Steroid-Functionalized Imidazolium Salts with an Extended Spectrum of Antifungal and Antibacterial Activity

It is established that high rates of morbidity and mortality caused by fungal infections are related to the current limited number of antifungal drugs and the toxicity of these agents. Imidazolium salts as azole derivatives can be successfully used in the treatment of fungal infections in humans. Steroid-functionalized imidazolium salts were synthesized using a new, more efficient method. As a result, 20 salts were obtained with high yields, 12 of which were synthesized and characterized for the first time. They were derivatives of lithocholic acid and 3-oxo-23,24-dinorchol-4-ene-22-al and were fully characterized by 1H and 13C nuclear magnetic resonance (NMR), infrared spectroscopy (IR), and high resolution mass spectrometry (HRMS). Due to the excellent activity against bacteria and Candida albicans, new research was extended to include tests on five species of pathogenic fungi and molds: Aspergillus niger ATCC 16888, Aspergillus fumigatus ATCC 204305, Trichophyton mentagrophytes ATCC 9533, Cryptococcus neoformans ATCC 14116, and Microsporum canis ATCC 11621. The results showed that the new salts are almost universal antifungal agents and have a broad spectrum of activity against other human pathogens. To initially assess the safety of the synthesized salts, hemocompatibility with host cells and cytotoxicity were also examined. No toxicity was observed at the concentration at which the compounds were active against pathogens.

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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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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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Screening Repurposing Libraries for Identification of Drugs with Novel Antifungal Activity

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00924-20 ◽

2020 ◽

Vol 64 (9) ◽

Cited By ~ 2

Author(s):

Gina Wall ◽

Jose L. Lopez-Ribot

Keyword(s):

Antifungal Activity ◽

Antifungal Agents ◽

Fungal Infections ◽

Alternative Pathway ◽

Drug Repurposing ◽

Pathogenic Fungi ◽

Multidrug Resistant ◽

Modern Medicine ◽

Antifungal Drugs ◽

Promising Alternative

ABSTRACT Fungal organisms are ubiquitous in nature, and progress of modern medicine is creating an expanding number of severely compromised patients susceptible to a variety of opportunistic fungal infections. These infections are difficult to diagnose and treat, leading to high mortality rates. The limited antifungal arsenal, the toxicity of current antifungal drugs, the development of resistance, and the emergence of new multidrug-resistant fungi, all highlight the urgent need for new antifungal agents. Unfortunately, the development of a novel antifungal is a rather long and expensive proposition, and no new classes of antifungal agents have reached the market in the last 2 decades. Drug repurposing, or finding new indications for old drugs, represents a promising alternative pathway to drug development that is particularly appealing within the academic environment. In the last few years, there has been a growing interest in repurposing approaches in the antifungal arena, with multiple groups of investigators having performed screenings of different repurposing libraries against different pathogenic fungi in search for drugs with previously unrecognized antifungal effects. Overall, these repurposing efforts may lead to the fast deployment of drugs with novel antifungal activity, which can rapidly bring benefits to patients, while at the same time reducing health care costs.

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Janus-Faced Molecules against Plant Pathogenic Fungi

International Journal of Molecular Sciences ◽

10.3390/ijms222212323 ◽

2021 ◽

Vol 22 (22) ◽

pp. 12323

Author(s):

Gaspar Banfalvi

Keyword(s):

Antifungal Agents ◽

Ethical Issues ◽

Fungal Infections ◽

Pathogenic Fungi ◽

Mutagenic Effect ◽

Human Pathogens ◽

Short Term ◽

High Cytotoxicity ◽

Apoptotic Effects

The high cytotoxicity of the secondary metabolites of mycotoxins is capable of killing microbes and tumour cells alike, similarly to the genotoxic effect characteristic of Janus-faced molecules. The “double-edged sword” effect of several cytotoxins is known, and these agents have, therefore, been utilized only reluctantly against fungal infections. In this review, consideration was given to (a) toxins that could be used against plant and human pathogens, (b) animal models that measure the effect of antifungal agents, (c) known antifungal agents that have been described and efficiently prevent the growth of fungal cells, and (d) the chemical interactions that are characteristic of antifungal agents. The utilization of apoptotic effects against tumour growth by agents that, at the same time, induce mutations may raise ethical issues. Nevertheless, it deserves consideration despite the mutagenic impact of Janus-faced molecules for those patients who suffer from plant pathogenic fungal infections and are older than their fertility age, in the same way that the short-term cytotoxicity of cancer treatment is favoured over the long-term mutagenic effect.

