Targeting Unconventional Pathways in Pursuit of Novel Antifungals

The impact of invasive fungal infections on human health is a serious, but largely overlooked, public health issue. Commonly affecting the immunocompromised community, fungal infections are predominantly caused by species of Candida, Cryptococcus, and Aspergillus. Treatments are reliant on the aggressive use of pre-existing antifungal drug classes that target the fungal cell wall and membrane. Despite their frequent use, these drugs are subject to unfavorable drug-drug interactions, can cause undesirable side-effects and have compromised efficacy due to the emergence of antifungal resistance. Hence, there is a clear need to develop novel classes of antifungal drugs. A promising approach involves exploiting the metabolic needs of fungi by targeted interruption of essential metabolic pathways. This review highlights potential antifungal targets including enolase, a component of the enolase-plasminogen complex, and enzymes from the mannitol biosynthesis and purine nucleotide biosynthesis pathways. There has been increased interest in the enzymes that comprise these particular pathways and further investigation into their merits as antifungal targets and roles in fungal survival and virulence are warranted. Disruption of these vital processes by targeting unconventional pathways with small molecules or antibodies may serve as a promising approach to discovering novel classes of antifungals.

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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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Duplication and overexpression of the genes encoding a beta 1,3-glucan synthase confer the intrinsic resistance to echinocandin in Mucor circinelloides

10.1101/2022.01.03.474814 ◽

2022 ◽

Author(s):

Soo Chan Lee ◽

Alexis Garcia ◽

Eun Young Huh

Keyword(s):

Fungal Infections ◽

Secondary Infection ◽

Effective Means ◽

Mucor Circinelloides ◽

Antifungal Drugs ◽

Solid Organ ◽

Intrinsic Resistance ◽

Glucan Synthase ◽

Drug Classes ◽

Genes Encoding

Procedures such as solid organ transplants and cancer treatments can leave many patients in an immunocompromised state resulting in an increased susceptibility to opportunistic diseases including fungal infections. Mucormycosis infections are continually emerging and pose a serious threat to immunocompromised patients. Currently there has been a sharp increase in mucormycosis cases as a secondary infection in patients battling SARS-CoV-2 infections. Mucorales fungi are notorious for presenting resistance to most antifungal drugs. The absence of effective means to treat these infections results in mortality rates approaching 100% in cases of disseminated infection. One of the most effective antifungal drug classes currently available are echinocandins. Echinocandins seem to be efficacious in treatment of many other fungal infections. Unfortunately, susceptibility testing has found that echinocandins have no to little effect on Mucorales. In this study, we found that the model Mucorales Mucor circinelloides genome carries three copies of the genes encoding for the echinocandin target protein β-(1,3)-D-glucan synthase (fksA, fksB, and fksC). Interestingly, we revealed that exposing M. circinelloides to micafungin significantly increased the expression of the fksA and fksB genes when compared to an untreated control. We further uncovered that the serine/threonine phosphatase calcineurin is responsible for the overexpression of fksA and fksB as deletion of calcineurin results in a decrease in expression of all three fks genes and a lower minimal inhibitory concentration (MIC) to micafungin. Taken together, this study demonstrates that the fks gene duplication and overexpression by calcineurin contribute to the intrinsic resistance to echinocandins in Mucor.

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Organic Antifungal Drugs and Targets of Their Action

Current Topics in Medicinal Chemistry ◽

10.2174/1568026621666210108122622 ◽

2021 ◽

Vol 21 ◽

Author(s):

Alexander Yu. Maksimov ◽

Svetlana Yu. Balandina ◽

Pavel A. Topanov ◽

Irina V. Mashevskaya ◽

Sandeep Chaudhary

Keyword(s):

