1
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Qubais Saeed B, Hamdy R, Akbar N, Sajeevan SE, Khan NA, Soliman SSM. Azole-based compounds as potential anti- Acanthamoeba agents. RSC Med Chem 2024; 15:1578-1588. [PMID: 38784450 PMCID: PMC11110792 DOI: 10.1039/d4md00029c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Accepted: 02/22/2024] [Indexed: 05/25/2024] Open
Abstract
Acanthamoeba castellanii is an opportunistic pathogen with public health implications, largely due to its invasive nature and non-specific symptoms. Our study focuses on the potential of azole compounds, particularly those with triazole scaffolds, as anti-amoebic agents. Out of 10 compounds, compounds T1 and T8 exhibited effective anti-Acanthamoeba activity with MIC50 values of 125.37 and 143.92 μg mL-1, respectively. Interestingly, compounds T1, T4, T5 and T8 revealed profound anti-excystation activity with MIC50 at 32.01, 85.53, 19.54 and 80.57 μg mL-1, respectively, alongside limited cytotoxicity to human cells. The study underscores the potential of T1, T4, T5, and T8, thiazole-based compounds, as anti-Acanthamoeba agents by both eliminating amoeba viability and preventing excystation, via preserving the amoeba in its latent cyst form, exposing them to elimination by the immune system. Notably, compounds T1, T4, T5, and T8 showed optimal molecular properties, moderate oral bioavailability, and stable complex formation with Acanthamoeba CYP51. They also display superior binding interactions. Further research is needed to understand their mechanisms and optimize their efficacy against Acanthamoeba infections.
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Affiliation(s)
- Balsam Qubais Saeed
- Research Institute of Medical and Health Sciences, University of Sharjah Sharjah 27272 United Arab Emirates
- Department of Clinical Sciences, College of Medicine, University of Sharjah Sharjah 27272 United Arab Emirates
| | - Rania Hamdy
- Research Institute of Medical and Health Sciences, University of Sharjah Sharjah 27272 United Arab Emirates
- Research Institute for Science and Engineering (RISE), University of Sharjah Sharjah 27272 United Arab Emirates
- Faculty of Pharmacy, Zagazig University Zagazig 44519 Egypt
| | - Noor Akbar
- Research Institute of Medical and Health Sciences, University of Sharjah Sharjah 27272 United Arab Emirates
- Department of Clinical Sciences, College of Medicine, University of Sharjah Sharjah 27272 United Arab Emirates
| | | | - Naveed Ahmed Khan
- Microbiota Research Centre, Istinye University Istanbul 34010 Turkey
| | - Sameh S M Soliman
- Research Institute of Medical and Health Sciences, University of Sharjah Sharjah 27272 United Arab Emirates
- Department of Medicinal Chemistry, College of Pharmacy, University of Sharjah Sharjah P.O. Box 27272 United Arab Emirates +97165057472
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2
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Rao K, Abdullah M, Ahmed U, Wehelie HI, Shah MR, Siddiqui R, Khan NA, Alawfi BS, Anwar A. Self-assembled micelles loaded with itraconazole as anti-Acanthamoeba nano-formulation. Arch Microbiol 2024; 206:134. [PMID: 38433145 DOI: 10.1007/s00203-024-03854-3] [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: 09/19/2023] [Revised: 01/13/2024] [Accepted: 01/17/2024] [Indexed: 03/05/2024]
Abstract
Acanthamoeba castellanii are opportunistic pathogens known to cause infection of the central nervous system termed: granulomatous amoebic encephalitis, that mostly effects immunocompromised individuals, and a sight threatening keratitis, known as Acanthamoeba keratitis, which mostly affects contact lens wearers. The current treatment available is problematic, and is toxic. Herein, an amphiphilic star polymer with AB2 miktoarms [A = hydrophobic poly(ℇ-Caprolacton) and B = hydrophilic poly (ethylene glycol)] was synthesized by ring opening polymerization and CuI catalyzed azide-alkyne cycloaddition. Characterization by 1H and 13C NMR spectroscopy, size-exclusion chromatography and fluorescence spectroscopy was accomplished. The hydrophobic drug itraconazole (ITZ) was incorporated in self-assembled micellar structure of AB2 miktoarms through co-solvent evaporation. The properties of ITZ loaded (ITZ-PCL-PEG2) and blank micelles (PCL-PEG2) were investigated through zeta sizer, scanning electron microscopy and Fourier-transform infrared spectroscopy. Itraconazole alone (ITZ), polymer (DPB-PCL), empty polymeric micelles (PCL-PEG2) alone, and itraconazole loaded in polymeric micelles (ITZ-PCL-PEG2) were tested for anti-amoebic potential against Acanthamoeba, and the cytotoxicity on human cells were determined. The polymer was able to self-assemble in aqueous conditions and exhibited low value for critical micelle concentration (CMC) 0.05-0.06 µg/mL. The maximum entrapment efficiency of ITZ was 68%. Of note, ITZ, DPB, PCL-PEG2 and ITZ-PCL-PEG2 inhibited amoebae trophozoites by 37.34%, 36.30%, 35.77%, and 68.24%, respectively, as compared to controls. Moreover, ITZ-PCL-PEG2 revealed limited cytotoxicity against human keratinocyte cells. These results are indicative that ITZ-PCL-PEG2 micelle show significantly better anti-amoebic effects as compared to ITZ alone and thus should be investigated further in vivo to determine its clinical potential.
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Affiliation(s)
- Komal Rao
- International Center for Chemical and Biological Sciences, HEJ Research Institute of Chemistry, Karachi University, Karachi, 75270, Pakistan
| | - Muhammad Abdullah
- International Center for Chemical and Biological Sciences, HEJ Research Institute of Chemistry, Karachi University, Karachi, 75270, Pakistan
| | - Usman Ahmed
- Department of Biological Sciences, School of Medical and Life Sciences, Sunway University, 47500, Subang Jaya, Selangor, Malaysia
| | - Hashi Isse Wehelie
- Department of Biological Sciences, School of Medical and Life Sciences, Sunway University, 47500, Subang Jaya, Selangor, Malaysia
| | - Muhammad Raza Shah
- International Center for Chemical and Biological Sciences, HEJ Research Institute of Chemistry, Karachi University, Karachi, 75270, Pakistan
| | - Ruqaiyyah Siddiqui
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University Edinburgh, Edinburgh, EH14 4AS, UK
- Microbiota Research Center, Istinye University, 34010, Istanbul, Turkey
| | - Naveed A Khan
- Microbiota Research Center, Istinye University, 34010, Istanbul, Turkey.
| | - Bader S Alawfi
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Taibah University, 42353, Madinah, Saudi Arabia
| | - Ayaz Anwar
- Department of Biological Sciences, School of Medical and Life Sciences, Sunway University, 47500, Subang Jaya, Selangor, Malaysia.
