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Nué-Martinez JJ, Cisneros D, Moreno-Blázquez MD, Fonseca-Berzal C, Manzano JI, Kraeutler D, Ungogo MA, Aloraini MA, Elati HAA, Ibáñez-Escribano A, Lagartera L, Herraiz T, Gamarro F, de Koning HP, Gómez-Barrio A, Dardonville C. Synthesis and Biophysical and Biological Studies of N-Phenylbenzamide Derivatives Targeting Kinetoplastid Parasites. J Med Chem 2023; 66:13452-13480. [PMID: 37729094 PMCID: PMC10578353 DOI: 10.1021/acs.jmedchem.3c00697] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Indexed: 09/22/2023]
Abstract
The AT-rich mitochondrial DNA (kDNA) of trypanosomatid parasites is a target of DNA minor groove binders. We report the synthesis, antiprotozoal screening, and SAR studies of three series of analogues of the known antiprotozoal kDNA binder 2-((4-(4-((4,5-dihydro-1H-imidazol-3-ium-2-yl)amino)benzamido)phenyl)amino)-4,5-dihydro-1H-imidazol-3-ium (1a). Bis(2-aminoimidazolines) (1) and bis(2-aminobenzimidazoles) (2) showed micromolar range activity against Trypanosoma brucei, whereas bisarylimidamides (3) were submicromolar inhibitors of T. brucei, Trypanosoma cruzi, and Leishmania donovani. None of the compounds showed relevant activity against the urogenital, nonkinetoplastid parasite Trichomonas vaginalis. We show that series 1 and 3 bind strongly and selectively to the minor groove of AT DNA, whereas series 2 also binds by intercalation. The measured pKa indicated different ionization states at pH 7.4, which correlated with the DNA binding affinities (ΔTm) for series 2 and 3. Compound 3a, which was active and selective against the three parasites and displayed adequate metabolic stability, is a fine candidate for in vivo studies.
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Affiliation(s)
- J. Jonathan Nué-Martinez
- Instituto
de Química Médica, IQM−CSIC, Juan de la Cierva 3, E-28006 Madrid, Spain
- PhD
Programme in Medicinal Chemistry, Doctoral School, Universidad Complutense de Madrid (UCM), 28040 Madrid, Spain
| | - David Cisneros
- Instituto
de Química Médica, IQM−CSIC, Juan de la Cierva 3, E-28006 Madrid, Spain
- PhD
Programme in Medicinal Chemistry, Doctoral School, Universidad Complutense de Madrid (UCM), 28040 Madrid, Spain
| | | | - Cristina Fonseca-Berzal
- Departamento
de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid (UCM), Plaza de Ramón y Cajal s/n, 28040 Madrid, Spain
| | - José Ignacio Manzano
- Instituto
de Parasitología y Biomedicina “Löpez Neyra”,
IPBLN-CSIC, Parque Tecnolögico
de Ciencias de la Salud, 18016 Granada, Spain
| | - Damien Kraeutler
- Instituto
de Química Médica, IQM−CSIC, Juan de la Cierva 3, E-28006 Madrid, Spain
| | - Marzuq A. Ungogo
- Institute
of Infection, Immunity and Inflammation, College of Medical, Veterinary
and Life Sciences, University of Glasgow, G12 8TA Glasgow, U.K.
| | - Maha A. Aloraini
- Institute
of Infection, Immunity and Inflammation, College of Medical, Veterinary
and Life Sciences, University of Glasgow, G12 8TA Glasgow, U.K.
| | - Hamza A. A. Elati
- Institute
of Infection, Immunity and Inflammation, College of Medical, Veterinary
and Life Sciences, University of Glasgow, G12 8TA Glasgow, U.K.
| | - Alexandra Ibáñez-Escribano
- Departamento
de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid (UCM), Plaza de Ramón y Cajal s/n, 28040 Madrid, Spain
| | - Laura Lagartera
- Instituto
de Química Médica, IQM−CSIC, Juan de la Cierva 3, E-28006 Madrid, Spain
| | - Tomás Herraiz
- Instituto
de Ciencia y Tecnología de Alimentos y Nutrición, ICTAN−CSIC, José Antonio Novais 10, Ciudad
Universitaria, 28040 Madrid, Spain
| | - Francisco Gamarro
- Instituto
de Parasitología y Biomedicina “Löpez Neyra”,
IPBLN-CSIC, Parque Tecnolögico
de Ciencias de la Salud, 18016 Granada, Spain
| | - Harry P. de Koning
- Institute
of Infection, Immunity and Inflammation, College of Medical, Veterinary
and Life Sciences, University of Glasgow, G12 8TA Glasgow, U.K.
