The newly synthesized thiazole derivatives as potential antifungal compounds against Candida albicans

Abstract Recently, the occurrence of candidiasis has increased dramatically, especially in immunocompromised patients. Additionally, their treatment is often ineffective due to the resistance of yeasts to antimycotics. Therefore, there is a need to search for new antifungals. A series of nine newly synthesized thiazole derivatives containing the cyclopropane system, showing promising activity against Candida spp., has been further investigated. We decided to verify their antifungal activity towards clinical Candida albicans isolated from the oral cavity of patients with hematological malignancies and investigate the mode of action on fungal cell, the effect of combination with the selected antimycotics, toxicity to erythrocytes, and lipophilicity. These studies were performed by the broth microdilution method, test with sorbitol and ergosterol, checkerboard technique, erythrocyte lysis assay, and reversed phase thin-layer chromatography, respectively. All derivatives showed very strong activity (similar and even higher than nystatin) against all C. albicans isolates with minimal inhibitory concentration (MIC) = 0.008–7.81 µg/mL Their mechanism of action may be related to action within the fungal cell wall structure and/or within the cell membrane. The interactions between the derivatives and the selected antimycotics (nystatin, chlorhexidine, and thymol) showed additive effect only in the case of combination some of them and thymol. The erythrocyte lysis assay confirmed the low cytotoxicity of these compounds as compared to nystatin. The high lipophilicity of the derivatives was related with their high antifungal activity. The present studies confirm that the studied thiazole derivatives containing the cyclopropane system appear to be a very promising group of compounds in treatment of infections caused by C. albicans. However, this requires further studies in vivo. Key points • The newly thiazoles showed high antifungal activity and some of them — additive effect in combination with thymol. • Their mode of action may be related with the influence on the structure of the fungal cell wall and/or the cell membrane. • The low cytotoxicity against erythrocytes and high lipophilicity of these derivatives are their additional good properties. Graphical abstract

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The Viscoelastic Properties of the Fungal Cell Wall Allow Traffic of AmBisome as Intact Liposome Vesicles

mBio ◽

10.1128/mbio.02383-17 ◽

2018 ◽

Vol 9 (1) ◽

Cited By ~ 55

Author(s):

Louise Walker ◽

Prashant Sood ◽

Megan D. Lenardon ◽

Gillian Milne ◽

Jon Olson ◽

...

Keyword(s):

Cell Wall ◽

Candida Albicans ◽

Cell Membrane ◽

Amphotericin B ◽

Mode Of Action ◽

Viscoelastic Properties ◽

Fungal Cell Wall ◽

Fungal Cell ◽

Pass Through ◽

Cell Wall Porosity

ABSTRACT The fungal cell wall is a critically important structure that represents a permeability barrier and protective shield. We probed Candida albicans and Cryptococcus neoformans with liposomes containing amphotericin B (AmBisome), with or without 15-nm colloidal gold particles. The liposomes have a diameter of 60 to 80 nm, and yet their mode of action requires them to penetrate the fungal cell wall to deliver amphotericin B to the cell membrane, where it binds to ergosterol. Surprisingly, using cryofixation techniques with electron microscopy, we observed that the liposomes remained intact during transit through the cell wall of both yeast species, even though the predicted porosity of the cell wall (pore size, ~5.8 nm) is theoretically too small to allow these liposomes to pass through intact. C. albicans mutants with altered cell wall thickness and composition were similar in both their in vitro AmBisome susceptibility and the ability of liposomes to penetrate the cell wall. AmBisome exposed to ergosterol-deficient C. albicans failed to penetrate beyond the mannoprotein-rich outer cell wall layer. Melanization of C. neoformans and the absence of amphotericin B in the liposomes were also associated with a significant reduction in liposome penetration. Therefore, AmBisome can reach cell membranes intact, implying that fungal cell wall viscoelastic properties are permissive to vesicular structures. The fact that AmBisome can transit through chemically diverse cell wall matrices when these liposomes are larger than the theoretical cell wall porosity suggests that the wall is capable of rapid remodeling, which may also be the mechanism for release of extracellular vesicles. IMPORTANCE AmBisome is a broad-spectrum fungicidal antifungal agent in which the hydrophobic polyene antibiotic amphotericin B is packaged within a 60- to 80-nm liposome. The mode of action involves perturbation of the fungal cell membrane by selectively binding to ergosterol, thereby disrupting membrane function. We report that the AmBisome liposome transits through the cell walls of both Candida albicans and Cryptococcus neoformans intact, despite the fact that the liposome is larger than the theoretical cell wall porosity. This implies that the cell wall has deformable, viscoelastic properties that are permissive to transwall vesicular traffic. These observations help explain the low toxicity of AmBisome, which can deliver its payload directly to the cell membrane without unloading the polyene in the cell wall. In addition, these findings suggest that extracellular vesicles may also be able to pass through the cell wall to deliver soluble and membrane-bound effectors and other molecules to the extracellular space.

