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Al Jaf AIA, Peria S, Fabiano T, Ragnini-Wilson A. Remyelinating Drugs at a Crossroad: How to Improve Clinical Efficacy and Drug Screenings. Cells 2024; 13:1326. [PMID: 39195216 DOI: 10.3390/cells13161326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2024] [Revised: 08/01/2024] [Accepted: 08/06/2024] [Indexed: 08/29/2024] Open
Abstract
Axons wrapped around the myelin sheath enable fast transmission of neuronal signals in the Central Nervous System (CNS). Unfortunately, myelin can be damaged by injury, viral infection, and inflammatory and neurodegenerative diseases. Remyelination is a spontaneous process that can restore nerve conductivity and thus movement and cognition after a demyelination event. Cumulative evidence indicates that remyelination can be pharmacologically stimulated, either by targeting natural inhibitors of Oligodendrocyte Precursor Cells (OPCs) differentiation or by reactivating quiescent Neural Stem Cells (qNSCs) proliferation and differentiation in myelinating Oligodendrocytes (OLs). Although promising results were obtained in animal models for demyelination diseases, none of the compounds identified have passed all the clinical stages. The significant number of patients who could benefit from remyelination therapies reinforces the urgent need to reassess drug selection approaches and develop strategies that effectively promote remyelination. Integrating Artificial Intelligence (AI)-driven technologies with patient-derived cell-based assays and organoid models is expected to lead to novel strategies and drug screening pipelines to achieve this goal. In this review, we explore the current literature on these technologies and their potential to enhance the identification of more effective drugs for clinical use in CNS remyelination therapies.
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Affiliation(s)
- Aland Ibrahim Ahmed Al Jaf
- Department of Biology, University of Rome "Tor Vergata", Via della Ricerca Scientifica 1, 00133 Rome, Italy
| | - Simone Peria
- Department of Biology, University of Rome "Tor Vergata", Via della Ricerca Scientifica 1, 00133 Rome, Italy
| | - Tommaso Fabiano
- Department of Biology, University of Rome "Tor Vergata", Via della Ricerca Scientifica 1, 00133 Rome, Italy
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
| | - Antonella Ragnini-Wilson
- Department of Biology, University of Rome "Tor Vergata", Via della Ricerca Scientifica 1, 00133 Rome, Italy
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Ostroumova OS, Efimova SS. Lipid-Centric Approaches in Combating Infectious Diseases: Antibacterials, Antifungals and Antivirals with Lipid-Associated Mechanisms of Action. Antibiotics (Basel) 2023; 12:1716. [PMID: 38136750 PMCID: PMC10741038 DOI: 10.3390/antibiotics12121716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/05/2023] [Accepted: 12/08/2023] [Indexed: 12/24/2023] Open
Abstract
One of the global challenges of the 21st century is the increase in mortality from infectious diseases against the backdrop of the spread of antibiotic-resistant pathogenic microorganisms. In this regard, it is worth targeting antibacterials towards the membranes of pathogens that are quite conservative and not amenable to elimination. This review is an attempt to critically analyze the possibilities of targeting antimicrobial agents towards enzymes involved in pathogen lipid biosynthesis or towards bacterial, fungal, and viral lipid membranes, to increase the permeability via pore formation and to modulate the membranes' properties in a manner that makes them incompatible with the pathogen's life cycle. This review discusses the advantages and disadvantages of each approach in the search for highly effective but nontoxic antimicrobial agents. Examples of compounds with a proven molecular mechanism of action are presented, and the types of the most promising pharmacophores for further research and the improvement of the characteristics of antibiotics are discussed. The strategies that pathogens use for survival in terms of modulating the lipid composition and physical properties of the membrane, achieving a balance between resistance to antibiotics and the ability to facilitate all necessary transport and signaling processes, are also considered.
