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Dos Santos Nascimento IJ, Albino SL, da Silva Menezes KJ, de Azevedo Teotônio Cavalcanti M, de Oliveira MS, Mali SN, de Moura RO. Targeting SmCB1: Perspectives and Insights to Design Antischistosomal Drugs. Curr Med Chem 2024; 31:2264-2284. [PMID: 37921174 DOI: 10.2174/0109298673255826231011114249] [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: 03/31/2023] [Revised: 09/01/2023] [Accepted: 09/14/2023] [Indexed: 11/04/2023]
Abstract
Neglected tropical diseases (NTDs) are prevalent in tropical and subtropical countries, and schistosomiasis is among the most relevant diseases worldwide. In addition, one of the two biggest problems in developing drugs against this disease is related to drug resistance, which promotes the demand to develop new drug candidates for this purpose. Thus, one of the drug targets most explored, Schistosoma mansoni Cathepsin B1 (SmCB1 or Sm31), provides new opportunities in drug development due to its essential functions for the parasite's survival. In this way, here, the latest developments in drug design studies targeting SmCB1 were approached, focusing on the most promising analogs of nitrile, vinyl sulphones, and peptidomimetics. Thus, it was shown that despite being a disease known since ancient times, it remains prevalent throughout the world, with high mortality rates. The therapeutic arsenal of antischistosomal drugs (ASD) consists only of praziquantel, which is widely used for this purpose and has several advantages, such as efficacy and safety. However, it has limitations, such as the impossibility of acting on the immature worm and exploring new targets to overcome these limitations. SmCB1 shows its potential as a cysteine protease with a catalytic triad consisting of Cys100, His270, and Asn290. Thus, design studies of new inhibitors focus on their catalytic mechanism for designing new analogs. In fact, nitrile and sulfonamide analogs show the most significant potential in drug development, showing that these chemical groups can be better exploited in drug discovery against schistosomiasis. We hope this manuscript guides the authors in searching for promising new antischistosomal drugs.
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Affiliation(s)
- Igor José Dos Santos Nascimento
- Pharmacy Department, Cesmac University Center, Maceió, 57051-160, Brazil
- Laboratório de Desenvolvimento e Síntese de Fármacos, Departamento de Farmácia, Universidade Estadual da Paraíba, Campina Grande 58429-500, Brazil
- Programa de Pós Graduação em Ciências Farmacêuticas, Universidade Estadual da Paraíba, Campina Grande, 58429-500, Brazil
| | - Sonaly Lima Albino
- Laboratório de Desenvolvimento e Síntese de Fármacos, Departamento de Farmácia, Universidade Estadual da Paraíba, Campina Grande 58429-500, Brazil
| | - Karla Joane da Silva Menezes
- Laboratório de Desenvolvimento e Síntese de Fármacos, Departamento de Farmácia, Universidade Estadual da Paraíba, Campina Grande 58429-500, Brazil
- Programa de Pós Graduação em Ciências Farmacêuticas, Universidade Estadual da Paraíba, Campina Grande, 58429-500, Brazil
| | - Misael de Azevedo Teotônio Cavalcanti
- Laboratório de Desenvolvimento e Síntese de Fármacos, Departamento de Farmácia, Universidade Estadual da Paraíba, Campina Grande 58429-500, Brazil
- Programa de Pós Graduação em Ciências Farmacêuticas, Universidade Estadual da Paraíba, Campina Grande, 58429-500, Brazil
| | - Mozaniel Santana de Oliveira
- Coordination of Botany-Laboratory Adolpho Ducke, Avenida Perimetral, Museu Paraense Emílio Goeldi, 1901, Belém, 66077-530, PA Brazil
| | - Suraj N Mali
- Department of Pharmaceutical Sciences and Technology, Institute of Chemical Technology, Matunga East, Mumbai, 400019, India
| | - Ricardo Olimpio de Moura
- Laboratório de Desenvolvimento e Síntese de Fármacos, Departamento de Farmácia, Universidade Estadual da Paraíba, Campina Grande 58429-500, Brazil
- Programa de Pós Graduação em Ciências Farmacêuticas, Universidade Estadual da Paraíba, Campina Grande, 58429-500, Brazil
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Silva DVSPD, Nascimento PHDB, Rocha JVRD, Marques DSC, Brayner FA, Alves LC, Araújo HDAD, Cruz Filho IJD, Albuquerque MCPDA, Lima MDCAD, Aires ADL. In vitro activity, ultrastructural analysis and in silico pharmacokinetic properties (ADMET) of thiazole compounds against adult worms of Schistosoma mansoni. Acta Trop 2023; 245:106965. [PMID: 37295486 DOI: 10.1016/j.actatropica.2023.106965] [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: 04/12/2023] [Revised: 06/03/2023] [Accepted: 06/06/2023] [Indexed: 06/12/2023]
Abstract
The present work aimed to carry out in vitro biological assays of thiazole compounds against adult worms of Schistosoma mansoni, as well as the in silico determination of pharmacokinetic parameters to predict the oral bioavailability of these compounds. In addition to presenting moderate to low cytotoxicity against mammalian cells, thiazole compounds are not considered hemolytic. All compounds were initially tested at concentrations ranging from 200 to 6.25 μM against adult worms of S. mansoni parasites. The results showed the best activity of PBT2 and PBT5 at a concentration of 200 μM, which caused 100% mortality after 3 h of incubation. While at 6 h of exposure, 100% mortality was observed at the concentration of 100 µM. Subsequent studies with these same compounds allowed classifying PBT5, PBT2, PBT6 and PBT3 compounds, which were considered active and PBT1 and PBT4 compounds, which were considered inactive. In the ultrastructural analysis the compounds PBT2 and PBT5 (200 µM) promoted integumentary changes with exposure of the muscles, formation of integumentary blisters, integuments with abnormal morphology and destruction of tubercles and spicules. Therefore, the compounds PBT2 and PBT5 are promising antiparasitics against S. mansoni.
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Affiliation(s)
| | - Pedro Henrique do Bomfim Nascimento
- Departamento de Antibióticos, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego, 1235 - Cidade Universitária, CEP 50.670-901, Recife, PE, Brazil
| | - João Victor Ritinto da Rocha
- Centro de Ciências Médicas - Programa de Pós-graduação em Medicina Tropical, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Diego Santa Clara Marques
- Departamento de Antibióticos, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego, 1235 - Cidade Universitária, CEP 50.670-901, Recife, PE, Brazil
| | - Fábio André Brayner
- Departamento de Parasitologia, Instituto Aggeu Magalhães, Avenida Prof. Moraes Rego, 1235, Cidade Universitária. CEP 50670-901, Recife, PE, Brazil; Instituto Keizo Asami - iLIKA, UFPE, Av. Prof. Moraes Rego, 1235 - Cidade Universitária, CEP 50670-901, Recife-PE, Brazil
| | - Luiz Carlos Alves
- Departamento de Parasitologia, Instituto Aggeu Magalhães, Avenida Prof. Moraes Rego, 1235, Cidade Universitária. CEP 50670-901, Recife, PE, Brazil; Instituto Keizo Asami - iLIKA, UFPE, Av. Prof. Moraes Rego, 1235 - Cidade Universitária, CEP 50670-901, Recife-PE, Brazil
| | - Hallysson Douglas Andrade de Araújo
- Instituto Keizo Asami - iLIKA, UFPE, Av. Prof. Moraes Rego, 1235 - Cidade Universitária, CEP 50670-901, Recife-PE, Brazil; Departamento de Bioquímica. Universidade Federal de Pernambuco, Av. Prof. Moraes Rego, 1235 - Cidade Universitária, CEP 50.670-901, Recife, PE, Brazil
| | - Iranildo José da Cruz Filho
- Centro de Biociências, Programa de Pós-graduação em Morfotecnologia, Universidade Federal de Pernambuco, Recife, Brazil; Departamento de Antibióticos, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego, 1235 - Cidade Universitária, CEP 50.670-901, Recife, PE, Brazil
| | | | - Maria do Carmo Alves de Lima
- Departamento de Parasitologia, Instituto Aggeu Magalhães, Avenida Prof. Moraes Rego, 1235, Cidade Universitária. CEP 50670-901, Recife, PE, Brazil
| | - André de Lima Aires
- Centro de Biociências, Programa de Pós-graduação em Morfotecnologia, Universidade Federal de Pernambuco, Recife, Brazil; Centro de Ciências Médicas - Programa de Pós-graduação em Medicina Tropical, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil; Instituto Keizo Asami - iLIKA, UFPE, Av. Prof. Moraes Rego, 1235 - Cidade Universitária, CEP 50670-901, Recife-PE, Brazil.
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Leussa ANN, Rautenbach M. Antiplasmodial Cyclodecapeptides from Tyrothricin Share a Target with Chloroquine. Antibiotics (Basel) 2022; 11:antibiotics11060801. [PMID: 35740207 PMCID: PMC9219824 DOI: 10.3390/antibiotics11060801] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 06/03/2022] [Accepted: 06/09/2022] [Indexed: 12/10/2022] Open
Abstract
Previous research found that the six major cyclodecapeptides from the tyrothricin complex, produced by Brevibacillus parabrevis, showed potent activity against chloroquine sensitive (CQS) Plasmodium falciparum. The identity of the aromatic residues in the aromatic dipeptide unit in cyclo-(D-Phe1-Pro2-(Phe3/Trp3)-D-Phe4/D-Trp4)-Asn5-Gln6-(Tyr7/Phe7/Trp7)-Val8-(Orn9/Lys9)-Leu10 was proposed to have an important role in activity. CQS and resistant (CQR) P. falciparum strains were challenged with three representative cyclodecapeptides. Our results confirmed that cyclodecapeptides from tyrothricin had significantly higher antiplasmodial activity than the analogous gramicidin S, rivaling that of CQ. However, the previously hypothesized size and hydrophobicity dependent activity for these peptides did not hold true for P. falciparum strains, other than for the CQS 3D7 strain. The Tyr7 in tyrocidine A (TrcA) with Phe3-D-Phe4 seem to be related with loss in activity correlating with CQ antagonism and resistance, indicating a shared target and/or resistance mechanism in which the phenolic groups play a role. Phe7 in phenycidine A, the second peptide containing Phe3-D-Phe4, also showed CQ antagonism. Conversely, Trp7 in tryptocidine C (TpcC) with Trp3-D-Trp4 showed improved peptide selectivity and activity towards the more resistant strains, without overt antagonism towards CQ. However, TpcC lead to similar parasite stage inhibition and parasite morphology changes than previously observed for TrcA. The disorganization of chromatin packing and neutral lipid structures, combined with amorphous hemozoin crystals, could account for halted growth in late trophozoite/early schizont stage and the nanomolar non-lytic activity of these peptides. These targets related to CQ antagonism, changes in neural lipid distribution, leading to hemozoin malformation, indicate that the tyrothricin cyclodecapeptides and CQ share a target in the malaria parasite. The differing activities of these cyclic peptides towards CQS and CQR P. falciparum strains could be due to variable target interaction in multiple modes of activity. This indicated that the cyclodecapeptide activity and parasite resistance response depended on the aromatic residues in positions 3, 4 and 7. This new insight on these natural cyclic decapeptides could also benefit the design of unique small peptidomimetics in which activity and resistance can be modulated.