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Spilanthol as a promising antifungal alkylamide for the treatment of vulvovaginal candidiasis

Medical Mycology ◽

10.1093/mmy/myab054 ◽

2021 ◽

Author(s):

Rodrigo L Fabri ◽

Jhamine C O Freitas ◽

Ari S O Lemos ◽

Lara M Campos ◽

Irley O M Diniz ◽

...

Keyword(s):

Cell Wall ◽

Candida Albicans ◽

Antifungal Activity ◽

Cell Membrane ◽

Multidrug Resistant ◽

Fungal Strain ◽

Vulvovaginal Candidiasis ◽

Biofilm Matrix

Abstract Spilanthol is a bioactive alkylamide from the native Amazon plant species, Acmella oleracea. However, antifungal activities of spilanthol and its application to the therapeutic treatment of candidiasis remains to be explored. This study sought to evaluate the in vitro and in vivo antifungal activity of spilanthol previously isolated from A. oleracea (spilanthol(AcO)) against Candida albicans ATCC® 10231™, a multidrug-resistant fungal strain. Microdilution methods were used to determine inhibitory and fungicidal concentrations of spilanthol(AcO). In planktonic cultures, the fungal growth kinetics, yeast cell metabolic activity, cell membrane permeability and cell wall integrity were investigated. The effect of spilanthol(AcO) on the proliferation and adhesion of fungal biofilms was evaluated by whole slide imaging and scanning electron microscopy. The biochemical composition of the biofilm matrix was also analyzed. In parallel, spilanthol(AcO) was tested in vivo in an experimental vulvovaginal candidiasis model. Our in vitro analyses in C. albicans planktonic cultures detected a significant inhibitory effect of spilanthol(AcO), which affects both yeast cell membrane and cell wall integrity, interfering with the fungus growth. C. albicans biofilm proliferation and adhesion, as well as, carbohydrates and DNA in biofilm matrix were reduced after spilanthol(AcO) treatment. Moreover, infected rats treated with spilanthol(AcO) showed consistent reduction of both fungal burden and inflammatory processes compared to the untreated animals. Altogether, our findings demonstrated that spilanthol(AcO) is an bioactive compound against planktonic and biofilm forms of a multidrug resistant C. albicans strain. Furthermore, spilanthol(AcO) can be potentially considered for therapeutical treatment of vulvovaginal candidiasis caused by C. albicans. Lay Abstract This study sought to evaluate the antifungal activity of spilanthol against Candida albicans ATCC® 10 231™, a multidrug-resistant fungal strain. Our findings demonstrated that spilanthol(AcO) can be potentially considered for therapeutical treatment of vulvovaginal candidiasis caused by C. albicans.

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Screening and Antifungal Activity of a β-Carboline Derivative against Cryptococcus neoformans and C. gattii

International Journal of Microbiology ◽

10.1155/2019/7157845 ◽

2019 ◽

Vol 2019 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Kátia Santana Cruz ◽

Emerson Silva Lima ◽

Marcia de Jesus Amazonas da Silva ◽

Erica Simplício de Souza ◽

Andreia Montoia ◽

...