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Affiliation(s)
- Olga S. Ostroumova
- Laboratory of Membrane and Ion Channel Modeling, Institute of Cytology, Russian Academy of Sciences, Tikhoretsky Ave. 4, St. Petersburg 194064, Russia;
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Khalifa A, Guijarro A, Ravera S, Bertola N, Adorni MP, Papotti B, Raffaghello L, Benelli R, Becherini P, Namatalla A, Verzola D, Reverberi D, Monacelli F, Cea M, Pisciotta L, Bernini F, Caffa I, Nencioni A. Cyclic fasting bolsters cholesterol biosynthesis inhibitors' anticancer activity. Nat Commun 2023; 14:6951. [PMID: 37907500 PMCID: PMC10618279 DOI: 10.1038/s41467-023-42652-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 10/17/2023] [Indexed: 11/02/2023] Open
Abstract
Identifying oncological applications for drugs that are already approved for other medical indications is considered a possible solution for the increasing costs of cancer treatment. Under the hypothesis that nutritional stress through fasting might enhance the antitumour properties of at least some non-oncological agents, by screening drug libraries, we find that cholesterol biosynthesis inhibitors (CBIs), including simvastatin, have increased activity against cancers of different histology under fasting conditions. We show fasting's ability to increase CBIs' antitumour effects to depend on the reduction in circulating insulin, insulin-like growth factor-1 and leptin, which blunts the expression of enzymes from the cholesterol biosynthesis pathway and enhances cholesterol efflux from cancer cells. Ultimately, low cholesterol levels through combined fasting and CBIs reduce AKT and STAT3 activity, oxidative phosphorylation and energy stores in the tumour. Our results support further studies of CBIs in combination with fasting-based dietary regimens in cancer treatment and highlight the value of fasting for drug repurposing in oncology.
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Affiliation(s)
- Amr Khalifa
- Department of Internal Medicine and Medical Specialties, University of Genoa, Viale Benedetto XV 6, 16132, Genoa, Italy
- Ospedale Policlinico San Martino IRCCS, Largo Rosanna Benzi 10, 16132, Genoa, Italy
| | - Ana Guijarro
- Department of Internal Medicine and Medical Specialties, University of Genoa, Viale Benedetto XV 6, 16132, Genoa, Italy
- Ospedale Policlinico San Martino IRCCS, Largo Rosanna Benzi 10, 16132, Genoa, Italy
| | - Silvia Ravera
- Department of Experimental Medicine, University of Genoa, Via Leon Battista Alberti 2, 16132, Genoa, Italy
| | - Nadia Bertola
- Department of Experimental Medicine, University of Genoa, Via Leon Battista Alberti 2, 16132, Genoa, Italy
| | - Maria Pia Adorni
- Department of Medicine and Surgery, University of Parma, 43125, Parma, Italy
| | - Bianca Papotti
- Department of Food and Drug, University of Parma, 43124, Parma, Italy
| | - Lizzia Raffaghello
- Center of Translational and Experimental Myology, IRCCS Istituto Giannina Gaslini, 16147, Genoa, Italy
| | - Roberto Benelli
- Ospedale Policlinico San Martino IRCCS, Largo Rosanna Benzi 10, 16132, Genoa, Italy
| | - Pamela Becherini
- Department of Internal Medicine and Medical Specialties, University of Genoa, Viale Benedetto XV 6, 16132, Genoa, Italy
| | - Asmaa Namatalla
- Department of Internal Medicine and Medical Specialties, University of Genoa, Viale Benedetto XV 6, 16132, Genoa, Italy
| | - Daniela Verzola
- Department of Internal Medicine and Medical Specialties, University of Genoa, Viale Benedetto XV 6, 16132, Genoa, Italy
| | - Daniele Reverberi
- Ospedale Policlinico San Martino IRCCS, Largo Rosanna Benzi 10, 16132, Genoa, Italy
| | - Fiammetta Monacelli
- Department of Internal Medicine and Medical Specialties, University of Genoa, Viale Benedetto XV 6, 16132, Genoa, Italy
- Ospedale Policlinico San Martino IRCCS, Largo Rosanna Benzi 10, 16132, Genoa, Italy
| | - Michele Cea
- Department of Internal Medicine and Medical Specialties, University of Genoa, Viale Benedetto XV 6, 16132, Genoa, Italy
- Ospedale Policlinico San Martino IRCCS, Largo Rosanna Benzi 10, 16132, Genoa, Italy
| | - Livia Pisciotta
- Department of Internal Medicine and Medical Specialties, University of Genoa, Viale Benedetto XV 6, 16132, Genoa, Italy
- Ospedale Policlinico San Martino IRCCS, Largo Rosanna Benzi 10, 16132, Genoa, Italy
| | - Franco Bernini
- Department of Food and Drug, University of Parma, 43124, Parma, Italy
| | - Irene Caffa
- Department of Internal Medicine and Medical Specialties, University of Genoa, Viale Benedetto XV 6, 16132, Genoa, Italy.