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Kekessie FK, Amengor CDK, Brobbey A, Addotey JN, Danquah CA, Peprah P, Harley BK, Ben IO, Zoiku FK, Borquaye LS, Gasu EN, Ofori-Attah E, Tetteh M. Synthesis, molecular docking studies and ADME prediction of some new triazoles as potential antimalarial agents. SCIENTIFIC AFRICAN 2021. [DOI: 10.1016/j.sciaf.2021.e00998] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Fayyazi N, Esmaeili S, Taheri S, Ribeiro FF, Scotti MT, Scotti L, Ghasemi JB, Saghaei L, Fassihi A. Pharmacophore Modeling, Synthesis, Scaffold Hopping and Biological β- Hematin Inhibition Interaction Studies for Anti-malaria Compounds. Curr Top Med Chem 2020; 19:2743-2765. [DOI: 10.2174/1568026619666191116160326] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 08/02/2019] [Accepted: 10/01/2019] [Indexed: 01/23/2023]
Abstract
Backgound:Exploring potent compounds is critical to generating multi-target drug discovery. Hematin crystallization is an important mechanism of malaria.Methods:A series of chloroquine analogues were designed using a repositioning approach to develop new anticancer compounds. Protein-ligand interaction fingerprints and ADMET descriptors were used to assess docking performance in virtual screenings to design chloroquine hybrid β-hematin inhibitors. A PLS algorithm was applied to correlate the molecular descriptors to IC50 values. The modeling presented excellent predictive power with correlation coefficients for calibration and cross-validation of r2 = 0.93 and q2 = 0.72. Using the model, a series of 4-aminoquinlin hybrids were synthesized and evaluated for their biological activity as an external test series. These compounds were evaluated for cytotoxic cell lines and β-hematin inhibition.Results:The target compounds exhibited high β-hematin inhibition activity and were 3-9 times more active than the positive control. Furthermore, all the compounds exhibited moderate to high cytotoxic activity. The most potent compound in the dataset was docked with hemoglobin and its pharmacophore features were generated. These features were used as input to the Pharmit server for screening of six databases.Conclusion:The compound with the best score from ChEMBL was 2016904, previously reported as a VEGFR-2 inhibitor. The 11 compounds selected presented the best Gold scores with drug-like properties and can be used for drug development.
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Affiliation(s)
- Neda Fayyazi
- Department of Medicinal Chemistry, School of Pharmacy and Pharmaceutical Sciences, Isfahan, Iran
| | - Somayeh Esmaeili
- Traditional Medicine and Medical Material Research Center (TMRC), Shahid beheshti University of Medical Sciences, Tehran, Iran
| | - Salman Taheri
- Chemistry and Chemical Engineering Research Center of Iran, Tehran, Iran
| | - Frederico F. Ribeiro
- Synthesis and Drug Delivery Laboratory, Biological Sciences Department, Paraíba State University, João Pessoa, Brazil
| | | | | | - Jahan B. Ghasemi
- College of Sciences, Faculty of Chemistry, University of Tehran, Tehran, Iran
| | - Lotfollah Saghaei
- Department of Medicinal Chemistry, School of Pharmacy and Pharmaceutical Sciences, Isfahan, Iran
| | - Afshin Fassihi
- Department of Medicinal Chemistry, School of Pharmacy and Pharmaceutical Sciences, Isfahan, Iran
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Ma R, Guo DX, Li HF, Liu HX, Zhang YR, Ji JB, Xing J, Wang SQ. Spectroscopic methodologies and molecular docking studies on the interaction of antimalarial drug piperaquine and its metabolites with human serum albumin. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2019; 222:117158. [PMID: 31181505 DOI: 10.1016/j.saa.2019.117158] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 05/19/2019] [Accepted: 05/25/2019] [Indexed: 06/09/2023]
Abstract
Artemisinin-based combination therapy is widely used for the treatment of uncomplicated Plasmodium falciparum malaria, and piperaquine (PQ) is one of the important partner drugs. During the biotransformation of PQ, M1 (N-oxidation product), M2 (N-oxidation product), M3 (carboxylic acid product), M4 (N-dealkylation product), and M5 (N-oxidated product of M4) are formed by cytochrome P450 pathways. Despite decades of clinical use, the interactions between PQ and its main metabolites (PQs) with human serum albumin (HSA) have not been reported. In the present study, the binding of PQs with HSA under physiological conditions was investigated systematically through fluorescence, circular dichroism (CD) spectroscopy, and molecular docking methods. The experimental results show that the intrinsic fluorescence quenching of HSA was induced by those compounds resulting from the formation of stable HSA-compound complexes. The main forces involved in the interactions between PQ, M1, and M2 which bind to HSA were hydrogen s and van der Waals forces, while the interactions of M3, M4, and M5 were driven by hydrophobic forces. The main binding sites of the compounds to HSA were also examined by classical fluorescent marker experiments and molecular docking studies. Binding constants (Kb) revealed that the affinities of the PQ, M1, M2, M3, and M4 to HSA were stronger than that of M5. Additionally, the binding rates of PQs with HSA were determined by ultrafiltration methods. Consistent with the binding constant results, the binding rate of M5 was lower than the binding rates of PQ, M1, M2, M3, and M4. Furthermore, PQs binding to HSA led to conformational and structural alterations of HSA, as revealed by multi-spectroscopic studies. In order to investigate one possible mechanism by which PQs inhibit the growth of malaria-causing Plasmodium parasites, 1H NMR spectroscopy was performed to investigate the interaction of the PQs with heme. This study is beneficial to enhance our understanding of the ecotoxicology and environmental behaviors of PQ and its metabolites.
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Affiliation(s)
- Rui Ma
- School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China
| | - Dong-Xiao Guo
- Shandong Institute for Food and Drug Control, Jinan, Shandong 250101, China
| | - Hui-Fen Li
- Shandong University of Traditional Chinese Medicine, Jinan, Shandong 250355, China
| | - Hui-Xiang Liu
- School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China
| | - Yun-Rui Zhang
- School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China
| | - Jian-Bo Ji
- School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China
| | - Jie Xing
- School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China
| | - Shu-Qi Wang
- School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China.
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Summers KL. A Structural Chemistry Perspective on the Antimalarial Properties of Thiosemicarbazone Metal Complexes. Mini Rev Med Chem 2019; 19:569-590. [DOI: 10.2174/1389557518666181015152657] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Revised: 06/26/2018] [Accepted: 09/30/2018] [Indexed: 01/14/2023]
Abstract
Malaria is a potentially life-threatening disease, affecting approx. 214 million people worldwide. Malaria is caused by a protozoan, Plasmodium falciparum, which is transmitted through the Anopheles mosquito. Malaria treatment is becoming more challenging due to rising resistance against the antimalarial drug, chloroquine. Novel compounds that target aspects of parasite development are being explored in attempts to overcome this wide-spread problem. Anti-malarial drugs target specific aspects of parasite growth and development within the human host. One of the most effective targets is the inhibition of hematin formation, either through inhibition of cysteine proteases or through iron chelation. Metal-thiosemicarbazone (TSC) complexes have been tested for antimalarial efficacy against drug-sensitive and drug-resistant strains of P. falciparum. An array of TSC complexes with numerous transition metals, including ruthenium, palladium, and gold has displayed antiplasmodial activity. Au(I)- and Pd(II)-TSC complexes displayed the greatest potency; 4-amino-7-chloroquine moieties were also found to improve antiplasmodial activity of TSCs. Although promising metal-TSC drug candidates have been tested against laboratory strains of P. falciparum, problems arise when attempting to compare between studies. Future work should strive to completely characterize synthesized metal-TSC structures and assess antiplasmodial potency against several drug-sensitive and drugresistant strains. Future studies need to precisely determine IC50 values for antimalarial drugs, chloroquine and ferroquine, to establish accurate standard values. This will make future comparisons across studies more feasible and potentially help reveal structure-function relationships. Investigations that attempt to link drug structures or properties to antiplasmodial mechanism(s) of action will aid in the design of antimalarial drugs that may combat rising drug resistance.
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Affiliation(s)
- Kelly L. Summers
- Department of Chemistry, College of Arts and Science, University of Saskatchewan, Saskatoon, SK S7N 5C9, Canada
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Schloetel JG, Heine J, Cowman AF, Pasternak M. Guided STED nanoscopy enables super-resolution imaging of blood stage malaria parasites. Sci Rep 2019; 9:4674. [PMID: 30886187 PMCID: PMC6423018 DOI: 10.1038/s41598-019-40718-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 02/19/2019] [Indexed: 12/27/2022] Open
Abstract
Malaria remains a major burden world-wide, but the disease-causing parasites from the genus Plasmodium are difficult to study in vitro. Owing to the small size of the parasites, subcellular imaging poses a major challenge and the use of super-resolution techniques has been hindered by the parasites' sensitivity to light. This is particularly apparent during the blood-stage of the Plasmodium life cycle, which presents an important target for drug research. The iron-rich food vacuole of the parasite undergoes disintegration when illuminated with high-power lasers such as those required for high resolution in Stimulated Emission Depletion (STED) microscopy. This causes major damage to the sample precluding the use of this super-resolution technique. Here we present guided STED, a novel adaptive illumination (AI) STED approach, which takes advantage of the highly-reflective nature of the iron deposit in the cell to identify the most light-sensitive parts of the sample. Specifically in these parts, the high-power STED laser is deactivated automatically to prevent local damage. Guided STED nanoscopy finally allows super-resolution imaging of the whole Plasmodium life cycle, enabling multicolour imaging of blood-stage malaria parasites with resolutions down to 35 nm without sample destruction.
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Affiliation(s)
| | - Jörn Heine
- Abberior Instruments GmbH, 37077, Göttingen, Germany
| | - Alan F Cowman
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Michał Pasternak
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.
- Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia.
