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Ali M, Xu C, Nawaz S, Ahmed AE, Hina Q, Li K. Anti-Cryptosporidial Drug-Discovery Challenges and Existing Therapeutic Avenues: A "One-Health" Concern. Life (Basel) 2024; 14:80. [PMID: 38255695 PMCID: PMC10820218 DOI: 10.3390/life14010080] [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: 11/22/2023] [Revised: 12/20/2023] [Accepted: 12/28/2023] [Indexed: 01/24/2024] Open
Abstract
Cryptosporidiosis is the leading cause of life-threatening diarrheal infection, especially in infants. Oocysts contaminate the environment, and also, being a zoonotic disease, cryptosporidiosis is a threat to One Health. Nitazoxanide is the only FDA-approved drug, effective only in immunocompetent adults, and is not safe for infants. The absence of mitochondria and apicoplast, the presence of an electron-dense band (ED band), hindrances in its genetic and phenotypic manipulations, and its unique position inside the host cell are some challenges to the anti-cryptosporidial drug-discovery process. However, many compounds, including herbal products, have shown efficacy against Cryptosporidium during in vitro and in vivo trials. Still, the "drug of choice" against this protozoan parasite, especially in immunocompromised individuals and infants, has not yet been explored. The One-Health approach addresses this issue, focusing on the intersection of animal, human, and environmental health. The objective of this review is to provide knowledge about novel anti-cryptosporidial drug targets, available treatment options with associated limitations, and possible future shifts toward natural products to treat cryptosporidiosis. The current review is organized to address the treatment and prevention of cryptosporidiosis. An anti-cryptosporidial drug that is effective in immunocompromised individuals and infants is a necessity of our time.
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Affiliation(s)
- Munwar Ali
- Institute of Traditional Chinese Veterinary Medicine, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; (M.A.); (C.X.)
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Chang Xu
- Institute of Traditional Chinese Veterinary Medicine, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; (M.A.); (C.X.)
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Shah Nawaz
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China;
| | - Ahmed Ezzat Ahmed
- Biology Department, College of Science, King Khalid University, Abha 61413, Saudi Arabia;
| | - Qazal Hina
- Department of Animal Nutrition, University of Veterinary and Animal Sciences, Lahore 54000, Pakistan;
| | - Kun Li
- Institute of Traditional Chinese Veterinary Medicine, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; (M.A.); (C.X.)
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
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Chao AT, Lee BH, Wan KF, Selva J, Zou B, Gedeck P, Beer DJ, Diagana TT, Bonamy GMC, Manjunatha UH. Development of a Cytopathic Effect-Based Phenotypic Screening Assay against Cryptosporidium. ACS Infect Dis 2018; 4:635-645. [PMID: 29341586 DOI: 10.1021/acsinfecdis.7b00247] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cryptosporidiosis is a diarrheal disease predominantly caused by Cryptosporidium parvum ( Cp) and Cryptosporidium hominis ( Ch), apicomplexan parasites which infect the intestinal epithelial cells of their human hosts. The only approved drug for cryptosporidiosis is nitazoxanide, which shows limited efficacy in immunocompromised children, the most vulnerable patient population. Thus, new therapeutics and in vitro infection models are urgently needed to address the current unmet medical need. Toward this aim, we have developed novel cytopathic effect (CPE)-based Cp and Ch assays in human colonic tumor (HCT-8) cells and compared them to traditional imaging formats. Further model validation was achieved through screening a collection of FDA-approved drugs and confirming many previously known anti- Cryptosporidium hits as well as identifying a few novel candidates. Collectively, our data reveals this model to be a simple, functional, and homogeneous gain of signal format amenable to high throughput screening, opening new avenues for the discovery of novel anticryptosporidials.