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3
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Sharma V, Madia VN, Tudino V, Nguyen JV, Debnath A, Messore A, Ialongo D, Patacchini E, Palenca I, Basili Franzin S, Seguella L, Esposito G, Petrucci R, Di Matteo P, Bortolami M, Saccoliti F, Di Santo R, Scipione L, Costi R, Podust LM. Miconazole-like Scaffold is a Promising Lead for Naegleria fowleri-Specific CYP51 Inhibitors. J Med Chem 2023; 66:17059-17073. [PMID: 38085955 PMCID: PMC10758121 DOI: 10.1021/acs.jmedchem.3c01898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/17/2023] [Accepted: 11/22/2023] [Indexed: 12/29/2023]
Abstract
Developing drugs for brain infection by Naegleria fowleri is an unmet medical need. We used a combination of cheminformatics, target-, and phenotypic-based drug discovery methods to identify inhibitors that target an essential N. fowleri enzyme, sterol 14-demethylase (NfCYP51). A total of 124 compounds preselected in silico were tested against N. fowleri. Nine primary hits with EC50 ≤ 10 μM were phenotypically identified. Cocrystallization with NfCYP51 focused attention on one primary hit, miconazole-like compound 2a. The S-enantiomer of 2a produced a 1.74 Å cocrystal structure. A set of analogues was then synthesized and evaluated to confirm the superiority of the S-configuration over the R-configuration and the advantage of an ether linkage over an ester linkage. The two compounds, S-8b and S-9b, had an improved EC50 and KD compared to 2a. Importantly, both were readily taken up into the brain. The brain-to-plasma distribution coefficient of S-9b was 1.02 ± 0.12, suggesting further evaluation as a lead for primary amoebic meningoencephalitis.
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Affiliation(s)
- Vandna Sharma
- Skaggs
School of Pharmacy and Pharmaceutical Sciences, Center for Discovery
and Innovation in Parasitic Diseases, University
of California San Diego, La Jolla, California 92093, United States
| | - Valentina Noemi Madia
- Dipartimento
di Chimica e Tecnologie del Farmaco, Istituto Pasteur-Fondazione Cenci
Bolognetti, “Sapienza” Università
di Roma, p.le Aldo Moro 5, Rome I-00185, Italy
| | - Valeria Tudino
- Dipartimento
di Biotecnologie, Università degli
Studi di Siena, Chimica e Farmacia via Aldo Moro 2, Siena 53100, Italy
| | - Jennifer V. Nguyen
- Skaggs
School of Pharmacy and Pharmaceutical Sciences, Center for Discovery
and Innovation in Parasitic Diseases, University
of California San Diego, La Jolla, California 92093, United States
| | - Anjan Debnath
- Skaggs
School of Pharmacy and Pharmaceutical Sciences, Center for Discovery
and Innovation in Parasitic Diseases, University
of California San Diego, La Jolla, California 92093, United States
| | - Antonella Messore
- Dipartimento
di Chimica e Tecnologie del Farmaco, Istituto Pasteur-Fondazione Cenci
Bolognetti, “Sapienza” Università
di Roma, p.le Aldo Moro 5, Rome I-00185, Italy
| | - Davide Ialongo
- Dipartimento
di Chimica e Tecnologie del Farmaco, Istituto Pasteur-Fondazione Cenci
Bolognetti, “Sapienza” Università
di Roma, p.le Aldo Moro 5, Rome I-00185, Italy
| | - Elisa Patacchini
- Dipartimento
di Chimica e Tecnologie del Farmaco, Istituto Pasteur-Fondazione Cenci
Bolognetti, “Sapienza” Università
di Roma, p.le Aldo Moro 5, Rome I-00185, Italy
| | - Irene Palenca
- Department
of Physiology and Pharmacology “V. Erspamer”, “Sapienza″ Università di Roma, p.le Aldo Moro 5, Rome I-00185, Italy
| | - Silvia Basili Franzin
- Department
of Physiology and Pharmacology “V. Erspamer”, “Sapienza″ Università di Roma, p.le Aldo Moro 5, Rome I-00185, Italy
| | - Luisa Seguella
- Department
of Physiology and Pharmacology “V. Erspamer”, “Sapienza″ Università di Roma, p.le Aldo Moro 5, Rome I-00185, Italy
| | - Giuseppe Esposito
- Department
of Physiology and Pharmacology “V. Erspamer”, “Sapienza″ Università di Roma, p.le Aldo Moro 5, Rome I-00185, Italy
| | - Rita Petrucci
- Dipartimento
di Scienze di Base e Applicate per l’Ingegneria, “Sapienza” Università di Roma, Via Castro Laurenziano 7, Rome 00161, Italy
| | - Paola Di Matteo
- Dipartimento
di Scienze di Base e Applicate per l’Ingegneria, “Sapienza” Università di Roma, Via Castro Laurenziano 7, Rome 00161, Italy
| | - Martina Bortolami
- Dipartimento
di Scienze di Base e Applicate per l’Ingegneria, “Sapienza” Università di Roma, Via Castro Laurenziano 7, Rome 00161, Italy
| | - Francesco Saccoliti
- D3 PharmaChemistry, Italian
Institute of Technology, Via Morego 30, Genova 16163, Italy
| | - Roberto Di Santo
- Dipartimento
di Chimica e Tecnologie del Farmaco, Istituto Pasteur-Fondazione Cenci
Bolognetti, “Sapienza” Università
di Roma, p.le Aldo Moro 5, Rome I-00185, Italy
| | - Luigi Scipione
- Dipartimento
di Chimica e Tecnologie del Farmaco, Istituto Pasteur-Fondazione Cenci
Bolognetti, “Sapienza” Università
di Roma, p.le Aldo Moro 5, Rome I-00185, Italy
| | - Roberta Costi
- Dipartimento
di Chimica e Tecnologie del Farmaco, Istituto Pasteur-Fondazione Cenci
Bolognetti, “Sapienza” Università
di Roma, p.le Aldo Moro 5, Rome I-00185, Italy
| | - Larissa M. Podust
- Skaggs
School of Pharmacy and Pharmaceutical Sciences, Center for Discovery
and Innovation in Parasitic Diseases, University
of California San Diego, La Jolla, California 92093, United States
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4
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Shareef O, Shareef S, Saeed HN. New Frontiers in Acanthamoeba Keratitis Diagnosis and Management. BIOLOGY 2023; 12:1489. [PMID: 38132315 PMCID: PMC10740828 DOI: 10.3390/biology12121489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/01/2023] [Accepted: 12/01/2023] [Indexed: 12/23/2023]
Abstract
Acanthamoeba Keratitis (AK) is a severe corneal infection caused by the Acanthamoeba species of protozoa, potentially leading to permanent vision loss. AK requires prompt diagnosis and treatment to mitigate vision impairment. Diagnosing AK is challenging due to overlapping symptoms with other corneal infections, and treatment is made complicated by the organism's dual forms and increasing virulence, and delayed diagnosis. In this review, new approaches in AK diagnostics and treatment within the last 5 years are discussed. The English-language literature on PubMed was reviewed using the search terms "Acanthamoeba keratitis" and "diagnosis" or "treatment" and focused on studies published between 2018 and 2023. Two hundred sixty-five publications were initially identified, of which eighty-seven met inclusion and exclusion criteria. This review highlights the findings of these studies. Notably, advances in PCR-based diagnostics may be clinically implemented in the near future, while antibody-based and machine-learning approaches hold promise for the future. Single-drug topical therapy (0.08% PHMB) may improve drug access and efficacy, while oral medication (i.e., miltefosine) may offer a treatment option for patients with recalcitrant disease.