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DC-SIGN targets amphotericin B-loaded liposomes to diverse pathogenic fungi

Fungal Biology and Biotechnology ◽

10.1186/s40694-021-00126-3 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Suresh Ambati ◽

Tuyetnhu Pham ◽

Zachary A. Lewis ◽

Xiaorong Lin ◽

Richard B. Meagher

Keyword(s):

Amphotericin B ◽

Fungal Infections ◽

Pathogenic Fungi ◽

Antifungal Drugs ◽

Protein Isoforms ◽

Viral Pathogens ◽

Life Threatening ◽

Better Than

Abstract Background Life-threatening invasive fungal infections are treated with antifungal drugs such as Amphotericin B (AmB) loaded liposomes. Our goal herein was to show that targeting liposomal AmB to fungal cells with the C-type lectin pathogen recognition receptor DC-SIGN improves antifungal activity. DC-SIGN binds variously crosslinked mannose-rich and fucosylated glycans and lipomannans that are expressed by helminth, protist, fungal, bacterial and viral pathogens including three of the most life-threatening fungi, Aspergillus fumigatus, Candida albicans and Cryptococcus neoformans. Ligand recognition by human DC-SIGN is provided by a carbohydrate recognition domain (CRD) linked to the membrane transit and signaling sequences. Different combinations of the eight neck repeats (NR1 to NR8) expressed in different protein isoforms may alter the orientation of the CRD to enhance its binding to different glycans. Results We prepared two recombinant isoforms combining the CRD with NR1 and NR2 in isoform DCS12 and with NR7 and NR8 in isoform DCS78 and coupled them to a lipid carrier. These constructs were inserted into the membrane of pegylated AmB loaded liposomes AmB-LLs to produce DCS12-AmB-LLs and DCS78-AmB-LLs. Relative to AmB-LLs and Bovine Serum Albumin coated BSA-AmB-LLs, DCS12-AmB-LLs and DCS78-AmB-LLs bound more efficiently to the exopolysaccharide matrices produced by A. fumigatus, C. albicans and C. neoformans in vitro, with DCS12-AmB-LLs performing better than DCS78-AmB-LLs. DCS12-AmB-LLs inhibited and/or killed all three species in vitro significantly better than AmB-LLs or BSA-AmB-LLs. In mouse models of invasive candidiasis and pulmonary aspergillosis, one low dose of DCS12-AmB-LLs significantly reduced the fungal burden in the kidneys and lungs, respectively, several-fold relative to AmB-LLs. Conclusions DC-SIGN’s CRD specifically targeted antifungal liposomes to three highly evolutionarily diverse pathogenic fungi and enhanced the antifungal efficacy of liposomal AmB both in vitro and in vivo. Targeting significantly reduced the effective dose of antifungal drug, which may reduce drug toxicity, be effective in overcoming dose dependent drug resistance, and more effectively kill persister cells. In addition to fungi, DC-SIGN targeting of liposomal packaged anti-infectives have the potential to alter treatment paradigms for a wide variety of pathogens from different kingdoms including protozoans, helminths, bacteria, and viruses which express its cognate ligands.