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Affiliation(s)
- Alexander T. Chao
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
- Novartis Institute for Tropical Diseases, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Boon Heng Lee
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
| | - Kah Fei Wan
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
| | - Jeremy Selva
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
| | - Bin Zou
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
| | - Peter Gedeck
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
| | - David John Beer
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
| | - Thierry T. Diagana
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
- Novartis Institute for Tropical Diseases, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Ghislain M. C. Bonamy
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
- Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore, 138669, Singapore
| | - Ujjini H. Manjunatha
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
- Novartis Institute for Tropical Diseases, 5300 Chiron Way, Emeryville, California 94608, United States
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El Kouni MH. Pyrimidine metabolism in schistosomes: A comparison with other parasites and the search for potential chemotherapeutic targets. Comp Biochem Physiol B Biochem Mol Biol 2017; 213:55-80. [PMID: 28735972 PMCID: PMC5593796 DOI: 10.1016/j.cbpb.2017.07.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 06/29/2017] [Accepted: 07/03/2017] [Indexed: 12/18/2022]
Abstract
Schistosomes are responsible for the parasitic disease schistosomiasis, an acute and chronic parasitic ailment that affects >240 million people in 70 countries worldwide. It is the second most devastating parasitic disease after malaria. At least 200,000 deaths per year are associated with the disease. In the absence of the availability of vaccines, chemotherapy is the main stay for combating schistosomiasis. The antischistosomal arsenal is currently limited to a single drug, Praziquantel, which is quite effective with a single-day treatment and virtually no host-toxicity. Recently, however, the question of reduced activity of Praziquantel has been raised. Therefore, the search for alternative antischistosomal drugs merits the study of new approaches of chemotherapy. The rational design of a drug is usually based on biochemical and physiological differences between pathogens and host. Pyrimidine metabolism is an excellent target for such studies. Schistosomes, unlike most of the host tissues, require a very active pyrimidine metabolism for the synthesis of DNA and RNA. This is essential for the production of the enormous numbers of eggs deposited daily by the parasite to which the granulomas response precipitates the pathogenesis of schistosomiasis. Furthermore, there are sufficient differences between corresponding enzymes of pyrimidine metabolism from the host and the parasite that can be exploited to design specific inhibitors or "subversive substrates" for the parasitic enzymes. Specificities of pyrimidine transport also diverge significantly between parasites and their mammalian host. This review deals with studies on pyrimidine metabolism in schistosomes and highlights the unique characteristic of this metabolism that could constitute excellent potential targets for the design of safe and effective antischistosomal drugs. In addition, pyrimidine metabolism in schistosomes is compared with that in other parasites where studies on pyrimidine metabolism have been more elaborate, in the hope of providing leads on how to identify likely chemotherapeutic targets which have not been looked at in schistosomes.
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Affiliation(s)
- Mahmoud H El Kouni
- Department of Pharmacology and Toxicology, Center for AIDS Research, Comprehensive Cancer Center, General Clinical Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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Love MS, Beasley FC, Jumani RS, Wright TM, Chatterjee AK, Huston CD, Schultz PG, McNamara CW. A high-throughput phenotypic screen identifies clofazimine as a potential treatment for cryptosporidiosis. PLoS Negl Trop Dis 2017; 11:e0005373. [PMID: 28158186 PMCID: PMC5310922 DOI: 10.1371/journal.pntd.0005373] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 02/15/2017] [Accepted: 01/30/2017] [Indexed: 11/19/2022] Open
Abstract
Cryptosporidiosis has emerged as a leading cause of non-viral diarrhea in children under five years of age in the developing world, yet the current standard of care to treat Cryptosporidium infections, nitazoxanide, demonstrates limited and immune-dependent efficacy. Given the lack of treatments with universal efficacy, drug discovery efforts against cryptosporidiosis are necessary to find therapeutics more efficacious than the standard of care. To date, cryptosporidiosis drug discovery efforts have been limited to a few targeted mechanisms in the parasite and whole cell phenotypic screens against small, focused collections of compounds. Using a previous screen as a basis, we initiated the largest known drug discovery effort to identify novel anticryptosporidial agents. A high-content imaging assay for inhibitors of Cryptosporidium parvum proliferation within a human intestinal epithelial cell line was miniaturized and automated to enable high-throughput phenotypic screening against a large, diverse library of small molecules. A screen of 78,942 compounds identified 12 anticryptosporidial hits with sub-micromolar activity, including clofazimine, an FDA-approved drug for the treatment of leprosy, which demonstrated potent and selective in vitro activity (EC50 = 15 nM) against C. parvum. Clofazimine also displayed activity against C. hominis-the other most clinically-relevant species of Cryptosporidium. Importantly, clofazimine is known to accumulate within epithelial cells of the small intestine, the primary site of Cryptosporidium infection. In a mouse model of acute cryptosporidiosis, a once daily dosage regimen for three consecutive days or a single high dose resulted in reduction of oocyst shedding below the limit detectable by flow cytometry. Recently, a target product profile (TPP) for an anticryptosporidial compound was proposed by Huston et al. and highlights the need for a short dosing regimen (< 7 days) and formulations for children < 2 years. Clofazimine has a long history of use and has demonstrated a good safety profile for a disease that requires chronic dosing for a period of time ranging 3-36 months. These results, taken with clofazimine's status as an FDA-approved drug with over four decades of use for the treatment of leprosy, support the continued investigation of clofazimine both as a new chemical tool for understanding cryptosporidium biology and a potential new treatment of cryptosporidiosis.
