scholarly journals Pyridines and Pyrimidines Mediating Activity against an Efflux-Negative Strain of Candida albicans through Putative Inhibition of Lanosterol Demethylase

2004 ◽  
Vol 48 (1) ◽  
pp. 313-318 ◽  
Author(s):  
Ed T. Buurman ◽  
April E. Blodgett ◽  
Kenneth G. Hull ◽  
Daniel Carcanague
Keyword(s):  
Candida Albicans ◽  
Antifungal Activity ◽  
Ergosterol Biosynthesis ◽  
Clear Correlation ◽  
Wild Type ◽  
Inhibition Of Growth ◽  
Ergosterol Synthesis ◽  
A Cell ◽  
Sterol Profile ◽  
Lanosterol Demethylase

ABSTRACT The first step in ergosterol biosynthesis in Saccharomyces cerevisiae consists of the condensation of two acetyl coenzyme A (acetyl-CoA) moieties by acetoacetyl-CoA thiolase, encoded by ERG10. The inhibition of the sterol pathway results in feedback activation of ERG10 transcription. A cell-based reporter assay, in which increased ERG10 transcription results in elevated specific β-galactosidase activity, was used to find novel inhibitors of ergosterol biosynthesis that could serve as chemical starting points for the development of novel antifungal agents. A class of pyridines and pyrimidines identified in this way had no detectable activity against the major fungal pathogen Candida albicans (MICs > 64 μg · ml−1). However, a strain of C. albicans lacking the Cdr1p and Cdr2p efflux pumps was sensitive to the compounds (with MICs ranging from 2 to 64 μg · ml−1), suggesting that they are efficiently removed from wild-type cells. Quantitative analysis of sterol intermediates that accumulated during growth inhibition revealed the accumulation of lanosterol at the expense of ergosterol. Furthermore, a clear correlation was found between the 50% inhibitory concentration at which the sterol profile was altered and the antifungal activity, measured as the MIC. This finding strongly suggests that the inhibition of growth was caused by a reduction in ergosterol synthesis. The compounds described here are a novel class of antifungal pyridines and pyrimidines and the first pyri(mi)dines to be shown to putatively mediate their antifungal activity against C. albicans via lanosterol demethylase.

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 PHYTOCHEMICALS AS POTENTIAL INHIBITORS OF LANOSTEROL 14 Α-DEMETHYLASE (CYP51) ENZYME: AN IN SILICO STUDY ON SIXTY MOLECULES

2020 ◽  
pp. 18-30
Author(s):  
ASHWINI KHANDERAO JADHAV ◽  
PATHAN KAMRAN KHAN ◽  
SANKUNNY MOHAN KARUPPAYIL
Keyword(s):  
Hydrogen Bond ◽  
Candida Albicans ◽  
Docking Study ◽  
Docking Studies ◽  
Antifungal Drugs ◽  
Ergosterol Biosynthesis ◽  
Binding Residue ◽  
Therapeutic Drugs ◽  
Ergosterol Synthesis ◽  
Potential Inhibitors

Lanosterol 14 α-demethylase (CYP51) is a key protein involved in ergosterol biosynthesis of Candida albicans and a crucial target for ergosterol synthesis inhibition. However, in the last two decades drug resistance is reported under clinical situations to most of the prescribed antifungal drugs like azole group of drugs. In this study, molecular docking of sixty plant molecules with Lanosterol 14 α-demethylase protein has been done. The homology modeling tool PHYRE2 was used to predict the structure of Lanosterol 14 α-demethylase. Predicted structure was used for docking studies with sixty plant molecules by using Autodock 1.5.6 cr2™. Among the sixty plant molecules, forty-seven were found to form hydrogen bond and the rest of the plant molecules did not form a hydrogen bond with Lanosterol 14 α-demethylase. Docking study of a library of sixty molecules revealed that 48 plant molecules showed an excellent and good binding affinity with predicted protein model Lanosterol 14 α-demethylase of Candida albicans. The binding residue comparison of docked molecules with that of Ketoconazole revealed, fourteen molecules have similar binding residue. These fourteen molecules may have a similar mode of action as that of Ketoconazole. These molecules should be screened and used to discover new antifungal therapeutic drugs.