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Affiliation(s)
- Omar Shareef
- School of Engineering and Applied Sciences, Harvard College, Cambridge, MA 02138, USA;
| | - Sana Shareef
- Department of Bioethics, Columbia University, New York, NY 10027, USA
| | - Hajirah N. Saeed
- Department of Ophthalmology, University of Illinois Chicago, Chicago, IL 60607, USA
- Department of Ophthalmology, Harvard Medical School, Boston, MA 02115, USA
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5
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Antiamoebic Properties of Ceftriaxone and Zinc-Oxide-Cyclodextrin-Conjugated Ceftriaxone. Antibiotics (Basel) 2022; 11:antibiotics11121721. [PMID: 36551378 PMCID: PMC9774710 DOI: 10.3390/antibiotics11121721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/20/2022] [Accepted: 11/20/2022] [Indexed: 12/05/2022] Open
Abstract
Acanthamoeba castellanii is a ubiquitous free-living amoeba capable of instigating keratitis and granulomatous amoebic encephalitis in humans. Treatment remains limited and inconsistent. Accordingly, there is a pressing need for novel compounds. Nanotechnology has been gaining attention for enhancing drug delivery and reducing toxicity. Previous work has shown that various antibiotic classes displayed antiamoebic activity. Herein, we employed two antibiotics: ampicillin and ceftriaxone, conjugated with the nanocarrier zinc oxide and β-cyclodextrin, and tested them against A. castellanii via amoebicidal, amoebistatic, encystment, excystment, cytopathogenicity, and cytotoxicity assays at a concentration of 100 μg/mL. Notably, zinc oxide β-cyclodextrin ceftriaxone significantly inhibited A. castellanii growth and cytopathogenicity. Additionally, both zinc oxide β-cyclodextrin ceftriaxone and ceftriaxone markedly inhibited A. castellanii encystment. Furthermore, all the tested compounds displayed negligible cytotoxicity. However, minimal anti-excystment or amoebicidal effects were observed for the compounds. Accordingly, this novel nanoconjugation should be employed in further studies in hope of discovering novel anti-Acanthamoeba compounds.
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6
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Mohamed A, Chilingerian JN, Bali P, Obonyo M, Debnath A. A Bioluminescence-Based Drug Screen Identifies Activities of Fexinidazole and Its Metabolites against Helicobacter pylori. Antibiotics (Basel) 2022; 11:1605. [PMID: 36421252 PMCID: PMC9686901 DOI: 10.3390/antibiotics11111605] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2023] Open
Abstract
Helicobacter pylori is responsible for a wide range of gastric diseases, including gastric cancer and gastritis. With half of the world’s population infected by H. pylori and the current standard of care associated with suboptimal outcomes, a search for more effective drugs is critical. To facilitate drug screening for H. pylori, we developed a microtiter plate-based compound screening method that is faster and can screen multiple compounds. We identified activities of fexinidazole and its sulfoxide and sulfone metabolites against H. pylori. Both fexinidazole and its metabolites exhibited equipotency against SS1, 60190, and G27 strains, which were about 3–6-fold more potent than the currently used metronidazole. We also determined the minimal inhibitory concentration (MIC) of metronidazole, fexinidazole, and its metabolites against these strains by a traditional agar plate-based method. While MIC values of fexinidazole and metronidazole were similar against all the strains, both sulfoxide and sulfone showed lower MIC values than metronidazole against SS1 and 60190. Given the recent FDA approval of fexinidazole, our data on the in vitro antibacterial activities of fexinidazole and its metabolites support further evaluation of this drug with the goal of producing an alternative nitro-based antimicrobial with good safety profiles for the treatment of H. pylori infection.
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7
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The Transcription Factor CsAtf1 Negatively Regulates the Cytochrome P450 Gene CsCyp51G1 to Increase Fludioxonil Sensitivity in Colletotrichum siamense. J Fungi (Basel) 2022; 8:jof8101032. [PMID: 36294597 PMCID: PMC9605597 DOI: 10.3390/jof8101032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 09/26/2022] [Accepted: 09/26/2022] [Indexed: 11/30/2022] Open
Abstract
Previous studies have shown that the high-osmolarity glycerol mitogen-activated protein kinase (HOG MAPK) signaling pathway and its downstream transcription factor CsAtf1 are involved in the regulation of fludioxonil sensitivity in C. siamense. However, the downstream target genes of CsAtf1 related to the fludioxonil stress response remain unclear. Here, we performed chromatin immunoprecipitation sequencing (ChIP-Seq) and high-throughput RNA-sequencing (RNA-Seq) to identify genome-wide potential CsAtf1 target genes. A total of 3809 significantly differentially expressed genes were predicted to be directly regulated by CsAtf1, including 24 cytochrome oxidase-related genes. Among them, a cytochrome P450-encoding gene, designated CsCyp51G1, was confirmed to be a target gene, and its transcriptional expression was negatively regulated by CsAtf1, as determined using an electrophoretic mobility shift assay (EMSA), a yeast one-hybrid (Y1H) assay, and quantitative real-time PCR (qRT-PCR). Moreover, the overexpression mutant CsCYP51G1 of C. siamense exhibited increased fludioxonil tolerance, and the CsCYP51G1 deletion mutant exhibited decreased fludioxonil resistance, which revealed that CsCyp51G1 is involved in fludioxonil sensitivity regulation in C. siamense. However, the cellular ergosterol content of the mutants was not consistent with the phenotype of fludioxonil sensitivity, which indicated that CsCyp51G1 regulates fludioxonil sensitivity by affecting factors other than the ergosterol level in C. siamense. In conclusion, our data indicate that the transcription factor CsAtf1 negatively regulates the cytochrome P450 gene CsCyp51G1 to increase fludioxonil sensitivity in C. siamense.