Molecular Design ◽

Fungal Infections ◽

Wide Spectrum ◽

Molecular Targets ◽

Antifungal Drugs ◽

The Body ◽

Fungal Diseases ◽

Fungal Cell ◽

Genomics And Proteomics

: In recent decades, there has been a significant increase in the number of fungal diseases. This is due to a wide spectrum of action, immunosuppressants and other group drugs. In terms of frequency, rapid spread and globality, fungal infections are approaching acute respiratory infections. Antimycotics are medicinal substances endorsed with fungicidal or fungistatic properties. For the treatment of fungal diseases, several groups of compounds are used that differ in their origin (natural or synthetic), molecular targets and mechanism of action, antifungal effect (fungicidal or fungistatic), indications for use (local or systemic infections), methods of administration (parenteral, oral, outdoor). Several efforts have been made by various medicinal chemists around the world for the development of antifungal drugs with high efficacy with least toxicity and maximum selectivity in the area of antifungal chemotherapy. The pharmacokinetic properties of the new antimycotics are also important: the ability to penetrate biological barriers, be absorbed and distributed in tissues and organs, get accumulated in tissues affected by micromycetes, drug metabolism in the intestinal microflora and human organs, and in the kinetics of excretion from the body. There are several ways to search for new effective antimycotics: - Obtaining new derivatives of the already used classes of antimycotics with improved activity properties. - Screening of new chemical classes of synthetic antimycotic compounds. - Screening of natural compounds. - Identification of new unique molecular targets in the fungal cell. - Development of new compositions and dosage forms with effective delivery vehicles. The methods of informatics, bioinformatics, genomics and proteomics were extensively investigated for the development of new antimycotics. These techniques were employed in finding and identification of new molecular proteins in a fungal cell; in the determination of the selectivity of drug-protein interactions, evaluation of drug-drug interactions and synergism of drugs; determination of the structure-activity relationship (SAR) studies; determination of the molecular design of the most active, selective and safer drugs for the humans, animals and plants. In medical applications, the methods of information analysis and pharmacogenomics allows to take into account the individual phenotype of the patient, the level of expression of the targets of antifungal drugs when choosing antifungal agents and its dosage. This review article incorporates some of the most significant studies covering the basic structures and approaches for the synthesis of antifungal drugs and the directions for their further development.

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Divergent patterns of selection on metabolite levels and gene expression

BMC Ecology and Evolution ◽

10.1186/s12862-021-01915-5 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Alexander F. Kern ◽

Grace Xiaolu Yang ◽

Neil M. Khosla ◽

Roy Moh Lik Ang ◽

Michael P. Snyder ◽

...

Keyword(s):

Gene Expression ◽

Metabolic Pathways ◽

Antifungal Drugs ◽

Ergosterol Biosynthesis ◽

Expression Data ◽

Yeast Strains ◽

Genetic Cross ◽

Polygenic Adaptation ◽

Trait Locus ◽

The Impact

Abstract Background Natural selection can act on multiple genes in the same pathway, leading to polygenic adaptation. For example, adaptive changes were found to down-regulate six genes involved in ergosterol biosynthesis—an essential pathway targeted by many antifungal drugs—in some strains of the yeast Saccharomyces cerevisiae. However, the impact of this polygenic adaptation on metabolite levels was unknown. Here, we performed targeted mass spectrometry to measure the levels of eight metabolites in this pathway in 74 yeast strains from a genetic cross. Results Through quantitative trait locus (QTL) mapping we identified 19 loci affecting ergosterol pathway metabolite levels, many of which overlap loci that also impact gene expression within the pathway. We then used the recently developed v-test, which identified selection acting upon three metabolite levels within the pathway, none of which were predictable from the gene expression adaptation. Conclusions These data showed that effects of selection on metabolite levels were complex and not predictable from gene expression data. This suggests that a deeper understanding of metabolism is necessary before we can understand the impacts of even relatively straightforward gene expression adaptations on metabolic pathways.

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Antifungal Polymeric Materials and Nanocomposites

Frontiers in Bioengineering and Biotechnology ◽

10.3389/fbioe.2021.780328 ◽

2021 ◽

Vol 9 ◽

Author(s):

Winnie Ntow-Boahene ◽

David Cook ◽

Liam Good

Keyword(s):