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Affiliation(s)
- Melissa S. Love
- California Institute for Biomedical Research, La Jolla, California, United States of America
| | - Federico C. Beasley
- California Institute for Biomedical Research, La Jolla, California, United States of America
| | - Rajiv S. Jumani
- Department of Medicine, University of Vermont College of Medicine, Burlington, Vermont, United States of America
| | - Timothy M. Wright
- California Institute for Biomedical Research, La Jolla, California, United States of America
| | - Arnab K. Chatterjee
- California Institute for Biomedical Research, La Jolla, California, United States of America
| | - Christopher D. Huston
- Department of Medicine, University of Vermont College of Medicine, Burlington, Vermont, United States of America
| | - Peter G. Schultz
- California Institute for Biomedical Research, La Jolla, California, United States of America
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Case W. McNamara
- California Institute for Biomedical Research, La Jolla, California, United States of America
- * E-mail:
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Nyíri K, Vértessy BG. Perturbation of genome integrity to fight pathogenic microorganisms. Biochim Biophys Acta Gen Subj 2016; 1861:3593-3612. [PMID: 27217086 DOI: 10.1016/j.bbagen.2016.05.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 05/05/2016] [Accepted: 05/18/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND Resistance against antibiotics is unfortunately still a major biomedical challenge for a wide range of pathogens responsible for potentially fatal diseases. SCOPE OF REVIEW In this study, we aim at providing a critical assessment of the recent advances in design and use of drugs targeting genome integrity by perturbation of thymidylate biosynthesis. MAJOR CONCLUSION We find that research efforts from several independent laboratories resulted in chemically highly distinct classes of inhibitors of key enzymes within the routes of thymidylate biosynthesis. The present article covers numerous studies describing perturbation of this metabolic pathway in some of the most challenging pathogens like Mycobacterium tuberculosis, Plasmodium falciparum, and Staphylococcus aureus. GENERAL SIGNIFICANCE Our comparative analysis allows a thorough summary of the current approaches to target thymidylate biosynthesis enzymes and also include an outlook suggesting novel ways of inhibitory strategies. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo.
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Affiliation(s)
- Kinga Nyíri
- Dept. Biotechnology, Budapest University of Technology and Economics, 4 Szent Gellért tér, Budapest HU 1111, Hungary; Institute of Enzymology, RCNS, Hungarian Academy of Sciences, 2 Magyar tudósok körútja, Budapest HU 1117, Hungary.
| | - Beáta G Vértessy
- Dept. Biotechnology, Budapest University of Technology and Economics, 4 Szent Gellért tér, Budapest HU 1111, Hungary; Institute of Enzymology, RCNS, Hungarian Academy of Sciences, 2 Magyar tudósok körútja, Budapest HU 1117, Hungary.
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Abstract
Study of the diarrhoea-causing pathogen Cryptosporidium has been hindered by a lack of genetic-modification and culture tools. A description of genome editing and propagation methods for the parasite changes this picture.