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Hyperactive TORC1 sensitizes yeast cells to endoplasmic reticulum stress by compromising cell wall integrity

10.1101/605824 ◽

2019 ◽

Author(s):

Khadija Ahmed ◽

David E. Carter ◽

Patrick Lajoie

Keyword(s):

Endoplasmic Reticulum ◽

Cell Wall ◽

Endoplasmic Reticulum Stress ◽

Er Stress ◽

Fungal Infections ◽

Pathogenic Fungi ◽

Stress Sensitivity ◽

Antifungal Drugs ◽

Cell Wall Integrity ◽

Yeast Cells

ABSTRACTThe disruption of protein folding homeostasis in the endoplasmic reticulum (ER) results in an accumulation of toxic misfolded proteins and activates a network of signaling events collectively known as the unfolded protein response (UPR). While UPR activation upon ER stress is well characterized, how other signaling pathways integrate into the ER proteostasis network is unclear. Here, we sought to investigate how the target of rapamycin complex 1 (TORC1) signaling cascade acts in parallel with the UPR to regulate ER stress sensitivity. Using S. cerevisiae, we found that TORC1 signaling is attenuated during ER stress and constitutive activation of TORC1 increases sensitivity to ER stressors such as tunicamycin and inositol deprivation. This phenotype is independent of the UPR. Transcriptome analysis revealed that TORC1 hyperactivation results in cell wall remodelling. Conversely, hyperactive TORC1 sensitizes cells to cell wall stressors, including the antifungal caspofungin. Elucidating the crosstalk between the UPR, cell wall integrity, and TORC1 signaling may uncover new paradigms through which the response to protein misfolding is regulated, and thus have crucial implications for the development of novel therapeutics against pathogenic fungal infections.IMPORTANCEThe prevalence of pathogenic fungal infections, coupled with the emergence of new fungal pathogens, has brought these diseases to the forefront of global health problems. While antifungal treatments have advanced over the last decade, patient outcomes have not substantially improved. These shortcomings are largely attributed to the evolutionary similarity between fungi and humans, which limits the scope of drug development. As such, there is a pressing need to understand the unique cellular mechanisms that govern fungal viability. Given that Saccharomyces cerevisiae is evolutionarily related to a number of pathogenic fungi, and in particular to the Candida species, most genes from S. cerevisiae are highly conserved in pathogenic fungal strains. Here we show that hyperactivation of TORC1 signaling sensitizes S. cerevisiae cells to both endoplasmic reticulum stress and cell wall stressors by compromising cell wall integrity. Therefore, targeting TORC1 signaling and endoplasmic reticulum stress pathways may be useful in developing novel targets for antifungal drugs.

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A Nanoemulsion as an Effective Treatment Against Human Pathogenic Fungi

10.1101/737767 ◽

2019 ◽

Author(s):

Alexis Garcia ◽

Yong Yi Fan ◽

Sandeep Vellanki ◽

Eun Young Huh ◽

DiFernando Vanegas ◽

...

Keyword(s):

Fungal Pathogens ◽

Fungal Infections ◽

Healing Process ◽

Pathogenic Fungi ◽

Multidrug Resistant ◽

Antifungal Drugs ◽

Therapeutic Approaches ◽

New Therapeutic Approaches ◽

Development Of Resistance

AbstractThe emergence of immunocompromising diseases such as HIV/AIDS or other immunosuppressive medical conditions have opened an opportunity for fungal infections to afflict patients globally. An increase antifungal drug resistant fungi have posed a serious threat to patients. Combining these circumstances with a limited variety of antifungal drugs available to treat patients has left us in a situation where we need to develop new therapeutic approaches that are less prone to development of resistance by pathogenic fungi. In this study we present the utilization of the nanoemulsion NB-201 to control human pathogenic fungi. We found that the NB-201 exhibited in vitro activity against C. albicans, including both planktonic growth and biofilms. Furthermore, treatments with NB-201 significantly reduced the fungal burden at the infection site and presented enhanced healing process after subcutaneous infections by multidrug resistant C. albicans in a murine host system. NB-201 also exhibited in vitro growth inhibition activity against other fungal pathogens, including Cryptococcus spp, Aspergillus fumigatus, and Mucorales. Due to the nature of the activity of this nanoemulsion, there is a minimized chance of drug resistance to develop, thus presents a novel treatment to control fungal wound or skin infections.