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8
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Akbar N, Kaman WE, Sarink M, Nazmi K, Bikker FJ, Khan NA, Siddiqui R. Novel Antiamoebic Tyrocidine-Derived Peptide against Brain-Eating Amoebae. ACS OMEGA 2022; 7:28797-28805. [PMID: 36033708 PMCID: PMC9404165 DOI: 10.1021/acsomega.2c01614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 07/28/2022] [Indexed: 06/15/2023]
Abstract
Acanthamoeba castellanii (A. castellanii) can cause Acanthamoeba keratitis, a sight-threatening infection, as well as a fatal brain infection termed granulomatous amoebic encephalitis, mostly in immunocompromised individuals. In contrast, Naegleria fowleri (N. fowleri) causes a deadly infection involving the central nervous system, recognized as primary amoebic encephalitis, mainly in individuals partaking in recreational water activities or those with nasal exposure to contaminated water. Worryingly, mortality rates due to these infections are more than 90%, suggesting the need to find alternative therapies. In this study, antiamoebic activity of a peptide based on the structure of the antibiotic tyrocidine was evaluated against A. castellanii and N. fowleri. The tyrocidine-derived peptide displayed significant amoebicidal efficacy against A. castellanii and N. fowleri. At 250 μg/mL, the peptide drastically reduced amoebae viability up to 13% and 21% after 2 h of incubation against N. fowleri and A. castellanii., whereas, after 24 h of incubation, the peptide showed 86% and 94% amoebicidal activity against A. castellanii and N. fowleri. Furthermore, amoebae pretreated with 100 μg/mL peptide inhibited 35% and 53% A. castellanii and N. fowleri, while, at 250 μg/mL, 84% and 94% A. castellanii and N. fowleri failed to adhere to human cells. Amoeba-mediated cell cytopathogenicity assays revealed 31% and 42% inhibition at 100 μg/mL, while at 250 μg/mL 75% and 86% A. castellanii and N. fowleri were inhibited. Assays revealed inhibition of encystation in both A. castellanii (58% and 93%) and N. fowleri (73% and 97%) at concentrations of 100 and 250 μg/mL respectively. Importantly, tyrocidine-derived peptide depicted minimal cytotoxicity to human cells and, thus, may be a potential candidate in the rational development of a treatment regimen against free-living amoebae infections. Future studies are necessary to elucidate the in vivo effects of tyrocidine-derived peptide against these and other pathogenic amoebae of importance.
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Affiliation(s)
- Noor Akbar
- College
of Arts and Sciences, American University
of Sharjah, University
City, Sharjah 26666, United Arab Emirates
| | - Wendy E. Kaman
- Department
of Oral Biochemistry, Academic Centre for Dentistry Amsterdam, University of Amsterdam and VU University Amsterdam, 1081 LA Amsterdam, The Netherlands
| | - Maarten Sarink
- Erasmus MC, University Medical Center
Rotterdam, Department
of Medical Microbiology and Infectious Diseases, Wytemaweg 80, 3015
CE Rotterdam, The Netherlands
| | - Kamran Nazmi
- Department
of Oral Biochemistry, Academic Centre for Dentistry Amsterdam, University of Amsterdam and VU University Amsterdam, 1081 LA Amsterdam, The Netherlands
| | - Floris J. Bikker
- Department
of Oral Biochemistry, Academic Centre for Dentistry Amsterdam, University of Amsterdam and VU University Amsterdam, 1081 LA Amsterdam, The Netherlands
| | - Naveed Ahmed Khan
- Department
of Clinical Sciences, College of Medicine, University of Sharjah, University
City, Sharjah 27272, Unites Arab Emirates
| | - Ruqaiyyah Siddiqui
- College
of Arts and Sciences, American University
of Sharjah, University
City, Sharjah 26666, United Arab Emirates
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9
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Martín-Escolano R, Pérez-Cordón G, Arán VJ, Marín C, Sánchez-Moreno M, Rosales MJ. 5-Nitroindazole derivatives as potential therapeutic alternatives against Acanthamoeba castellanii. Acta Trop 2022; 232:106538. [PMID: 35618027 DOI: 10.1016/j.actatropica.2022.106538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 05/20/2022] [Accepted: 05/22/2022] [Indexed: 11/29/2022]
Abstract
Amoebas of the genus Acanthamoeba are distributed worldwide, including species with a high pathogenic capacity for humans. In a similar way to what occurs with other parasitic protozoa, the available treatments show variable effectiveness in addition to high toxicity, which demands the development of new treatments. Positive results of 5-nitroindazole derivatives against several protozoa parasites suggest that these compounds may be a promising tool for the development of efficient antiparasitic drugs. In the present work we have evaluated the in vitro activity of ten 5-nitroindazole derivatives against Acanthamoeba castellanii trophozoites and cysts. To that end, AlamarBlue Assay Reagent® was used to determine the activity against trophozoites compared to the reference drug chlorhexidine digluconate. Cytotoxicity of the compounds was evaluated using Vero cells. The activity on cysts was evaluated by light microscopy and using a Neubauer chamber to quantifying cysts and presence of trophozoites, as an indication of cyst. Our results showed the effectiveness of the 5-nitroindazole derivatives tested against both trophozoites and cysts of A. castellani highlighting 5-nitroindazole derivative 8 which showed a 80% activity on cysts, which is higher than that of the reference drug. Moreover, 5-nitroindazole derivatives 8, 9 and 10 were more effective on trophozoites than the reference drug showing IC50 values lower than 5 µM. Taking together these results, these 5-nitroindazole derivatives specially compound 8, might be a promising alternative for the development of more efficient treatments against A. castellani infection.
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Affiliation(s)
- Rubén Martín-Escolano
- Laboratory of Molecular & Evolutionary Parasitology, RAPID group, School of Biosciences, University of Kent, Canterbury, CT27NJ, UK.
| | - Gregorio Pérez-Cordón
- Department of Parasitology, University of Granada, Severo Ochoa s/n, E-18071, Granada, Spain
| | - Vicente J Arán
- Instituto de Química Médica (IQM), Consejo Superior de Investigaciones Científicas (CSIC), Calle Juan de la Cierva 3, 28006 Madrid, Spain
| | - Clotilde Marín
- Department of Parasitology, University of Granada, Severo Ochoa s/n, E-18071, Granada, Spain
| | - Manuel Sánchez-Moreno
- Department of Parasitology, University of Granada, Severo Ochoa s/n, E-18071, Granada, Spain
| | - María José Rosales
- Department of Parasitology, University of Granada, Severo Ochoa s/n, E-18071, Granada, Spain.
