Alexidine dihydrochloride has broad spectrum a ctivities against diverse fungal pathogens

AbstractInvasive fungal infections due to Candida albicans, Aspergillus fumigatus and Cryptococcus neoformans, constitute a substantial threat to hospitalized, immunocompromised patients. Further, the presence of drug-recalcitrant biofilms on medical devices, and emergence of drug-resistant fungi such as Candida auris, introduce treatment challenges with current antifungal drugs. Worse, currently there is no approved drug capable of obviating preformed biofilms which increases the chance of infection relapses. Here, we screened a small molecule Prestwick Chemical Library, consisting of 1200 FDA approved off-patent drugs, against C. albicans, C. auris and A. fumigatus, to identify those that inhibit growth of all three pathogens. Inhibitors were further prioritized for their potency against other fungal pathogens, and their ability to kill preformed biofilms. Our studies identified the bis-biguanide Alexidine dihydrochloride (AXD), as a drug with the highest antifungal and anti-biofilm activity against a diverse range of fungal pathogens. Finally, AXD significantly potentiated the efficacy of fluconazole against biofilms, displayed low mammalian cell toxicity, and eradicated biofilms growing in mice central venous catheters in vivo, highlighting its potential as a pan-antifungal drug.ImportanceThe prevalence of fungal infections has seen a rise in the past decades due to advances in modern medicine leading to an expanding population of device-associated and immunocompromised patients. Furthermore, the spectrum of pathogenic fungi has changed, with the emergence of multi-drug resistant strains such as C. auris. High mortality related to fungal infections point to major limitations of current antifungal therapy, and an unmet need for new antifungal drugs. We screened a library of repurposed FDA approved inhibitors to identify compounds with activities against a diverse range of fungi, in varied phases of growth. The assays identified Alexidine dihydrochloride (AXD) to have pronounced antifungal activity including against preformed biofilms, at concentrations lower than mammalian cell toxicity. AXD potentiated the activity of fluconazole and amphotericin B against Candida biofilms in vitro, and prevented biofilm growth in vivo. Thus AXD has the potential to be developed as a pan-antifungal, anti-biofilm drug.

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Alexidine Dihydrochloride Has Broad-Spectrum Activities against Diverse Fungal Pathogens

mSphere ◽

10.1128/msphere.00539-18 ◽

2018 ◽

Vol 3 (5) ◽

Cited By ~ 8

Author(s):

Zeinab Mamouei ◽

Abdullah Alqarihi ◽

Shakti Singh ◽

Shuying Xu ◽

Michael K. Mansour ◽

...

Keyword(s):

Mammalian Cell ◽

Fungal Pathogens ◽

Fungal Infections ◽

Antifungal Drugs ◽

Immunocompromised Patients ◽

Cell Toxicity ◽

Diverse Range ◽

Content Type ◽

Mammalian Cell Toxicity

ABSTRACT Invasive fungal infections due to Candida albicans, Aspergillus fumigatus, and Cryptococcus neoformans constitute a substantial threat to hospitalized immunocompromised patients. Further, the presence of drug-recalcitrant biofilms on medical devices and emergence of drug-resistant fungi, such as Candida auris, introduce treatment challenges with current antifungal drugs. Worse, currently there is no approved drug capable of obviating preformed biofilms, which increase the chance of infection relapses. Here, we screened a small-molecule New Prestwick Chemical Library, consisting of 1,200 FDA-approved off-patent drugs against C. albicans, C. auris, and A. fumigatus, to identify those that inhibit growth of all three pathogens. Inhibitors were further prioritized for their potency against other fungal pathogens and their ability to kill preformed biofilms. Our studies identified the bis-biguanide alexidine dihydrochloride (AXD) as a drug with the highest antifungal and antibiofilm activity against a diverse range of fungal pathogens. Finally, AXD significantly potentiated the efficacy of fluconazole against biofilms, displayed low mammalian cell toxicity, and eradicated biofilms growing in mouse central venous catheters in vivo, highlighting its potential as a pan-antifungal drug. IMPORTANCE The prevalence of fungal infections has seen a rise in the past decades due to advances in modern medicine leading to an expanding population of device-associated and immunocompromised patients. Furthermore, the spectrum of pathogenic fungi has changed, with the emergence of multidrug-resistant strains such as C. auris. High mortality related to fungal infections points to major limitations of current antifungal therapy and an unmet need for new antifungal drugs. We screened a library of repurposed FDA-approved inhibitors to identify compounds with activities against a diverse range of fungi in varied phases of growth. The assays identified alexidine dihydrochloride (AXD) to have pronounced antifungal activity, including against preformed biofilms, at concentrations lower than mammalian cell toxicity. AXD potentiated the activity of fluconazole and amphotericin B against Candida biofilms in vitro and prevented biofilm growth in vivo. Thus, AXD has the potential to be developed as a pan-antifungal, antibiofilm drug.

