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Olasehinde G, Ojurongbe D, Akinjogunl O, Egwari L, Adeyeba A. Prevalence of Malaria and Predisposing Factors to Antimalarial Drug Resistance in Southwestern Nigeria. ACTA ACUST UNITED AC 2015. [DOI: 10.3923/jp.2015.92.101] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Abstract
In recent years, the field of Raman spectroscopy has witnessed a surge in technological development, with the incorporation of ultrasensitive, charge-coupled devices, improved laser sources and precision Rayleigh-filter systems. This has led to the development of sensitive confocal micro-Raman spectrometers and imaging spectrometers that are capable of obtaining high spatial-resolution spectra and images of subcellular components within single living cells. This review reports on the application of resonance micro-Raman spectroscopy to the study of malaria pigment (hemozoin), a by-product of hemoglobin catabolization by the malaria parasite, which is an important target site for antimalarial drugs. The review aims to briefly describe recent studies on the application of this technology, elucidate molecular and electronic properties of the malaria pigment and its synthetic analog beta-hematin, provide insight into the mechanism of hemozoin formation within the food vacuole of the parasite, and comment on developing strategies for using this technology in drug-screening protocols.
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Affiliation(s)
- Bayden R Wood
- Monash University, Centre for Biospectroscopy and School of Chemistry, Victoria, 3800, Australia.
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Interaction of quinoline antimalarial drugs with ferriprotoporphyrin IX, a solid state spectroscopy study. J Inorg Biochem 2011; 105:1662-9. [DOI: 10.1016/j.jinorgbio.2011.08.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 08/05/2011] [Accepted: 08/05/2011] [Indexed: 11/21/2022]
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Nguta JM, Mbaria JM, Gathumbi PK, Gakuya D, Kabasa JD, Kiama SG. Ethnodiagnostic skills of the digo community for malaria: a lead to traditional bioprospecting. Front Pharmacol 2011; 2:30. [PMID: 21738507 PMCID: PMC3125516 DOI: 10.3389/fphar.2011.00030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 06/06/2011] [Indexed: 11/13/2022] Open
Abstract
Malaria is a major public health problem that is presently complicated by the development of resistance by Plasmodium falciparum to the mainstay drugs. Thus, new drugs with unique structures and mechanism of action are required to treat drug-resistant strains of malaria. Historically, compounds containing a novel structure from natural origin represent a major source for the discovery and development of new drugs for several diseases. This paper presents ethnophytotherapeutic remedies, ethnodiagnostic skills, and related traditional knowledge utilized by the Digo community of the Kenyan Coast to diagnose malaria as a lead to traditional bioprospecting. The current study was carried out in three Digo villages of Diani sub-location between May 2009 and December 2009. Data was collected using semi-structured interviews, and open and close-ended questionnaires. A total of 60 respondents (34 men and 26 women) provided the targeted information. The results show that the indigenous knowledge of Digo community on malaria encompasses not only the symptoms of malaria but also the factors that are responsible for causing malaria, attributes favoring the breeding of mosquitoes and practices employed to guard against mosquito bites or to protect households against malaria. This knowledge is closely in harmony with scientific approaches to the treatment and control of the disease. The Digo community uses 60 medicinal plants distributed in 52 genera and 27 families to treat malaria. The most frequently mentioned symptoms were fever, joint pains, and vomiting while the most frequently mentioned practices employed to guard against mosquito bites and/or to protect households against malaria was burning of herbal plants such as Ocimum suave and ingestion of herbal decoctions and concoctions. The Digo community has abundant ethnodiagnostic skills for malaria which forms the basis of their traditional bioprospecting techniques.