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10
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Shing B, Balen M, Fenical W, Debnath A. Development of a Machine Learning-Based Cysticidal Assay and Identification of an Amebicidal and Cysticidal Marine Microbial Metabolite against Acanthamoeba. Microbiol Spectr 2022; 10:e0007722. [PMID: 35467370 PMCID: PMC9241814 DOI: 10.1128/spectrum.00077-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 04/10/2022] [Indexed: 11/20/2022] Open
Abstract
Traditional cysticidal assays for Acanthamoeba species revolve around treating cysts with compounds and manually observing the culture for evidence of excystation. This method is time-consuming, labor-intensive, and low throughput. We adapted and trained a YOLOv3 machine learning, object detection neural network to recognize Acanthamoeba castellanii trophozoites and cysts in microscopy images to develop an automated cysticidal assay. This trained neural network was used to count trophozoites in wells treated with compounds of interest to determine if a compound treatment was cysticidal. We validated this new assay with known cysticidal and noncysticidal compounds. In addition, we undertook a large-scale bioluminescence-based screen of 9,286 structurally unique marine microbial metabolite fractions against the trophozoites of A. castellanii and identified 29 trophocidal hits. These hits were then subjected to this machine learning-based automated cysticidal assay. One marine microbial metabolite fraction was identified as both trophocidal and cysticidal. IMPORTANCE The free-living Acanthamoeba can exist as a trophozoite or cyst and both stages can cause painful blinding keratitis. Infection recurrence occurs in approximately 10% of cases due to the lack of efficient drugs that can kill both trophozoites and cysts. Therefore, the discovery of therapeutics that are effective against both stages is a critical unmet need to avert blindness. Current efforts to identify new anti-Acanthamoeba compounds rely primarily upon assays that target the trophozoite stage of the parasite. We adapted and trained a machine learning, object detection neural network to recognize Acanthamoeba trophozoites and cysts in microscopy images. Our machine learning-based cysticidal assay improved throughput, demonstrated high specificity, and had an exquisite ability to identify noncysticidal compounds. We combined this cysticidal assay with our bioluminescence-based trophocidal assay to screen about 9,000 structurally unique marine microbial metabolites against A. castellanii. Our screen identified a marine metabolite that was both trophocidal and cysticidal.
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Affiliation(s)
- Brian Shing
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
| | - Mina Balen
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
| | - William Fenical
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, USA
| | - Anjan Debnath
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
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Siddiqui R, Makhlouf Z, Akbar N, Khamis M, Ibrahim T, Khan AS, Khan NA. Antiamoebic properties of salicylic acid-based deep eutectic solvents for the development of contact lens disinfecting solutions against Acanthamoeba. Mol Biochem Parasitol 2022; 250:111493. [PMID: 35753525 DOI: 10.1016/j.molbiopara.2022.111493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 05/30/2022] [Accepted: 06/20/2022] [Indexed: 10/17/2022]
Abstract
Acanthamoeba castellanii is a protist pathogen that can cause sight-threatening keratitis and a fatal infection of the central nervous system, known as granulomatous amoebic encephalitis. In this study, effects of five malonic acid and salicylic acid-based deep eutectic solvents (DES) on A. castellanii were investigated. These are salicylic acid-trioctylphosphine (DES 1), salicylic acid- trihexylamine (DES 2), salicylic acid-trioctylamine (DES 3), malonic acid-trioctylphosphine (DES 4) and malonic acid-trihexylamine (DES 5). The experiments were done by performing amoebicidal, encystment, excystment, cytopathogenicity, and cytotoxicity assays. At micromolar dosage, the solvents DES 2 and DES 3 displayed significant amoebicidal effects (P<0.05), inhibited encystment and excystment, undermined the cell-mediated cytopathogenicity of A. castellanii, and also displayed minimal cytotoxicity to human cells. Conversely, the chemical components of these solvents: salicylic acid, trihexylamine, and trioctylamine showed minimal effects when tested individually. These results are very promising and to the best of our knowledge, are reported for the first time on the effects of deep eutectic solvents on amoebae. These results can be applied in the development of new formulations of novel contact lens disinfectants against Acanthamoeba castellanii.
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Affiliation(s)
- Ruqaiyyah Siddiqui
- College of Arts and Sciences, American University of Sharjah, University City, Sharjah 26666, United Arab Emirates
| | - Zinb Makhlouf
- College of Arts and Sciences, American University of Sharjah, University City, Sharjah 26666, United Arab Emirates
| | - Noor Akbar
- College of Arts and Sciences, American University of Sharjah, University City, Sharjah 26666, United Arab Emirates
| | - Mustafa Khamis
- College of Arts and Sciences, American University of Sharjah, University City, Sharjah 26666, United Arab Emirates
| | - Taleb Ibrahim
- Department of Chemical Engineering, College of Engineering, American University of Sharjah, P.O. Box 26666, Sharjah, United Arab Emirates
| | - Amir Sada Khan
- Department of Chemical Engineering, College of Engineering, American University of Sharjah, P.O. Box 26666, Sharjah, United Arab Emirates
| | - Naveed Ahmed Khan
- Department of Clinical Sciences, College of Medicine, University of Sharjah, University, City, Sharjah, 27272, United Arab Emirates.
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Nienhaus K, Sharma V, Nienhaus GU, Podust LM. Homodimerization Counteracts the Detrimental Effect of Nitrogenous Heme Ligands on the Enzymatic Activity of Acanthamoeba castellanii CYP51. Biochemistry 2022; 61:1363-1377. [PMID: 35730528 DOI: 10.1021/acs.biochem.2c00198] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Acanthamoeba castellanii is a free-living amoeba that can cause severe eye and brain infections in humans. At present, there is no uniformly effective treatment for any of these infections. However, sterol 14α-demethylases (CYP51s), heme-containing cytochrome P450 enzymes, are known to be validated drug targets in pathogenic fungi and protozoa. The catalytically active P450 form of CYP51 from A. castellanii (AcCYP51) is stabilized against conversion to the inactive P420 form by dimerization. In contrast, Naegleria fowleri CYP51 (NfCYP51) is monomeric in its active P450 and inactive P420 forms. For these two CYP51 enzymes, we have investigated the interplay between the enzyme activity and oligomerization state using steady-state and time-resolved UV-visible absorption spectroscopy. In both enzymes, the P450 → P420 transition is favored under reducing conditions. The transition is accelerated at higher pH, which excludes a protonated thiol as the proximal ligand in P420. Displacement of the proximal thiolate ligand is also promoted by adding exogenous nitrogenous ligands (N-ligands) such as imidazole, isavuconazole, and clotrimazole that bind at the opposite, distal heme side. In AcCYP51, the P450 → P420 transition is faster in the monomer than in the dimer, indicating that the dimeric assembly is critical for stabilizing thiolate coordination to the heme and thus for sustaining AcCYP51 activity. The spectroscopic experiments were complemented with size-exclusion chromatography and X-ray crystallography studies. Collectively, our results indicate that effective inactivation of the AcCYP51 function by azole drugs is due to synergistic interference with AcCYP51 dimerization and promoting irreversible displacement of the proximal heme-thiolate ligand.