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Affiliation(s)
- Stephen M. Beverley
- Department of Molecular Microbiology, Washington University School
of Medicine, St Louis, Missouri 63110, USA
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Structural and Kinetic Characterization of Thymidine Kinase from Leishmania major. PLoS Negl Trop Dis 2015; 9:e0003781. [PMID: 25978379 PMCID: PMC4433323 DOI: 10.1371/journal.pntd.0003781] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 04/23/2015] [Indexed: 01/17/2023] Open
Abstract
Leishmania spp. is a protozoan parasite and the causative agent of leishmaniasis. Thymidine kinase (TK) catalyses the transfer of the γ-phosphate of ATP to 2’-deoxythymidine (dThd) forming thymidine monophosphate (dTMP). L. major Type II TK (LmTK) has been previously shown to be important for infectivity of the parasite and therefore has potential as a drug target for anti-leishmanial therapy. In this study, we determined the enzymatic properties and the 3D structures of holo forms of the enzyme. LmTK efficiently phosphorylates dThd and dUrd and has high structural homology to TKs from other species. However, it significantly differs in its kinetic properties from Trypanosoma brucei TK since purines are not substrates of the enzyme and dNTPs such as dUTP inhibit LmTK. The enzyme had Km and kcat values for dThd of 1.1 μM and 2.62 s-1 and exhibits cooperative binding for ATP. Additionally, we show that the anti-retroviral prodrug zidovudine (3-azido-3-deoxythymidine, AZT) and 5’-modified dUrd can be readily phosphorylated by LmTK. The production of recombinant enzyme at a level suitable for structural studies was achieved by the construction of C-terminal truncated versions of the enzyme and the use of a baculoviral expression system. The structures of the catalytic core of LmTK in complex with dThd, the negative feedback regulator dTTP and the bi-substrate analogue AP5dT, were determined to 2.74, 3.00 and 2.40 Å, respectively, and provide the structural basis for exclusion of purines and dNTP inhibition. The results will aid the process of rational drug design with LmTK as a potential target for anti-leishmanial drugs. The DNA within the genome of an organism encodes all the information, firstly for reproduction and secondly for translation into proteins—the workhorses of a biological cell. Proteins carry out a host of essential biological activities within the cell. A full understanding of a protein now requires determination of a wide range of its properties in solution in the cell and in vitro in solution, but in addition, its 3D structure usually determined by X-ray crystallography. Leishmania species are a family of protozoan parasites of humans and the causative agent of leishmaniasis, a major health concern in the developing world. Selective inhibition of key enzymes in these parasites is a key route for combating these diseases. We have focused our work on thymidine kinase, an important enzyme from Leishmania major, and a potential target for the development of new drugs. We have carried out kinetic studies of the enzyme’s activity in solution and determined its 3D crystal structure, enabling rational drug design.
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Validation of IMP dehydrogenase inhibitors in a mouse model of cryptosporidiosis. Antimicrob Agents Chemother 2013; 58:1603-14. [PMID: 24366728 DOI: 10.1128/aac.02075-13] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Cryptosporidium parasites are a major cause of diarrhea and malnutrition in the developing world, a frequent cause of waterborne disease in the developed world, and a potential bioterrorism agent. Currently, available treatment is limited, and Cryptosporidium drug discovery remains largely unsuccessful. As a result, the pharmacokinetic properties required for in vivo efficacy have not been established. We have been engaged in a Cryptosporidium drug discovery program targeting IMP dehydrogenase (CpIMPDH). Here, we report the activity of eight potent and selective inhibitors of CpIMPDH in the interleukin-12 (IL-12) knockout mouse model, which mimics acute human cryptosporidiosis. Two compounds displayed significant antiparasitic activity, validating CpIMPDH as a drug target. The best compound, P131 (250 mg/kg of body weight/day), performed equivalently to paromomycin (2,000 mg/kg/day) when administered in a single dose and better than paromomycin when administered in three daily doses. One compound, A110, appeared to promote Cryptosporidium infection. The pharmacokinetic, uptake, and permeability properties of the eight compounds were measured. P131 had the lowest systemic distribution but accumulated to high concentrations within intestinal cells. A110 had the highest systemic distribution. These observations suggest that systemic distribution is not required, and may be a liability, for in vivo antiparasitic activity. Intriguingly, A110 caused specific alterations in fecal microbiota that were not observed with P131 or vehicle alone. Such changes may explain how A110 promotes parasitemia. Collectively, these observations suggest a blueprint for the development of anticryptosporidial therapy.