- Ospedale Policlinico San Martino IRCCS, Largo Rosanna Benzi 10, 16132, Genoa, Italy.
| | - Alessio Nencioni
- Department of Internal Medicine and Medical Specialties, University of Genoa, Viale Benedetto XV 6, 16132, Genoa, Italy.
- Ospedale Policlinico San Martino IRCCS, Largo Rosanna Benzi 10, 16132, Genoa, Italy.
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Churchman LR, Salisbury LJ, De Voss JJ. Synthesis of obtusifoliol and analogues as CYP51 substrates. Org Biomol Chem 2022; 20:7316-7324. [PMID: 36069327 DOI: 10.1039/d2ob01307j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Sterol 14α-demethylases (CYP51s) are a ubiquitous superfamily of cytochrome P450 enzymes that play an essential role in sterol biosynthesis. As fungal CYP51s are the target of azole-based antifungal agents, which are facing the problem of increasing resistance, the substrate specificity of this enzyme subclass has recently garnered significant attention. Herein we report the first chemical synthesis of the final endogenous substrate of this enzyme class, obtusifoliol, in 1.3% yield across ten steps from a commercially available lanosterol mixture. Intermediates along this pathway provide a basis for further derivatisation of the sterol skeleton and future investigation into CYP51 inhibition to overcome pathogens' azole resistance.
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Affiliation(s)
- Luke R Churchman
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, 4072, Australia.
| | - Lauren J Salisbury
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, 4072, Australia.
| | - James J De Voss
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, 4072, Australia.
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Price CL, Warrilow AGS, Rolley NJ, Parker JE, Thoss V, Kelly DE, Corcionivoschi N, Kelly SL. Cytochrome P450 168A1 from Pseudomonas aeruginosa is involved in the hydroxylation of biologically relevant fatty acids. PLoS One 2022; 17:e0265227. [PMID: 35312722 PMCID: PMC8936499 DOI: 10.1371/journal.pone.0265227] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 02/24/2022] [Indexed: 11/26/2022] Open
Abstract
The cytochrome P450 CYP168A1 from Pseudomonas aeruginosa was cloned and expressed in Escherichia coli followed by purification and characterization of function. CYP168A1 is a fatty acid hydroxylase that hydroxylates saturated fatty acids, including myristic (0.30 min-1), palmitic (1.61 min-1) and stearic acids (1.24 min-1), at both the ω-1- and ω-2-positions. However, CYP168A1 only hydroxylates unsaturated fatty acids, including palmitoleic (0.38 min-1), oleic (1.28 min-1) and linoleic acids (0.35 min-1), at the ω-1-position. CYP168A1 exhibited a catalytic preference for palmitic, oleic and stearic acids as substrates in keeping with the phosphatidylcholine-rich environment deep in the lung that is colonized by P. aeruginosa.