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Affiliation(s)
- Karin Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), D-76049 Karlsruhe, Germany
| | - Vandna Sharma
- Skaggs School of Pharmacy and Pharmaceutical Sciences, Center for Discovery and Innovation in Parasitic Diseases, University of California San Diego, La Jolla, California 92093, United States
| | - Gerd Ulrich Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), D-76049 Karlsruhe, Germany.,Institute of Nanotechnology, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany.,Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Larissa M Podust
- Skaggs School of Pharmacy and Pharmaceutical Sciences, Center for Discovery and Innovation in Parasitic Diseases, University of California San Diego, La Jolla, California 92093, United States
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Novel Plant-Based Metabolites as Disinfectants against Acanthamoeba castellanii. Antibiotics (Basel) 2022; 11:antibiotics11020248. [PMID: 35203850 PMCID: PMC8868186 DOI: 10.3390/antibiotics11020248] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 02/04/2022] [Accepted: 02/10/2022] [Indexed: 01/27/2023] Open
Abstract
Due to global warming, coupled with global water shortages and the reliance of the public on household water tanks, especially in developing countries, it is anticipated that infections caused by free-living amoebae such as Acanthamoeba will rise. Thus, the development of novel disinfectant(s) which can target pathogenic free-living amoebae effectively is warranted. Herein, we extracted and isolated several plant-based secondary metabolites as novel disinfectants for use against pathogenic Acanthamoeba. The identity of the compounds was confirmed by nuclear magnetic resonance and tested for antiamoebic activities against clinical isolate of A. castellanii, belonging to the T4 genotype. Amoebicidal assays revealed that the compounds tested showed antiamoebic properties. Betulinic acid and betulin exhibited parasite killing of more than 65%. When tested against the cyst stage, betulinic acid, betulin, and vanillic acid inhibited both encystation and excystation processes. Furthermore, the plant-based metabolites significantly inhibited the binding capability of A. castellanii to host cells. Finally, most of the tested compounds displayed minimal cytotoxic activities against human cells and noticeably perturbed amoeba-mediated host cell cytotoxicity. Notably, both alkaloid and betulinic acid showed 20% cytotoxic effects, whereas betulin and lupeol had cytotoxic effects of 24% and 30%, respectively. Overall, our findings indicate that plant-based natural compounds demonstrate anti-Acanthamoebic properties, and they have potential candidates for water disinfectants or contact lens disinfecting solutions, as well as possible therapeutic drugs against Acanthamoeba infections.
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Wang YJ, Chen CH, Chen JW, Lin WC. Commensals Serve as Natural Barriers to Mammalian Cells during Acanthamoeba castellanii Invasion. Microbiol Spectr 2021; 9:e0051221. [PMID: 34935418 PMCID: PMC8693914 DOI: 10.1128/spectrum.00512-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 11/02/2021] [Indexed: 12/23/2022] Open
Abstract
Acanthamoeba castellanii is a free-living, pathogenic ameba found in the soil and water. It invades the body through ulcerated skin, the nasal passages, and eyes and can cause blinding keratitis and granulomatous encephalitis. However, the mechanisms underlying the opportunistic pathogenesis of A. castellanii remain unclear. In this study, we observed that commensal bacteria significantly reduced the cytotoxicity of the ameba on mammalian cells. This effect occurred in the presence of both Gram-positive and Gram-negative commensals. Additionally, commensals mitigated the disruption of cell junctions. Ex vivo experiments on mouse eyeballs further showed that the commensals protected the corneal epithelial layer. Together, these findings indicate that A. castellanii is pathogenic to individuals with a dysbiosis of the microbiota at infection sites, further highlighting the role of commensals as a natural barrier during parasite invasion. IMPORTANCE Acanthamoeba castellanii, an opportunistic protozoan widely present in the environment, can cause Acanthamoeba keratitis and encephalitis in humans. However, only a few reports describe how the ameba acts as an opportunistic pathogen. Our study showed that the normal microbiota interfered with the cytotoxicity of Acanthamoeba, persevered during Acanthamoeba invasion, and reduced corneal epithelium peeling in the mouse eyeball model. This suggests that commensals may act as a natural barrier against Acanthamoeba invasion. In future, individuals who suffer from Acanthamoeba keratitis should be examined for microbiota absence or dysbiosis to reduce the incidence of Acanthamoeba infection in clinical settings.
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Affiliation(s)
- Yu-Jen Wang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Department of Clinical Laboratory, Chest Hospital, Ministry of Health and Welfare, Tainan, Taiwan
| | - Chun-Hsien Chen
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Jenn-Wei Chen
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Wei-Chen Lin
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Department of Parasitology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
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Evaluation of Amebicidal and Cysticidal Activities of Antifungal Drug Isavuconazonium Sulfate against Acanthamoeba T4 Strains. Pharmaceuticals (Basel) 2021; 14:ph14121294. [PMID: 34959694 PMCID: PMC8707217 DOI: 10.3390/ph14121294] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 12/08/2021] [Accepted: 12/08/2021] [Indexed: 11/30/2022] Open
Abstract
Acanthamoeba species of amebae are often associated with Acanthamoeba keratitis, a severe corneal infection. Isavuconazonium sulfate is an FDA-approved drug for the treatment of invasive aspergillosis and mucormycosis. This prodrug is metabolized into the active isavuconazole moiety. Isavuconazole was previously identified to have amebicidal and cysticidal activity against Acanthamoeba T4 strains, but the activity of its prodrug, isavuconazonium sulfate, against trophozoites and cysts remains unknown. Since it is not known if isavuconazonium can be metabolized into isavuconazole in the human eye, we evaluated the activities of isavuconazonium sulfate against trophozoites and cysts of three T4 genotype strains of Acanthamoeba. Isavuconazonium displayed amebicidal activity at nanomolar concentrations as low as 1.4 nM and prevented excystation of cysts at concentrations as low as 136 μM. We also investigated the cysticidal activity of isavuconazonium sulfate in combination with a currently used amebicidal drug polyhexamethylene biguanide (PHMB). Although combination of isavuconazonium with PHMB did not elicit an obvious synergistic cysticidal activity, the combination did not cause an antagonistic effect on the cysts of Acanthamoeba T4 strains. Collectively, these findings suggest isavuconazonium retains potency against Acanthamoeba T4 strains and could be adapted for Acanthamoeba keratitis treatment.