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A marine microbiome antifungal targets urgent-threat drug-resistant fungi

Science ◽

10.1126/science.abd6919 ◽

2020 ◽

Vol 370 (6519) ◽

pp. 974-978 ◽

Cited By ~ 1

Author(s):

Fan Zhang ◽

Miao Zhao ◽

Doug R. Braun ◽

Spencer S. Ericksen ◽

Jeff S. Piotrowski ◽

...

Keyword(s):

Mode Of Action ◽

Fungal Pathogens ◽

Antifungal Drugs ◽

Multiple Drug ◽

Drug Resistant ◽

Candida Auris ◽

Marine Animals ◽

Multiple Drug Resistant

New antifungal drugs are urgently needed to address the emergence and transcontinental spread of fungal infectious diseases, such as pandrug-resistant Candida auris. Leveraging the microbiomes of marine animals and cutting-edge metabolomics and genomic tools, we identified encouraging lead antifungal molecules with in vivo efficacy. The most promising lead, turbinmicin, displays potent in vitro and mouse-model efficacy toward multiple-drug–resistant fungal pathogens, exhibits a wide safety index, and functions through a fungal-specific mode of action, targeting Sec14 of the vesicular trafficking pathway. The efficacy, safety, and mode of action distinct from other antifungal drugs make turbinmicin a highly promising antifungal drug lead to help address devastating global fungal pathogens such as C. auris.

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Anticapsular and Antifungal Activity of α-Cyperone

Antibiotics ◽

10.3390/antibiotics10010051 ◽

2021 ◽

Vol 10 (1) ◽

pp. 51

Author(s):

Connor Horn ◽

Govindsamy Vediyappan

Keyword(s):

Antifungal Activity ◽

Fungal Pathogens ◽

Fungal Infections ◽

Antifungal Drugs ◽

Cyperus Rotundus ◽

Drug Resistant ◽

Fungal Virulence ◽

Medical Needs ◽

Number Of Patients ◽

Immunosuppressed Patients

Fungal infections affect 300 million people and cause 1.5 million deaths globally per year. With the number of immunosuppressed patients increasing steadily, there is an increasing number of patients infected with opportunistic fungal infections such as infections caused by the species of Candida and Cryptococcus. In fact, the drug-resistant Can. krusei and the emerging pan-antifungal resistant Can. auris pose a serious threat to human health as the existing limited antifungals are futile. To further complicate therapy, fungi produce capsules and spores that are resistant to most antifungal drugs/host defenses. Novel antifungal drugs are urgently needed to fill unmet medical needs. From screening a collection of medicinal plant sources for antifungal activity, we have identified an active fraction from the rhizome of Cyperus rotundus, the nut grass plant. The fraction contained α-Cyperone, an essential oil that showed fungicidal activity against different species of Candida. Interestingly, the minimal inhibitory concentration of α-Cyperone was reduced 8-fold when combined with a clinical antifungal drug, fluconazole, indicating its antifungal synergistic potential and could be useful for combination therapy. Furthermore, α-Cyperone affected the synthesis of the capsule in Cryp. neoformans, a causative agent of fungal meningitis in humans. Further work on mechanistic understanding of α-Cyperone against fungal virulence could help develop a novel antifungal agent for drug-resistant fungal pathogens.

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Visible Lights Combined with Photosensitizing Compounds Are Effective against Candida albicans Biofilms

Microorganisms ◽

10.3390/microorganisms9030500 ◽

2021 ◽

Vol 9 (3) ◽

pp. 500 ◽

Cited By ~ 1

Author(s):

Priyanka Bapat ◽

Gurbinder Singh ◽

Clarissa J. Nobile

Keyword(s):

Candida Albicans ◽

Photodynamic Therapy ◽

Biofilm Formation ◽

Fungal Pathogens ◽

Fungal Infections ◽

Therapeutic Strategies ◽

Antifungal Drugs ◽

Clinical Settings ◽

Drug Resistant ◽

Candida Albicans Biofilms

Fungal infections are increasing in prevalence worldwide, especially in immunocompromised individuals. Given the emergence of drug-resistant fungi and the fact that there are only three major classes of antifungal drugs available to treat invasive fungal infections, there is a need to develop alternative therapeutic strategies effective against fungal infections. Candida albicans is a commensal of the human microbiota that is also one of the most common fungal pathogens isolated from clinical settings. C. albicans possesses several virulence traits that contribute to its pathogenicity, including the ability to form drug-resistant biofilms, which can make C. albicans infections particularly challenging to treat. Here, we explored red, green, and blue visible lights alone and in combination with common photosensitizing compounds for their efficacies at inhibiting and disrupting C. albicans biofilms. We found that blue light inhibited biofilm formation and disrupted mature biofilms on its own and that the addition of photosensitizing compounds improved its antibiofilm potential. Red and green lights, however, inhibited biofilm formation only in combination with photosensitizing compounds but had no effects on disrupting mature biofilms. Taken together, these results suggest that photodynamic therapy may be an effective non-drug treatment for fungal biofilm infections that is worthy of further exploration.