scholarly journals Synthesis, Molecular Docking Studies and Antifungal Activity Evaluation of New Thiazolyl-methylen-1,3,4-oxadiazolines as Potential Lanosterol 14a-demethylase Inhibitors

2019 ◽  
Vol 70 (10) ◽  
pp. 3522-3526
Author(s):  
Smaranda Oniga ◽  
Catalin Araniciu ◽  
Gabriel Marc ◽  
Livia Uncu ◽  
Mariana Palage ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Molecular Docking ◽  
Antifungal Activity ◽  
Active Site ◽  
Docking Studies ◽  
Molecular Docking Studies ◽  
Activity Evaluation ◽  
Lanosterol Demethylase ◽  
Target Enzyme

Considering the well-established antifungal activity of azole compounds, a new series of thiazolyl-methylen-1,3,4-oxadiazolines derivatives were designed and synthesized as lanosterol-demethylase inhibitors. The final compounds were screened for antifungal activity against the Candida albicans ATCC 90028 strain. Molecular docking studies were performed to investigate the interaction modes between the compounds and the active site of lanosterol 14a-demethylase, which is a target enzyme for anticandidal azoles. Theoretical ADME predictions were also calculated for the final compounds 5a-h.

scholarly journals An Antifungal Benzimidazole Derivative Inhibits Ergosterol Biosynthesis and Reveals Novel Sterols

2015 ◽  
Vol 59 (10) ◽  
pp. 6296-6307 ◽  
Author(s):  
Petra Keller ◽  
Christoph Müller ◽  
Isabel Engelhardt ◽  
Ekkehard Hiller ◽  
Karin Lemuth ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Fungal Infections ◽  
Transcriptional Profiling ◽  
Benzimidazole Derivative ◽  
Benzimidazole Derivatives ◽  
Ergosterol Biosynthesis ◽  
Screening Assay ◽  
Content Type ◽  
Life Threatening ◽  
A Cell

ABSTRACTFungal infections are a leading cause of morbidity and death for hospitalized patients, mainly because they remain difficult to diagnose and to treat. Diseases range from widespread superficial infections such as vulvovaginal infections to life-threatening systemic candidiasis. For systemic mycoses, only a restricted arsenal of antifungal agents is available. Commonly used classes of antifungal compounds include azoles, polyenes, and echinocandins. Due to emerging resistance to standard therapies, significant side effects, and high costs for several antifungals, there is a need for new antifungals in the clinic. In order to expand the arsenal of compounds with antifungal activity, we previously screened a compound library using a cell-based screening assay. A set of novel benzimidazole derivatives, including (S)-2-(1-aminoisobutyl)-1-(3-chlorobenzyl)benzimidazole (EMC120B12), showed high antifungal activity against several species of pathogenic yeasts, includingCandida glabrataandCandida krusei(species that are highly resistant to antifungals). In this study, comparative analysis of EMC120B12 versus fluconazole and nocodazole, using transcriptional profiling and sterol analysis, strongly suggested that EMC120B12 targets Erg11p in the ergosterol biosynthesis pathway and not microtubules, like other benzimidazoles. In addition to the marker sterol 14-methylergosta-8,24(28)-dien-3β,6α-diol, indicating Erg11p inhibition, related sterols that were hitherto unknown accumulated in the cells during EMC120B12 treatment. The novel sterols have a 3β,6α-diol structure. In addition to the identification of novel sterols, this is the first time that a benzimidazole structure has been shown to result in a block of the ergosterol pathway.

scholarly journals Ergosterol Biosynthesis Inhibitors Become Fungicidal when Combined with Calcineurin Inhibitors against Candida albicans, Candida glabrata, and Candida krusei

2003 ◽  
Vol 47 (3) ◽  
pp. 956-964 ◽  
Author(s):  
Chiatogu Onyewu ◽  
Jill R. Blankenship ◽  
Maurizio Del Poeta ◽  
Joseph Heitman
Keyword(s):  
Candida Albicans ◽  
Antifungal Agents ◽  
Calcineurin Inhibitors ◽  
Therapeutic Window ◽  
Ergosterol Biosynthesis ◽  
Drug Synergism ◽  
Wild Type ◽  
Ergosterol Biosynthesis Inhibitors ◽  
Biosynthesis Inhibitors ◽  
Mutant Strains

