scholarly journals High-Throughput Screening of a Collection of Known Pharmacologically Active Small Compounds for Identification of Candida albicans Biofilm Inhibitors

2013 ◽  
Vol 57 (8) ◽  
pp. 3681-3687 ◽  
Author(s):  
Samuel A. Siles ◽  
Anand Srinivasan ◽  
Christopher G. Pierce ◽  
José L. Lopez-Ribot ◽  
Anand K. Ramasubramanian
Keyword(s):  
Candida Albicans ◽  
Antifungal Activity ◽  
Biofilm Formation ◽  
High Throughput Screening ◽  
Fungal Infections ◽  
Rapid Development ◽  
Unmet Need ◽  
Antifungal Drugs ◽  
Content Type ◽  
Pharmacologically Active

ABSTRACTCandida albicansis the most common etiologic agent of systemic fungal infections with unacceptably high mortality rates. The existing arsenal of antifungal drugs is very limited and is particularly ineffective againstC. albicansbiofilms. To address the unmet need for novel antifungals, particularly those active against biofilms, we have screened a small molecule library consisting of 1,200 off-patent drugs already approved by the Food and Drug Administration (FDA), the Prestwick Chemical Library, to identify inhibitors ofC. albicansbiofilm formation. According to their pharmacological applications that are currently known, we classified these bioactive compounds as antifungal drugs, as antimicrobials/antiseptics, or as miscellaneous drugs, which we considered to be drugs with no previously characterized antifungal activity. Using a 96-well microtiter plate-based high-content screening assay, we identified 38 pharmacologically active agents that inhibitC. albicansbiofilm formation. These drugs were subsequently tested for their potency and efficacy against preformed biofilms, and we identified three drugs with novel antifungal activity. Thus, repurposing FDA-approved drugs opens up a valuable new avenue for identification and potentially rapid development of antifungal agents, which are urgently needed.

Efficacy of Novel Schiff base Derivatives as Antifungal Compounds in Combination with Approved Drugs Against Candida Albicans

2019 ◽  
Vol 15 (6) ◽  
pp. 648-658 ◽  
Author(s):  
Manzoor Ahmad Malik ◽  
Shabir Ahmad Lone ◽  
Parveez Gull ◽  
Ovas Ahmad Dar ◽  
Mohmmad Younus Wani ◽  
...  
Keyword(s):  
Schiff Base ◽  
Candida Albicans ◽  
Antifungal Activity ◽  
Fungal Infections ◽  
Total Sterol ◽  
Antifungal Drugs ◽  
New Drugs ◽  
Ergosterol Biosynthesis ◽  
Dependent Manner ◽  
Schiff Base Derivatives

Background: The increasing incidence of fungal infections, especially caused by Candida albicans, and their increasing drug resistance has drastically increased in recent years. Therefore, not only new drugs but also alternative treatment strategies are promptly required. Methods: We previously reported on the synergistic interaction of some azole and non-azole compounds with fluconazole for combination antifungal therapy. In this study, we synthesized some non-azole Schiff-base derivatives and evaluated their antifungal activity profile alone and in combination with the most commonly used antifungal drugs- fluconazole (FLC) and amphotericin B (AmB) against four drug susceptible, three FLC resistant and three AmB resistant clinically isolated Candida albicans strains. To further analyze the mechanism of antifungal action of these compounds, we quantified total sterol contents in FLC-susceptible and resistant C. albicans isolates. Results: A pyrimidine ring-containing derivative SB5 showed the most potent antifungal activity against all the tested strains. After combining these compounds with FLC and AmB, 76% combinations were either synergistic or additive while as the rest of the combinations were indifferent. Interestingly, none of the combinations was antagonistic, either with FLC or AmB. Results interpreted from fractional inhibitory concentration index (FICI) and isobolograms revealed 4-10-fold reduction in MIC values for synergistic combinations. These compounds also inhibit ergosterol biosynthesis in a concentration-dependent manner, supported by the results from docking studies. Conclusion: The results of the studies conducted advocate the potential of these compounds as new antifungal drugs. However, further studies are required to understand the other mechanisms and in vivo efficacy and toxicity of these compounds.

scholarly journals The Effects of Tormentic Acid and Extracts from Callistemon citrinus on Candida albicans and Candida tropicalis Growth and Inhibition of Ergosterol Biosynthesis in Candida albicans