Cell Membrane ◽

Small Molecule ◽

Plant Pathogens ◽

Fungal Infections ◽

Synergistic Effects ◽

Polymeric Materials ◽

Antifungal Drugs ◽

Candida Spp ◽

Fungal Cell ◽

Antimicrobial Polymers

Rising global populations due to medicinal advancements increases the patient population susceptible to superficial and severe fungal infections. Fungi often implicated in these diseases includes the dermatophytes (Microsporum spp., Epidermophtyon spp., Trichophyton spp.) as well as species of the Candida spp., Aspergillosis spp. and Cryptococcus spp. genera. In addition, increasing global populations leads to increasing agricultural demands. Thus, fungal infections of preharvested crops and stored food by plant pathogens such as Magnaporthe oryzae and Fusarium oxysporum can have detrimental socioeconomic effects due to food insecurity. Current antifungal strategies are based mainly on small molecule antifungal drugs. However, these drugs are limited by poor solubility and bioavailability. Furthermore, antifungal resistance against these drugs are on the rise. Thus, antimicrobial polymers offer an alternative antifungal strategy. Antifungal polymers are characterised by cationic and hydrophobic regions where the cationic regions have been shown to interact with microbial phospholipids and membranes. These polymers can be synthetic or natural and demonstrate distinct antifungal mechanisms ranging from fungal cell membrane permeabilisation, cell membrane depolarisation or cell entry. Although the relative importance of such mechanisms is difficult to decipher. Due to the chemical properties of these polymers, they can be combined with other antimicrobial compounds including existing antifungal drugs, charcoals, lipids and metal ions to elicit synergistic effects. In some cases, antifungal polymers and nanocomposites show better antifungal effects or reduced toxicity compared to the widely used small molecule antifungal drugs. This review provides an overview of antimicrobial polymers and nanocomposites with antifungal activity and the current understanding of their antifungal mechanisms.

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Synthesis of 5-amino-1-aryl-3-methyl-1H-pyrazole-4-carbonitriles, Antifungal Activity and In Silico Analysis

Letters in Organic Chemistry ◽

10.2174/1570178617666200210105246 ◽

2020 ◽

Vol 17 (10) ◽

pp. 779-787

Author(s):

Luciana Terra ◽

Daiane de Jesus Viegas ◽

Alice Maria Rolim Bernardino ◽

Jéssica Venância Faria ◽

Percilene Fazolin Vegi ◽

...

Keyword(s):

Antifungal Activity ◽

Fungal Infections ◽

In Silico Analysis ◽

Single Step ◽

Antifungal Drugs ◽

Candida Spp ◽

Disk Diffusion Test ◽

Chemical Structures ◽

Microdilution Method ◽

Drug Classes

Serious fungal infections are increasing worldwide and have become a great concern in the medical field since antifungal drugs are restricted to a few drug classes. This work aims to evaluate the antifungal activity of a series of 5-amino-1-aryl-3-methyl-1H-pyrazole-4-carbonitriles (1a-g) and to establish a structure-activity relationship (SAR). The synthesis of these compounds was carried out in a single step followed by cyclization in good to excellent yields i.e. 73-94%. The chemical structures were confirmed by melting point, IR, 1H-NMR, 13C-NMR, and HRMS. These seven compounds were submitted to the disk diffusion test against Candida spp. and the active compound was evaluated by means of the microdilution method to determine the minimum inhibitory concentration (MIC). In addition, the stereo electronic descriptors were evaluated and pharmacokinetic and toxicological properties were calculated to predict the potential of these compounds as a drug. All the compounds presented good theoretical physicochemical parameters and one of them showed reasonably good antifungal activity.

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Insights into the global emergence of antifungal drug resistance

Microbiology Australia ◽

10.1071/ma19024 ◽

2019 ◽

Vol 40 (2) ◽

pp. 87

Author(s):

Kylie Boyce ◽

Orla Morrissey ◽

Alexander Idnurm ◽

Ian Macreadie

Keyword(s):

Drug Resistance ◽

Intensive Care ◽

Fungal Infections ◽

Invasive Fungal Disease ◽

Antifungal Drugs ◽

Antifungal Drug ◽

Global Burden ◽

Median Cost ◽

Antifungal Drug Resistance ◽

Drug Classes

The global prevalence of fungal diseases has escalated in the last several decades. Currently, it is estimated that fungi infect 1.7 billion people annually and result in 1.5 million deaths every year1. Deaths due to fungal infections are increasing, with mortality often exceeding 50%, further increasing to 100% if treatment is delayed1. Despite these staggering figures, the contribution of fungal infections to the global burden of disease remains under-recognised. In Australia, over a 5-year period fungal infections cost Australia an estimated $583 million2. The median cost for one invasive fungal disease (IFD) is AU$30957, increasing to AU$80291 if the patient is admitted to an intensive care unit3. Treatment of fungal infections poses significant challenges due to the small number of safe and effective antifungal drugs available and emerging antifungal drug resistance. Resistance to every class of antifungal drugs has been described and for some drug classes is extremely common4,5.

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Characterization, Biological Activity, and Mechanism of Action of a Plant-Based Novel Antifungal Peptide, Cc-AFP1, Isolated From Carum carvi

Frontiers in Cellular and Infection Microbiology ◽

10.3389/fcimb.2021.743346 ◽

2021 ◽

Vol 11 ◽

Author(s):

Sima Sadat Seyedjavadi ◽

Soghra Khani ◽

Mehdi Goudarzi ◽

Hadi Zare-Zardini ◽

Masoomeh Shams-Ghahfarokhi ◽

...

