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Djimde M, Tshiongo JK, Muhindo HM, Tinto H, Sevene E, Traore M, Vala A, Macuacua S, Kabore B, Dabira ED, Erhart A, Diakite H, Keita M, Piqueras M, González R, Menendez C, Dorlo TP, Sagara I, Mens P, Schallig H, D'Alessandro U, Kayentao K. Efficacy and safety of pyronaridine-artesunate (PYRAMAX) for the treatment of P. falciparum uncomplicated malaria in African pregnant women (PYRAPREG): study protocol for a phase 3, non-inferiority, randomised open-label clinical trial. BMJ Open 2023; 13:e065295. [PMID: 37813539 PMCID: PMC10565244 DOI: 10.1136/bmjopen-2022-065295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 08/31/2023] [Indexed: 10/13/2023] Open
Abstract
INTRODUCTION Malaria infection during pregnancy increases the risk of low birth weight and infant mortality and should be prevented and treated. Artemisinin-based combination treatments are generally well tolerated, safe and effective; the most used being artemether-lumefantrine (AL) and dihydroartemisinin-piperaquine (DP). Pyronaridine-artesunate (PA) is a new artemisinin-based combination. The main objective of this study is to determine the efficacy and safety of PA versus AL or DP when administered to pregnant women with confirmed Plasmodium falciparum infection in the second or third trimester. The primary hypothesis is the pairwise non-inferiority of PA as compared with either AL or DP. METHODS AND ANALYSIS A phase 3, non-inferiority, randomised, open-label clinical trial to determine the safety and efficacy of AL, DP and PA in pregnant women with malaria in five sub-Saharan, malaria-endemic countries (Burkina Faso, Democratic Republic of the Congo, Mali, Mozambique and the Gambia). A total of 1875 pregnant women will be randomised to one of the treatment arms. Women will be actively monitored until Day 63 post-treatment, at delivery and 4-6 weeks after delivery, and infants' health will be checked on their first birthday. The primary endpoint is the PCR-adjusted rate of adequate clinical and parasitological response at Day 42 in the per-protocol population. ETHICS AND DISSEMINATION This protocol has been approved by the Ethics Committee for Health Research in Burkina Faso, the National Health Ethics Committee in the Democratic Republic of Congo, the Ethics Committee of the Faculty of Medicine and Odontostomatology/Faculty of Pharmacy in Mali, the Gambia Government/MRCG Joint Ethics Committee and the National Bioethics Committee for Health in Mozambique. Written informed consent will be obtained from each individual prior to her participation in the study. The results will be published in peer-reviewed open access journals and presented at (inter)national conferences and meetings. TRIAL REGISTRATION NUMBER PACTR202011812241529.
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Affiliation(s)
- Moussa Djimde
- Malaria Research and Training Center, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Japhet Kabalu Tshiongo
- Département of Tropical Médecine, Universite de Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Hypolite Mavoko Muhindo
- Department of Tropical Medicine, Universite de Kinshasa Faculte de Medecine, Kinshasa, Democratic Republic of Congo
| | - Halidou Tinto
- Institut de Recherche en Sciences de la Santé (IRSS) - Unité de Recherche Clinique de Nanoro, Nanoro, Burkina Faso
| | - Esperanca Sevene
- Centro de Investigacao em Saude de Manhica, Manhica, Mozambique
- Universidade Eduardo Mondlane, Maputo, Mozambique
| | - Maminata Traore
- Institut de Recherche en Sciences de la Santé (IRSS) - Unité de Recherche Clinique de Nanoro, Ouagadougou, Burkina Faso
| | - Anifa Vala
- Centro de Investigação em Saúde de Manhiça, Manhica, Mozambique
| | - Salesio Macuacua
- Centro de Investigação em Saúde da Manhiça (CISM), Maputo, Mozambique
| | - Berenger Kabore