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Chido Bvumbi ◽  
Godloves Fru Chi ◽  
Marc Y. Stevens ◽  
Molly Mombeshora ◽  
Stanley Mukanganyama
Keyword(s):  
Candida Albicans ◽  
Antifungal Activity ◽  
Candida Tropicalis ◽  
Methanol Extract ◽  
Fungal Infections ◽  
Water Extract ◽  
Antifungal Drugs ◽  
Ergosterol Content ◽  
Broth Microdilution Method ◽  
Tormentic Acid

Candida albicans and Candida tropicalis are the leading causes of human fungal infections worldwide. There is an increase in resistance of Candida pathogens to existing antifungal drugs leading to a need to find new sources of antifungal agents. Tormentic acid has been isolated from different plants including Callistemon citrinus and has been found to possess antimicrobial properties, including antifungal activity. The study aimed to determine the effects of tormentic and extracts from C. citrinus on C. albicans and C. tropicalis and a possible mode of action. The extracts and tormentic acid were screened for antifungal activity using the broth microdilution method. The growth of both species was inhibited by the extracts, and C. albicans was more susceptible to the extract compared to C. tropicalis. The growth of C. albicans was inhibited by 80% at 100 μg/ml of both the DCM: methanol extract and the ethanol: water extract. Tormentic acid reduced the growth of C. albicans by 72% at 100 μg/ml. The effects of the extracts and tormentic acid on ergosterol content in C. albicans were determined using a UV/Vis scanning spectrophotometer. At concentrations of tormentic acid of 25 μg/ml, 50 μg/ml, 100 μg/ml, and 200 μg/ml, the content of ergosterol was decreased by 22%, 36%, 48%, and 78%, respectively. Similarly, the DCM: methanol extract at 100 μg/ml and 200 μg/ml decreased the content by 78% and 88%, respectively. A dose-dependent decrease in ergosterol content was observed in cells exposed to miconazole with a 25 μg/ml concentration causing a 100% decrease in ergosterol content. Therefore, tormentic acid inhibits the synthesis of ergosterol in C. albicans. Modifications of the structure of tormentic acid to increase its antifungal potency may be explored in further studies.

scholarly journals Crystal Structure of the New Investigational Drug Candidate VT-1598 in Complex with Aspergillus fumigatus Sterol 14α-Demethylase Provides Insights into Its Broad-Spectrum Antifungal Activity

2017 ◽  
Vol 61 (7) ◽  
Author(s):  
Tatiana Y. Hargrove ◽  
Edward P. Garvey ◽  
William J. Hoekstra ◽  
Christopher M. Yates ◽  
Zdzislaw Wawrzak ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Aspergillus Fumigatus ◽  
Broad Spectrum ◽  
Fungal Infections ◽  
Enzymatic Reaction ◽  
Heme Iron ◽  
Antifungal Drugs ◽  
Drug Candidate ◽  
Investigational Drug ◽  
Content Type

ABSTRACT Within the past few decades, the incidence and complexity of human fungal infections have increased, and therefore, the need for safer and more efficient, broad-spectrum antifungal agents is high. In the study described here, we characterized the new tetrazole-based drug candidate VT-1598 as an inhibitor of sterol 14α-demethylase (CYP51B) from the filamentous fungus Aspergillus fumigatus. VT-1598 displayed a high affinity of binding to the enzyme in solution (dissociation constant, 13 ± 1 nM) and in the reconstituted enzymatic reaction was revealed to have an inhibitory potency stronger than the potencies of all other simultaneously tested antifungal drugs, including fluconazole, voriconazole, ketoconazole, and posaconazole. The X-ray structure of the VT-1598/A. fumigatus CYP51 complex was determined and depicts the distinctive binding mode of the inhibitor in the enzyme active site, suggesting the molecular basis of the improved drug potency and broad-spectrum antifungal activity. These data show the formation of an optimized hydrogen bond between the phenoxymethyl oxygen of VT-1598 and the imidazole ring nitrogen of His374, the CYP51 residue that is highly conserved across fungal pathogens and fungus specific. Comparative structural analysis of A. fumigatus CYP51/voriconazole and Candida albicans CYP51/VT-1161 complexes supports the role of H bonding in fungal CYP51/inhibitor complexes and emphasizes the importance of an optimal distance between this interaction and the inhibitor-heme iron interaction. Cellular experiments using two A. fumigatus strains (strains 32820 and 1022) displayed a direct correlation between the effects of the drugs on CYP51B activity and fungal growth inhibition, indicating the noteworthy anti-A. fumigatus potency of VT-1598 and confirming its promise as a broad-spectrum antifungal agent.