Keyword(s):

Cell Wall ◽

Candida Albicans ◽

Antifungal Activity ◽

Cryptococcus Neoformans ◽

Active Compound ◽

Cell Walls ◽

Human Fibroblasts ◽

Lead Compound ◽

Fungal Cell ◽

Fungal Cell Walls

Background. Cryptococcosis is a fungal disease of bad prognosis due to its pathogenicity and the toxicity of the drugs used for its treatment. The aim of this study was to investigate the medicinal potential of carbazole and β-carboline alkaloids and derivatives against Cryptococcus neoformans and C. gattii. Methods. MICs were established in accordance with the recommendations of the Clinical and Laboratory Standards Institute for alkaloids and derivatives against C. neoformans and C. gattii genotypes VNI and VGI, respectively. A single active compound was further evaluated against C. neoformans genotypes VNII, VNIII, and VNIV, C. gattii genotypes VGI, VGIII, and VGIV, Candida albicans ATCC 36232, for cytotoxicity against the MRC-5 lineage of human fibroblasts and for effects on fungal cells (cell wall, ergosterol, and leakage of nucleic acids). Results. Screening of 11 compounds revealed 8-nitroharmane as a significant inhibitor (MIC 40 μg/mL) of several C. neoformans and C. gattii genotypes. It was not toxic to fibroblasts (IC50 > 50 µg/mL) nor did it alter fungal cell walls or the concentration of ergosterol in C. albicans or C. neoformans. It increased leakage of substances that absorb at 260 nm. Conclusions. The synthetic β-carboline 8-nitroharmane significantly inhibits pathogenic Cryptococcus species and is interesting as a lead compound towards new therapy for Cryptococcus infections.

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Antifungal Activity Directed Toward the Cell Wall by 2-Cyclohexylidenhydrazo- 4-Phenyl-Thiazole Against Candida albicans

Infectious Disorders - Drug Targets ◽

10.2174/1871526518666180531101605 ◽

2019 ◽

Vol 19 (4) ◽

pp. 428-438 ◽

Cited By ~ 1

Author(s):

Nívea P. de Sá ◽

Ana P. Pôssa ◽

Pilar Perez ◽

Jaqueline M.S. Ferreira ◽

Nayara C. Fonseca ◽

...

Keyword(s):

Cell Wall ◽

Candida Albicans ◽

Antifungal Activity ◽

Mammalian Cells ◽

C Elegans ◽

Buccal Epithelial Cells ◽

Mutant Strains ◽

Low Toxicity ◽

High Concentrations ◽

Mic Value

Background: The increasing incidence of invasive forms of candidiasis and resistance to antifungal therapy leads us to seek new and more effective antifungal compounds. Objective: To investigate the antifungal activity and toxicity as well as to evaluate the potential targets of 2- cyclohexylidenhydrazo-4-phenyl-thiazole (CPT) in Candida albicans. Methods: The antifungal activity of CPT against the survival of C. albicans was investigated in Caenorhabditis elegans. Additionally, we determined the effect of CPT on the inhibition of C. albicans adhesion capacity to buccal epithelial cells (BECs), the toxicity of CPT in mammalian cells, and the potential targets of CPT in C. albicans. Results: CPT exhibited a minimum inhibitory concentration (MIC) value of 0.4-1.9 µg/mL. Furthermore, CPT at high concentrations (>60 x MIC) showed no or low toxicity in HepG2 cells and <1% haemolysis in human erythrocytes. In addition, CPT decreased the adhesion capacity of yeasts to the BECs and prolonged the survival of C. elegans infected with C. albicans. Analysis of CPT-treated cells showed that their cell wall was thinner than that of untreated cells, especially the glucan layer. We found that there was a significantly lower quantity of 1,3-β-D-glucan present in CPT-treated cells than that in untreated cells. Assays performed on several mutant strains showed that the MIC value of CPT was high for its antifungal activity on yeasts with defective 1,3-β-glucan synthase. Conclusion: In conclusion, CPT appears to target the cell wall of C. albicans, exhibits low toxicity in mammalian cells, and prolongs the survival of C. elegans infected with C. albicans.