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Thiangtrongjit T, Adisakwattana P, Limpanont Y, Dekumyoy P, Nuamtanong S, Chusongsang P, Chusongsang Y, Reamtong O. Proteomic and immunomic analysis of Schistosoma mekongi egg proteins. Exp Parasitol 2018; 191:88-96. [PMID: 30009810 DOI: 10.1016/j.exppara.2018.07.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 07/02/2018] [Accepted: 07/11/2018] [Indexed: 12/29/2022]
Abstract
Schistosomiasis remains a global health problem. In the Mekong river basin, approximately 80,000 people are at risk of infection by Schistosoma mekongi. The parasite's eggs become entrapped in the host's organs and induce massive inflammation, contributing to the pathogenesis of schistosomiasis. In addition, egg antigens are important in circumoval precipitin tests (COPTs) and other diagnostic techniques. Little is known regarding the egg proteins of S. mekongi, and so we applied immunoblotting and mass spectrometry-based proteomic approaches to study these proteins and their antigenicity. A total of 360 unique proteins were identified in S. mekongi eggs using proteomic analyses. The major protein components of S. mekongi eggs were classified into several groups by functions, including proteins of unknown function, structural proteins, and regulators of transcription and translation. The most abundant proteins in S. mekongi eggs were antioxidant proteins, potentially reflecting the need to neutralize reactive oxidative species released from host immune cells. Immunomic analyses revealed that only DNA replication factor Cdt1 and heat shock protein 70 overlap between the proteins recognized by sera of infected mice and humans, illustrating the challenges of knowledge transfer from animal models to human patients. Forty-one immunoreactive protein bands were recognized by either mouse or patient sera. Phosphoglycerate kinase, fructose-1,6-bisphosphate aldolase and elongation factor 1 appeared to be interesting immunogens of S. mekongi eggs as these proteins were recognized by polyclonal IgMs and IgGs in patient sera. Our findings provide new information on the protein composition of S. mekongi eggs as well as the beginnings of a S. mekongi immunogen dataset. These data may help us better understand the pathology of schistosomiasis as well as natural antibody responses against S. mekongi egg proteins, both of which may be useful in including S. mekongi to other schistosoma diagnostic, vaccine and immunotherapy development.
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Affiliation(s)
- Tipparat Thiangtrongjit
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand.
| | - Poom Adisakwattana
- Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand.
| | - Yanin Limpanont
- Department of Social and Environmental Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand.
| | - Paron Dekumyoy
- Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand.
| | - Supaporn Nuamtanong
- Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand.
| | - Phiraphol Chusongsang
- Department of Social and Environmental Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand.
| | - Yupa Chusongsang
- Department of Social and Environmental Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand.
| | - Onrapak Reamtong
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand.
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Bouchery T, Filbey K, Shepherd A, Chandler J, Patel D, Schmidt A, Camberis M, Peignier A, Smith AAT, Johnston K, Painter G, Pearson M, Giacomin P, Loukas A, Bottazzi ME, Hotez P, LeGros G. A novel blood-feeding detoxification pathway in Nippostrongylus brasiliensis L3 reveals a potential checkpoint for arresting hookworm development. PLoS Pathog 2018; 14:e1006931. [PMID: 29566094 PMCID: PMC5864084 DOI: 10.1371/journal.ppat.1006931] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 02/09/2018] [Indexed: 11/18/2022] Open
Abstract
As part of on-going efforts to control hookworm infection, the "human hookworm vaccine initiative" has recognised blood feeding as a feasible therapeutic target for inducing immunity against hookworm infection. To this end, molecular approaches have been used to identify candidate targets, such as Necator americanus (Na) haemoglobinase aspartic protease-1 (APR-1), with immunogenicity profiled in canine and hamster models. We sought to accelerate the immune analysis of these identified therapeutic targets by developing an appropriate mouse model. Here we demonstrate that Nippostrongylus brasiliensis (Nb), a phylogenetically distant strongylid nematode of rodents, begins blood feeding early in its development and that immunisation with Na-APR-1 can block its growth and completion of its life cycle. Furthermore, we identify a new haem detoxification pathway in Nb required for blood feeding that can be blocked by drugs of the quinolone family, reducing both infection burden and the associated anaemia in rodents. Collectively, our findings show that haem metabolism has potential as a checkpoint for interrupting hookworm development in early stages of the hookworm life cycle and that the Nippostrongylus brasiliensis rodent model is relevant for identifying novel therapeutic targets against human hookworm.
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Affiliation(s)
- Tiffany Bouchery
- Malaghan Institute of Medical Research, Wellington, New Zealand
- * E-mail: (GL); (TB)
| | - Kara Filbey
- Malaghan Institute of Medical Research, Wellington, New Zealand
| | - Amy Shepherd
- Malaghan Institute of Medical Research, Wellington, New Zealand
| | - Jodie Chandler
- Malaghan Institute of Medical Research, Wellington, New Zealand
| | - Deepa Patel
- Malaghan Institute of Medical Research, Wellington, New Zealand
| | - Alfonso Schmidt
- Malaghan Institute of Medical Research, Wellington, New Zealand
| | - Mali Camberis
- Malaghan Institute of Medical Research, Wellington, New Zealand
| | | | | | - Karen Johnston
- The Ferrier Research Institute, Victoria University of Wellington, Lower Hutt, Wellington, New Zealand
| | - Gavin Painter
- The Ferrier Research Institute, Victoria University of Wellington, Lower Hutt, Wellington, New Zealand
| | - Mark Pearson
- Centre for Biodiscovery and Molecular Development of Therapeutics, Australian Institute for Tropical Health and Medicine, James Cook University, Cairns, Queensland, Australia
| | - Paul Giacomin
- Centre for Biodiscovery and Molecular Development of Therapeutics, Australian Institute for Tropical Health and Medicine, James Cook University, Cairns, Queensland, Australia
| | - Alex Loukas
- Centre for Biodiscovery and Molecular Development of Therapeutics, Australian Institute for Tropical Health and Medicine, James Cook University, Cairns, Queensland, Australia
| | - Maria-Elena Bottazzi
- Departments of Pediatrics and Molecular Virology and Microbiology, National School of Tropical Medicine, Baylor College of Medicine, Houston, Texas, United States of America
- Texas Children's Hospital Center for Vaccine Development, Houston, Texas, United States of America
- Department of Biology, Baylor University, Waco, Texas, United States of America
| | - Peter Hotez
- Departments of Pediatrics and Molecular Virology and Microbiology, National School of Tropical Medicine, Baylor College of Medicine, Houston, Texas, United States of America
- Texas Children's Hospital Center for Vaccine Development, Houston, Texas, United States of America
- Department of Biology, Baylor University, Waco, Texas, United States of America
| | - Graham LeGros
- Malaghan Institute of Medical Research, Wellington, New Zealand
- * E-mail: (GL); (TB)
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Tripathi M, Khan SI, Ponnan P, Kholiya R, Rawat DS. Aminoquinoline-Pyrimidine-Modified Anilines: Synthesis, In Vitro Antiplasmodial Activity, Cytotoxicity, Mechanistic Studies and ADME Predictions. ChemistrySelect 2017. [DOI: 10.1002/slct.201701558] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Mohit Tripathi
- Department of Chemistry; University of Delhi; Delhi- 110007 India
| | - Shabana I. Khan
- National Centre for Natural Products Research; University of Mississippi; MS-38677 USA
| | - Prija Ponnan
- Department of Chemistry; University of Delhi; Delhi- 110007 India
| | - Rohit Kholiya
- Department of Chemistry; University of Delhi; Delhi- 110007 India
| | - Diwan S. Rawat
- Department of Chemistry; University of Delhi; Delhi- 110007 India
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12
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Satish P, Sunita K. Antimalarial efficacy of Pongamia pinnata (L) Pierre against Plasmodium falciparum (3D7 strain) and Plasmodium berghei (ANKA). BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2017; 17:458. [PMID: 28893216 PMCID: PMC5594526 DOI: 10.1186/s12906-017-1958-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 08/31/2017] [Indexed: 11/20/2022]
Abstract
Background The objective of the current study was to assess the in vitro antiplasmodial activities of leaf, bark, flower, and the root of Pongamia pinnata against chloroquine-sensitive Plasmodium falciparum (3D7 strain), cytotoxicity against Brine shrimp larvae and THP-1 cell line. For in vivo study, the plant extract which has shown potent in vitro antimalarial activity was tested against Plasmodium berghei (ANKA strain). Methods The plant Pongamia pinnata was collected from the herbal garden of Acharya Nagarjuna University of Guntur district, Andhra Pradesh, India. Sequentially crude extracts of methanol (polar), chloroform (non-polar), hexane (non-polar), ethyl acetate (non-polar) and aqueous (polar) of dried leaves, bark, flowers and roots of Pongamia pinnata were prepared using Soxhlet apparatus. The extracts were screened for in vitro antimalarial activity against P. falciparum 3D7 strain. The cytotoxicity studies of crude extracts were conducted against Brine shrimp larvae and THP-1 cell line. Phytochemical analysis of the plant extracts was carried out by following the standard methods. The chemical injury to erythrocytes due to the plant extracts was checked. The in vivo study was conducted on P. berghei (ANKA) infected BALB/c albino mice by following 4-Day Suppressive, Repository, and Curative tests. Results Out of all the tested extracts, the methanol extract of the bark of Pongamia pinnata had shown an IC50 value of 11.67 μg/mL with potent in vitro antimalarial activity and cytotoxicity evaluation revealed that this extract was not toxic against Brine shrimp and THP-1 cells. The injury to erythrocytes analysis had not shown any morphological alterations and damage to the erythrocytes after 48 h of incubation. Because methanolic bark extract of Pongamia pinnata has shown good antimalarial activity in vitro, it was also tested in vivo. So the extract had exhibited an excellent activity against P. berghei malaria parasite while decrement of parasite counts was moderately low and dose-dependent (P < 0.05) when compared to the control groups, which shown a daily increase of parasitemia, unlike the CQ-treated groups. The highest concentration of the extract (1000 mg/kg b.wt./day) had shown 83.90, 87.47 and 94.67% of chemo-suppression during Suppressive, Repository, and Curative tests respectively which is almost nearer to the standard drug Chloroquine (5 mg/kg b.wt./day). Thus, the study has revealed that the methanolic bark extract had shown promisingly high ((P < 0.05) and dose-dependent chemo-suppression. The phytochemical screening of the crude extracts had shown the presence of alkaloids, flavonoids, triterpenes, tannins, carbohydrates, phenols, coumarins, saponins, phlobatannins and steroids. Conclusions The present study is useful to develop new antimalarial drugs in the scenario of the growing resistance to the existing antimalarials. Thus, additional research is needed to characterize the bioactive molecules of the extracts of Pongamia pinnata that are responsible for inhibition of malaria parasite.