- Institut de Recherche en Sciences de la Santé (IRSS) - Unité de Recherche Clinique de Nanoro, Ouagadougou, Burkina Faso
| | - Edgard Diniba Dabira
- MRC Unit The Gambia (MRCG) at the London School of Hygiene and Tropical Medicine, The Gambia London, UK
| | - Annette Erhart
- MRC Unit The Gambia (MRCG) at the London School of Hygiene and Tropical Medicine, The Gambia London, UK
| | - Hamadoun Diakite
- Malaria Research and Training Center, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Mohamed Keita
- Faculty of Medicine Odontostomatology, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | | | | | | | - Thomas Pc Dorlo
- Netherlands Cancer Institute / Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands
- Department of Pharmacy, Uppsala University, Uppsala, UK
| | - Issaka Sagara
- Malaria Research and Training Center, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Petra Mens
- Amsterdam University Medical Centres, Academic Medical Centre at the University of Amsterdam (AMC), Amsterdam, The Netherlands
| | - Henk Schallig
- Amsterdam University Medical Centres, Academic Medical Centre at the University of Amsterdam (AMC), Amsterdam, The Netherlands
| | | | - Kassoum Kayentao
- Malaria Research and Training Center, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
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Sahu SK, Behera PK, Choudhury P, Panda S, Rout L. Strategy and Problems for Synthesis of Antimalaria Artemisinin (Qinghaosu). ChemistrySelect 2020. [DOI: 10.1002/slct.202002885] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Santosh Kumar Sahu
- Department of Chemistry Berhampur University Bhanjabihar Ganjam Odisha 760007
| | | | | | - Subhalaxmi Panda
- Department of Chemistry Berhampur University Bhanjabihar Ganjam Odisha 760007
| | - Laxmidhar Rout
- Department of Chemistry Berhampur University Bhanjabihar Ganjam Odisha 760007
- Adjunct Faculty Department of Chemical Science IISER Berhampur Odisha
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Fadiji AE, Babalola OO. Elucidating Mechanisms of Endophytes Used in Plant Protection and Other Bioactivities With Multifunctional Prospects. Front Bioeng Biotechnol 2020; 8:467. [PMID: 32500068 PMCID: PMC7242734 DOI: 10.3389/fbioe.2020.00467] [Citation(s) in RCA: 147] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 04/22/2020] [Indexed: 01/06/2023] Open
Abstract
Endophytes are abundant in plants and studies are continuously emanating on their ability to protect plants from pathogens that cause diseases especially in the field of agriculture. The advantage that endophytes have over other biocontrol agents is the ability to colonize plant's internal tissues. Despite this attributes, a deep understanding of the mechanism employed by endophytes in protecting the plant from diseases is still required for both effectiveness and commercialization. Also, there are increasing cases of antibiotics resistance among most causative agents of diseases in human beings, which calls for an alternative drug discovery using natural sources. Endophytes present themselves as a storehouse of many bioactive metabolites such as phenolic acids, alkaloids, quinones, steroids, saponins, tannins, and terpenoids which makes them a promising candidate for anticancer, antimalarial, antituberculosis, antiviral, antidiabetic, anti-inflammatory, antiarthritis, and immunosuppressive properties among many others, even though the primary function of bioactive compounds from endophytes is to make the host plants resistant to both abiotic and biotic stresses. Endophytes still present themselves as a peculiar source of possible drugs. This study elucidates the mechanisms employed by endophytes in protecting the plant from diseases and different bioactivities of importance to humans with a focus on endophytic bacteria and fungi.