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Insights into the Mode of Action of Chitosan as an Antibacterial Compound

Applied and Environmental Microbiology ◽

10.1128/aem.00453-08 ◽

2008 ◽

Vol 74 (12) ◽

pp. 3764-3773 ◽

Cited By ~ 402

Author(s):

Dina Raafat ◽

Kristine von Bargen ◽

Albert Haas ◽

Hans-Georg Sahl

Keyword(s):

Antimicrobial Activity ◽

Cell Wall ◽

Cell Membrane ◽

Mode Of Action ◽

Membrane Lipids ◽

Expression Profiles ◽

Transcriptional Response ◽

Response Analysis ◽

Sequence Of Events ◽

Wide Range

ABSTRACT Chitosan is a polysaccharide biopolymer that combines a unique set of versatile physicochemical and biological characteristics which allow for a wide range of applications. Although its antimicrobial activity is well documented, its mode of action has hitherto remained only vaguely defined. In this work we investigated the antimicrobial mode of action of chitosan using a combination of approaches, including in vitro assays, killing kinetics, cellular leakage measurements, membrane potential estimations, and electron microscopy, in addition to transcriptional response analysis. Chitosan, whose antimicrobial activity was influenced by several factors, exhibited a dose-dependent growth-inhibitory effect. A simultaneous permeabilization of the cell membrane to small cellular components, coupled to a significant membrane depolarization, was detected. A concomitant interference with cell wall biosynthesis was not observed. Chitosan treatment of Staphylococcus simulans 22 cells did not give rise to cell wall lysis; the cell membrane also remained intact. Analysis of transcriptional response data revealed that chitosan treatment leads to multiple changes in the expression profiles of Staphylococcus aureus SG511 genes involved in the regulation of stress and autolysis, as well as genes associated with energy metabolism. Finally, a possible mechanism for chitosan's activity is postulated. Although we contend that there might not be a single classical target that would explain chitosan's antimicrobial action, we speculate that binding of chitosan to teichoic acids, coupled with a potential extraction of membrane lipids (predominantly lipoteichoic acid) results in a sequence of events, ultimately leading to bacterial death.

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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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Ketoconazole - an antifungal drug for oral use

Drug and Therapeutics Bulletin ◽

10.1136/dtb.19.23.91 ◽

1981 ◽

Vol 19 (23) ◽

pp. 91-92

Keyword(s):

Antifungal Activity ◽

Cell Membrane ◽

Oral Administration ◽

Antifungal Agent ◽

Systemic Effect ◽

Antifungal Drug ◽

The Other ◽

Membrane Synthesis ◽

Fungal Cell

Ketoconazole (Nizoral - Janssen) is a new antifungal agent. Like the other imidazoles with antifungal activity such as miconazole,1 clotrimazole2 and econazole,3 it acts by inhibiting fungal cell-membrane synthesis.4 It is well absorbed and exerts a systemic effect; it is thus suitable for oral administration.

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Isolation of Fungal Cell Wall Degrading Proteins from Barley (Hordeum vulgare L.) Leaves Infected with Rhynchosporium secalis

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.2002.15.10.1031 ◽

2002 ◽

Vol 15 (10) ◽

pp. 1031-1039 ◽

Cited By ~ 35

Author(s):

Reza Zareie ◽

Dara L. Melanson ◽

Peter J. Murphy

Keyword(s):