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Okombo J, Chibale K. Insights into Integrated Lead Generation and Target Identification in Malaria and Tuberculosis Drug Discovery. Acc Chem Res 2017. [PMID: 28636311 PMCID: PMC5518282 DOI: 10.1021/acs.accounts.6b00631] [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: 01/02/2023]
Abstract
New, safe and effective drugs are urgently needed to treat and control malaria and tuberculosis, which affect millions of people annually. However, financial return on investment in the poor settings where these diseases are mostly prevalent is very minimal to support market-driven drug discovery and development. Moreover, the imminent loss of therapeutic lifespan of existing therapies due to evolution and spread of drug resistance further compounds the urgency to identify novel effective drugs. However, the advent of new public-private partnerships focused on tropical diseases and the recent release of large data sets by pharmaceutical companies on antimalarial and antituberculosis compounds derived from phenotypic whole cell high throughput screening have spurred renewed interest and opened new frontiers in malaria and tuberculosis drug discovery. This Account recaps the existing challenges facing antimalarial and antituberculosis drug discovery, including limitations associated with experimental animal models as well as biological complexities intrinsic to the causative pathogens. We enlist various highlights from a body of work within our research group aimed at identifying and characterizing new chemical leads, and navigating these challenges to contribute toward the global drug discovery and development pipeline in malaria and tuberculosis. We describe a catalogue of in-house efforts toward deriving safe and efficacious preclinical drug development candidates via cell-based medicinal chemistry optimization of phenotypic whole-cell medium and high throughput screening hits sourced from various small molecule chemical libraries. We also provide an appraisal of target-based screening, as invoked in our laboratory for mechanistic evaluation of the hits generated, with particular focus on the enzymes within the de novo pyrimidine biosynthetic and hemoglobin degradation pathways, the latter constituting a heme detoxification process and an associated cysteine protease-mediated hydrolysis of hemoglobin. We further expound on the recombinant enzyme assays, heme fractionation experiments, and genomic and chemoproteomic methods that we employed to identify Plasmodium falciparum falcipain 2 (PfFP2), hemozoin formation, phosphatidylinositol 4-kinase (PfPI4K) and Mycobacterium tuberculosis cytochrome bc1 complex as the targets of the antimalarial chalcones, pyrido[1,2-a]benzimidazoles, aminopyridines, and antimycobacterial pyrrolo[3,4-c]pyridine-1,3(2H)-diones, respectively. In conclusion, we argue for the expansion of chemical space through exploitation of privileged natural product scaffolds and diversity-oriented synthesis, as well as the broadening of druggable spaces by exploiting available protein crystal structures, -omics data, and bioinformatics infrastructure to explore hitherto untargeted spaces like lipid metabolism and protein kinases in P. falciparum. Finally, we audit the merits of both target-based and whole-cell phenotypic screening in steering antimalarial and antituberculosis chemical matter toward populating drug discovery pipelines with new lead molecules.
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Affiliation(s)
- John Okombo
- Department
of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Kelly Chibale
- Department
of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
- South
African Medical Research Council Drug Discovery and Development Research
Unit, Drug Discovery and Development Centre (H3D), Department of Chemistry
and Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
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Antimalarials inhibit hematin crystallization by unique drug-surface site interactions. Proc Natl Acad Sci U S A 2017; 114:7531-7536. [PMID: 28559329 DOI: 10.1073/pnas.1700125114] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
In malaria pathophysiology, divergent hypotheses on the inhibition of hematin crystallization posit that drugs act either by the sequestration of soluble hematin or their interaction with crystal surfaces. We use physiologically relevant, time-resolved in situ surface observations and show that quinoline antimalarials inhibit β-hematin crystal surfaces by three distinct modes of action: step pinning, kink blocking, and step bunch induction. Detailed experimental evidence of kink blocking validates classical theory and demonstrates that this mechanism is not the most effective inhibition pathway. Quinolines also form various complexes with soluble hematin, but complexation is insufficient to suppress heme detoxification and is a poor indicator of drug specificity. Collectively, our findings reveal the significance of drug-crystal interactions and open avenues for rationally designing antimalarial compounds.
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Wang W, Li Q, Wei Y, Xue J, Sun X, Yu Y, Chen Z, Li S, Duan L. Novel carbazole aminoalcohols as inhibitors of β-hematin formation: Antiplasmodial and antischistosomal activities. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2017; 7:191-199. [PMID: 28395189 PMCID: PMC5384886 DOI: 10.1016/j.ijpddr.2017.03.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 03/29/2017] [Accepted: 03/29/2017] [Indexed: 01/24/2023]
Abstract
Malaria and schistosomiasis are two of the most socioeconomically devastating parasitic diseases in tropical and subtropical countries. Since current chemotherapeutic options are limited and defective, there is an urgent need to develop novel antiplasmodials and antischistosomals. Hemozoin is a disposal product formed from the hemoglobin digestion by some blood-feeding parasites. Hemozoin formation is an essential process for the parasites to detoxify free heme, which is a reliable therapeutic target for identifying novel antiparasitic agents. A series of novel carbazole aminoalcohols were designed and synthesized as potential antiplasmodial and antischistosomal agents, and several compounds showed potent in vitro activities against Plasmodium falciparum 3D7 and Dd2 strains and adult and juvenile Schistosoma japonicum. Investigations on the dual antiparasitic mechanisms showed the correlation between inhibitory activity of β-hematin formation and antiparasitic activity. Inhibiting hemozoin formation was identified as one of the mechanisms of action of carbazole aminoalcohols. Compound 7 displayed potent antiplasmodial (Pf3D7 IC50 = 0.248 μM, PfDd2 IC50 = 0.091 μM) and antischistosomal activities (100% mortality of adult and juvenile schistosomes at 5 and 10 μg/mL, respectively) and exhibited low cytotoxicity (CC50 = 7.931 μM), which could be considered as a promising lead for further investigation. Stoichiometry determination and molecular docking studies were also performed to explain the mode of action of compound 7. Carbazole aminoalcohol was confirmed as a novel antiplasmodial and antischistosomal scaffold. The mechanism of action relied on β-hematin formation inhibition. The carbazole aminoalcohols interacted with hematin through forming a 1:1 complex. Compound 7 showed potent antiplasmodial ability (Pf3D7 IC50 = 0.248 μM, PfDd2 IC50 = 0.091 μM). In vitro antischistosomal effect of 7 meets the WHO's criterion of “hit” for schistosomiasis control.
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Affiliation(s)
- Weisi Wang
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, WHO Collaborating Centre for Malaria, Schistosomiasis, and Filariasis, Key Laboratory of Parasitology and Vector Biology of the Chinese Ministry of Health, Shanghai 200025, China; ZJU-ENS Joint Laboratory of Medicinal Chemistry, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Qiang Li
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, WHO Collaborating Centre for Malaria, Schistosomiasis, and Filariasis, Key Laboratory of Parasitology and Vector Biology of the Chinese Ministry of Health, Shanghai 200025, China
| | - Yufen Wei
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, WHO Collaborating Centre for Malaria, Schistosomiasis, and Filariasis, Key Laboratory of Parasitology and Vector Biology of the Chinese Ministry of Health, Shanghai 200025, China
| | - Jian Xue
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, WHO Collaborating Centre for Malaria, Schistosomiasis, and Filariasis, Key Laboratory of Parasitology and Vector Biology of the Chinese Ministry of Health, Shanghai 200025, China
| | - Xiao Sun
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China
| | - Yang Yu
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China
| | - Zhuo Chen
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China
| | - Shizhu Li
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, WHO Collaborating Centre for Malaria, Schistosomiasis, and Filariasis, Key Laboratory of Parasitology and Vector Biology of the Chinese Ministry of Health, Shanghai 200025, China
| | - Liping Duan
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, WHO Collaborating Centre for Malaria, Schistosomiasis, and Filariasis, Key Laboratory of Parasitology and Vector Biology of the Chinese Ministry of Health, Shanghai 200025, China; Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
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In Silico Mining for Antimalarial Structure-Activity Knowledge and Discovery of Novel Antimalarial Curcuminoids. Molecules 2016; 21:molecules21070853. [PMID: 27367660 PMCID: PMC6273176 DOI: 10.3390/molecules21070853] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Revised: 06/04/2016] [Accepted: 06/10/2016] [Indexed: 11/17/2022] Open
Abstract
Malaria is a parasitic tropical disease that kills around 600,000 patients every year. The emergence of resistant Plasmodium falciparum parasites to artemisinin-based combination therapies (ACTs) represents a significant public health threat, indicating the urgent need for new effective compounds to reverse ACT resistance and cure the disease. For this, extensive curation and homogenization of experimental anti-Plasmodium screening data from both in-house and ChEMBL sources were conducted. As a result, a coherent strategy was established that allowed compiling coherent training sets that associate compound structures to the respective antimalarial activity measurements. Seventeen of these training sets led to the successful generation of classification models discriminating whether a compound has a significant probability to be active under the specific conditions of the antimalarial test associated with each set. These models were used in consensus prediction of the most likely active from a series of curcuminoids available in-house. Positive predictions together with a few predicted as inactive were then submitted to experimental in vitro antimalarial testing. A large majority from predicted compounds showed antimalarial activity, but not those predicted as inactive, thus experimentally validating the in silico screening approach. The herein proposed consensus machine learning approach showed its potential to reduce the cost and duration of antimalarial drug discovery.
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17
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Kiraithe MN, Nguta JM, Mbaria JM, Kiama SG. Evaluation of the use of Ocimum suave Willd. (Lamiaceae), Plectranthus barbatus Andrews (Lamiaceae) and Zanthoxylum chalybeum Engl. (Rutaceae) as antimalarial remedies in Kenyan folk medicine. JOURNAL OF ETHNOPHARMACOLOGY 2016; 178:266-271. [PMID: 26705665 DOI: 10.1016/j.jep.2015.12.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 10/20/2015] [Accepted: 12/13/2015] [Indexed: 06/05/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Crude extracts from the leaves of Ocimum suave Willd (Lamiaceae) and the root barks of Plectranthus barbatus Andrews (Lamiaceae) and Zanthoxylum chalybeum Engl. (Rutaceae) were studied to ascertain the ethnopharmacological standing of their antimalarial usage in Kenyan folk medicine. MATERIALS AND METHODS Aqueous and Chloroform: Methanol (1:1) extracts of the plants were used in this study. Toxicity of the extracts was investigated by using brine shrimp lethality test and acute oral toxicity in mice. The antimalarial activity at a dose of 100 mg/kg was screened in Swiss albino mice against chloroquine sensitive Plasmodium berghei (D6) using Peters 4-day suppressive test. Chloroquine, at a dosage rate of 20 mg/kg was used as a reference drug. RESULTS The extracts showed some signs of acute toxicity in the brine shrimp lethality test. However, no signs of toxicity were observed in the mice at a dose of 2000 mg/kg of the crude extracts. The results revealed that all the tested crude extracts were safe. Z. chalybeum aqueous extract and P. barbatus organic extract showed chemosuppressive activities of 81.45% and 78.69%, respectively. This antimalarial activity was not significantly different from that of chloroquine (P<0.05). CONCLUSION The findings suggest that the Kenyan folkloric medicinal application of these plants has a pharmacological basis. Bioactivity guided fractionation and isolation of bioactive molecules from the two species could lead to new hits against Plasmodium falciparum malaria.
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Affiliation(s)
- Micheni N Kiraithe
- School of Biological Sciences, College of Biological and Physical Sciences, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya.
| | - Joseph M Nguta
- Department of Public Health, Pharmacology & Toxicology, College of Agriculture and Veterinary Sciences, University of Nairobi, P.O. Box 29053-00625, Nairobi, Kenya
| | - James M Mbaria
- Department of Public Health, Pharmacology & Toxicology, College of Agriculture and Veterinary Sciences, University of Nairobi, P.O. Box 29053-00625, Nairobi, Kenya
| | - Stephen G Kiama
- Department of Veterinary Anatomy, College of Agriculture and Veterinary Sciences, University of Nairobi, P.O. Box 29053-00625, Nairobi, Kenya
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18
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Ekengard E, Kumar K, Fogeron T, de Kock C, Smith PJ, Haukka M, Monari M, Nordlander E. Pentamethylcyclopentadienyl-rhodium and iridium complexes containing (N^N and N^O) bound chloroquine analogue ligands: synthesis, characterization and antimalarial properties. Dalton Trans 2016; 45:3905-17. [DOI: 10.1039/c5dt03739e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Rhodium and iridium cyclopentadienyl complexes have been examined for anti-malarial activity. Three rhodium complexes are especially active.