| | - Alicia Gómez-Barrio
- Departamento
de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid (UCM), Plaza de Ramón y Cajal s/n, 28040 Madrid, Spain
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Moreno-Herrera A, Cortez-Maya S, Bocanegra-Garcia V, Banik BK, Rivera G. Recent Advances in the Development of Broad-Spectrum Antiprotozoal Agents. Curr Med Chem 2021; 28:583-606. [PMID: 32124688 DOI: 10.2174/0929867327666200303170000] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 11/05/2019] [Accepted: 01/01/2020] [Indexed: 11/22/2022]
Abstract
Infections caused by Trypanosoma brucei, Trypanosoma cruzi, Leishmania spp., Entamoeba histolytica, Giardia lamblia, Plasmodium spp., and Trichomonas vaginalis, are part of a large list of human parasitic diseases. Together, they cause more than 500 million infections per year. These protozoa parasites affect both low- and high-income countries and their pharmacological treatments are limited. Therefore, new and more effective drugs in preclinical development could improve overall therapy for parasitic infections even when their mechanisms of action are unknown. In this review, a number of heterocyclic compounds (diamidine, guanidine, quinoline, benzimidazole, thiazole, diazanaphthalene, and their derivatives) reported as antiprotozoal agents are discussed as options for developing new pharmacological treatments for parasitic diseases.
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Affiliation(s)
- Antonio Moreno-Herrera
- Laboratorio de Biotecnologia Farmaceutica, Centro de Biotecnologia Genomica, Instituto Politecnico Nacional, Reynosa 88710, Mexico
| | - Sandra Cortez-Maya
- Instituto de Quimica, Universidad Nacional Autonoma de Mexico, Cd. Universitaria, Circuito Exterior, Coyoacan, Ciudad de Mexico 04510, Mexico
| | - Virgilio Bocanegra-Garcia
- Laboratorio de Biotecnologia Farmaceutica, Centro de Biotecnologia Genomica, Instituto Politecnico Nacional, Reynosa 88710, Mexico
| | - Bimal Krishna Banik
- Department of Mathematics and Natural Sciences, College of Sciences and Human Studies, Deanship of Research, Prince Mohammad Bin Fahd University, Al Khobar, Saudi Arabia
| | - Gildardo Rivera
- Laboratorio de Biotecnologia Farmaceutica, Centro de Biotecnologia Genomica, Instituto Politecnico Nacional, Reynosa 88710, Mexico
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3
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Lee SM, Kim MS, Hayat F, Shin D. Recent Advances in the Discovery of Novel Antiprotozoal Agents. Molecules 2019; 24:E3886. [PMID: 31661934 PMCID: PMC6864685 DOI: 10.3390/molecules24213886] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 10/15/2019] [Accepted: 10/23/2019] [Indexed: 11/16/2022] Open
Abstract
Parasitic diseases have serious health, social, and economic impacts, especially in the tropical regions of the world. Diseases caused by protozoan parasites are responsible for considerable mortality and morbidity, affecting more than 500 million people worldwide. Globally, the burden of protozoan diseases is increasing and is been exacerbated because of a lack of effective medication due to the drug resistance and toxicity of current antiprotozoal agents. These limitations have prompted many researchers to search for new drugs against protozoan parasites. In this review, we have compiled the latest information (2012-2017) on the structures and pharmacological activities of newly developed organic compounds against five major protozoan diseases, giardiasis, leishmaniasis, malaria, trichomoniasis, and trypanosomiasis, with the aim of showing recent advances in the discovery of new antiprotozoal drugs.
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Affiliation(s)
- Seong-Min Lee
- College of Pharmacy, Gachon University, 191 Hambakmoe-ro, Yeonsu-gu, Incheon 21936, Korea.
| | - Min-Sun Kim
- College of Pharmacy, Gachon University, 191 Hambakmoe-ro, Yeonsu-gu, Incheon 21936, Korea.
| | - Faisal Hayat
- College of Pharmacy, Gachon University, 191 Hambakmoe-ro, Yeonsu-gu, Incheon 21936, Korea.
| | - Dongyun Shin
- College of Pharmacy, Gachon University, 191 Hambakmoe-ro, Yeonsu-gu, Incheon 21936, Korea.