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Affiliation(s)
- Joseph Mwanzia Nguta
- Department of Public Health, Pharmacology and Toxicology, University of NairobiNairobi, Kenya
| | - James M. Mbaria
- Department of Public Health, Pharmacology and Toxicology, University of NairobiNairobi, Kenya
| | - Peter K. Gathumbi
- Department of Veterinary Pathology, Microbiology and Parasitology, University of NairobiNairobi, Kenya
| | - Daniel Gakuya
- Department of Clinical Studies, University of NairobiNairobi, Kenya
| | - John David Kabasa
- Department of Physiology, Makerere UniversityKampala, Uganda
- Department of Pharmacology, Makerere UniversityKampala, Uganda
| | - Stephen Gitahi Kiama
- Department of Veterinary Anatomy and Physiology, University of NairobiNairobi, Kenya
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Investigation of some medicinal plants traditionally used for treatment of malaria in Kenya as potential sources of antimalarial drugs. Exp Parasitol 2011; 127:609-26. [DOI: 10.1016/j.exppara.2010.11.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Revised: 11/01/2010] [Accepted: 11/09/2010] [Indexed: 11/23/2022]
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Al-Adhroey AH, Nor ZM, Al-Mekhlafi HM, Amran AA, Mahmud R. Antimalarial activity of methanolic leaf extract of Piper betle L. Molecules 2010; 16:107-18. [PMID: 21189459 PMCID: PMC6259093 DOI: 10.3390/molecules16010107] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Revised: 12/18/2010] [Accepted: 12/21/2010] [Indexed: 11/25/2022] Open
Abstract
The need for new compounds active against malaria parasites is made more urgent by the rapid spread of drug-resistance to available antimalarial drugs. The crude methanol extract of Piper betle leaves (50-400 mg/kg) was investigated for its antimalarial activity against Plasmodium berghei (NK65) during early and established infections. The phytochemical and antioxidant potentials of the crude extract were evaluated to elucidate the possibilities of its antimalarial effects. The safety of the extract was also investigated in ICR mice of both sexes by the acute oral toxicity limit test. The leaf extract demonstrated significant (P < 0.05) schizonticidal activity in all three antimalarial evaluation models. Phytochemical screening showed that the leaf extract contains some vital antiplasmodial chemical constituents. The extract also exhibited a potent ability to scavenge the free radicals. The results of acute toxicity showed that the methanol extract of Piper betle leaves is toxicologically safe by oral administration. The results suggest that the Malaysian folklorical medicinal application of the extract of Piper betle leaf has a pharmacological basis.
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Affiliation(s)
- Abdulelah H. Al-Adhroey
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia; E-Mails: (Z.M.N.); (H.M.A.); (R.M.)
| | - Zurainee M. Nor
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia; E-Mails: (Z.M.N.); (H.M.A.); (R.M.)
| | - Hesham M. Al-Mekhlafi
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia; E-Mails: (Z.M.N.); (H.M.A.); (R.M.)
| | - Adel A. Amran
- Department of Physiology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur 50300, Malaysia; E-Mail (A.A.A.)
| | - Rohela Mahmud
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia; E-Mails: (Z.M.N.); (H.M.A.); (R.M.)
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Recent advances in the discovery of haem-targeting drugs for malaria and schistosomiasis. Molecules 2009; 14:2868-87. [PMID: 19701131 PMCID: PMC6254801 DOI: 10.3390/molecules14082868] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 07/20/2009] [Accepted: 07/22/2009] [Indexed: 01/29/2023] Open
Abstract
Haem is believed to be the target of some of the historically most important antimalarial drugs, most notably chloroquine. This target is almost ideal as haem is host-derived and the process targeted, haemozoin formation, is a physico-chemical process with no equivalent in the host. The result is that the target remains viable despite resistance to current drugs, which arises from mutations in parasite membrane transport proteins. Recent advances in high-throughput screening methods, together with a better understanding of the interaction of existing drugs with this target, have created new prospects for discovering novel haem-targeting chemotypes and for target-based structural design of new drugs. Finally, the discovery that Schistosoma mansoni also produces haemozoin suggests that new drugs of this type may be chemotherapeutic not only for malaria, but also for schistosomiasis. These recent developments in the literature are reviewed.