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

2021 ◽  
Vol 9 (3) ◽  
pp. 500 ◽  
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.

scholarly journals Transcriptome Assembly and Profiling of Candida auris Reveals Novel Insights into Biofilm-Mediated Resistance

mSphere ◽  
2018 ◽  
Vol 3 (4) ◽  
Author(s):  
Ryan Kean ◽  
Christopher Delaney ◽  
Leighann Sherry ◽  
Andrew Borman ◽  
Elizabeth M. Johnson ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Antifungal Agents ◽  
Fungal Infections ◽  
Transcriptome Assembly ◽  
Efflux Pumps ◽  
Antifungal Drugs ◽  
Hospital Environment ◽  
Planktonic Cells ◽  
Candida Auris ◽  
Content Type

ABSTRACT Candida auris has emerged as a significant global nosocomial pathogen. This is primarily due to its antifungal resistance profile but also its capacity to form adherent biofilm communities on a range of clinically important substrates. While we have a comprehensive understanding of how other Candida species resist and respond to antifungal challenge within the sessile phenotype, our current understanding of C. auris biofilm-mediated resistance is lacking. In this study, we are the first to perform transcriptomic analysis of temporally developing C. auris biofilms, which were shown to exhibit phase- and antifungal class-dependent resistance profiles. A de novo transcriptome assembly was performed, where sequenced sample reads were assembled into an ~11.5-Mb transcriptome consisting of 5,848 genes. Differential expression (DE) analysis demonstrated that 791 and 464 genes were upregulated in biofilm formation and planktonic cells, respectively, with a minimum 2-fold change. Adhesin-related glycosylphosphatidylinositol (GPI)-anchored cell wall genes were upregulated at all time points of biofilm formation. As the biofilm developed into intermediate and mature stages, a number of genes encoding efflux pumps were upregulated, including ATP-binding cassette (ABC) and major facilitator superfamily (MFS) transporters. When we assessed efflux pump activity biochemically, biofilm efflux was greater than that of planktonic cells at 12 and 24 h. When these were inhibited, fluconazole sensitivity was enhanced 4- to 16-fold. This study demonstrates the importance of efflux-mediated resistance within complex C. auris communities and may explain the resistance of C. auris to a range of antimicrobial agents within the hospital environment. IMPORTANCE Fungal infections represent an important cause of human morbidity and mortality, particularly if the fungi adhere to and grow on both biological and inanimate surfaces as communities of cells (biofilms). Recently, a previously unrecognized yeast, Candida auris, has emerged globally that has led to widespread concern due to the difficulty in treating it with existing antifungal agents. Alarmingly, it is also able to grow as a biofilm that is highly resistant to antifungal agents, yet we are unclear about how it does this. Here, we used a molecular approach to investigate the genes that are important in causing the cells to be resistant within the biofilm. The work provides significant insights into the importance of efflux pumps, which actively pump out toxic antifungal drugs and therefore enhance fungal survival within a variety of harsh environments.

scholarly journals Candida albicans rvs161Δ and rvs167Δ Endocytosis Mutants Are Defective in Invasion into the Oral Cavity

mBio ◽  
2019 ◽  
Vol 10 (6) ◽  
Author(s):  
Shamoon Naseem ◽  
Lois M. Douglas ◽  
James B. Konopka
Keyword(s):  
Candida Albicans ◽  
Environmental Factors ◽  
Oral Cavity ◽  
Fungal Infections ◽  
Hyphal Growth ◽  
Antifungal Drugs ◽  
Invasive Growth ◽  
Oropharyngeal Candidiasis ◽  
Content Type ◽  
Therapeutic Value