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Rahman A, O'Sullivan P, Rozas I. Recent developments in compounds acting in the DNA minor groove. MEDCHEMCOMM 2018; 10:26-40. [PMID: 30774852 DOI: 10.1039/c8md00425k] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 12/11/2018] [Indexed: 12/12/2022]
Abstract
The macromolecule that carries genetic information, DNA, is considered as an exceptional target for diseases depending on cellular division of malignant cells (i.e. cancer), microbes (i.e. bacteria) or parasites (i.e. protozoa). To aim for a comprehensive review to cover all aspects related to DNA targeting would be an impossible task and, hence, the objective of the present review is to present, from a medicinal chemistry point of view, recent developments of compounds targeting the minor groove of DNA. Accordingly, we discuss the medicinal chemistry aspects of heterocyclic small-molecules binding the DNA minor groove, as novel anticancer, antibacterial and antiparasitic agents.
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Affiliation(s)
- Adeyemi Rahman
- School of Chemistry , Trinity Biomedical Sciences Institute , Trinity College Dublin , 152-160-Pearse Street , Dublin 2 , Ireland .
| | - Patrick O'Sullivan
- School of Chemistry , Trinity Biomedical Sciences Institute , Trinity College Dublin , 152-160-Pearse Street , Dublin 2 , Ireland .
| | - Isabel Rozas
- School of Chemistry , Trinity Biomedical Sciences Institute , Trinity College Dublin , 152-160-Pearse Street , Dublin 2 , Ireland .
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Millan CR, Acosta-Reyes FJ, Lagartera L, Ebiloma GU, Lemgruber L, Nué Martínez JJ, Saperas N, Dardonville C, de Koning HP, Campos JL. Functional and structural analysis of AT-specific minor groove binders that disrupt DNA-protein interactions and cause disintegration of the Trypanosoma brucei kinetoplast. Nucleic Acids Res 2017. [PMID: 28637278 PMCID: PMC5737332 DOI: 10.1093/nar/gkx521] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Trypanosoma brucei, the causative agent of sleeping sickness (Human African Trypanosomiasis, HAT), contains a kinetoplast with the mitochondrial DNA (kDNA), comprising of >70% AT base pairs. This has prompted studies of drugs interacting with AT-rich DNA, such as the N-phenylbenzamide bis(2-aminoimidazoline) derivatives 1 [4-((4,5-dihydro-1H-imidazol-2-yl)amino)-N-(4-((4,5-dihydro-1H-imidazol-2-yl)amino)phenyl)benzamide dihydrochloride] and 2 [N-(3-chloro-4-((4,5-dihydro-1H-imidazol-2-yl)amino)phenyl)-4-((4,5-dihydro-1H-imidazol-2-yl)amino)benzamide] as potential drugs for HAT. Both compounds show in vitro effects against T. brucei and in vivo curative activity in a mouse model of HAT. The main objective was to identify their cellular target inside the parasite. We were able to demonstrate that the compounds have a clear effect on the S-phase of T. brucei cell cycle by inflicting specific damage on the kinetoplast. Surface plasmon resonance (SPR)–biosensor experiments show that the drug can displace HMG box-containing proteins essential for kDNA function from their kDNA binding sites. The crystal structure of the complex of the oligonucleotide d[AAATTT]2 with compound 1 solved at 1.25 Å (PDB-ID: 5LIT) shows that the drug covers the minor groove of DNA, displaces bound water and interacts with neighbouring DNA molecules as a cross-linking agent. We conclude that 1 and 2 are powerful trypanocides that act directly on the kinetoplast, a structure unique to the order Kinetoplastida.
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Affiliation(s)
- Cinthia R Millan
- Departament d'Enginyeria Química, EEBE, Universitat Politècnica de Catalunya, 08019 Barcelona, Spain
| | - Francisco J Acosta-Reyes
- Departament d'Enginyeria Química, EEBE, Universitat Politècnica de Catalunya, 08019 Barcelona, Spain
| | | | - Godwin U Ebiloma
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, UK
| | - Leandro Lemgruber
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, UK.,The Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow G12 8TA, UK
| | | | - Núria Saperas
- Departament d'Enginyeria Química, EEBE, Universitat Politècnica de Catalunya, 08019 Barcelona, Spain
| | | | - Harry P de Koning
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, UK
| | - J Lourdes Campos
- Departament d'Enginyeria Química, EEBE, Universitat Politècnica de Catalunya, 08019 Barcelona, Spain
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Alkhaldi AAM, Martinek J, Panicucci B, Dardonville C, Zíková A, de Koning HP. Trypanocidal action of bisphosphonium salts through a mitochondrial target in bloodstream form Trypanosoma brucei. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2015; 6:23-34. [PMID: 27054061 PMCID: PMC4805778 DOI: 10.1016/j.ijpddr.2015.12.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 12/03/2015] [Accepted: 12/07/2015] [Indexed: 12/21/2022]
Abstract
