies are urgently needed. In response to that need, we have developed NP339, a 2-kDa polyarginine peptide that is active against pathogenic fungi from the genera Candida, Aspergillus, Cryptococcus, and others. NP339 was designed based on endogenous cationic human defence peptides, which are constituents of the cornerstone of immune defence against pathogenic microbes. NP339 specifically targets the fungal cell membrane through a charge-charge initiated, membrane interaction and therefore possesses a differentiated safety and toxicity profile to existing antifungal classes. NP339 is rapidly fungicidal and does not elicit resistance in target fungi upon extensive passaging in vitro. Preliminary analyses in murine models indicate scope for therapeutic application of NP339 against a range of systemic and mucocutaneous fungal infections. Collectively, these data indicate that NP339 can be developed into a highly differentiated, first-in-class antifungal candidate for poorly served invasive and other serious fungal diseases.

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Gingerol Derivatives as 14α-demethylase Inhibitors: Design and Development of Natural, Safe Antifungals for Immune-compromised Patients

Letters in Drug Design & Discovery ◽

10.2174/1570180816666191025105752 ◽

2020 ◽

Vol 17 (7) ◽

pp. 918-928

Author(s):

Sweta Sharma ◽

Arpita Yadav

Keyword(s):

Cell Membranes ◽

Fungal Infections ◽

Dynamics Simulation ◽

Stable Complex ◽

Active Site Residues ◽

Design And Development ◽

Triazole Derivative ◽

Fungal Cell ◽

Term Administration ◽

Compromised Patients

Background: : Currently, clinically used drugs for internal fungal infections have severe side effects. Patients suffering from severe fungal infections and those at a constant risk of developing such infections require long-term administration of safe antifungals. Objective: : This work deals with the design and development of safe, non-toxic antifungals derived from natural compounds for immune-compromised patients, such as HIV patients, who are at a constant risk of developing internal fungal infections. Methods: : Molecular modeling, docking and molecular dynamics simulation studies were performed on the main constituents of ginger and their derivatives to study their capability to inhibit 14α- demethylase enzyme. Results: : Ergosterol is the key component of the fungal cell membrane for its integrity and rigidity, synthesized from lanosterol catalyzed by 14α-demethylase enzyme. In our studies, it is determined that 6-gingerol, 6-paradol, 6-shogaol and their imidazole and triazole derivatives can inhibit the synthesis of ergosterol thus weakening the fungal cell membranes. The triazole derivative of 6-gingerol forms enhanced binding interactions with the active site residues of 14α-demethylase, carries an affinity for catalytically required cofactor heme and forms a stable complex with time without the probability of premature expulsion. Thus, this compound inhibits the formation of ergosterol leading to weakened fungal cell membranes and eventually death of fungal cells. Conclusion: : The triazole derivative of 6-gingerol is recommended as a lead compound for the development of non-toxic antifungals.

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The Role of Fungi in the Cocoa Production Chain and the Challenge of Climate Change

Journal of Fungi ◽

10.3390/jof7030202 ◽

2021 ◽

Vol 7 (3) ◽

pp. 202

Author(s):

Johannes Delgado-Ospina ◽

Junior Bernardo Molina-Hernández ◽

Clemencia Chaves-López ◽

Gianfranco Romanazzi ◽

Antonello Paparella

Keyword(s):

Climate Change ◽

Fungal Infections ◽

Close Association ◽

Pathogenic Fungi ◽

Fungal Species ◽

Mitigation Strategies ◽

Plant Diseases ◽

Production Chain ◽

Cocoa Production

Background: The role of fungi in cocoa crops is mainly associated with plant diseases and contamination of harvest with unwanted metabolites such as mycotoxins that can reach the final consumer. However, in recent years there has been interest in discovering other existing interactions in the environment that may be beneficial, such as antagonism, commensalism, and the production of specific enzymes, among others. Scope and approach: This review summarizes the different fungi species involved in cocoa production and the cocoa supply chain. In particular, it examines the presence of fungal species during cultivation, harvest, fermentation, drying, and storage, emphasizing the factors that possibly influence their prevalence in the different stages of production and the health risks associated with the production of mycotoxins in the light of recent literature. Key findings and conclusion: Fungi associated with the cocoa production chain have many different roles. They have evolved in a varied range of ecosystems in close association with plants and various habitats, affecting nearly all the cocoa chain steps. Reports of the isolation of 60 genera of fungi were found, of which only 19 were involved in several stages. Although endophytic fungi can help control some diseases caused by pathogenic fungi, climate change, with increased rain and temperatures, together with intensified exchanges, can favour most of these fungal infections, and the presence of highly aggressive new fungal genotypes increasing the concern of mycotoxin production. For this reason, mitigation strategies need to be determined to prevent the spread of disease-causing fungi and preserve beneficial ones.

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