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Gathirwa JW, Rukunga GM, Njagi ENM, Omar SA, Guantai AN, Muthaura CN, Mwitari PG, Kimani CW, Kirira PG, Tolo FM, Ndunda TN, Ndiege IO. In vitro anti-plasmodial and in vivo anti-malarial activity of some plants traditionally used for the treatment of malaria by the Meru community in Kenya. J Nat Med 2007. [DOI: 10.1007/s11418-007-0140-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Muregi FW, Ishih A, Suzuki T, Kino H, Amano T, Mkoji GM, Miyase T, Terada M. In Vivo antimalarial activity of aqueous extracts from Kenyan medicinal plants and their Chloroquine (CQ) potentiation effects against a blood-induced CQ-resistant rodent parasite in mice. Phytother Res 2007; 21:337-43. [PMID: 17221829 DOI: 10.1002/ptr.2067] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Hot water extracts from eight medicinal plants representing five families, used for malaria treatment in Kenya were screened for their in vivo antimalarial activity in mice against a chloroquine (CQ) resistant Plasmodium berghei NK65, either alone or in combination with CQ. Extracts of three plants, Toddalia asiatica (root bark), Rhamnus prinoides (leaves and root bark) and Vernonia lasiopus (root bark) showed high chemosuppression in the range 51%-75%. Maytenus acuminata, M. heterophylla, M. senegalensis and Rhamnus staddo had moderate activities of 33%-49% parasitaemia suppression in the root bark and/or leaf extracts, while Withania somnifera (root bark) had a non-significant suppression (21%). In combination with CQ, extracts of V. lasiopus (all parts), leaf extracts of M. senegalensis, R. prinoides and T. asiatica as well as root barks of M. heterophylla, R. staddo and T. asiatica had improved parasitaemia suppression in the range 38%-66%, indicating synergistic interactions. Remarkable parasitaemia suppression by the extracts, either alone or in combination with CQ resulted into longer survival of mice relative to the controls, in some cases by more than 2 weeks. Plants, which showed significant antimalarial activity including V. lasiopus, T. asiatica and R. prinoides, should further be evaluated in the search for novel agents against drug-resistant malaria.
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Affiliation(s)
- Francis W Muregi
- Department of Parasitology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu 431-3192, Japan.
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Florent I, Lecaille F, Montagne JJ, Gauthier F, Schrével J, Lalmanach G. Labelling of four distinct trophozoite falcipains of Plasmodium falciparum by a cystatin-derived probe. Biol Chem 2005; 386:401-6. [PMID: 15899703 DOI: 10.1515/bc.2005.048] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Trophozoite cysteine protease (TCP) activity, isolated from Plasmodium falciparum soluble 100,000 g extracts, displayed native falcipain-1 kinetic parameters towards peptidyl substrates. The labelling of either isolated TCP or soluble 100,000 g extracts by a cystatin-derived probe (biotinyl-Leu-Val-Gly-CHN2) revealed a single band of ca. 30 kDa by SDS-PAGE, which was resolved into four spots displaying isoelectric points (pI) from 4.7 to 5.3 after two-dimensional separation. The molecular mass and pI correspond to those of falcipain-3, falcipain-2, falcipain-2' and falcipain-1, respectively. The two central spots were identified by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry as falcipain-2 and falcipain-2'. This activity-based probe represents a potential tool for profiling active falcipains in parasites.
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Affiliation(s)
- Isabelle Florent
- Biologie Fonctionnelle des Protozoaires, Département Régulation, Dévelopement, Diversité Moléculaire, Muséum National d'Histoire Naturelle, 61, rue Buffon, F-75005 Paris, France.
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Waters NC, Dow GS, Kozar MP. Antimalarial compound identification and design: advances in the patent literature, 2000 – 2003. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.14.8.1125] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Wood BR, Langford SJ, Cooke BM, Lim J, Glenister FK, Duriska M, Unthank JK, McNaughton D. Resonance Raman Spectroscopy Reveals New Insight into the Electronic Structure of β-Hematin and Malaria Pigment. J Am Chem Soc 2004; 126:9233-9. [PMID: 15281812 DOI: 10.1021/ja038691x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Resonance Raman spectra of beta-hematin and hemin are reported for a range of excitation wavelengths including 406, 488, 514, 568, 633, 780, 830, and 1064 nm. Dramatic enhancement of A(1g) modes (1570, 1371, 795, 677, and 344 cm(-1)), ring breathing modes (850-650 cm(-1)), and out-of-plane modes including iron-ligand modes (400-200 cm(-1)) were observed when irradiating with 780- and 830-nm laser excitation wavelengths for beta-hematin and to a lesser extent hemin. Absorbance spectra recorded during the transformation of hemin to beta-hematin showed a red-shift of the Soret and Q (0-1) bands, which has been interpreted as excitonic coupling resulting from porphyrin aggregation. A small broad electronic transition observed at 867 nm was assigned to a z-polarized charge-transfer transition d(xy) --> e(g)(pi). The extraordinary band enhancement observed when exciting with near-infrared excitation wavelengths in beta-hematin when compared to hemin is explained in terms of an aggregated enhanced Raman scattering hypothesis based on the intermolecular excitonic interactions between porphyrinic units. This study provides new insight into the electronic structure of beta-hematin and therefore hemozoin (malaria pigment). The results have important implications in the design and testing of new anti-malaria drugs that specifically interfere with hemozoin formation.