Lipophilic bisphosphonium salts are among the most promising antiprotozoal leads currently under investigation. As part of their preclinical evaluation we here report on their mode of action against African trypanosomes, the etiological agents of sleeping sickness. The bisphosphonium compounds CD38 and AHI-9 exhibited rapid inhibition of Trypanosoma brucei growth, apparently the result of cell cycle arrest that blocked the replication of mitochondrial DNA, contained in the kinetoplast, thereby preventing the initiation of S-phase. Incubation with either compound led to a rapid reduction in mitochondrial membrane potential, and ATP levels decreased by approximately 50% within 1 h. Between 4 and 8 h, cellular calcium levels increased, consistent with release from the depolarized mitochondria. Within the mitochondria, the Succinate Dehydrogenase complex (SDH) was investigated as a target for bisphosphonium salts, but while its subunit 1 (SDH1) was present at low levels in the bloodstream form trypanosomes, the assembled complex was hardly detectable. RNAi knockdown of the SDH1 subunit produced no growth phenotype, either in bloodstream or in the procyclic (insect) forms and we conclude that in trypanosomes SDH is not the target for bisphosphonium salts. Instead, the compounds inhibited ATP production in intact mitochondria, as well as the purified F1 ATPase, to a level that was similar to 1 mM azide. Co-incubation with azide and bisphosphonium compounds did not inhibit ATPase activity more than either product alone. The results show that, in T. brucei, bisphosphonium compounds do not principally act on succinate dehydrogenase but on the mitochondrial FoF1 ATPase. Bisphosphonium salts display highly promising antiprotozoal activity. It has been reported that, in Leishmania, they act on the mitochondrial SDH complex. We show that in Trypanosoma brucei SDH is not essential and not the drug target. Instead, we present strong evidence that the F1F0 ATPase is the target.
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Affiliation(s)
- Abdulsalam A M Alkhaldi
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Jan Martinek
- Institute of Parasitology, Biology Centre & Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Brian Panicucci
- Institute of Parasitology, Biology Centre & Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | | | - Alena Zíková
- Institute of Parasitology, Biology Centre & Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.
| | - Harry P de Koning
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.
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Lowering the pKa of a bisimidazoline lead with halogen atoms results in improved activity and selectivity against Trypanosoma brucei in vitro. Eur J Med Chem 2015; 101:806-17. [PMID: 26231081 DOI: 10.1016/j.ejmech.2015.07.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 07/03/2015] [Accepted: 07/07/2015] [Indexed: 11/20/2022]
Abstract
Diphenyl-based bis(2-iminoimidazolidines) are promising antiprotozoal agents that are curative in mouse models of stage 1 trypanosomiasis but devoid of activity in the late-stage disease, possibly due to poor brain penetration caused by their dicationic nature. We present here a strategy consisting in reducing the pKa of the basic 2-iminoimidazolidine groups though the introduction of chlorophenyl, fluorophenyl and pyridyl ring in the structure of the trypanocidal lead 4-(imidazolidin-2-ylideneamino)-N-(4-(imidazolidin-2-ylideneamino)phenyl)benzamide (1). The new compounds showed reduced pKa values (in the range 1-3 pKa units) for the imidazolidine group linked to the substituted phenyl ring. In vitro activities (EC50) against wild type and resistant strains of T. b. brucei (s427 and B48, respectively) were in the submicromolar range with four compounds being more active and selective than 1 (SI > 340). In particular, the two most potent compounds (3b and 5a) acted approximately 6-times faster than 1 to kill trypanosomes in vitro. No cross-resistance with the diamidine and melaminophenyl class of trypanocides was observed indicating that these compounds represent interesting leads for further in vivo studies.
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Montalvo-Quirós S, Taladriz-Sender A, Kaiser M, Dardonville C. Antiprotozoal activity and DNA binding of dicationic acridones. J Med Chem 2015; 58:1940-9. [PMID: 25642604 DOI: 10.1021/jm5018303] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dicationic acridone derivatives were synthesized and their antiparasitic activity was evaluated. Acridones displayed in vitro nanomolar IC50 values against Trypanosoma brucei rhodesiense STIB900 with selectivity indices >1000. Compounds 1b, 3a, and 3b were as potent as the reference drug melarsoprol in this assay. Submicromolar-range activities were observed against wild-type (NF54) and resistant (K1) strains of Plasmodium falciparum, whereas no significant activity was detected against Trypanosoma cruzi or Leishmania donovani. Compounds 1a and 1b were curative in the STIB900 mouse model for human African trypanosomiasis. UV spectrophotometric titrations and circular dichroism (CD) experiments with fish sperm (FS) DNA showed that these compounds form complexes with DNA with binding affinities in the 10(4) M(-1) range. Biological and biophysical data show that antiparasitic activity, toxicity, and DNA binding of this series of acridones are dependent on the relative position of both imidazolinium cations on the heterocyclic scaffold.