Cell Wall ◽

Antifungal Activity ◽

Plant Disease Resistance ◽

High Performance ◽

Peptide Mapping ◽

Rhynchosporium Secalis ◽

Active Components ◽

Hordeum Vulgare L ◽

Fungal Cell ◽

Barley Leaves

Proteins with antifungal activity towards Rhynchosporium secalis conidia were isolated from the intercellular washing fluid (IWF) of barley leaves. The active components were purified by high-performance liquid chromatography under conditions that maintained biological activity. Five major barley IWF proteins deleterious to the cell wall of viable R. secalis conidia were isolated and identified by a combination of N-terminal amino acid sequencing, peptide mapping, and determination of mass and isoelectric point. They were a 32-kDa β-1,3-glucanase (Pr32), a 25-kDa chitinase (Pr25), and three 22-kDa thaumatin-like (TL) proteins (Pr22-1, Pr22-2, and Pr22-3). Pr22-1 and Pr22-2 were similar to the protein R class of TL proteins, whereas Pr22-3 was more similar to the S class. Pr22-3 was shown to digest laminarin, indicating that this TL protein has glucanase activity. In addition, Pr22-3 was more active in the spore bioassay than Pr22-2. Various combinations of the five proteins had a greater effect on R. secalis spores than did the individual proteins. The extraction of proteins with antifungal activity from the IWF of barley leaves indicates their possible role in defense against leaf pathogens. A similar bioassay may be developed for other systems to identify particular isoforms of pathogenicity-related proteins that might have a role in plant disease resistance.

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11g, a Potent Antifungal Candidate, Enhances Candida albicans Immunogenicity by Unmasking β-Glucan in Fungal Cell Wall

Frontiers in Microbiology ◽

10.3389/fmicb.2020.01324 ◽

2020 ◽

Vol 11 ◽

Author(s):

Xin Huang ◽

Yu Liu ◽

Tingjunhong Ni ◽

Liping Li ◽

Lan Yan ◽

...

Keyword(s):

Cell Wall ◽

Candida Albicans ◽

Fungal Cell Wall ◽

Fungal Cell

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Evaluation of Antifungal Activity and Mode of Action of New Coumarin Derivative, 7-Hydroxy-6-nitro-2H-1-benzopyran-2-one, againstAspergillusspp.

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2015/925096 ◽

2015 ◽

Vol 2015 ◽

pp. 1-8 ◽

Cited By ~ 11

Author(s):

Felipe Queiroga Sarmento Guerra ◽

Rodrigo Santos Aquino de Araújo ◽

Janiere Pereira de Sousa ◽

Fillipe de Oliveira Pereira ◽

Francisco J. B. Mendonça-Junior ◽

...

Keyword(s):

Cell Wall ◽

Mode Of Action ◽

Cell Walls ◽

Coumarin Derivative ◽

Antifungal Drugs ◽

Azole Resistance ◽

Subinhibitory Concentration ◽

Fungal Cell ◽

Mycelia Growth

Aspergillusspp. produce a wide variety of diseases. For the treatment of such infections, the azoles and Amphotericin B are used in various formulations. The treatment of fungal diseases is often ineffective, because of increases in azole resistance and their several associated adverse effects. To overcome these problems, natural products and their derivatives are interesting alternatives. The aim of this study was to examine the effects of coumarin derivative, 7-hydroxy-6-nitro-2H-1-benzopyran-2-one (Cou-NO2), both alone and with antifungal drugs. Its mode of action againstAspergillusspp. Cou-NO2was tested to evaluate its effects on mycelia growth and germination of fungal conidia ofAspergillusspp. We also investigated possible Cou-NO2action on cell walls (0.8 M sorbitol) and on Cou-NO2to ergosterol binding in the cell membrane. The study shows that Cou-NO2is capable of inhibiting both the mycelia growth and germination of conidia for the species tested, and that its action affects the structure of the fungal cell wall. At subinhibitory concentration, Cou-NO2enhanced thein vitroeffects of azoles. Moreover, in combination with azoles (voriconazole and itraconazole) Cou-NO2displays an additive effect. Thus, our study supports the use of coumarin derivative 7-hydroxy-6-nitro-2H-1-benzopyran-2-one as an antifungal agent againstAspergillusspecies.

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