ABSTRACT Invasive growth in tissues by the human fungal pathogen Candida albicans is promoted by a switch from budding to hyphal morphogenesis that is stimulated by multiple environmental factors that can vary at different sites of infection. To identify genes that promote invasive growth in the oral cavity to cause oropharyngeal candidiasis (OPC), we first identified C. albicans mutants that failed to invade agar medium. Analysis of nine severely defective mutants in a mouse model of OPC revealed that the strongest defects were seen for the rvs161Δ and rvs167Δ mutants, which lack amphiphysin proteins needed for endocytosis. The rvsΔ mutants initially adhered to the tongue but failed to invade efficiently and were lost from the oral cavity. Previous studies indicated that rvsΔ mutants formed filamentous hyphae in the kidney albeit with morphological abnormalities, suggesting that the rvsΔ mutants were influenced by factors that vary at different sites of infection. Consistent with this, increasing concentrations of CO2, an inducer of hyphal growth that is more abundant in internal organs than air, partially rescued the invasive-growth defects of the rvsΔ mutants in vitro. Interestingly, preinduction of the rvsΔ mutants to form hyphae prior to introduction into the oral cavity restored their ability to cause OPC, identifying a key role for endocytosis in initiating invasive hyphal growth. These results highlight the influence of distinct environmental factors in promoting invasive hyphal growth in the oral cavity and indicate that blocking endocytosis could have therapeutic value in preventing the initiation of OPC. IMPORTANCE Oropharyngeal candidiasis (OPC) is a common fungal infection that is associated with severe morbidity. Another concern is that patients at risk for developing OPC often take long courses of antifungal drugs, which can lead to the emergence of drug-resistant C. albicans strains. We therefore identified nine mutants with defects in undergoing invasive hyphal growth in the oral cavity, increasing the number of genes known to be involved in OPC by more than 30%. The two strongest mutants, rvs161Δ and rvs167Δ, have defects in endocytosis. The rvsΔ mutants appear to have a specific defect in initiating invasive growth, as preinducing the cells to form hyphae prior to infection restored their ability to cause OPC. These results indicate that blocking endocytosis could have therapeutic value in preventing the initiation of OPC without leading to development of resistance against drugs currently used to treat fungal infections.

scholarly journals Derivatives of the Antimalarial Drug Mefloquine Are Broad-Spectrum Antifungal Molecules with Activity against Drug-Resistant Clinical Isolates

2020 ◽  
Vol 64 (3) ◽  
Author(s):  
Marhiah C. Montoya ◽  
Sarah Beattie ◽  
Kathryn M. Alden ◽  
Damian J. Krysan
Keyword(s):  
Antifungal Activity ◽  
Mechanism Of Action ◽  
Broad Spectrum ◽  
Antimalarial Drug ◽  
Fungal Infections ◽  
Antifungal Drugs ◽  
Clinical Isolates ◽  
Content Type ◽  
Recent Emergence ◽  
Derivatives Of

ABSTRACT The antifungal pharmacopeia is critically small, particularly in light of the recent emergence of multidrug-resistant pathogens, such as Candida auris. Here, we report that derivatives of the antimalarial drug mefloquine have broad-spectrum antifungal activity against pathogenic yeasts and molds. In addition, the mefloquine derivatives have activity against clinical isolates that are resistant to one or more of the three classes of antifungal drugs currently used to treat invasive fungal infections, indicating that they have a novel mechanism of action. Importantly, the in vitro toxicity profiles obtained using human cell lines indicated that the toxicity profiles of the mefloquine derivatives are very similar to those of the parent mefloquine, despite being up to 64-fold more active against fungal cells. In addition to direct antifungal activity, subinhibitory concentrations of the mefloquine derivatives inhibited the expression of virulence traits, including filamentation in Candida albicans and capsule formation/melanization in Cryptococcus neoformans. Mode/mechanism-of-action experiments indicated that the mefloquine derivatives interfere with both mitochondrial and vacuolar function as part of a multitarget mechanism of action. The broad-spectrum scope of activity, blood-brain barrier penetration, and large number of previously synthesized analogs available combine to support the further optimization and development of the antifungal activity of this general class of drug-like molecules.

scholarly journals Discovery of Cercosporamide, a Known Antifungal Natural Product, as a Selective Pkc1 Kinase Inhibitor through High-Throughput Screening

2004 ◽  
Vol 3 (4) ◽  
pp. 932-943 ◽  
Author(s):  
Andrea Sussman ◽  
Karen Huss ◽  
Li-Chun Chio ◽  
Steve Heidler ◽  
Margaret Shaw ◽  
...  
Keyword(s):  
Cell Wall ◽  
Antifungal Activity ◽  
High Throughput ◽  
Broad Spectrum ◽  
High Throughput Screening ◽  
Kinase Inhibitor ◽  
Fungal Infections ◽  
Antifungal Drugs ◽  
Antifungal Compound ◽  
Glucan Synthase