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Affiliation(s)
- Sandra Montalvo-Quirós
- Instituto de Química Médica, Consejo Superior de Investigaciones Científicas (IQM-CSIC) , Juan de la Cierva 3, E-28006 Madrid, Spain
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Ríos Martínez CH, Lagartera L, Trujillo C, Dardonville C. Bisimidazoline arylamides binding to the DNA minor groove: N1-hydroxylation enhances binding affinity and selectivity to AATT sites. MEDCHEMCOMM 2015. [DOI: 10.1039/c5md00292c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Selective binding of N-hydroxy bisimidazolines to dsDNA GCAATTGC is derived from a tighter fit to this narrower minor groove.
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Affiliation(s)
| | | | - Cristina Trujillo
- School of Chemistry
- Trinity Biomedical Sciences Institute
- Trinity College Dublin
- Dublin 2
- Ireland
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Moreno-Fuquen R, Melo V, Ellena J. Crystal structure of 4-bromo-N-(2-hydroxy-phen-yl)benzamide. Acta Crystallogr Sect E Struct Rep Online 2014; 70:o1261-2. [PMID: 25553033 PMCID: PMC4257397 DOI: 10.1107/s1600536814024696] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 11/10/2014] [Indexed: 06/04/2023]
Abstract
In the title compound, C13H10BrNO2, the mean plane of the non-H atoms of the central amide C-N-C(=O)-C fragment (r.m.s. deviation = 0.004 Å) forms a dihedral angle of 73.97 (12)° with the hy-droxy-substituted benzene ring and 25.42 (19)° with the bromo-substituted benzene ring. The two aromatic rings are inclined to one another by 80.7 (2)°. In the crystal, mol-ecules are linked by O-H⋯O and N-H⋯O hydrogen bonds, forming chains along [010]. The chains are linked by weak C-H⋯O hydrogen bonds, forming sheets parallel to (100), and enclosing R (3) 3(17) and R (3) 2(9) ring motifs.
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Affiliation(s)
- Rodolfo Moreno-Fuquen
- Departamento de Química – Facultad de Ciencias Naturales y Exactas, Universidad del Valle, Apartado 25360, Santiago de Cali, Colombia
| | - Vanessa Melo
- Departamento de Química – Facultad de Ciencias Naturales y Exactas, Universidad del Valle, Apartado 25360, Santiago de Cali, Colombia
| | - Javier Ellena
- Instituto de Física de São Carlos, IFSC, Universidade de São Paulo, USP, São Carlos, SP, Brazil
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A new nonpolar N-hydroxy imidazoline lead compound with improved activity in a murine model of late-stage Trypanosoma brucei brucei infection is not cross-resistant with diamidines. Antimicrob Agents Chemother 2014; 59:890-904. [PMID: 25421467 DOI: 10.1128/aac.03958-14] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Treatment of late-stage sleeping sickness requires drugs that can cross the blood-brain barrier (BBB) to reach the parasites located in the brain. We report here the synthesis and evaluation of four new N-hydroxy and 12 new N-alkoxy derivatives of bisimidazoline leads as potential agents for the treatment of late-stage sleeping sickness. These compounds, which have reduced basicity compared to the parent leads (i.e., are less ionized at physiological pH), were evaluated in vitro against Trypanosoma brucei rhodesiense and in vivo in murine models of first- and second-stage sleeping sickness. Resistance profile, physicochemical parameters, in vitro BBB permeability, and microsomal stability also were determined. The N-hydroxy imidazoline analogues were the most effective in vivo, with 4-((1-hydroxy-4,5-dihydro-1H-imidazol-2-yl)amino)-N-(4-((1-hydroxy-4,5-dihydro-1H-imidazol-2-yl)amino)phenyl)benzamide (14d) showing 100% cures in the first-stage disease, while 15d, 16d, and 17d appeared to slightly improve survival. In addition, 14d showed weak activity in the chronic model of central nervous system infection in mice. No evidence of reduction of this compound with hepatic microsomes and mitochondria was found in vitro, suggesting that N-hydroxy imidazolines are metabolically stable and have intrinsic activity against T. brucei. In contrast to its unsubstituted parent compound, the uptake of 14d in T. brucei was independent of known drug transporters (i.e., T. brucei AT1/P2 and HAPT), indicating a lower predisposition to cross-resistance with other diamidines and arsenical drugs. Hence, the N-hydroxy bisimidazolines (14d in particular) represent a new class of promising antitrypanosomal agents.
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