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Affiliation(s)
- Erik Ekengard
- Inorganic Chemistry Research Group
- Chemical Physics
- Center for Chemistry and Chemical Engineering
- Lund University
- SE-221 00 Lund
| | - Kamlesh Kumar
- Inorganic Chemistry Research Group
- Chemical Physics
- Center for Chemistry and Chemical Engineering
- Lund University
- SE-221 00 Lund
| | - Thibault Fogeron
- Inorganic Chemistry Research Group
- Chemical Physics
- Center for Chemistry and Chemical Engineering
- Lund University
- SE-221 00 Lund
| | - Carmen de Kock
- Division of Pharmacology
- Department of Medicine
- University of Cape Town Medical School
- Observatory 7925
- South Africa
| | - Peter J. Smith
- Division of Pharmacology
- Department of Medicine
- University of Cape Town Medical School
- Observatory 7925
- South Africa
| | - Matti Haukka
- Department of Chemistry
- University of Jyväskylä
- Jyväskylä
- Finland
| | - Magda Monari
- Dipartimento di Chimica “G. Ciamician”
- Alma Mater Studiorum Università di Bologna
- 40126 Bologna
- Italy
| | - Ebbe Nordlander
- Inorganic Chemistry Research Group
- Chemical Physics
- Center for Chemistry and Chemical Engineering
- Lund University
- SE-221 00 Lund
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Mechanisms of hematin crystallization and inhibition by the antimalarial drug chloroquine. Proc Natl Acad Sci U S A 2015; 112:4946-51. [PMID: 25831526 DOI: 10.1073/pnas.1501023112] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Hematin crystallization is the primary mechanism of heme detoxification in malaria parasites and the target of the quinoline class of antimalarials. Despite numerous studies of malaria pathophysiology, fundamental questions regarding hematin growth and inhibition remain. Among them are the identity of the crystallization medium in vivo, aqueous or organic; the mechanism of crystallization, classical or nonclassical; and whether quinoline antimalarials inhibit crystallization by sequestering hematin in the solution, or by blocking surface sites crucial for growth. Here we use time-resolved in situ atomic force microscopy (AFM) and show that the lipid subphase in the parasite may be a preferred growth medium. We provide, to our knowledge, the first evidence of the molecular mechanisms of hematin crystallization and inhibition by chloroquine, a common quinoline antimalarial drug. AFM observations demonstrate that crystallization strictly follows a classical mechanism wherein new crystal layers are generated by 2D nucleation and grow by the attachment of solute molecules. We identify four classes of surface sites available for binding of potential drugs and propose respective mechanisms of drug action. Further studies reveal that chloroquine inhibits hematin crystallization by binding to molecularly flat {100} surfaces. A 2-μM concentration of chloroquine fully arrests layer generation and step advancement, which is ∼10(4)× less than hematin's physiological concentration. Our results suggest that adsorption at specific growth sites may be a general mode of hemozoin growth inhibition for the quinoline antimalarials. Because the atomic structures of the identified sites are known, this insight could advance the future design and/or optimization of new antimalarials.
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Mossallam SF, Amer EI, El-Faham MH. Efficacy of Synriam™, a new antimalarial combination of OZ277 and piperaquine, against different developmental stages of Schistosoma mansoni. Acta Trop 2015; 143:36-46. [PMID: 25530543 DOI: 10.1016/j.actatropica.2014.12.005] [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: 08/24/2014] [Revised: 12/03/2014] [Accepted: 12/05/2014] [Indexed: 01/11/2023]
Abstract
Control of schistosomiasis relies on a single drug, praziquantel (PZQ). Given the rising concerns about the potential emergence of PZQ-resistant strains, it has now become necessary to search for novel therapeutics. However, the current pace for anti-schistosomal drug discovery is slow; hence, repositioning of existing approved drugs can offer a safe, rapid and cost-effective solution. The anti-malarial synthetic artemisinin-derivatives trioxolanes demonstrated anti-schistosomal efficacies against the three major species infecting humans and, unlike PZQ, showed activities against both juvenile and adult worm stages. The 1,2,4-trioxolane/OZ277 (arterolane maleate) in combination with a partner drug: piperaquine phosphate was recently developed as an anti-malarial drug and manufactured by Ranbaxy (India) as Synriam™ (SYN). Herein, the in vivo activities of SYN were investigated in a mouse model of Schistosoma mansoni (S. mansoni), compared to PZQ. We show that a single fixed dose of 240mg/kg SYN (40mg/kg arterolane and 200mg/kg piperaqine) induced significant protective effects in mice, in terms of reduction in worm and tissue egg burdens, which were evident against all schistosome developmental stages. Extensive alterations in the tegument and subtegumental tissues of SYN-exposed worms were revealed by both scanning and transmission electron microscopes. Progressive decrease in worm activity and occurrence of death were noticed in vitro upon exposure to the drug - more pronounced in the presence of haemin. This report provides the first evidence of the efficacy of a combination of 1,2,4-trioxolane and piperaquine against S. mansoni in mice. Being effective against young stages, SYN could be used to prevent early Schistosoma infection.
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Raj R, Land KM, Kumar V. 4-Aminoquinoline-hybridization en route towards the development of rationally designed antimalarial agents. RSC Adv 2015. [DOI: 10.1039/c5ra16361g] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Recent developments in 4-aminoquinoline-hybridization, as an attractive strategy for averting and delaying the drug resistance along with improvement in efficacy of new antimalarials, are described.
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Affiliation(s)
- Raghu Raj
- Department of Chemistry
- Guru Nanak Dev University
- Amritsar-143005
- India
| | - Kirkwood M. Land
- Department of Biological Sciences
- University of the Pacific
- Stockton
- USA
| | - Vipan Kumar
- Department of Chemistry
- Guru Nanak Dev University
- Amritsar-143005
- India
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22
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Vekilov PG, Rimer JD, Olafson KN, Ketchum MA. Lipid or aqueous medium for hematin crystallization? CrystEngComm 2015. [DOI: 10.1039/c5ce01178g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hematin crystallization, the primary heme detoxification mechanism of malaria parasites infecting human erythrocytes, most likely requires the participation of lipid structures.
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Affiliation(s)
- Peter G. Vekilov
- Department of Chemical and Biomolecular Engineering
- University of Houston
- Houston, USA
- Department of Chemistry
- University of Houston
| | - Jeffrey D. Rimer
- Department of Chemical and Biomolecular Engineering
- University of Houston
- Houston, USA
| | - Katy N. Olafson
- Department of Chemical and Biomolecular Engineering
- University of Houston
- Houston, USA
| | - Megan A. Ketchum
- Department of Chemical and Biomolecular Engineering
- University of Houston
- Houston, USA
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Tripathi M, Khan SI, Thakur A, Ponnan P, Rawat DS. 4-Aminoquinoline-pyrimidine-aminoalkanols: synthesis, in vitro antimalarial activity, docking studies and ADME predictions. NEW J CHEM 2015. [DOI: 10.1039/c5nj00094g] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
4-Aminoquinoline-pyrimidine-aminoalkanols displaying good in vitro antimalarial activities against both CQ-sensitive and -resistant strains of P. falciparum, together with favourable resistance-indices and the predicted ADME properties, are reported.
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Affiliation(s)
- Mohit Tripathi
- Department of Chemistry
- University of Delhi
- Delhi 110007
- India
| | - Shabana I. Khan
- National Centre for Natural Products Research
- University of Mississippi
- MS-38677
- USA
| | - Anuj Thakur
- Department of Chemistry
- University of Delhi
- Delhi 110007
- India
| | - Prija Ponnan
- Department of Chemistry
- University of Delhi
- Delhi 110007
- India
| | - Diwan S. Rawat
- Department of Chemistry
- University of Delhi
- Delhi 110007
- India
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24
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Olafson KN, Rimer JD, Vekilov PG. Growth of Large Hematin Crystals in Biomimetic Solutions. CRYSTAL GROWTH & DESIGN 2014; 14:2123-2127. [PMID: 24839403 PMCID: PMC4018177 DOI: 10.1021/cg5002682] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2014] [Revised: 04/07/2014] [Indexed: 06/03/2023]
Abstract
Hematin crystallization is an essential component of the physiology of malaria parasites. Several antimalarial drugs are believed to inhibit crystallization and expose the parasites to toxic soluble hematin. Hence, understanding the mechanisms of hematin crystal growth and inhibition is crucial for the design of new drugs. A major obstacle to microscopic, spectroscopic, and crystallographic studies of hematin crystallization has been the unavailability of large hematin crystals grown under conditions representative of the parasite anatomy. We have developed a biomimetic method to reproducibly grow large hematin crystals reaching 50 μm in length. We imitate the digestive vacuole of Plasmodium falciparum and employ a two-phase solution of octanol and citric buffer. The nucleation of seeds is enhanced at the interface between the aqueous and organic phases, where an ordered layer of octanol molecules is known to serve as substrate for nucleation. The seeds are transferred to hematin-saturated octanol in contact with citric buffer. We show that the crystals grow in the octanol layer, while the buffer supplies hydrogen ions needed for bonds that link the hematin molecules in the crystal. The availability of large hematin crystals opens new avenues for studies of hematin detoxification of malaria parasites in host erythrocytes.
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Affiliation(s)
- Katy N. Olafson
- Department
of Chemical and Biomolecular Engineering,
and Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Jeffrey D. Rimer
- Department
of Chemical and Biomolecular Engineering,
and Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Peter G. Vekilov
- Department
of Chemical and Biomolecular Engineering,
and Department of Chemistry, University of Houston, Houston, Texas 77204, United States
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Ketchum MA, Olafson KN, Petrova EV, Rimer JD, Vekilov PG. Hematin crystallization from aqueous and organic solvents. J Chem Phys 2014; 139:121911. [PMID: 24089723 DOI: 10.1063/1.4816106] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Hematin crystallization is the main mechanism of detoxification of heme that is released in malaria-infected erythrocytes as a byproduct of the hemoglobin catabolism by the parasite. A controversy exists over whether hematin crystals grow from the aqueous medium of the parasite's digestive vacuole or in the lipid bodies present in the vacuole. To this end, we compare the basic thermodynamic and structural features of hematin crystallization in an aqueous buffer at pH 4.8, as in the digestive vacuole, and in water-saturated octanol that mimics the environment of the lipid nanospheres. We show that in aqueous solutions, hematin aggregation into mesoscopic disordered clusters is insignificant. We determine the solubility of the β-hematin crystals in the pH range 4.8-7.6. We image by atomic force microscopy crystals grown at pH 4.8 and show that their macroscopic and mesoscopic morphology features are incompatible with those reported for biological hemozoin. In contrast, crystals grown in the presence of octanol are very similar to those extracted from parasites. We determine the hematin solubility in water-saturated octanol at three temperatures. These solubilities are four orders of magnitude higher than that at pH 4.8, providing for faster crystallization from organic than from aqueous solvents. These observations further suggest that the lipid bodies play a role in mediating biological hemozoin crystal growth to ensure faster heme detoxification.