ABSTRACT Azoles target the ergosterol biosynthetic enzyme lanosterol 14α-demethylase and are a widely applied class of antifungal agents because of their broad therapeutic window, wide spectrum of activity, and low toxicity. Unfortunately, azoles are generally fungistatic and resistance to fluconazole is emerging in several fungal pathogens. We recently established that the protein phosphatase calcineurin allows survival of Candida albicans during the membrane stress exerted by azoles. The calcineurin inhibitors cyclosporine A (CsA) and tacrolimus (FK506) are dramatically synergistic with azoles, resulting in potent fungicidal activity, and mutant strains lacking calcineurin are markedly hypersensitive to azoles. Here we establish that drugs targeting other enzymes in the ergosterol biosynthetic pathway (terbinafine and fenpropimorph) also exhibit dramatic synergistic antifungal activity against wild-type C. albicans when used in conjunction with CsA and FK506. Similarly, C. albicans mutant strains lacking calcineurin B are markedly hypersensitive to terbinafine and fenpropimorph. The FK506 binding protein FKBP12 is required for FK506 synergism with ergosterol biosynthesis inhibitors, and a calcineurin mutation that confers FK506 resistance abolishes drug synergism. Additionally, we provide evidence of drug synergy between the nonimmunosuppressive FK506 analog L-685,818 and fenpropimorph or terbinafine against wild-type C. albicans. These drug combinations also exert synergistic effects against two other Candida species, C. glabrata and C. krusei, which are known for intrinsic or rapidly acquired resistance to azoles. These studies demonstrate that the activity of non-azole antifungal agents that target ergosterol biosynthesis can be enhanced by inhibition of the calcineurin signaling pathway, extending their spectrum of action and providing an alternative approach by which to overcome antifungal drug resistance.

scholarly journals Synthesis and Antifungal Potential of Some Novel Benzimidazole-1,3,4-Oxadiazole Compounds

Molecules ◽  
2019 ◽  
Vol 24 (1) ◽  
pp. 191 ◽  
Author(s):  
Ahmet Çağrı Karaburun ◽  
Betül Kaya Çavuşoğlu ◽  
Ulviye Acar Çevik ◽  
Derya Osmaniye ◽  
Begüm Nurpelin Sağlık ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Positive Control ◽  
Docking Studies ◽  
Mechanisms Of Action ◽  
Ergosterol Biosynthesis ◽  
In Vitro Activity ◽  
Active Compounds ◽  
Antifungal Potential ◽  
Ergosterol Synthesis

Discovery of novel anticandidal agents with clarified mechanisms of action, could be a rationalist approach against diverse pathogenic fungal strains due to the rise of resistance to existing drugs. In support to this hypothesis, in this paper, a series of benzimidazole-oxadiazole compounds were synthesized and subjected to antifungal activity evaluation. In vitro activity assays indicated that some of the compounds exhibited moderate to potent antifungal activities against tested Candida species when compared positive control amphotericin B and ketoconazole. The most active compounds 4h and 4p were evaluated in terms of inhibitory activity upon ergosterol biosynthesis by an LC-MS-MS method and it was determined that they inhibited ergosterol synthesis concentration dependently. Docking studies examining interactions between most active compounds and lanosterol 14-α-demethylase also supported the in vitro results.

scholarly journals A Gain-of-Function Mutation in the Transcription Factor Upc2p Causes Upregulation of Ergosterol Biosynthesis Genes and Increased Fluconazole Resistance in a Clinical Candida albicans Isolate

2008 ◽  
Vol 7 (7) ◽  
pp. 1180-1190 ◽  
Author(s):  
Nico Dunkel ◽  
Teresa T. Liu ◽  
Katherine S. Barker ◽  
Ramin Homayouni ◽  
Joachim Morschhäuser ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Candida Albicans ◽  
Clinical Isolates ◽  
Resistant Isolate ◽  
Ergosterol Biosynthesis ◽  
Gain Of Function ◽  
Zinc Cluster ◽  
Fluconazole Resistant ◽  
Lanosterol Demethylase