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Affiliation(s)
| | - Olubukola Oluranti Babalola
- Food Security and Safety Niche, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho, South Africa
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Ch JR, Rao T B, Kumar Goud P S, J S, K R. Development and validation of liquid chromatography method using the principles of QbD for antimalarials used in Artemisinin based combination therapy. J LIQ CHROMATOGR R T 2019. [DOI: 10.1080/10826076.2018.1492936] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Jaya Raju Ch
- Department of Chemistry, K. L. Education Foundation, Vaddeswaram, Guntur, Andhra Pradesh, India
- Analytical Research and Development, United States Pharmacopeial Convention-India (P) Ltd., Shameerpet, Hyderabad, India
| | - Bhaskara Rao T
- Department of Chemistry, K. L. Education Foundation, Vaddeswaram, Guntur, Andhra Pradesh, India
| | - Sanath Kumar Goud P
- Analytical Research and Development, United States Pharmacopeial Convention-India (P) Ltd., Shameerpet, Hyderabad, India
| | - Satish J
- Analytical Research and Development, United States Pharmacopeial Convention-India (P) Ltd., Shameerpet, Hyderabad, India
| | - Rajashekhar K
- Analytical Research and Development, United States Pharmacopeial Convention-India (P) Ltd., Shameerpet, Hyderabad, India
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Antiplasmodial Properties and Cytotoxicity of Endophytic Fungi from Symphonia globulifera (Clusiaceae). J Fungi (Basel) 2018; 4:jof4020070. [PMID: 29895768 PMCID: PMC6023428 DOI: 10.3390/jof4020070] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 06/07/2018] [Accepted: 06/08/2018] [Indexed: 12/02/2022] Open
Abstract
There is continuing need for new and improved drugs to tackle malaria, which remains a major public health problem, especially in tropical and subtropical regions of the world. Natural products represent credible sources of new antiplasmodial agents for antimalarial drug development. Endophytes that widely colonize healthy tissues of plants have been shown to synthesize a great variety of secondary metabolites that might possess antiplasmodial benefits. The present study was carried out to evaluate the antiplasmodial potential of extracts from endophytic fungi isolated from Symphonia globulifera against a chloroquine-resistant strain of Plasmodium falciparum (PfINDO). Sixty-one fungal isolates with infection frequency of 67.77% were obtained from the bark of S. globulifera. Twelve selected isolates were classified into six different genera including Fusarium, Paecilomyces, Penicillium, Aspergillus, Mucor, and Bipolaris. Extracts from the 12 isolates were tested against PfINDO, and nine showed good activity (IC50 < 10 μg·mL−1) with three fungi including Paecilomyces lilacinus (IC50 = 0.44 μg·mL−1), Penicillium janthinellum (IC50 = 0.2 μg·mL−1), and Paecilomyces sp. (IC50 = 0.55 μg·mL−1) showing the highest promise. These three isolates were found to be less cytotoxic against the HEK293T cell line with selectivity indices ranging from 24.52 to 70.56. Results from this study indicate that endophytic fungi from Symphonia globulifera are promising sources of hit compounds that might be further investigated as novel drugs against malaria. The chemical investigation of active extracts is ongoing.
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D'Alessandro U, Hill J, Tarning J, Pell C, Webster J, Gutman J, Sevene E. Treatment of uncomplicated and severe malaria during pregnancy. THE LANCET. INFECTIOUS DISEASES 2018; 18:e133-e146. [PMID: 29395998 DOI: 10.1016/s1473-3099(18)30065-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 07/19/2017] [Accepted: 10/13/2017] [Indexed: 12/13/2022]
Abstract
Over the past 10 years, the available evidence on the treatment of malaria during pregnancy has increased substantially. Owing to their relative ease of use, good sensitivity and specificity, histidine rich protein 2 based rapid diagnostic tests are appropriate for symptomatic pregnant women; however, such tests are less appropriate for systematic screening because they will not detect an important proportion of infections among asymptomatic women. The effect of pregnancy on the pharmacokinetics of antimalarial drugs varies greatly between studies and class of antimalarial drugs, emphasising the need for prospective studies in pregnant and non-pregnant women. For the treatment of malaria during the first trimester, international guidelines are being reviewed by WHO. For the second and third trimester of pregnancy, results from several trials have confirmed that artemisinin-based combination treatments are safe and efficacious, although tolerability and efficacy might vary by treatment. It is now essential to translate such evidence into policies and clinical practice that benefit pregnant women in countries where malaria is endemic. Access to parasitological diagnosis or appropriate antimalarial treatment remains low in many countries and regions. Therefore, there is a pressing need for research to identify quality improvement interventions targeting pregnant women and health providers. In addition, efficient and practical systems for pharmacovigilance are needed to further expand knowledge on the safety of antimalarial drugs, particularly in the first trimester of pregnancy.