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Affiliation(s)
- Bayden R Wood
- Centre for Biospectroscopy, School of Chemistry, and the Department of Microbiology, Monash University, Victoria, 3800, Australia.
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Cameron A, Read J, Tranter R, Winter VJ, Sessions RB, Brady RL, Vivas L, Easton A, Kendrick H, Croft SL, Barros D, Lavandera JL, Martin JJ, Risco F, García-Ochoa S, Gamo FJ, Sanz L, Leon L, Ruiz JR, Gabarró R, Mallo A, Gómez de las Heras F. Identification and Activity of a Series of Azole-based Compounds with Lactate Dehydrogenase-directed Anti-malarial Activity. J Biol Chem 2004; 279:31429-39. [PMID: 15117937 DOI: 10.1074/jbc.m402433200] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Plasmodium falciparum, the causative agent of malaria, relies extensively on glycolysis coupled with homolactic fermentation during its blood-borne stages for energy production. Selective inhibitors of the parasite lactate dehydrogenase (LDH), central to NAD(+) regeneration, therefore potentially provide a route to new antimalarial drugs directed against a novel molecular target. A series of heterocyclic, azole-based compounds are described that preferentially inhibit P. falciparum LDH at sub-micromolar concentrations, typically at concentrations about 100-fold lower than required for human lactate dehydrogenase inhibition. Crystal structures show these competitive inhibitors form a network of interactions with amino acids within the active site of the enzyme, stacking alongside the nicotinamide ring of the NAD(+) cofactor. These compounds display modest activity against parasitized erythrocytes, including parasite strains with known resistance to existing anti-malarials and against Plasmodium berghei in BALB/c mice. Initial toxicity data suggest the azole derivatives have generally low cytotoxicity, and preliminary pharmoco-kinetic data show favorable bioavailability and circulation times. These encouraging results suggest that further enhancement of these structures may yield candidates suitable for consideration as new therapeutics for the treatment of malaria. In combination these studies also provide strong support for the validity of targeting the Plasmodium glycolytic pathway and, in particular, LDH in the search for novel anti-malarials.
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Affiliation(s)
- Angus Cameron
- Department of Biochemistry and Molecular Recognition Centre, University of Bristol, Bristol BS8 1TD, United Kingdom
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Nwaka S, Ridley RG. Virtual drug discovery and development for neglected diseases through public-private partnerships. Nat Rev Drug Discov 2004; 2:919-28. [PMID: 14668812 DOI: 10.1038/nrd1230] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Bachi MD, Korshin EE, Hoos R, Szpilman AM, Ploypradith P, Xie S, Shapiro TA, Posner GH. A short synthesis and biological evaluation of potent and nontoxic antimalarial bridged bicyclic beta-sulfonyl-endoperoxides. J Med Chem 2003; 46:2516-33. [PMID: 12773055 DOI: 10.1021/jm020584a] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The syntheses and in vitro antimalarial screening of 50 bridged, bicyclic endoperoxides of types 9-13 are reported. In contrast to antimalarial trioxanes of the artemisinin family, but like yingzhaosu A and arteflene, the peroxide function of compounds 9-13 is contained in a 2,3-dioxabicyclo[3.3.1]nonane system 6. Peroxides 9 and 10 (R(1) = OH) are readily available through a multicomponent, sequential, free-radical reaction involving thiol-monoterpenes co-oxygenation (a TOCO reaction). beta-Sulfenyl peroxides 9 and 10 (R(1) = OH) are converted into beta-sulfinyl and beta-sulfonyl peroxides of types 11-13 by controlled S-oxidation and manipulation of the tert-hydroxyl group through acylation, alkylation, or dehydration followed by selective hydrogenation. Ten enantiopure beta-sulfonyl peroxides of types 12 and 13 exhibit in vitro antimalarial activity comparable to that of artemisinin (IC(50) = 6-24 nM against Plasmodium falciparum NF54). In vivo testing of a few selected peroxides against Plasmodium berghei N indicates that the antimalarial efficacies of beta-sulfonyl peroxides 39a, 46a, 46b, and 50a are comparable to those of some of the best antimalarial drugs and are higher than artemisinin against chloroquine-resistant Plasmodium yoelii ssp. NS. In view of the nontoxicity of beta-sulfonyl peroxides 39a, 46a, and 46b in mice, at high dosing, these compounds are regarded as promising antimalarial drug candidates.