ABSTRACT The Pkc1-mediated cell wall integrity-signaling pathway is highly conserved in fungi and is essential for fungal growth. We thus explored the potential of targeting the Pkc1 protein kinase for developing broad-spectrum fungicidal antifungal drugs through a Candida albicans Pkc1-based high-throughput screening. We discovered that cercosporamide, a broad-spectrum natural antifungal compound, but previously with an unknown mode of action, is actually a selective and highly potent fungal Pkc1 kinase inhibitor. This finding provides a molecular explanation for previous observations in which Saccharomyces cerevisiae cell wall mutants were found to be highly sensitive to cercosporamide. Indeed, S. cerevisiae mutant cells with reduced Pkc1 kinase activity become hypersensitive to cercosporamide, and this sensitivity can be suppressed under high-osmotic growth conditions. Together, the results demonstrate that cercosporamide acts selectively on Pkc1 kinase and, thus, they provide a molecular mechanism for its antifungal activity. Furthermore, cercosporamide and a β-1,3-glucan synthase inhibitor echinocandin analog, by targeting two different key components of the cell wall biosynthesis pathway, are highly synergistic in their antifungal activities. The synergistic antifungal activity between Pkc1 kinase and β-1,3-glucan synthase inhibitors points to a potential highly effective combination therapy to treat fungal infections.

Antifungal Activity of Peppermint Oil against Candida Albicans Isolated from Urine Samples

2019 ◽  
Vol 12 (4) ◽  
pp. 4611-4615
Author(s):  
Noura Berakda ◽  
Abdulkarim Radwan
Keyword(s):  
Candida Albicans ◽  
Urinary Tract ◽  
Antifungal Activity ◽  
Fungal Infections ◽  
In Vitro Study ◽  
Inhibition Zone ◽  
Antifungal Drugs ◽  
University Hospital ◽  
Peppermint Oil

Fungal infections with candida species are an important cause of morbidity and mortality. Situation is further worsened by increasing resistance to antifungal drugs. In this study, we sought to investigate the antifungal activity of peppermint oil against candida albicans of urinary tract candidiasis in females from Syria. An in vitro study was carried out using the following Candida albicans strains involved in urinary tract candidiasis using well diffusion (WD) testing: Candida albicans (ATCC 90028) and 15 strains were compiled from Aleppo university Hospital. It was taken from women having urinary tract candidiasis. The antifungal activity of peppermint oil was determined in the form of inhibition zone using antifungal assay agar WD testing. In all experiments, the obtained results indicated that peppermint oil has inhibitory effects on Candida albicans (ATCC 90028) and some 15 strains. This study showed that peppermint oil was active against the tested Candida albicans strains. Peppermint oil was more effective against Candida albicans compared to fluconazole. Peppermint oil may have potential for use in the development of clinically useful antifungal preparations. Therefore, peppermint oil might be highly effective in the natural prevention treatment of urinary tract candidiasis.

scholarly journals Chemical Analysis of Red Ginger (Zingiber officinale Roscoe var rubrum) Essential Oil and Its Anti-biofilm Activity against Candida albicans

2018 ◽  
Vol 13 (12) ◽  
pp. 1934578X1801301
Author(s):  
Tristia Rinanda ◽  
Rizki Puji Isnanda ◽  
Zulfitri
Keyword(s):  
Candida Albicans ◽  
Chemical Analysis ◽  
Essential Oil ◽  
Biofilm Formation ◽  
Fungal Infections ◽  
Clinical Sample ◽  
Significant Inhibition ◽  
Antifungal Drugs ◽  
Biofilm Inhibition ◽  
Red Ginger

Biofilm formation is one of the virulence factors of Candida albicans, contributing to the development of resistance to various antifungal drugs. In order to combat resistant microbes such as C. albicans, the discovery and development of antifungal substances must explore the anti-biofilm activity of substances, which are extracted from traditional medicinal plants widely available in tropical countries such as Indonesia. One of the natural ingredients that can be developed is red ginger. This plant has been used empirically in the treatment of various infectious diseases, including fungal infections. The aim of this study is to determine the composition of chemical compounds in the essential oil of the red ginger rhizomes planted in Aceh, Indonesia and the anti-biofilm activity of the essential oil against C. albicans, isolated from a clinical sample. The chemical analysis of the essential oil was performed by Gas Chromatography-Mass Spectrophotometry (GC-MS). Anti-biofilm activity was observed through biofilm inhibition and degradation activities, determined by Cristal Violet assay. Data were analyzed using ANOVA test and Duncan's post hoc test with 99% CI. The GC-MS results showed that the essential oil used in this study contained high monoterpenes (60.55%) which is dominated by E-citral/geranial (11.97%) and 1.8 - cineole (15.10%). The highest sesquiterpenes derivative was αr-curcumene (16.86%). The significant inhibition of C. albicans biofilm formation was obtained at a concentration of 0.5% and the biofilm degradation was obtained at a concentration of 0.125%. The data indicates that the high monoterpenoids-red ginger essential oil used in this study has performed significant anti-biofilm activity against C. albicans.

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