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Affiliation(s)
- Megan A Ketchum
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, USA
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Coronado LM, Nadovich CT, Spadafora C. Malarial hemozoin: from target to tool. Biochim Biophys Acta Gen Subj 2014; 1840:2032-41. [PMID: 24556123 DOI: 10.1016/j.bbagen.2014.02.009] [Citation(s) in RCA: 145] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 01/26/2014] [Accepted: 02/10/2014] [Indexed: 02/07/2023]
Abstract
BACKGROUND Malaria is an extremely devastating disease that continues to affect millions of people each year. A distinctive attribute of malaria infected red blood cells is the presence of malarial pigment or the so-called hemozoin. Hemozoin is a biocrystal synthesized by Plasmodium and other blood-feeding parasites to avoid the toxicity of free heme derived from the digestion of hemoglobin during invasion of the erythrocytes. SCOPE OF REVIEW Hemozoin is involved in several aspects of the pathology of the disease as well as in important processes such as the immunogenicity elicited. It is known that the once best antimalarial drug, chloroquine, exerted its effect through interference with the process of hemozoin formation. In the present review we explore what is known about hemozoin, from hemoglobin digestion, to its final structural analysis, to its physicochemical properties, its role in the disease and notions of the possible mechanisms that could kill the parasite by disrupting the synthesis or integrity of this remarkable crystal. MAJOR CONCLUSIONS The importance and peculiarities of this biocrystal have given researchers a cause to consider it as a target for new antimalarials and to use it through unconventional approaches for diagnostics and therapeutics against the disease. GENERAL SIGNIFICANCE Hemozoin plays an essential role in the biology of malarial disease. Innovative ideas could use all the existing data on the unique chemical and biophysical properties of this macromolecule to come up with new ways of combating malaria.
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Affiliation(s)
- Lorena M Coronado
- Centro de Biología Celular y Molecular de Enfermedades, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, Ciudad del Saber, Panama; Department of Biotechnology, Acharya Nagarjuna University, Guntur 522 510, A.P., India
| | | | - Carmenza Spadafora
- Centro de Biología Celular y Molecular de Enfermedades, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, Ciudad del Saber, Panama.
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27
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Xu W, Dziedzic-Kocurek K, Yu M, Wu Z, Marcelli A. Spectroscopic study and electronic structure of prototypical iron porphyrins and their μ-oxo-dimer derivatives with different functional configurations. RSC Adv 2014. [DOI: 10.1039/c4ra04685d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The electronic structures and the charge dynamics of prototypical porphyrins and their μ-oxo-dimer derivatives have been investigated to provide insight into their molecular biophysical mechanisms.
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Affiliation(s)
- Wei Xu
- Beijing Synchrotron Radiation Facility
- Institute of High Energy Physics
- Beijing, China
| | | | - Meijuan Yu
- Beijing Synchrotron Radiation Facility
- Institute of High Energy Physics
- Beijing, China
| | - Ziyu Wu
- Beijing Synchrotron Radiation Facility
- Institute of High Energy Physics
- Beijing, China
- NSRL
- University of Science and Technology of China
| | - Augusto Marcelli
- NSRL
- University of Science and Technology of China
- Hefei 230026, China
- INFN - Laboratori Nazionali di Frascati
- Frascati, Italy
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28
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Stringer T, Taylor D, de Kock C, Guzgay H, Au A, An SH, Sanchez B, O'Connor R, Patel N, Land KM, Smith PJ, Hendricks DT, Egan TJ, Smith GS. Synthesis, characterization, antiparasitic and cytotoxic evaluation of thioureas conjugated to polyamine scaffolds. Eur J Med Chem 2013; 69:90-8. [DOI: 10.1016/j.ejmech.2013.08.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 07/10/2013] [Accepted: 08/02/2013] [Indexed: 11/25/2022]
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Musila MF, Dossaji SF, Nguta JM, Lukhoba CW, Munyao JM. In vivo antimalarial activity, toxicity and phytochemical screening of selected antimalarial plants. JOURNAL OF ETHNOPHARMACOLOGY 2013; 146:557-561. [PMID: 23376043 DOI: 10.1016/j.jep.2013.01.023] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 11/26/2012] [Accepted: 01/15/2013] [Indexed: 06/01/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Malaria continues to kill over a million people each year and in many populations affected by malaria, conventional drugs are often unaffordable or inaccessible. Historically, plants have been a prominent source of antimalarial drugs. Those plants currently used by indigenous people to treat malaria should be documented and investigated as potential sources of new antimalarial drugs. AIM OF THE STUDY To investigate in vivo antimalarial activity, toxicity and carry out phytochemical screening of selected plants which have been used in traditional medicine for the treatment of malaria. MATERIALS AND METHODS Organic and water extracts of four medicinal plants used for the treatment of malaria in traditional health systems of Msambweni people in Kenya were tested for antimalarial activity against Plasmodium berghei and brine shrimp lethality. They were also screened for their major phytochemical constituents. RESULTS Aqueous extract of the stem bark of Adansonia digitata exhibited highest chemosuppression of parasitaemia, >60% in a murine model of Plasmodium berghei infected mice. Aqueous and organic extracts of Launaea cornuta and Zanthoxylum chalybeum were toxic to the brine shrimp (LD50<1000μg/ml) while aqueous and organic extracts of Adansonia digitata and aqueous extracts of Canthium glaucum were not toxic to brine shrimp (LD50>1000μg/ml). Phytochemical screening revealed the presence of alkaloids and flavonoids in all the crude extracts of the selected plant species studied. Sesquiterpene lactones and saponis were present in organic extracts but absent in the aqueous extracts of Adansonia digitata, Canthium glaucum, Launaea cornuta and Zanthoxylum chalybeum. CONCLUSION The results showed that the crude extracts of Adansonia digitata and Canthium glaucum demonstrated promising antimalarial activity and there is potential for isolation of lead compounds from their extracts.
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Affiliation(s)
- M F Musila
- School of Biological Sciences, College of Biological and Physical Sciences, University of Nairobi, PO Box 30197-00100, Nairobi, Kenya.
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Haynes RK, Cheu KW, Chan HW, Wong HN, Li KY, Tang MMK, Chen MJ, Guo ZF, Guo ZH, Sinniah K, Witte AB, Coghi P, Monti D. Interactions between artemisinins and other antimalarial drugs in relation to the cofactor model--a unifying proposal for drug action. ChemMedChem 2012; 7:2204-26. [PMID: 23112085 DOI: 10.1002/cmdc.201200383] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 09/30/2012] [Indexed: 01/14/2023]
Abstract
Artemisinins are proposed to act in the malaria parasite cytosol by oxidizing dihydroflavin cofactors of redox-active flavoenzymes, and under aerobic conditions by inducing their autoxidation. Perturbation of redox homeostasis coupled with the generation of reactive oxygen species (ROS) ensues. Ascorbic acid-methylene blue (MB), N-benzyl-1,4-dihydronicotinamide (BNAH)-MB, BNAH-lumiflavine, BNAH-riboflavin (RF), and NADPH-FAD-E. coli flavin reductase (Fre) systems at pH 7.4 generate leucomethylene blue (LMB) and reduced flavins that are rapidly oxidized in situ by artemisinins. These oxidations are inhibited by the 4-aminoquinolines piperaquine (PPQ), chloroquine (CQ), and others. In contrast, the arylmethanols lumefantrine, mefloquine (MFQ), and quinine (QN) have little or no effect. Inhibition correlates with the antagonism exerted by 4-aminoquinolines on the antimalarial activities of MB, RF, and artemisinins. Lack of inhibition correlates with the additivity/synergism between the arylmethanols and artemisinins. We propose association via π complex formation between the 4-aminoquinolines and LMB or the dihydroflavins; this hinders hydride transfer from the reduced conjugates to the artemisinins. The arylmethanols have a decreased tendency to form π complexes, and so exert no effect. The parallel between chemical reactivity and antagonism or additivity/synergism draws attention to the mechanism of action of all drugs described herein. CQ and QN inhibit the formation of hemozoin in the parasite digestive vacuole (DV). The buildup of heme-Fe(III) results in an enhanced efflux from the DV into the cytosol. In addition, the lipophilic heme-Fe(III) complexes of CQ and QN that form in the DV are proposed to diffuse across the DV membrane. At the higher pH of the cytosol, the complexes decompose to liberate heme-Fe(III) . The quinoline or arylmethanol reenters the DV, and so transfers more heme-Fe(III) out of the DV. In this way, the 4-aminoquinolines and arylmethanols exert antimalarial activities by enhancing heme-Fe(III) and thence free Fe(III) concentrations in the cytosol. The iron species enter into redox cycles through reduction of Fe(III) to Fe(II) largely mediated by reduced flavin cofactors and likely also by NAD(P)H-Fre. Generation of ROS through oxidation of Fe(II) by oxygen will also result. The cytotoxicities of artemisinins are thereby reinforced by the iron. Other aspects of drug action are emphasized. In the cytosol or DV, association by π complex formation between pairs of lipophilic drugs must adversely influence the pharmacokinetics of each drug. This explains the antagonism between PPQ and MFQ, for example. The basis for the antimalarial activity of RF mirrors that of MB, wherein it participates in redox cycling that involves flavoenzymes or Fre, resulting in attrition of NAD(P)H. The generation of ROS by artemisinins and ensuing Fenton chemistry accommodate the ability of artemisinins to induce membrane damage and to affect the parasite SERCA PfATP6 Ca(2+) transporter. Thus, the effect exerted by artemisinins is more likely a downstream event involving ROS that will also be modulated by mutations in PfATP6. Such mutations attenuate, but cannot abrogate, antimalarial activities of artemisinins. Overall, parasite resistance to artemisinins arises through enhancement of antioxidant defense mechanisms.
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Affiliation(s)
- Richard K Haynes
- Department of Chemistry, Institute of Molecular Technology for Drug Discovery and Synthesis, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR China.