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An Invertebrate Host to Study Fungal Infections, Mycotoxins and Antifungal Drugs: Tenebrio molitor

Journal of Fungi ◽

10.3390/jof4040125 ◽

2018 ◽

Vol 4 (4) ◽

pp. 125 ◽

Cited By ~ 11

Author(s):

Patrícia Canteri de Souza ◽

Carla Custódio Caloni ◽

Duncan Wilson ◽

Ricardo Sergio Almeida

Keyword(s):

Immune Responses ◽

Potential Model ◽

Fungal Infections ◽

Pathogenic Fungi ◽

Tenebrio Molitor ◽

Antifungal Drugs ◽

Innate Immune ◽

Fungal Virulence ◽

Host Immune Responses ◽

Evolutionarily Conserved

Faced with ethical conflict and social pressure, researchers have increasingly chosen to use alternative models over vertebrates in their research. Since the innate immune system is evolutionarily conserved in insects, the use of these animals in research is gaining ground. This review discusses Tenebrio molitor as a potential model host for the study of pathogenic fungi. Larvae of T. molitor are known as cereal pests and, in addition, are widely used as animal and human feed. A number of studies on mechanisms of the humoral system, especially in the synthesis of antimicrobial peptides, which have similar characteristics to vertebrates, have been performed. These studies demonstrate the potential of T. molitor larvae as a model host that can be used to study fungal virulence, mycotoxin effects, host immune responses to fungal infection, and the action of antifungal compounds.

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Nanoemulsion as an Effective Treatment against Human-Pathogenic Fungi

mSphere ◽

10.1128/msphere.00729-19 ◽

2019 ◽

Vol 4 (6) ◽

Cited By ~ 1

Author(s):

Alexis Garcia ◽

Yong Yi Fan ◽

Sandeep Vellanki ◽

Eun Young Huh ◽

DiFernando Vanegas ◽

...

Keyword(s):

Drug Resistance ◽

Fungal Infections ◽

Pathogenic Fungi ◽

Antifungal Drugs ◽

Solid Organ ◽

Therapeutic Approaches ◽

Content Type ◽

New Therapeutic Approaches ◽

Development Of Resistance

ABSTRACT Infections triggered by pathogenic fungi cause a serious threat to the public health care system. In particular, an increase of antifungal drug-resistant fungi has resulted in difficulty in treatment. A limited variety of antifungal drugs available to treat patients has left us in a situation where we need to develop new therapeutic approaches that are less prone to development of resistance by pathogenic fungi. In this study, we demonstrate the efficacy of the nanoemulsion NB-201, which utilizes the surfactant benzalkonium chloride, against human-pathogenic fungi. We found that NB-201 exhibited in vitro activity against Candida albicans, including both planktonic growth and biofilms. Furthermore, treatments with NB-201 significantly reduced the fungal burden at the infection site and presented an enhanced healing process after subcutaneous infections by multidrug-resistant C. albicans in a murine host system. NB-201 also exhibited in vitro growth inhibition activity against other fungal pathogens, including Cryptococcus spp., Aspergillus fumigatus, and Mucorales. Due to the nature of the activity of this nanoemulsion, there is a minimized chance of drug resistance developing, presenting a novel treatment to control fungal wound or skin infections. IMPORTANCE Advances in medicine have resulted in the discovery and implementation of treatments for human disease. While these recent advances have been beneficial, procedures such as solid-organ transplants and cancer treatments have left many patients in an immunocompromised state. Furthermore, the emergence of immunocompromising diseases such as HIV/AIDS or other immunosuppressive medical conditions have opened an opportunity for fungal infections to afflict patients globally. The development of drug resistance in human-pathogenic fungi and the limited array of antifungal drugs has left us in a scenario where we need to develop new therapeutic approaches to treat fungal infections that are less prone to the development of resistance by pathogenic fungi. The significance of our work lies in utilizing a novel nanoemulsion formulation to treat topical fungal infections while minimizing risks of drug resistance development.

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