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Affiliation(s)
- Claire L. Price
- Centre for Cytochrome P450 Biodiversity, Institute of Life Science, Swansea University Medical School, Swansea University, Swansea, Wales, United Kingdom
| | - Andrew G. S. Warrilow
- Centre for Cytochrome P450 Biodiversity, Institute of Life Science, Swansea University Medical School, Swansea University, Swansea, Wales, United Kingdom
| | - Nicola J. Rolley
- Centre for Cytochrome P450 Biodiversity, Institute of Life Science, Swansea University Medical School, Swansea University, Swansea, Wales, United Kingdom
| | - Josie E. Parker
- Centre for Cytochrome P450 Biodiversity, Institute of Life Science, Swansea University Medical School, Swansea University, Swansea, Wales, United Kingdom
| | - Vera Thoss
- Plant Chemistry Group, School of Chemistry, Bangor University, Bangor, Gwynedd, Wales, United Kingdom
| | - Diane E. Kelly
- Centre for Cytochrome P450 Biodiversity, Institute of Life Science, Swansea University Medical School, Swansea University, Swansea, Wales, United Kingdom
| | - Nicolae Corcionivoschi
- Agri-Food and Biosciences Institute, Veterinary Science Division, Bacteriology Branch, Stoney Road, Stormont, Belfast, Northern Ireland, United Kingdom
- Faculty of Bioengineering of Animal Resources, Banat University of Agricultural Sciences and Veterinary Medicine, King Michael I of Romania, Timisoara, Romania
| | - Steven L. Kelly
- Centre for Cytochrome P450 Biodiversity, Institute of Life Science, Swansea University Medical School, Swansea University, Swansea, Wales, United Kingdom
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Abstract
Malassezia are emerging fungal pathogens causing opportunistic skin and severe systemic infection. Nosocomial outbreaks are associated with azole resistance and understanding of the underlying mechanisms are limited to knowledge from other fungal species. Herein, we identified distinct antifungal susceptibility patterns in 26 Malassezia furfur isolates derived from healthy and diseased individuals. A Y67F CYP51 mutation was identified in five isolates of M. furfur However, this mutation alone was insufficient to induce reduce azole susceptibility in the wild type strain. RNA-seq and differential gene analysis of healthy and disease derived strains exposed to clotrimazole in vitro identified several key metabolic pathways and transporter proteins which are involved in reduce azole susceptibility. The pleiotropic drug transporter PDR10 was the single most highly upregulated transporter gene in multiple strains of M. furfur after azole treatment and increased expression of PDR10 is associated with reduced azole susceptibility in some systemic disease isolates of M. furfur Deletion of PDR10 in a pathogenic M. furfur strain with reduced susceptibility reduced MIC values to the level of that in susceptible isolates. The current dearth of antifungal technologies, globally emerging multi-azole resistance, and broad agriculture and consumer care use of azoles means improved understanding of the mechanisms underlying intrinsic and acquired azole resistance in Malassezia is crucial for development of antibiotic stewardship and antifungal treatment strategies.