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Kuter D, Venter GA, Naidoo KJ, Egan TJ. Experimental and time-dependent density functional theory characterization of the UV-visible spectra of monomeric and μ-oxo dimeric ferriprotoporphyrin IX. Inorg Chem 2012; 51:10233-50. [PMID: 22963249 DOI: 10.1021/ic301154e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Speciation of ferriprotoporphyrin IX, Fe(III)PPIX, in aqueous solution is complex. Despite the use of its characteristic spectroscopic features for identification, the theoretical basis of the unique UV-visible absorbance spectrum of μ-[Fe(III)PPIX](2)O has not been explored. To investigate this and to establish a structural and spectroscopic model for Fe(III)PPIX species, density functional theory (DFT) calculations were undertaken for H(2)O-Fe(III)PPIX and μ-[Fe(III)PPIX](2)O. The models agreed with related Fe(III)porphyrin crystal structures and reproduced vibrational spectra well. The UV-visible absorbance spectra of H(2)O-Fe(III)PPIX and μ-[Fe(III)PPIX](2)O were calculated using time-dependent DFT and reproduced major features of the experimental spectra of both. Transitions contributing to calculated excitations have been identified. The features of the electronic spectrum calculated for μ-[Fe(III)PPIX](2)O were attributed to delocalization of electron density between the two porphyrin rings of the dimer, the weaker ligand field of the axial ligand, and antiferromagnetic coupling of the Fe(III) centers. Room temperature magnetic circular dichroism (MCD) spectra have been recorded and are shown to be useful in distinguishing between these two Fe(III)PPIX species. Bands underlying major spectroscopic features were identified through simultaneous deconvolution of UV-visible and MCD spectra. Computed UV-visible spectra were compared to deconvoluted spectra. Interpretation of the prominent bands of H(2)O-Fe(III)PPIX largely conforms to previous literature. Owing to the weak paramagnetism of μ-[Fe(III)PPIX](2)O at room temperature and the larger number of underlying excitations, interpretation of its experimental UV-visible spectrum was necessarily tentative. Nonetheless, comparison with the calculated spectra of antiferromagnetically coupled and paramagnetic forms of the μ-oxo dimer of Fe(III)porphine suggested that the composition of the Soret band involves a mixture of π→π* and π→d(π) charge transfer transitions. The Q-band and charge transfer bands appear to amalgamate into a mixed low energy envelope consisting of excitations with heavily admixed π→π* and charge transfer transitions.
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Affiliation(s)
- David Kuter
- Department of Chemistry, Department of Chemistry, University of Cape Town, Private Bag, Rondebosch 7701 South Africa
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Ingram K, Schiaffo CE, Sittiwong W, Benner E, Dussault PH, Keiser J. In vitro and in vivo activity of 3-alkoxy-1,2-dioxolanes against Schistosoma mansoni. J Antimicrob Chemother 2012; 67:1979-86. [PMID: 22553141 DOI: 10.1093/jac/dks141] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
OBJECTIVES Compounds characterized by a peroxidic skeleton are an interesting starting point for antischistosomal drug discovery. Previously a series of 3-alkoxy-1,2-dioxolanes, which are chemically stable cyclic peroxides, demonstrated significant in vitro activity against Plasmodium falciparum. We aimed to evaluate the potential of these compounds against Schistosoma mansoni and elucidate the roles of iron and peroxidic groups in activity. METHODS Drugs were tested against juvenile and adult stages of S. mansoni in vitro and in vivo. Selected structures were assessed in vitro against schistosomes in the presence of additional iron sources. In addition, drugs were tested in vitro and in vivo against Echinostoma caproni, a non-blood-feeding intestinal fluke. Finally, the activity of non-peroxidic analogues was evaluated. RESULTS Three dioxolanes displayed IC₅₀s ≤ 20.1 μM against adult schistosomes and values as low as 4.2 μM against newly transformed schistosomula. Nonetheless, only moderate, non-significant worm burden reductions were observed after treatment of mice harbouring adult infections. Drugs lacked activity against juvenile schistosomes in vivo. Two selected dioxolanes showed in vitro activity against E. caproni down to concentrations of 5 mg/L, but none of the compounds revealed in vivo activity. All tested non-peroxidic analogues lacked activity in vitro against both parasites. CONCLUSIONS Selected dioxolanes presented interesting in vitro activity, but low in vivo activities have to be overcome to identify a lead candidate. Although the inactivity of non-peroxidic analogues underlines the necessity of a peroxide functional group, incubation of adult schistosomes with additional iron sources did not alter activity, supporting an iron-independent mode of activation.
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Affiliation(s)
- Katrin Ingram
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
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Muñoz-Durango K, Maciuk A, Harfouche A, Torijano-Gutiérrez S, Jullian JC, Quintin J, Spelman K, Mouray E, Grellier P, Figadère B. Detection, characterization, and screening of heme-binding molecules by mass spectrometry for malaria drug discovery. Anal Chem 2012; 84:3324-9. [PMID: 22409647 DOI: 10.1021/ac300065t] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Drug screening for antimalarials uses heme biocrystallization inhibition methods as an alternative to parasite cultures, but they involve complex processes and cannot detect artemisinin-like molecules. The described method detects heme-binding compounds by mass spectrometry, using dissociation of the drug-heme adducts to evaluate putative antiplasmodial activity. Applied to a chemical library, it showed a good hit-to-lead ratio and is an efficient early stage screening for complex mixtures like natural extracts.
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Affiliation(s)
- Katalina Muñoz-Durango
- Laboratoire de Pharmacognosie, UMR 8076 CNRS BioCIS, Faculté de Pharmacie, Université Paris-Sud, 5 rue J.-B. Clément, 92296 Châtenay-Malabry, France
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Glans L, Ehnbom A, de Kock C, Martínez A, Estrada J, Smith PJ, Haukka M, Sánchez-Delgado RA, Nordlander E. Ruthenium(II) arene complexes with chelating chloroquine analogue ligands: synthesis, characterization and in vitro antimalarial activity. Dalton Trans 2012; 41:2764-73. [PMID: 22249579 PMCID: PMC3303165 DOI: 10.1039/c2dt12083f] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Three new ruthenium complexes with bidentate chloroquine analogue ligands, [Ru(η(6)-cym)(L(1))Cl]Cl (1, cym = p-cymene, L(1) = N-(2-((pyridin-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine), [Ru(η(6)-cym)(L(2))Cl]Cl (2, L(2) = N-(2-((1-methyl-1H-imidazol-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine) and [Ru(η(6)-cym)(L(3))Cl] (3, L(3) = N-(2-((2-hydroxyphenyl)methylimino)ethyl)-7-chloroquinolin-4-amine) have been synthesized and characterized. In addition, the X-ray crystal structure of 2 is reported. The antimalarial activity of complexes 1-3 and ligands L(1), L(2) and L(3), as well as the compound N-(2-(bis((pyridin-2-yl)methyl)amino)ethyl)-7-chloroquinolin-4-amine (L(4)), against chloroquine sensitive and chloroquine resistant Plasmodium falciparum malaria strains was evaluated. While 1 and 2 are less active than the corresponding ligands, 3 exhibits high antimalarial activity. The chloroquine analogue L(2) also shows good activity against both the chloroquine sensitive and the chloroquine resistant strains. Heme aggregation inhibition activity (HAIA) at an aqueous buffer/n-octanol interface (HAIR(50)) and lipophilicity (D, as measured by water/n-octanol distribution coefficients) have been measured for all ligands and metal complexes. A direct correlation between the D and HAIR(50) properties cannot be made because of the relative structural diversity of the complexes, but it may be noted that these properties are enhanced upon complexation of the inactive ligand L(3) to ruthenium, to give a metal complex (3) with promising antimalarial activity.
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Affiliation(s)
- Lotta Glans
- Inorganic Chemistry Research Group, Chemical Physics, Center for Chemistry and Chemical Engineering, Lund University, Box 124, SE-221 00 Lund, Sweden
| | - Andreas Ehnbom
- Inorganic Chemistry Research Group, Chemical Physics, Center for Chemistry and Chemical Engineering, Lund University, Box 124, SE-221 00 Lund, Sweden
| | - Carmen de Kock
- Division of Pharmacology, Department of Medicine, University of Cape Town Medical School, Observatory 7925, South Africa
| | - Alberto Martínez
- Department of Chemistry, Brooklyn College and The Graduate Center, The City University of New York, CUNY, 2900 Bedford Avenue, Brooklyn, New York 11210, U.S.A
| | - Jesús Estrada
- Department of Chemistry, Brooklyn College and The Graduate Center, The City University of New York, CUNY, 2900 Bedford Avenue, Brooklyn, New York 11210, U.S.A
| | - Peter J. Smith
- Division of Pharmacology, Department of Medicine, University of Cape Town Medical School, Observatory 7925, South Africa
| | - Matti Haukka
- Department of Chemistry, University of Eastern Finland, Box 111, FIN-80101 Joensuu, Finland
| | - Roberto A. Sánchez-Delgado
- Department of Chemistry, Brooklyn College and The Graduate Center, The City University of New York, CUNY, 2900 Bedford Avenue, Brooklyn, New York 11210, U.S.A
| | - Ebbe Nordlander
- Inorganic Chemistry Research Group, Chemical Physics, Center for Chemistry and Chemical Engineering, Lund University, Box 124, SE-221 00 Lund, Sweden
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Huang HH, Rigouin C, Williams DL. The redox biology of schistosome parasites and applications for drug development. Curr Pharm Des 2012; 18:3595-3611. [PMID: 22607149 PMCID: PMC3638776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 03/09/2012] [Indexed: 05/31/2023]
Abstract
Schistosomiasis caused by Schistosoma spp. is a serious public health concern, especially in sub-Saharan Africa. Praziquantel is the only drug currently administrated to treat this disease. However, praziquantel-resistant parasites have been identified in endemic areas and can be generated in the laboratory. Therefore, it is essential to find new therapeutics. Antioxidants are appealing drug targets. In order to survive in their hosts, schistosomes are challenged by reactive oxygen species from intrinsic and extrinsic sources. Schistosome antioxidant enzymes have been identified as essential proteins and novel drug targets and inhibition of the antioxidant response can lead to parasite death. Because the organization of the redox network in schistosomes is significantly different from that in humans, new drugs are being developed targeting schistosome antioxidants. In this paper the redox biology of schistosomes is discussed and their potential use as drug targets is reviewed. It is hoped that compounds targeting parasite antioxidant responses will become clinically relevant drugs in the near future.
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Affiliation(s)
| | | | - David L. Williams
- Correspondence should be addressed to: Dr. David L. Williams, Department of Microbiology and Immunology, Rush University Medical Center, Chicago, IL 60612-3824 . Phone: (312) 942-1375; Fax: (312) 942-2808
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Johann L, Lanfranchi DA, Davioud-Charvet E, Elhabiri M. A physico-biochemical study on potential redox-cyclers as antimalarial and anti-schistosomal drugs. Curr Pharm Des 2012; 18:3539-66. [PMID: 22607146 PMCID: PMC3711147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 03/12/2012] [Indexed: 05/31/2023]
Abstract
The role of redox enzymes in establishing a microenvironment for parasite development is well characterized. Mimicking human glucose-6-phosphate dehydrogenase and glutathione reductase (GR) deficiencies by redox-cycling compounds thus represents a challenge to the design of new preclinical antiparasitic drug candidates. Schistosomes and malarial parasites feed on hemoglobin. Heme, the toxic prosthetic group of the protein, is not digested and represents a challenge to the redox metabolism of the parasites. Here, we report on old and new redox-cycling compounds--whose antiparasitic activities are related to their interference with (met)hemoglobin degradation and hematin crystallization. Three key-assays allowed probing and differentiating the mechanisms of drug actions. Inhibition of β-hematin was first compared to the heme binding as a possible mode of action. All tested ligands interact with the hematin π-π dimer with K(D) similar to those measured for the major antiparasitic drugs. No correlation between a high affinity for hematin and the capacity to prevent β-hematin formation was however deduced. Inhibition of β-hematin formation is consequently not the result of a single process but results from redox processes following electron transfers from the drugs to iron(III)-containing targets. The third experiment highlighted that several redox-active compounds (in their reduced forms) are able to efficiently reduce methemoglobin to hemoglobin in a GR/NADPH-coupled assay. A correlation between methemoglobin reduction and inhibition of β-hematin was shown, demonstrating that both processes are closely related. The ability of our redox-cyclers to trigger methemoglobin reduction therefore constitutes a critical step to understand the mechanism of action of our drug candidates.