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Expression of functional Plasmodium falciparum enzymes using a wheat germ cell-free system. EUKARYOTIC CELL 2013; 12:1653-63. [PMID: 24123271 DOI: 10.1128/ec.00222-13] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
One decade after the sequencing of the Plasmodium falciparum genome, 95% of malaria proteins in the genome cannot be expressed in traditional cell-based expression systems, and the targets of the best new leads for antimalarial drug discovery are either not known or not available in functional form. For a disease that kills up to 1 million people per year, routine expression of recombinant malaria proteins in functional form is needed both for the discovery of new therapeutics and for identification of targets of new drugs. We tested the general utility of cell-free systems for expressing malaria enzymes. Thirteen test enzyme sequences were reverse amplified from total RNA, cloned into a plant-like expression vector, and subjected to cell-free expression in a wheat germ system. Protein electrophoresis and autoradiography confirmed the synthesis of products of expected molecular masses. In rare problematic cases, truncated products were avoided by using synthetic genes carrying wheat codons. Scaled-up production generated 39 to 354 μg of soluble protein per 10 mg of translation lysate. Compared to rare proteins where cell-based systems do produce functional proteins, the cell-free yields are comparable or better. All 13 test products were enzymatically active, without failure. This general path to produce functional malaria proteins should now allow the community to access new tools, such as biologically active protein arrays, and lead to the discovery of new chemical functions, structures, and inhibitors of previously inaccessible malaria gene products.
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Sun R, Wang L. Inhibition of Mycoplasma pneumoniae growth by FDA-approved anticancer and antiviral nucleoside and nucleobase analogs. BMC Microbiol 2013; 13:184. [PMID: 23919755 PMCID: PMC3750255 DOI: 10.1186/1471-2180-13-184] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 07/24/2013] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Mycoplasma pneumoniae (Mpn) is a human pathogen that causes acute and chronic respiratory diseases and has been linked to many extrapulmonary diseases. Due to the lack of cell wall, Mpn is resistant to antibiotics targeting cell wall synthesis such as penicillin. During the last 10 years macrolide-resistant Mpn strains have been frequently reported in Asian countries and have been spreading to Europe and the United States. Therefore, new antibiotics are needed. In this study, 30 FDA-approved anticancer or antiviral drugs were screened for inhibitory effects on Mpn growth and selected analogs were further characterized by inhibition of target enzymes and metabolism of radiolabeled substrates. RESULTS Sixteen drugs showed varying inhibitory effects and seven showed strong inhibition of Mpn growth. The anticancer drug 6-thioguanine had a MIC (minimum inhibitory concentration required to cause 90% of growth inhibition) value of 0.20 μg ml(-1), whereas trifluorothymidine, gemcitabine and dipyridamole had MIC values of approximately 2 μg ml(-1). In wild type Mpn culture the presence of 6-thioguanine and dipyridamole strongly inhibited the uptake and metabolism of hypoxanthine and guanine while gemcitabine inhibited the uptake and metabolism of all nucleobases and thymidine. Trifluorothymidine and 5-fluorodeoxyuridine, however, stimulated the uptake and incorporation of radiolabeled thymidine and this stimulation was due to induction of thymidine kinase activity. Furthermore, Mpn hypoxanthine guanine phosphoribosyl transferase (HPRT) was cloned, expressed, and characterized. The 6-thioguanine, but not other purine analogs, strongly inhibited HPRT, which may in part explain the observed growth inhibition. Trifluorothymidine and 5-fluorodeoxyuridine were shown to be good substrates and inhibitors for thymidine kinase from human and Mycoplasma sources. CONCLUSION We have shown that several anticancer and antiviral nucleoside and nucleobase analogs are potent inhibitors of Mpn growth and that the mechanism of inhibition are most likely due to inhibition of enzymes in the nucleotide biosynthesis pathway and nucleoside transporter. Our results suggest that enzymes in Mycoplasma nucleotide biosynthesis are potential targets for future design of antibiotics against Mycoplasma infection.