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Affiliation(s)
- Umberto D'Alessandro
- Medical Research Council Unit, Banjul, The Gambia; London School of Hygiene & Tropical Medicine, London, UK.
| | - Jenny Hill
- Liverpool School of Tropical Medicine, Liverpool, UK
| | - Joel Tarning
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand; Centre for Tropical Medicine, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Christopher Pell
- Centre for Social Science and Global Health, University of Amsterdam, Amsterdam, Netherlands; Amsterdam Institute for Global Health and Development, Amsterdam, Netherlands
| | - Jayne Webster
- London School of Hygiene & Tropical Medicine, London, UK
| | - Julie Gutman
- Malaria Branch, US Centers for Diseases Control and Prevention, Atlanta, GA, USA
| | - Esperanca Sevene
- Manhiça Health Research Center (CISM), Manhiça, Mozambique; Faculty of Medicine, Eduardo Mondlane University, Maputo, Mozambique
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Synthetic strategy with representation on mechanistic pathway for the therapeutic applications of dihydroquinazolinones. Eur J Med Chem 2016; 123:596-630. [DOI: 10.1016/j.ejmech.2016.08.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 08/01/2016] [Accepted: 08/01/2016] [Indexed: 01/25/2023]
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Pekyi D, Ampromfi AA, Tinto H, Traoré-Coulibaly M, Tahita MC, Valéa I, Mwapasa V, Kalilani-Phiri L, Kalanda G, Madanitsa M, Ravinetto R, Mutabingwa T, Gbekor P, Tagbor H, Antwi G, Menten J, De Crop M, Claeys Y, Schurmans C, Van Overmeir C, Thriemer K, Van Geertruyden JP, D'Alessandro U, Nambozi M, Mulenga M, Hachizovu S, Kabuya JBB, Mulenga J. Four Artemisinin-Based Treatments in African Pregnant Women with Malaria. N Engl J Med 2016; 374:913-27. [PMID: 26962727 DOI: 10.1056/nejmoa1508606] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Information regarding the safety and efficacy of artemisinin combination treatments for malaria in pregnant women is limited, particularly among women who live in sub-Saharan Africa. METHODS We conducted a multicenter, randomized, open-label trial of treatments for malaria in pregnant women in four African countries. A total of 3428 pregnant women in the second or third trimester who had falciparum malaria (at any parasite density and regardless of symptoms) were treated with artemether-lumefantrine, amodiaquine-artesunate, mefloquine-artesunate, or dihydroartemisinin-piperaquine. The primary end points were the polymerase-chain-reaction (PCR)-adjusted cure rates (i.e., cure of the original infection; new infections during follow-up were not considered to be treatment failures) at day 63 and safety outcomes. RESULTS The PCR-adjusted cure rates in the per-protocol analysis were 94.8% in the artemether-lumefantrine group, 98.5% in the amodiaquine-artesunate group, 99.2% in the dihydroartemisinin-piperaquine group, and 96.8% in the mefloquine-artesunate group; the PCR-adjusted cure rates in the intention-to-treat analysis were 94.2%, 96.9%, 98.0%, and 95.5%, respectively. There was no significant difference among the amodiaquine-artesunate group, dihydroartemisinin-piperaquine group, and the mefloquine-artesunate group. The cure rate in the artemether-lumefantrine group was significantly lower than that in the other three groups, although the absolute difference was within the 5-percentage-point margin for equivalence. The unadjusted cure rates, used as a measure of the post-treatment prophylactic effect, were significantly lower in the artemether-lumefantrine group (52.5%) than in groups that received amodiaquine-artesunate (82.3%), dihydroartemisinin-piperaquine (86.9%), or mefloquine-artesunate (73.8%). No significant difference in the rate of serious adverse events and in birth outcomes was found among the treatment groups. Drug-related adverse events such as asthenia, poor appetite, dizziness, nausea, and vomiting occurred significantly more frequently in the mefloquine-artesunate group (50.6%) and the amodiaquine-artesunate group (48.5%) than in the dihydroartemisinin-piperaquine group (20.6%) and the artemether-lumefantrine group (11.5%) (P<0.001 for comparison among the four groups). CONCLUSIONS Artemether-lumefantrine was associated with the fewest adverse effects and with acceptable cure rates but provided the shortest post-treatment prophylaxis, whereas dihydroartemisinin-piperaquine had the best efficacy and an acceptable safety profile. (Funded by the European and Developing Countries Clinical Trials Partnership and others; ClinicalTrials.gov number, NCT00852423.).