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The Antifungal Drug Isavuconazole Is both Amebicidal and Cysticidal against Acanthamoeba castellanii. Antimicrob Agents Chemother 2020; 64:AAC.02223-19. [PMID: 32094126 DOI: 10.1128/aac.02223-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 02/17/2020] [Indexed: 11/20/2022] Open
Abstract
Current treatments for Acanthamoeba keratitis rely on a combination of chlorhexidine gluconate, propamidine isethionate, and polyhexamethylene biguanide. These disinfectants are nonspecific and inherently toxic, which limits their effectiveness. Furthermore, in 10% of cases, recurrent infection ensues due to the difficulty in killing both trophozoites and double-walled cysts. Therefore, development of efficient, safe, and target-specific drugs which are capable of preventing recurrent Acanthamoeba infection is a critical unmet need for averting blindness. Since both trophozoites and cysts contain specific sets of membrane sterols, we hypothesized that antifungal drugs targeting sterol 14-demethylase (CYP51), known as conazoles, would have deleterious effects on A. castellanii trophozoites and cysts. To test this hypothesis, we first performed a systematic screen of the FDA-approved conazoles against A. castellanii trophozoites using a bioluminescence-based viability assay adapted and optimized for Acanthamoeba The most potent drugs were then evaluated against cysts. Isavuconazole and posaconazole demonstrated low nanomolar potency against trophozoites of three clinical strains of A. castellanii Furthermore, isavuconazole killed trophozoites within 24 h and suppressed excystment of preformed Acanthamoeba cysts into trophozoites. The rapid action of isavuconazole was also evident from the morphological changes at nanomolar drug concentrations causing rounding of trophozoites within 24 h of exposure. Given that isavuconazole has an excellent safety profile, is well tolerated in humans, and blocks A. castellanii excystation, this opens an opportunity for the cost-effective repurposing of isavuconazole for the treatment of primary and recurring Acanthamoeba keratitis.
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Ebenazer A, Franklyne JS, Tiwari N, Raj.Ch PA, Mukherjee A, Chandrasekaran N. In Vivo Testing and Extended Drug Release of Chitosan-Coated Itraconazole Loaded Microemulsion Using Volatile Oil Thymus vulgaris. REVISTA BRASILEIRA DE FARMACOGNOSIA 2020; 30:279-289. [DOI: 10.1007/s43450-020-00042-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 01/03/2020] [Indexed: 10/26/2023]
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Amphiphilic silicone-bridged bis-triazoles as effective, selective metal ligands and biologically active agents in lipophilic environment. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.111560] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Gagini T, Borba-Santos LP, Messias Rodrigues A, Pires de Camargo Z, Rozental S. Clotrimazole is highly effective in vitro against feline Sporothrix brasiliensis isolates. J Med Microbiol 2017; 66:1573-1580. [PMID: 28984226 DOI: 10.1099/jmm.0.000608] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
PURPOSE Sporothrix brasiliensis, the most virulent species in the Sporothrix schenckii complex, is responsible for the ongoing epidemics of human and animal sporotrichosis in Brazil. Feline outbreaks are usually driven by S. brasiliensis and followed by extensive transmission to humans. Itraconazole is the first-line treatment for both feline and human sporotrichosis; however, reduced sensitivity is an emerging issue. Thus, we investigated the effect of the widely used antifungal clotrimazole - alone or in combination with itraconazole - against the pathogenic (yeast) form of feline and human S. brasiliensis isolates, in vitro. METHODOLOGY Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values were determined for treatment with clotrimazole and itraconazole, as monotherapy or in combination. In addition, the effect of the drugs on neutral lipid levels and the yeast ultrastructure were evaluated by flow cytometry and transmission electron microscopy (TEM), respectively. RESULTS The MIC and MFC values show that clotrimazole was more effective than itraconazole against feline S. brasiliensis isolates, while human isolates were more sensitive to itraconazole. Similarly to itraconazole, treatment with clotrimazole induced statistically significant neutral lipid accumulation in S. brasiliensis yeasts, and treated yeasts displayed irregularities in the cell membrane and a thicker cell wall when observed by TEM. Clotrimazole increased the antifungal activity of itraconazole in combination assays, with a synergistic effect for two feline isolates. CONCLUSION The strong activity of clotrimazole against feline S. brasiliensis isolates suggests that this drug is potentially a new alternative for the treatment of feline sporotrichosis, alone or in combination with itraconazole.