Keyword(s):

Antifungal Activity ◽

Sequence Analysis ◽

Fungal Infections ◽

Reversed Phase ◽

Antifungal Drugs ◽

Peptide Sequence ◽

Cell Membrane Permeability ◽

Iodide Uptake ◽

Fungal Cell ◽

Carum Carvi

Due to the increasing rate of invasive fungal infections and emerging antifungal resistance, development of novel antifungal drugs has been an urgent necessity. Antifungal peptides (AFPs) have recently attracted attention due to their unique ability to evade drug-resistant fungal pathogens. In this study, a novel AFP, Cc-AFP1, with a molecular weight of ~3.759 kDa, was isolated from Carum carvi L., purified by ammonium sulfate precipitation and reversed-phase HPLC and finally identified by sequence analysis using Edman degradation. Peptide sequence analysis revealed a fragment of 36 amino acid residues as RVCFRPVAPYLGVGVSGAVRDQIGVKLGSVYKGPRG for Cc-AFP1 with a net charge of +5 and a hydrophobicity ratio of 38%. The antifungal activity of Cc-AFP1 was confirmed against Aspergillus species with MIC values in the range of 8–16 µg/ml. Cc-AFP1 had less than 5% hemolytic activity at 8–16 µg/ml on human red blood cells with no obvious cytotoxicity against the HEK293 cell line. Stability analysis showed that the activity of Cc-AFP1 was maintained at different temperatures (20°C to 80°C) and pH (8 to 10). The results of a propidium iodide uptake and transmission electron microscopy showed that the antifungal activity of Cc-AFP1 could be attributed to alteration in the fungal cell membrane permeability. Taken together, these results indicate that Cc-AFP1 may be an attractive molecule to develop as a novel antifungal agent combating fungal infections cause by Aspergillus species.

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The impact of hearing loss

ORL ro ◽

10.26416/orl.33.4.2016.170 ◽

2016 ◽

Vol 4 (1) ◽

pp. 64-65

Author(s):

Mădălina Georgescu ◽

Violeta Necula ◽

Sebastian Cozma

Keyword(s):

Hearing Loss ◽

Health Services ◽

Hard Of Hearing ◽

Hearing Impaired ◽

Public Health Issue ◽

Health Politics ◽

Universal Newborn Hearing Screening ◽

Newborn Hearing ◽

Impaired Person ◽

The Impact

Hearing loss represents a frequently met sensorial handicap, which has a major and complex impact not only on the hearing-impaired person, but also on his family and society. The large number of hard-of-hearing persons justifies the acknowledgement of hearing loss as a public health issue, which oblige to appropriate health politics, to offer each hearing-impaired person health services like those in Europe. These can be obtained through: appropriate legislation for mandatory universal newborn hearing screening; national program for follow-up of hearing-impaired children up to school age; national register of hard-of-hearing persons; smooth access to rehabilitation methods; appropriate number of audiologists, trained for health services at European standards, trained through public programs of education in the field of audiology.

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The Chemistry of Drugs to Treat Candida albicans

Current Topics in Medicinal Chemistry ◽

10.2174/1568026619666191025153124 ◽

2019 ◽

Vol 19 (28) ◽

pp. 2554-2566 ◽

Cited By ~ 2

Author(s):

Aurelio Ortiz ◽

Estibaliz Sansinenea

Keyword(s):

Candida Species ◽

Antifungal Drugs ◽

New Drugs ◽

Drug Classes ◽

Life Threatening ◽

Antifungal Substances ◽

High Level ◽

Systemic Infections ◽

New Compounds ◽

Level Resistance

Background:: Candida species are in various parts of the human body as commensals. However, they can cause local mucosal infections and, sometimes, systemic infections in which Candida species can spread to all major organs and colonize them. Objective:: For the effective treatment of the mucosal infections and systemic life-threatening fungal diseases, a considerably large number of antifungal drugs have been developed and used for clinical purposes that comprise agents from four main drug classes: the polyenes, azoles, echinocandins, and antimetabolites. Method: : The synthesis of some of these drugs is available, allowing synthetic modification of the molecules to improve the biological activity against Candida species. The synthetic methodology for each compound is reviewed. Results: : The use of these compounds has caused a high-level resistance against these drugs, and therefore, new antifungal substances have been described in the last years. The organic synthesis of the known and new compounds is reported. Conclusion: : This article summarizes the chemistry of the existing agents, both the old drugs and new drugs, in the treatment of infections due to C. albicans, including the synthesis of the existing drugs.

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