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Understanding In-Silico Approaches to Design Synthetic Antifungal Peptides to Combat Fungal Infections like Mucormycosis

Journal of Bacteriology and Mycology ◽

10.26420/jbacteriolmycol.2021.1188 ◽

2021 ◽

Vol 8 (6) ◽

Author(s):

Bajwa T ◽

◽

Sharma R ◽

Keyword(s):

In Silico ◽

Fungal Pathogens ◽

Fungal Infections ◽

Structural Features ◽

Antifungal Drugs ◽

Diverse Range ◽

Naturally Occurring ◽

Antifungal Peptides ◽

Range Of Functions

Antimicrobial peptides are the small sized molecule ranging in size from 2 to 9 kDa with expansive range of antimicrobial activity against bacteria, fungi, viruses etc. They are also used as first line of defense against various pathogens. With the emergence of various fungal infections in the present day and uprising antifungal resistance has made the choice of antifungal drugs very limited, the conventional drugs are slowly becoming ineffective to these fungal pathogens. Researchers have turned to these naturally occurring molecules which represent diverse range of functions and structural features but these naturally occurring peptides exhibit high toxicity, instability and low specificity towards the target which can be combatted by using various in silico and computational approaches to design and modify these AMPs in such a way that their efficiency is increased. In this article, we have specifically focused on Mucormycosis infection because of its high mortality rates and a very few synthetic AMPs have been produced against Mucorales considering the severity of this disease and the rapid surge in Mucormycosis cases emerged in the country. In this paper we will discuss about the present scenario of the disease, AMPs as antifungal therapy, role, classification of antifungal peptides, mechanism of action, advantages and limitations of natural AMPs, important physicochemical properties taken into account while designing synthetic AMPs (SAMPs) and the workflow pipeline to characterize and predict potential synthetic AMPs by using the existing web servers, databases and bioinformatics tools to develop new alternatives of conventional drugs available in the market against fungal infections.

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The Use of Galleria mellonella Larvae to Identify Novel Antimicrobial Agents against Fungal Species of Medical Interest

Journal of Fungi ◽

10.3390/jof4030113 ◽

2018 ◽

Vol 4 (3) ◽

pp. 113 ◽

Cited By ~ 23

Author(s):

Kevin Kavanagh ◽

Gerard Sheehan

Keyword(s):

Fungal Pathogens ◽

Antimicrobial Agents ◽

Galleria Mellonella ◽

Fungal Infections ◽

Fungal Species ◽

Molecular Techniques ◽

Antifungal Drugs ◽

Immune Priming ◽

Greater Wax Moth

The immune system of insects and the innate immune response of mammals share many similarities and, as a result, insects may be used to assess the virulence of fungal pathogens and give results similar to those from mammals. Larvae of the greater wax moth Galleria mellonella are widely used in this capacity and also for assessing the toxicity and in vivo efficacy of antifungal drugs. G. mellonella larvae are easy to use, inexpensive to purchase and house, and have none of the legal/ethical restrictions that are associated with use of mammals. Larvae may be inoculated by intra-hemocoel injection or by force-feeding. Larvae can be used to assess the in vivo toxicity of antifungal drugs using a variety of cellular, proteomic, and molecular techniques. Larvae have also been used to identify the optimum combinations of antifungal drugs for use in the treatment of recalcitrant fungal infections in mammals. The introduction of foreign material into the hemocoel of larvae can induce an immune priming effect which may operate independently with the activity of the antifungal drug. Procedures to identify this effect and limit its action are required.