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Wehelie YI, Khan NA, Fatima I, Anwar A, Kanwal K, Khan KM, Siddiqui R, Tong YK, Anwar A. Novel Tetrazoles against Acanthamoeba castellanii Belonging to the T4 Genotype. Chemotherapy 2021; 67:183-192. [PMID: 34724675 DOI: 10.1159/000520585] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 10/31/2021] [Indexed: 11/19/2022]
Abstract
BACKGROUND Acanthamoeba castellanii is a pathogenic free-living amoeba responsible for blinding keratitis and fatal granulomatous amoebic encephalitis. However, treatments are not standardized but can involve the use of amidines, biguanides, and azoles. OBJECTIVES The aim of this study was to synthesize a variety of synthetic tetrazole derivatives and test their activities against A. castellanii. METHODS A series of novel tetrazole compounds were synthesized by one-pot method and characterized by NMR and mass spectroscopy. These compounds were subjected to amoebicidal, and cytotoxicity assays against A. castellanii belonging to the T4 genotype and human keratinocyte skin cells respectively. Additionally, reactive oxygen species determination and electron microscopy studies were carried out. Furthermore, two of the seven compounds were conjugated with silver nanoparticles to study their antiamoebic potential. RESULTS A series of seven tetrazole derivatives were synthesized successfully. The selected tetrazoles showed anti-amoebic activities at 10µM concentration against A. castellanii in vitro. The compounds tested caused increased reactive oxygen species generation in A castellanii, and significant morphological damage to amoebal membranes. Moreover, conjugation of silver nanoparticles enhanced antiamoebic effects of two tetrazoles. CONCLUSIONS The results showed that azole compounds hold promise in the development of new formulations of anti-Acanthamoebic agents.
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Affiliation(s)
- Yassmin Isse Wehelie
- Department of Biological Sciences, School of Medical and Life Sciences, Sunway University, Selangor, Malaysia
| | - Naveed Ahmed Khan
- Department of Clinical Sciences, College of Medicine, University of Sharjah, University City, Sharjah, United Arab Emirates
| | - Itrat Fatima
- H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
| | - Areeba Anwar
- Faculty of Defence Science and Technology, National Defence University of Malaysia, Kuala Lumpur, Malaysia
| | - Kanwal Kanwal
- Institute of Marine Biotechnology, University Malaysia Terengganu, Kuala Terengganu, Malaysia
| | - Khalid M Khan
- H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
| | - Ruqaiyyah Siddiqui
- College of Arts and Sciences, American University of Sharjah, University City, Sharjah, United Arab Emirates
| | - Yuh Koon Tong
- Department of Biological Sciences, School of Medical and Life Sciences, Sunway University, Selangor, Malaysia
| | - Ayaz Anwar
- Department of Biological Sciences, School of Medical and Life Sciences, Sunway University, Selangor, Malaysia
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Shing B, Balen M, McKerrow JH, Debnath A. Acanthamoeba Keratitis: an update on amebicidal and cysticidal drug screening methodologies and potential treatment with azole drugs. Expert Rev Anti Infect Ther 2021; 19:1427-1441. [PMID: 33929276 PMCID: PMC8551003 DOI: 10.1080/14787210.2021.1924673] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 04/28/2021] [Indexed: 01/10/2023]
Abstract
Introduction: Acanthamoeba encompasses several species of free-living ameba encountered commonly throughout the environment. Unfortunately, these species of ameba can cause opportunistic infections that result in Acanthamoeba keratitis, granulomatous amebic encephalitis, and occasionally systemic infection.Areas covered: This review discusses relevant literature found through PubMed and Google scholar published as of January 2021. The review summarizes current common Acanthamoeba keratitis treatments, drug discovery methodologies available for screening potential anti-Acanthamoeba compounds, and the anti-Acanthamoeba activity of various azole antifungal agents.Expert opinion: While several biguanide and diamidine antimicrobial agents are available to clinicians to effectively treat Acanthamoeba keratitis, no singular treatment can effectively treat every Acanthamoeba keratitis case.Efforts to identify new anti-Acanthamoeba agents include trophozoite cell viability assays, which are amenable to high-throughput screening. Cysticidal assays remain largely manual and would benefit from further automation development. Additionally, the existing literature on the effectiveness of various azole antifungal agents for treating Acanthamoeba keratitis is incomplete or contradictory, suggesting the need for a systematic review of all azoles against different pathogenic Acanthamoeba strains.
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Affiliation(s)
- Brian Shing
- Biomedical Sciences Graduate Division, University of California San Diego, 9500 Gilman Drive, MC 0685, La Jolla, CA 92093-0756, USA
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, 9500 Gilman Drive, MC 0756, La Jolla, CA 92093-0756, USA
| | - Mina Balen
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, 9500 Gilman Drive, MC 0756, La Jolla, CA 92093-0756, USA
- Division of Biological Sciences, University of California San Diego, San Diego, 9500 Gilman Drive, MC 0346, La Jolla, CA 92093-0756, USA
| | - James H. McKerrow
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, 9500 Gilman Drive, MC 0756, La Jolla, CA 92093-0756, USA
| | - Anjan Debnath
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, 9500 Gilman Drive, MC 0756, La Jolla, CA 92093-0756, USA
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Amara AAAF. Improving Animal Immunity to Prevent Fungal Infections with Folk Remedies and Advanced Medicine. FUNGAL DISEASES IN ANIMALS 2021:127-162. [DOI: 10.1007/978-3-030-69507-1_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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Sharma V, Shing B, Hernandez-Alvarez L, Debnath A, Podust LM. Domain-Swap Dimerization of Acanthamoeba castellanii CYP51 and a Unique Mechanism of Inactivation by Isavuconazole. Mol Pharmacol 2020; 98:770-780. [PMID: 33008918 DOI: 10.1124/molpharm.120.000092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 09/17/2020] [Indexed: 01/14/2023] Open
Abstract
Cytochromes P450 (P450, CYP) metabolize a wide variety of endogenous and exogenous lipophilic molecules, including most drugs. Sterol 14α-demethylase (CYP51) is a target for antifungal drugs known as conazoles. Using X-ray crystallography, we have discovered a domain-swap homodimerization mode in CYP51 from a human pathogen, Acanthamoeba castellanii CYP51 (AcCYP51). Recombinant AcCYP51 with a truncated transmembrane helix was purified as a heterogeneous mixture corresponding to the dimer and monomer units. Spectral analyses of these two populations have shown that the CO-bound ferrous form of the dimeric protein absorbed at 448 nm (catalytically competent form), whereas the monomeric form absorbed at 420 nm (catalytically incompetent form). AcCYP51 dimerized head-to-head via N-termini swapping, resulting in formation of a nonplanar protein-protein interface exceeding 2000 Å2 with a total solvation energy gain of -35.4 kcal/mol. In the dimer, the protomers faced each other through the F and G α-helices, thus blocking the substrate access channel. In the presence of the drugs clotrimazole and isavuconazole, the AcCYP51 drug complexes crystallized as monomers. Although clotrimazole-bound AcCYP51 adopted a typical CYP monomer structure, isavuconazole-bound AcCYP51 failed to refold 74 N-terminal residues. The failure of AcCYP51 to fully refold upon inhibitor binding in vivo would cause an irreversible loss of a structurally aberrant enzyme through proteolytic degradation. This assumption explains the superior potency of isavuconazole against A. castellanii The dimerization mode observed in this work is compatible with membrane association and may be relevant to other members of the CYP family of biologic, medical, and pharmacological importance. SIGNIFICANCE STATEMENT: We investigated the mechanism of action of antifungal drugs in the human pathogen Acanthamoeba castellanii. We discovered that the enzyme target [Acanthamoeba castellanii sterol 14α-demethylase (AcCYP51)] formed a dimer via an N-termini swap, whereas drug-bound AcCYP51 was monomeric. In the AcCYP51-isavuconazole complex, the protein target failed to refold 74 N-terminal residues, suggesting a fundamentally different mechanism of AcCYP51 inactivation than only blocking the active site. Proteolytic degradation of a structurally aberrant enzyme would explain the superior potency of isavuconazole against A. castellanii.