ABSTRACT In the pathogenic yeast Candida albicans, the zinc cluster transcription factor Upc2p has been shown to regulate the expression of ERG11 and other genes involved in ergosterol biosynthesis upon exposure to azole antifungals. ERG11 encodes lanosterol demethylase, the target enzyme of this antifungal class. Overexpression of UPC2 reduces azole susceptibility, whereas its disruption results in hypersusceptibility to azoles and reduced accumulation of exogenous sterols. Overexpression of ERG11 leads to the increased production of lanosterol demethylase, which contributes to azole resistance in clinical isolates of C. albicans, but the mechanism for this has yet to be determined. Using genome-wide gene expression profiling, we found UPC2 and other genes involved in ergosterol biosynthesis to be coordinately upregulated with ERG11 in a fluconazole-resistant clinical isolate compared with a matched susceptible isolate from the same patient. Sequence analysis of the UPC2 alleles of these isolates revealed that the resistant isolate contained a single-nucleotide substitution in one UPC2 allele that resulted in a G648D exchange in the encoded protein. Introduction of the mutated allele into a drug-susceptible strain resulted in constitutive upregulation of ERG11 and increased resistance to fluconazole. By comparing the gene expression profiles of the fluconazole-resistant isolate and of strains carrying wild-type and mutated UPC2 alleles, we identified target genes that are controlled by Upc2p. Here we show for the first time that a gain-of-function mutation in UPC2 leads to the increased expression of ERG11 and imparts resistance to fluconazole in clinical isolates of C. albicans.

scholarly journals Azole Resistance by Loss of Function of the Sterol Δ5,6-Desaturase Gene (ERG3) in Candida albicans Does Not Necessarily Decrease Virulence

2012 ◽  
Vol 56 (4) ◽  
pp. 1960-1968 ◽  
Author(s):  
L. A. Vale-Silva ◽  
A. T. Coste ◽  
F. Ischer ◽  
J. E. Parker ◽  
S. L. Kelly ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Premature Stop Codon ◽  
Antifungal Drugs ◽  
Ergosterol Biosynthesis ◽  
Azole Resistance ◽  
Wild Type ◽  
Disseminated Candidiasis ◽  
Double Base

ABSTRACTThe inactivation ofERG3, a gene encoding sterol Δ5,6-desaturase (essential for ergosterol biosynthesis), is a known mechanism ofin vitroresistance to azole antifungal drugs in the human pathogenCandida albicans. ERG3inactivation typically results in loss of filamentation and attenuated virulence in animal models of disseminated candidiasis. In this work, we identified aC. albicansclinical isolate (VSY2) with high-level resistance to azole drugsin vitroand an absence of ergosterol but normal filamentation. Sequencing ofERG3in VSY2 revealed a double base deletion leading to a premature stop codon and thus a nonfunctional enzyme. The reversion of the double base deletion in the mutant allele (erg3-1) restored ergosterol biosynthesis and full fluconazole susceptibility in VSY2, confirming thatERG3inactivation was the mechanism of azole resistance. Additionally, the replacement of bothERG3alleles byerg3-1in the wild-type strain SC5314 led to the absence of ergosterol and to fluconazole resistance without affecting filamentation. In a mouse model of disseminated candidiasis, the clinicalERG3mutant VSY2 produced kidney fungal burdens and mouse survival comparable to those obtained with the wild-type control. Interestingly, while VSY2 was resistant to fluconazole bothin vitroandin vivo, theERG3-derived mutant of SC5314 was resistant onlyin vitroand was less virulent than the wild type. This suggests that VSY2 compensated for thein vivofitness defect ofERG3inactivation by a still unknown mechanism(s). Taken together, our results provide evidence that contrary to previous reports inactivation ofERG3does not necessarily affect filamentation and virulence.

scholarly journals Erg4A and Erg4B Are Required for Conidiation and Azole Resistance via Regulation of Ergosterol Biosynthesis in Aspergillus fumigatus