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Affiliation(s)
- Thalita Gagini
- Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Luana Pereira Borba-Santos
- Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Anderson Messias Rodrigues
- Cell Biology Division, Department of Microbiology, Immunology and Parasitology, Federal University of São Paulo, São Paulo, SP, Brazil
| | - Zoilo Pires de Camargo
- Cell Biology Division, Department of Microbiology, Immunology and Parasitology, Federal University of São Paulo, São Paulo, SP, Brazil
| | - Sonia Rozental
- Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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The Tetrazole VT-1161 Is a Potent Inhibitor of Trichophyton rubrum through Its Inhibition of T. rubrum CYP51. Antimicrob Agents Chemother 2017; 61:AAC.00333-17. [PMID: 28483956 DOI: 10.1128/aac.00333-17] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 04/28/2017] [Indexed: 11/20/2022] Open
Abstract
Prior to characterization of antifungal inhibitors that target CYP51, Trichophyton rubrum CYP51 was expressed in Escherichia coli, purified, and characterized. T. rubrum CYP51 bound lanosterol, obtusifoliol, and eburicol with similar affinities (dissociation constant [Kd ] values, 22.7, 20.3, and 20.9 μM, respectively) but displayed substrate specificity, insofar as only eburicol was demethylated in CYP51 reconstitution assays (turnover number, 1.55 min-1; Km value, 2 μM). The investigational agent VT-1161 bound tightly to T. rubrum CYP51 (Kd = 242 nM) with an affinity similar to that of clotrimazole, fluconazole, ketoconazole, and voriconazole (Kd values, 179, 173, 312, and 304 nM, respectively) and with an affinity lower than that of itraconazole (Kd = 53 nM). Determinations of 50% inhibitory concentrations (IC50s) using 0.5 μM CYP51 showed that VT-1161 was a tight-binding inhibitor of T. rubrum CYP51 activity, yielding an IC50 of 0.14 μM, whereas itraconazole, fluconazole, and ketoconazole had IC50s of 0.26, 0.4, and 0.6 μM, respectively. When the activity of VT-1161 was tested against 34 clinical isolates, VT-1161 was a potent inhibitor of T. rubrum growth, with MIC50, MIC90, and geometric mean MIC values of ≤0.03, 0.06, and 0.033 μg ml-1, respectively. With its selectivity versus human CYP51 and drug-metabolizing cytochrome P450s having already been established, VT-1161 should prove to be safe and effective in combating T. rubrum infections in patients.
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Antifungal Susceptibility Testing of Malassezia spp. with an Optimized Colorimetric Broth Microdilution Method. J Clin Microbiol 2017; 55:1883-1893. [PMID: 28381607 DOI: 10.1128/jcm.00338-17] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Accepted: 03/29/2017] [Indexed: 02/07/2023] Open
Abstract
Malassezia is a genus of lipid-dependent yeasts. It is associated with common skin diseases such as pityriasis versicolor and atopic dermatitis and can cause systemic infections in immunocompromised individuals. Owing to the slow growth and lipid requirements of these fastidious yeasts, convenient and reliable antifungal drug susceptibility testing assays for Malassezia spp. are not widely available. Therefore, we optimized a broth microdilution assay for the testing of Malassezia that is based on the CLSI and EUCAST assays for Candida and other yeasts. The addition of ingredients such as lipids and esculin provided a broth medium formulation that enabled the growth of all Malassezia spp. and could be read, with the colorimetric indicator resazurin, by visual and fluorescence readings. We tested the susceptibility of 52 strains of 13 Malassezia species to 11 commonly used antifungals. MIC values determined by visual readings were in good agreement with MIC values determined by fluorescence readings. The lowest MICs were found for the azoles itraconazole, posaconazole, and voriconazole, with MIC90 values of 0.03 to 1.0 μg/ml, 0.06 to 0.5 μg/ml, and 0.03 to 2.0 μg/ml, respectively. All Malassezia spp. were resistant to echinocandins and griseofulvin. Some Malassezia spp. also showed high MIC values for ketoconazole, which is the most widely recommended topical antifungal to treat Malassezia skin infections. In summary, our assay enables the fast and reliable susceptibility testing of Malassezia spp. with a large panel of different antifungals.
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