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Sserwanga A, Sears D, Kapella BK, Kigozi R, Rubahika D, Staedke SG, Kamya M, Yoon SS, Chang MA, Dorsey G, Mpimbaza A. Anti-malarial prescription practices among children admitted to six public hospitals in Uganda from 2011 to 2013. Malar J 2015; 14:331. [PMID: 26306395 PMCID: PMC4549911 DOI: 10.1186/s12936-015-0851-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 08/16/2015] [Indexed: 11/21/2022] Open
Abstract
Background In 2011, Uganda’s Ministry of Health switched policy from presumptive treatment of malaria to recommending parasitological diagnosis prior to treatment, resulting in an expansion of diagnostic services at all levels of public health facilities including hospitals. Despite this change, anti-malarial drugs are often prescribed even when test results are negative. Presented is data on anti-malarial prescription practices among hospitalized children who underwent diagnostic testing after adoption of new treatment guidelines. Methods Anti-malarial prescription practices were collected as part of an inpatient malaria surveillance program generating high quality data among children admitted for any reason at government hospitals in six districts. A standardized medical record form was used to collect detailed patient information including presenting symptoms and signs, laboratory test results, admission and final diagnoses, treatments administered, and final outcome upon discharge. Results Between July 2011 and December 2013, 58,095 children were admitted to the six hospitals (hospital range 3294–20,426).A total of 56,282 (96.9 %) patients were tested for malaria, of which 26,072 (46.3 %) tested positive (hospital range 5.9–57.3 %). Among those testing positive, only 84 (0.3 %) were first tested after admission and 295 of 30,389 (1.0 %) patients who tested negative at admission later tested positive. Of 30,210 children with only negative test results, 11,977 (39.6 %) were prescribed an anti-malarial (hospital range 14.5–53.6 %). The proportion of children with a negative test result who were prescribed an anti-malarial fluctuated over time and did not show a significant trend at any site with the exception of one hospital where a steady decline was observed. Among those with only negative test results, children 6–12 months of age (aOR 3.78; p < 0.001) and those greater than 12 months of age (aOR 4.89; p < 0.001) were more likely to be prescribed an anti-malarial compared to children less than 6 months of age. Children with findings suggestive of severe malaria were also more likely to be prescribed an anti-malarial after a negative test result (aOR 1.98; p < 0.001). Conclusions Despite high testing rates for malaria at all sites, prescription of anti-malarials to patients with negative test results remained high, with the exception of one site where a steady decline occurred.
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Affiliation(s)
- Asadu Sserwanga
- Infectious Diseases Research Collaboration, Kampala, Uganda.
| | - David Sears
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, USA.
| | - Bryan K Kapella
- Malaria Branch, Division of Parasitic Diseases and Malaria, US Centers for Disease Control and Prevention, Atlanta, USA.
| | - Ruth Kigozi
- Infectious Diseases Research Collaboration, Kampala, Uganda.
| | - Denis Rubahika
- National Malaria Control Programme, Ministry of Health Uganda, Kampala, Uganda.
| | - Sarah G Staedke
- Infectious Diseases Research Collaboration, Kampala, Uganda. .,London School of Hygiene and Tropical Medicine, London, UK.
| | - Moses Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda. .,Child Health and Development Centre, Makerere University College of Health Sciences, Kampala, Uganda.
| | - Steven S Yoon
- Malaria Branch, Division of Parasitic Diseases and Malaria, US Centers for Disease Control and Prevention, Atlanta, USA.
| | - Michelle A Chang
- Malaria Branch, Division of Parasitic Diseases and Malaria, US Centers for Disease Control and Prevention, Atlanta, USA.
| | - Grant Dorsey
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, USA.
| | - Arthur Mpimbaza
- Infectious Diseases Research Collaboration, Kampala, Uganda. .,Child Health and Development Centre, Makerere University College of Health Sciences, Kampala, Uganda.