2016 ◽  
Vol 83 (4) ◽  
Author(s):  
Nanbiao Long ◽  
Xiaoling Xu ◽  
Qiuqiong Zeng ◽  
Hong Sang ◽  
Ling Lu
Keyword(s):  
Endoplasmic Reticulum ◽  
Aspergillus Fumigatus ◽  
Plasma Membranes ◽  
Current Knowledge ◽  
Hyphal Growth ◽  
Antifungal Drugs ◽  
Ergosterol Biosynthesis ◽  
Wild Type ◽  
Content Type ◽  
Ergosterol Synthesis

ABSTRACT Ergosterol, a fungus-specific sterol enriched in cell plasma membranes, is an effective antifungal drug target. However, current knowledge of the ergosterol biosynthesis process in the saprophytic human fungal pathogen Aspergillus fumigatus remains limited. In this study, we found that two endoplasmic reticulum-localized sterol C-24 reductases encoded by both erg4A and erg4B homologs are required to catalyze the reaction during the final step of ergosterol biosynthesis. Loss of one homolog of Erg4 induces the overexpression of the other one, accompanied by almost normal ergosterol synthesis and wild-type colony growth. However, double deletions of erg4A and erg4B completely block the last step of ergosterol synthesis, resulting in the accumulation of ergosta-5,7,22,24(28)-tetraenol, a precursor compound of ergosterol. Further studies indicate that erg4A and erg4B are required for conidiation but not for hyphal growth. Importantly, the Δerg4A Δerg4B mutant still demonstrates wild-type virulence in a compromised mouse model but displays remarkable increased susceptibility to antifungal azoles. Our data suggest that inhibitors of Erg4A and Erg4B may serve as effective candidates for adjunct antifungal agents with azoles. IMPORTANCE Knowledge of the ergosterol biosynthesis pathway in the human opportunistic pathogen A. fumigatus is useful for designing and finding new antifungal drugs. In this study, we demonstrated that the endoplasmic reticulum-localized sterol C-24 reductases Erg4A and Erg4B are required for conidiation via regulation of ergosterol biosynthesis. Moreover, inactivation of both Erg4A and Erg4B results in hypersensitivity to the clinical guideline-recommended antifungal drugs itraconazole and voriconazole. Therefore, our finding indicates that inhibition of Erg4A and Erg4B might be an effective approach for alleviating A. fumigatus infection.

scholarly journals The R467K Amino Acid Substitution in Candida albicans Sterol 14α-Demethylase Causes Drug Resistance through Reduced Affinity

2000 ◽  
Vol 44 (1) ◽  
pp. 63-67 ◽  
Author(s):  
David C. Lamb ◽  
Diane E. Kelly ◽  
Theodore C. White ◽  
Steven L. Kelly
Keyword(s):  
Candida Albicans ◽  
Amino Acid ◽  
Amino Acid Substitution ◽  
Specific Activity ◽  
Difference Spectrum ◽  
Microsomal Protein ◽  
Ergosterol Biosynthesis ◽  
Wild Type ◽  
Binding Studies ◽  
Directed Mutation

ABSTRACT The cytochrome P450 sterol 14α-demethylase (CYP51) ofCandida albicans is involved in an essential step of ergosterol biosynthesis and is the target for azole antifungal compounds. We have undertaken site-directed mutation of C. albicans CYP51 to produce a recombinant mutant protein with the amino acid substitution R467K corresponding to a mutation observed clinically. This alteration perturbed the heme environment causing an altered reduced-carbon monoxide difference spectrum with a maximum at 452 nm and reduced the affinity of the enzyme for fluconazole, as shown by ligand binding studies. The specific activity of CYP51(R467K) for the release of formic acid from 3β-[32-3H]hydroxylanost-7-en-32-ol was 70 pmol/nmol of P450/min for microsomal protein compared to 240 pmol/nmol of P450/min for microsomal fractions expressing wild-type CYP51. Furthermore, inhibition of activity by fluconazole revealed a 7.5-fold-greater azole resistance of the recombinant protein than that of the wild type. This study demonstrates that resistance observed clinically can result from the altered azole affinity of the fungal CYP51 enzyme.

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