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Affiliation(s)
- Vandna Sharma
- Skaggs School of Pharmacy and Pharmaceutical Sciences, Center for Discovery and Innovation in Parasitic Diseases, University of California San Diego, La Jolla, California (V.S., B.S., L.H.-A., A.D., L.M.P.) and Departamento de Física, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Julio de Mesquita Filho, São José do Rio Preto, São Paulo, Brazil (L.H.-A.)
| | - Brian Shing
- Skaggs School of Pharmacy and Pharmaceutical Sciences, Center for Discovery and Innovation in Parasitic Diseases, University of California San Diego, La Jolla, California (V.S., B.S., L.H.-A., A.D., L.M.P.) and Departamento de Física, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Julio de Mesquita Filho, São José do Rio Preto, São Paulo, Brazil (L.H.-A.)
| | - Lilian Hernandez-Alvarez
- Skaggs School of Pharmacy and Pharmaceutical Sciences, Center for Discovery and Innovation in Parasitic Diseases, University of California San Diego, La Jolla, California (V.S., B.S., L.H.-A., A.D., L.M.P.) and Departamento de Física, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Julio de Mesquita Filho, São José do Rio Preto, São Paulo, Brazil (L.H.-A.)
| | - Anjan Debnath
- Skaggs School of Pharmacy and Pharmaceutical Sciences, Center for Discovery and Innovation in Parasitic Diseases, University of California San Diego, La Jolla, California (V.S., B.S., L.H.-A., A.D., L.M.P.) and Departamento de Física, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Julio de Mesquita Filho, São José do Rio Preto, São Paulo, Brazil (L.H.-A.)
| | - Larissa M Podust
- Skaggs School of Pharmacy and Pharmaceutical Sciences, Center for Discovery and Innovation in Parasitic Diseases, University of California San Diego, La Jolla, California (V.S., B.S., L.H.-A., A.D., L.M.P.) and Departamento de Física, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Julio de Mesquita Filho, São José do Rio Preto, São Paulo, Brazil (L.H.-A.)
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In Vitro Effect of Pitavastatin and Its Synergistic Activity with Isavuconazole against Acanthamoeba castellanii. Pathogens 2020; 9:pathogens9090681. [PMID: 32825652 PMCID: PMC7559540 DOI: 10.3390/pathogens9090681] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 08/18/2020] [Accepted: 08/19/2020] [Indexed: 02/06/2023] Open
Abstract
Acanthamoeba keratitis (AK) can occur in healthy individuals wearing contact lenses and it is a painful, blinding infection of the cornea caused by a free-living ameba Acanthamoeba. Current treatment for AK relies on a combination of chlorhexidine, propamidine isethionate, and polyhexamethylene biguanide. However, the current regimen includes an aggressive disinfectant and in 10% of cases recurrent infection ensues. Therefore, development of efficient and safe drugs is a critical unmet need to avert blindness. Acanthamoeba sterol biosynthesis includes two essential enzymes HMG-CoA reductase (HMGR) and sterol 14-demethylase (CYP51), and we earlier identified a CYP51 inhibitor isavuconazole that demonstrated nanomolar potency against A. castellanii trophozoites. In this study, we investigated the effect of well-tolerated HMGR inhibitors and identified pitavastatin that is active against trophozoites of three different clinical strains of A.castellanii. Pitavastatin demonstrated an EC50 of 0.5 to 1.9 µM, depending on strains. Combination of pitavastatin and isavuconazole is synergistic and led to 2- to 9-fold dose reduction for pitavastatin and 11- to 4000-fold dose reduction for isavuconazole to achieve 97% of growth inhibition. Pitavastatin, either alone or in combination with isavuconazole, may lead to repurposing for the treatment of Acanthamoeba keratitis.
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Drug Discovery against Acanthamoeba Infections: Present Knowledge and Unmet Needs. Pathogens 2020; 9:pathogens9050405. [PMID: 32456110 PMCID: PMC7281112 DOI: 10.3390/pathogens9050405] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 05/09/2020] [Accepted: 05/12/2020] [Indexed: 12/12/2022] Open
Abstract
Although major strides have been made in developing and testing various anti-acanthamoebic drugs, recurrent infections, inadequate treatment outcomes, health complications, and side effects associated with the use of currently available drugs necessitate the development of more effective and safe therapeutic regimens. For any new anti-acanthamoebic drugs to be more effective, they must have either superior potency and safety or at least comparable potency and an improved safety profile compared to the existing drugs. The development of the so-called 'next-generation' anti-acanthamoebic agents to address this challenge is an active area of research. Here, we review the current status of anti-acanthamoebic drugs and discuss recent progress in identifying novel pharmacological targets and new approaches, such as drug repurposing, development of small interfering RNA (siRNA)-based therapies and testing natural products and their derivatives. Some of the discussed approaches have the potential to change the therapeutic landscape of Acanthamoeba infections.
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