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Affiliation(s)
- Laure Johann
- Laboratoire de Chimie Bioorganique et Médicinale, European School of Chemistry, Polymers and Materials (ECPM), University of Strasbourg and Centre National de la Recherche Scientifique, UMR 7509, 25, rue Becquerel, F-67087 Strasbourg, France
| | - Don Antoine Lanfranchi
- Laboratoire de Chimie Bioorganique et Médicinale, European School of Chemistry, Polymers and Materials (ECPM), University of Strasbourg and Centre National de la Recherche Scientifique, UMR 7509, 25, rue Becquerel, F-67087 Strasbourg, France
| | - Elisabeth Davioud-Charvet
- Laboratoire de Chimie Bioorganique et Médicinale, European School of Chemistry, Polymers and Materials (ECPM), University of Strasbourg and Centre National de la Recherche Scientifique, UMR 7509, 25, rue Becquerel, F-67087 Strasbourg, France
| | - Mourad Elhabiri
- Laboratoire de Chimie Bioorganique et Médicinale, European School of Chemistry, Polymers and Materials (ECPM), University of Strasbourg and Centre National de la Recherche Scientifique, UMR 7509, 25, rue Becquerel, F-67087 Strasbourg, France
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Vargas S, Ndjoko Ioset K, Hay AE, Ioset JR, Wittlin S, Hostettmann K. Screening medicinal plants for the detection of novel antimalarial products applying the inhibition of β-hematin formation. J Pharm Biomed Anal 2011; 56:880-6. [PMID: 21872416 DOI: 10.1016/j.jpba.2011.06.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 06/27/2011] [Accepted: 06/28/2011] [Indexed: 10/18/2022]
Abstract
The identification of novel scaffolds for the development of effective and safe treatments to fight malaria is urgently needed. One of the main opportunities is the discovery of new molecules from natural origin. A simple, robust and cost-effective colorimetric assay based on the inhibition of β-hematin has been adapted to routinely screen plant extracts with the ultimate goal to identify novel antimalarial ingredients. The development of this assay has included a careful optimization of all critical experimental parameters. The β-hematin assay can be completed in less than one working day, requiring a 96-well UV-vis plate reader and low-cost commercially available reagents using a standard operating protocol. It can be used on its own or in combination with the well-known Plasmodium growth inhibition assay and has the obvious merit to be informative at the early stage of drug discovery regarding the mechanism of action of the actives. A total of 40 diverse natural products and 219 plants extracts were tested. Good correlations in respect with specificity (pure compounds 85%, extracts 93%) and positive predictive value (pure compounds 72%, extracts 50%) were obtained in comparison with Plasmodium growth inhibition assay that was used as the reference assay.
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Affiliation(s)
- S Vargas
- School of Pharmaceutical Sciences, University of Geneva, 1211 Geneva 4, Switzerland
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Opsenica I, Burnett JC, Gussio R, Opsenica D, Todorović N, Lanteri CA, Sciotti RJ, Gettayacamin M, Basilico N, Taramelli D, Nuss JE, Wanner L, Panchal RG, Šolaja BA, Bavari S. A chemotype that inhibits three unrelated pathogenic targets: the botulinum neurotoxin serotype A light chain, P. falciparum malaria, and the Ebola filovirus. J Med Chem 2011; 54:1157-69. [PMID: 21265542 PMCID: PMC3056319 DOI: 10.1021/jm100938u] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
A 1,7-bis(alkylamino)diazachrysene-based small molecule was previously identified as an inhibitor of the botulinum neurotoxin serotype A light chain metalloprotease. Subsequently, a variety of derivatives of this chemotype were synthesized to develop structure-activity relationships, and all are inhibitors of the BoNT/A LC. Three-dimensional analyses indicated that half of the originally discovered 1,7-DAAC structure superimposed well with 4-amino-7-chloroquinoline-based antimalarial agents. This observation led to the discovery that several of the 1,7-DAAC derivatives are potent in vitro inhibitors of Plasmodium falciparum and, in general, are more efficacious against CQ-resistant strains than against CQ-susceptible strains. In addition, by inhibiting β-hematin formation, the most efficacious 1,7-DAAC-based antimalarials employ a mechanism of action analogous to that of 4,7-ACQ-based antimalarials and are well tolerated by normal cells. One candidate was also effective when administered orally in a rodent-based malaria model. Finally, the 1,7-DAAC-based derivatives were examined for Ebola filovirus inhibition in an assay employing Vero76 cells, and three provided promising antiviral activities and acceptably low toxicities.
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Affiliation(s)
- Igor Opsenica
- Faculty of Chemistry, University of Belgrade, Studentski trg 16, P.O. Box 51, 11158, Belgrade, Serbia
| | - James C. Burnett
- Target Structure-Based Drug Discovery Group, SAIC-Frederick, Inc., National Cancer Institute at Frederick, P.O. Box B, Frederick, MD 21702, USA
| | - Rick Gussio
- Developmental Therapeutics Program, National Cancer Institute at Frederick, P.O. Box B, F.V.C. 310, Frederick, MD 21702, USA
| | - Dejan Opsenica
- Institute of Chemistry, Technology, and Metallurgy, Belgrade, Serbia
| | - Nina Todorović
- Institute of Chemistry, Technology, and Metallurgy, Belgrade, Serbia
| | - Charlotte A. Lanteri
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
| | - Richard J. Sciotti
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
| | - Montip Gettayacamin
- United States Army Medical Component, Armed Forces Research Institute of Medical Science, Department of Veterinary Medicine, Bangkok, Thailand
| | - Nicoletta Basilico
- Dipartimento di Sanità Pubblica- Microbiologia-Virologia, Università di Milano, Via Pascal 36, 20133 Milano, Italy
| | - Donatella Taramelli
- Dipartimento di Sanità Pubblica- Microbiologia-Virologia, Università di Milano, Via Pascal 36, 20133 Milano, Italy
| | - Jonathan E. Nuss
- United States Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Frederick, MD 21702; USA
| | - Laura Wanner
- United States Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Frederick, MD 21702; USA
| | - Rekha G. Panchal
- United States Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Frederick, MD 21702; USA
| | - Bogdan A. Šolaja
- Faculty of Chemistry, University of Belgrade, Studentski trg 16, P.O. Box 51, 11158, Belgrade, Serbia
| | - Sina Bavari
- United States Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Frederick, MD 21702; USA
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Verbeken M, Suleman S, Baert B, Vangheluwe E, Van Dorpe S, Burvenich C, Duchateau L, Jansen FH, De Spiegeleer B. Stability-indicating HPLC-DAD/UV-ESI/MS impurity profiling of the anti-malarial drug lumefantrine. Malar J 2011; 10:51. [PMID: 21356068 PMCID: PMC3059303 DOI: 10.1186/1475-2875-10-51] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Accepted: 02/28/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Lumefantrine (benflumetol) is a fluorene derivative belonging to the aryl amino alcohol class of anti-malarial drugs and is commercially available in fixed combination products with β-artemether. Impurity characterization of such drugs, which are widely consumed in tropical countries for malaria control programmes, is of paramount importance. However, until now, no exhaustive impurity profile of lumefantrine has been established, encompassing process-related and degradation impurities in active pharmaceutical ingredients (APIs) and finished pharmaceutical products (FPPs). METHODS Using HPLC-DAD/UV-ESI/ion trap/MS, a comprehensive impurity profile was established based upon analysis of market samples as well as stress, accelerated and long-term stability results. In-silico toxicological predictions for these lumefantrine related impurities were made using Toxtree® and Derek®. RESULTS Several new impurities are identified, of which the desbenzylketo derivative (DBK) is proposed as a new specified degradant. DBK and the remaining unspecified lumefantrine related impurities are predicted, using Toxtree® and Derek®, to have a toxicity risk comparable to the toxicity risk of the API lumefantrine itself. CONCLUSIONS From unstressed, stressed and accelerated stability samples of lumefantrine API and FPPs, nine compounds were detected and characterized to be lumefantrine related impurities. One new lumefantrine related compound, DBK, was identified and characterized as a specified degradation impurity of lumefantrine in real market samples (FPPs). The in-silico toxicological investigation (Toxtree® and Derek®) indicated overall a toxicity risk for lumefantrine related impurities comparable to that of the API lumefantrine itself.
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Affiliation(s)
- Mathieu Verbeken
- Drug Quality and Registration group, Faculty of Pharmaceutical Sciences, Ghent University, Harelbekestraat 72, B-9000 Ghent, Belgium
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Frosch T, Popp J. Structural analysis of the antimalarial drug halofantrine by means of Raman spectroscopy and density functional theory calculations. JOURNAL OF BIOMEDICAL OPTICS 2010; 15:041516. [PMID: 20799794 DOI: 10.1117/1.3432656] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The structure of the antimalarial drug halofantrine is analyzed by means of density functional theory (DFT) calculations, IR, and Raman spectroscopy. Strong, selective enhancements of the Raman bands of halofantrine at 1621 and 1590 cm(-1) are discovered by means of UV resonance Raman spectroscopy with excitation wavelength lambda(exc)=244 nm. These signal enhancements can be exploited for a localization of small concentrations of halofantrine in a biological environment. The Raman spectrum of halofantrine is calculated by means of DFT calculations [B3LYP/6-311+G(d,p)]. The calculation is very useful for a thorough mode assignment of the Raman bands of halofantrine. The strong bands at 1621 and 1590 cm(-1) in the UV Raman spectrum are assigned to combined C[Double Bond]C stretching vibrations in the phenanthrene ring of halofantrine. These bands are considered as putative marker bands for pipi interactions with the biological target molecules. The calculation of the electron density demonstrates a strong distribution across the phenanthrene ring of halofantrine, besides the electron withdrawing effect of the Cl and CF(3) substituents. This strong and even electron density distribution supports the hypothesis of pipi stacking as a possible mode of action of halofantrine. Complementary IR spectroscopy is performed for an investigation of vibrations of polar functional groups of the halofantrine molecule.
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Affiliation(s)
- Torsten Frosch
- Friedrich-Schiller-Universitat Jena, Institut fur Physikalische Chemie, Jena, Germany.
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