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Fungal biofilm architecture produces hypoxic microenvironments that drive antifungal resistance

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2003700117 ◽

2020 ◽

Vol 117 (36) ◽

pp. 22473-22483 ◽

Cited By ~ 2

Author(s):

Caitlin H. Kowalski ◽

Kaesi A. Morelli ◽

Daniel Schultz ◽

Carey D. Nadell ◽

Robert A. Cramer

Keyword(s):

Drug Resistance ◽

Fungal Infections ◽

Antifungal Drugs ◽

Antifungal Drug ◽

Drug Resistant ◽

Antifungal Drug Resistance ◽

Oxygen Gradients ◽

Biofilm Architecture

Human fungal infections may fail to respond to contemporary antifungal therapies in vivo despite in vitro fungal isolate drug susceptibility. Such a discrepancy between in vitro antimicrobial susceptibility and in vivo treatment outcomes is partially explained by microbes adopting a drug-resistant biofilm mode of growth during infection. The filamentous fungal pathogenAspergillus fumigatusforms biofilms in vivo, and during biofilm growth it has reduced susceptibility to all three classes of contemporary antifungal drugs. Specific features of filamentous fungal biofilms that drive antifungal drug resistance remain largely unknown. In this study, we applied a fluorescence microscopy approach coupled with transcriptional bioreporters to define spatial and temporal oxygen gradients and single-cell metabolic activity withinA. fumigatusbiofilms. Oxygen gradients inevitably arise duringA. fumigatusbiofilm maturation and are both critical for, and the result of,A. fumigatuslate-stage biofilm architecture. We observe that these self-induced hypoxic microenvironments not only contribute to filamentous fungal biofilm maturation but also drive resistance to antifungal treatment. Decreasing oxygen levels toward the base ofA. fumigatusbiofilms increases antifungal drug resistance. Our results define a previously unknown mechanistic link between filamentous fungal biofilm physiology and contemporary antifungal drug resistance. Moreover, we demonstrate that drug resistance mediated by dynamic oxygen gradients, found in many bacterial biofilms, also extends to the fungal kingdom. The conservation of hypoxic drug-resistant niches in bacterial and fungal biofilms is thus a promising target for improving antimicrobial therapy efficacy.

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Galleria mellonella for the Evaluation of Antifungal Efficacy against Medically Important Fungi, a Narrative Review

Microorganisms ◽

10.3390/microorganisms8030390 ◽

2020 ◽

Vol 8 (3) ◽

pp. 390 ◽

Cited By ~ 8

Author(s):

Sana Jemel ◽

Jacques Guillot ◽

Kalthoum Kallel ◽

Françoise Botterel ◽

Eric Dannaoui

Keyword(s):

Fungal Pathogens ◽

Galleria Mellonella ◽

Fungal Infections ◽

Antifungal Susceptibility ◽

Antifungal Drugs ◽

New Drugs ◽

Development Of Resistance ◽

Antifungal Efficacy

The treatment of invasive fungal infections remains challenging and the emergence of new fungal pathogens as well as the development of resistance to the main antifungal drugs highlight the need for novel therapeutic strategies. Although in vitro antifungal susceptibility testing has come of age, the proper evaluation of therapeutic efficacy of current or new antifungals is dependent on the use of animal models. Mammalian models, particularly using rodents, are the cornerstone for evaluation of antifungal efficacy, but are limited by increased costs and ethical considerations. To circumvent these limitations, alternative invertebrate models, such as Galleria mellonella, have been developed. Larvae of G. mellonella have been widely used for testing virulence of fungi and more recently have proven useful for evaluation of antifungal efficacy. This model is suitable for infection by different fungal pathogens including yeasts (Candida, Cryptococcus, Trichosporon) and filamentous fungi (Aspergillus, Mucorales). Antifungal efficacy may be easily estimated by fungal burden or mortality rate in infected and treated larvae. The aim of the present review is to summarize the actual data about the use of G. mellonella for testing the in vivo efficacy of licensed antifungal drugs, new drugs, and combination therapies.

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Catalytic defense against fungal pathogens using nanozymes

Nanotechnology Reviews ◽

10.1515/ntrev-2021-0084 ◽

2021 ◽

Vol 10 (1) ◽

pp. 1277-1292

Author(s):

Wu Qingzhi ◽

Sijia Zou ◽

Qian Wang ◽

Lei Chen ◽

Xiyun Yan ◽

...

Keyword(s):

Fungal Pathogens ◽

Fungal Infections ◽

Low Cost ◽

Enzymatic Catalysis ◽

Antifungal Drugs ◽

Drug Resistant ◽

Enzyme Mimics ◽

Artificial Enzyme ◽

Promising Alternative ◽

Promising Strategy

Abstract Fungal infections are still a major challenge for clinics, resulting from the resistance of drug-resistant fungi and the toxicity of antifungal drugs. Defense against fungal invasions via enzymatic catalysis has been found in nature. The use of nanozymes, as artificial enzyme mimics, may be a promising strategy to induce fungal death due to their advantages such as tunable catalytic activity, high stability, low cost, and easy preparation. Here, the importance of natural enzymes in the defense against fungi is outlined. The progress in antifungal performance and potential application of nanozymes and the related antifungal mechanisms are also summarized. Finally, the perspective and challenges in this field for future study, pointing out that nanozyme-based catalytic therapy represents a promising alternative strategy for antifungal treatment, are highlighted.

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