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Affiliation(s)
- Ren Sun
- Department of Anatomy, Physiology, and Biochemistry, Swedish University of Agricultural Sciences, The Biomedical Centre, Box 575, SE-751 23 Uppsala, Sweden
| | - Liya Wang
- Department of Anatomy, Physiology, and Biochemistry, Swedish University of Agricultural Sciences, The Biomedical Centre, Box 575, SE-751 23 Uppsala, Sweden
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Drug repurposing screen reveals FDA-approved inhibitors of human HMG-CoA reductase and isoprenoid synthesis that block Cryptosporidium parvum growth. Antimicrob Agents Chemother 2013; 57:1804-14. [PMID: 23380723 DOI: 10.1128/aac.02460-12] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cryptosporidiosis, a diarrheal disease usually caused by Cryptosporidium parvum or Cryptosporidium hominis in humans, can result in fulminant diarrhea and death in AIDS patients and chronic infection and stunting in children. Nitazoxanide, the current standard of care, has limited efficacy in children and is no more effective than placebo in patients with advanced AIDS. Unfortunately, the lack of financial incentives and the technical difficulties associated with working with Cryptosporidium parasites have crippled efforts to develop effective treatments. In order to address these obstacles, we developed and validated (Z' score = 0.21 to 0.47) a cell-based high-throughput assay and screened a library of drug repurposing candidates (the NIH Clinical Collections), with the hopes of identifying safe, FDA-approved drugs to treat cryptosporidiosis. Our screen yielded 21 compounds with confirmed activity against C. parvum growth at concentrations of <10 μM, many of which had well-defined mechanisms of action, making them useful tools to study basic biology in addition to being potential therapeutics. Additional work, including structure-activity relationship studies, identified the human 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase inhibitor itavastatin as a potent inhibitor of C. parvum growth (50% inhibitory concentration [IC(50)] = 0.62 μM). Bioinformatic analysis of the Cryptosporidium genomes indicated that the parasites lack all known enzymes required for the synthesis of isoprenoid precursors. Additionally, itavastatin-induced growth inhibition of C. parvum was partially reversed by the addition of exogenous isopentenyl pyrophosphate, suggesting that itavastatin reduces Cryptosporidium growth via on-target inhibition of host HMG-CoA reductase and that the parasite is dependent on the host cell for synthesis of isoprenoid precursors.
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Johnson CR, Gorla SK, Kavitha M, Zhang M, Liu X, Striepen B, Mead JR, Cuny GD, Hedstrom L. Phthalazinone inhibitors of inosine-5'-monophosphate dehydrogenase from Cryptosporidium parvum. Bioorg Med Chem Lett 2012; 23:1004-7. [PMID: 23324406 DOI: 10.1016/j.bmcl.2012.12.037] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 12/10/2012] [Accepted: 12/13/2012] [Indexed: 11/27/2022]
Abstract
Cryptosporidium parvum (Cp) is a potential biowarfare agent and major cause of diarrhea and malnutrition. This protozoan parasite relies on inosine 5'-monophosphate dehydrogenase (IMPDH) for the production of guanine nucleotides. A CpIMPDH-selective N-aryl-3,4-dihydro-3-methyl-4-oxo-1-phthalazineacetamide inhibitor was previously identified in a high throughput screening campaign. Herein we report a structure-activity relationship study for the phthalazinone-based series that resulted in the discovery of benzofuranamide analogs that exhibit low nanomolar inhibition of CpIMPDH. In addition, the antiparasitic activity of select analogs in a Toxoplasma gondii model of C. parvum infection is also presented.
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Affiliation(s)
- Corey R Johnson
- Department of Chemistry, Brandeis University, MS009, 415 South Street, Waltham, MA 02454, USA
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