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Affiliation(s)
- Mario D Bachi
- Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel.
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Waters NC, Geyer JA. Cyclin-dependent protein kinases as therapeutic drug targets for antimalarial drug development. Expert Opin Ther Targets 2003; 7:7-17. [PMID: 12556199 DOI: 10.1517/14728222.7.1.7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Cyclin-dependent protein kinases (CDKs) have been attractive drug targets for the development of anticancer therapies due to their direct and crucial role in the regulation of cellular proliferation. Following this trend, CDKs have been pursued as potential drug targets for several other diseases. Structure-based drug design programmes have focused on the plasmodial CDKs to develop new candidate antimalarial compounds. This review discusses the most recent advances relating to three Plasmodium falciparum CDKs (PfPK5, PfPK6 and Pfmrk) as they are developed as antimalarial drug targets. CDKs are highly conserved, and focus must be placed upon the amino acid differences between human and plasmodial CDKs in order to develop specific inhibitors. Comparisons of the active sites of human and parasite CDKs reveal sequence and potential structural variations. Using sequence analysis, molecular modelling and in vitro drug screening, it is possible to identify and develop inhibitors that specifically target the plasmodial CDKs. These efforts are aimed at identifying new classes of CDK inhibitors that may be exploited for antimalarial drug development.
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Affiliation(s)
- Norman C Waters
- United States Army Medical Research Unit-Kenya, MRU 64109 APO, AE 09831-4109, Kenya.
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An efficient synthesis of bridged-bicyclic peroxides structurally related to antimalarial yingzhaosu A based on radical co-oxygenation of thiols and monoterpenes. Tetrahedron 2002. [DOI: 10.1016/s0040-4020(02)00126-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
Continued and sustainable improvements in antimalarial medicines through focused research and development are essential for the world's future ability to treat and control malaria. Unfortunately, malaria is a disease of poverty, and despite a wealth of scientific knowledge there is insufficient market incentive to generate the competitive, business-driven industrial antimalarial drug research and development that is normally needed to deliver new products. Mechanisms of partnering with industry have been established to overcome this obstacle and to open up and build on scientific opportunities for improved chemotherapy in the future.
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Kurosawa Y, Dorn A, Kitsuji-Shirane M, Shimada H, Satoh T, Matile H, Hofheinz W, Masciadri R, Kansy M, Ridley RG. Hematin polymerization assay as a high-throughput screen for identification of new antimalarial pharmacophores. Antimicrob Agents Chemother 2000; 44:2638-44. [PMID: 10991837 PMCID: PMC90128 DOI: 10.1128/aac.44.10.2638-2644.2000] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hematin polymerization is a parasite-specific process that enables the detoxification of heme following its release in the lysosomal digestive vacuole during hemoglobin degradation, and represents both an essential and a unique pharmacological drug target. We have developed a high-throughput in vitro microassay of hematin polymerization based on the detection of (14)C-labeled hematin incorporated into polymeric hemozoin (malaria pigment). The assay uses 96-well filtration microplates and requires 12 h and a Wallac 1450 MicroBeta liquid scintillation counter. The robustness of the assay allowed the rapid screening and evaluation of more than 100, 000 compounds. Random screening was complemented by the development of a pharmacophore hypothesis using the "Catalyst" program and a large amount of data available on the inhibitory activity of a large library of 4-aminoquinolines. Using these methods, we identified "hit" compounds belonging to several chemical structural classes that had potential antimalarial activity. Follow-up evaluation of the antimalarial activity of these compounds in culture and in the Plasmodium berghei murine model further identified compounds with actual antimalarial activity. Of particular interest was a triarylcarbinol (Ro 06-9075) and a related benzophenone (Ro 22-8014) that showed oral activity in the murine model. These compounds are chemically accessible and could form the basis of a new antimalarial medicinal chemistry program.
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Affiliation(s)
- Y Kurosawa
- Department of Pharmaceutical Screening, Nippon Roche Research Center, 200 Kajiwara, Kamakura, Kanagawa Prefecture 247, Japan
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