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Buchko GW, Yee A, Semesi A, Myler PJ, Arrowsmith CH, Hui R. Solution-state NMR structure of the putative morphogene protein BolA (PFE0790c) from Plasmodium falciparum. Acta Crystallogr F Struct Biol Commun 2015; 71:514-21. [PMID: 25945703 PMCID: PMC4427159 DOI: 10.1107/s2053230x1402799x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 12/23/2014] [Indexed: 12/22/2022] Open
Abstract
Protozoa of the genus Plasmodium are responsible for malaria, which is perhaps the most important parasitic disease to infect mankind. The emergence of Plasmodium strains resistant to current therapeutics and prophylactics makes the development of new treatment strategies urgent. Among the potential targets for new antimalarial drugs is the BolA-like protein PFE0790c from Plasmodium falciparum (Pf-BolA). While the function of BolA is unknown, it has been linked to cell morphology by regulating transcription in response to stress. Using an NMR-based method, an ensemble of 20 structures of Pf-BolA was determined and deposited in the PDB (PDB entry 2kdn). The overall topology of the Pf-BolA structure, α1-β1-β2-η1-α2/η2-β3-α3, with the β-strands forming a mixed β-sheet, is similar to the fold observed in other BolA structures. A helix-turn-helix motif similar to the class II KH fold associated with nucleic acid-binding proteins is present, but contains an FXGXXXL signature sequence that differs from the GXXG signature sequence present in class II KH folds, suggesting that the BolA family of proteins may use a novel protein-nucleic acid interface. A well conserved arginine residue, Arg50, hypothesized to play a role in governing the formation of the C-terminal α-helix in the BolA family of proteins, is too distant to form polar contacts with any side chains in this α-helix in Pf-BolA, suggesting that this conserved arginine may only serve a role in guiding the orientation of this C-terminal helix in some BolA proteins. A survey of BolA structures suggests that the C-terminal helix may not have a functional role and that the third helix (α2/η2) has a `kink' that appears to be conserved among the BolA protein structures. Circular dichroism spectroscopy shows that Pf-BolA is fairly robust, partially unfolding when heated to 353 K and refolding upon cooling to 298 K.
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Affiliation(s)
- Garry W. Buchko
- Seattle Structural Genomics Center for Infectious Disease, USA
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Adelinda Yee
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Anthony Semesi
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Peter J. Myler
- Seattle Structural Genomics Center for Infectious Disease, USA
- Seattle BioMed, Seattle, Washington, USA
- Department of Medical Education and Biomedical Informatics and Department of Global Health, University of Washington, Seattle, Washington, USA
| | - Cheryl H. Arrowsmith
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Structural Genomics Consortium, England
| | - Raymond Hui
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Structural Genomics Consortium, England
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Pharmacokinetic-pharmacodynamic analysis of spiroindolone analogs and KAE609 in a murine malaria model. Antimicrob Agents Chemother 2014; 59:1200-10. [PMID: 25487807 PMCID: PMC4335872 DOI: 10.1128/aac.03274-14] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Limited information is available on the pharmacokinetic (PK) and pharmacodynamic (PD) parameters driving the efficacy of antimalarial drugs. Our objective in this study was to determine dose-response relationships of a panel of related spiroindolone analogs and identify the PK-PD index that correlates best with the efficacy of KAE609, a selected class representative. The dose-response efficacy studies were conducted in the Plasmodium berghei murine malaria model, and the relationship between dose and efficacy (i.e., reduction in parasitemia) was examined. All spiroindolone analogs studied displayed a maximum reduction in parasitemia, with 90% effective dose (ED90) values ranging between 6 and 38 mg/kg of body weight. Further, dose fractionation studies were conducted for KAE609, and the relationship between PK-PD indices and efficacy was analyzed. The PK-PD indices were calculated using the in vitro potency against P. berghei (2× the 99% inhibitory concentration [IC99]) as a threshold (TRE). The percentage of the time in which KAE609 plasma concentrations remained at >2× the IC99 within 48 h (%T>TRE) and the area under the concentration-time curve from 0 to 48 h (AUC0–48)/TRE ratio correlated well with parasite reduction (R2 = 0.97 and 0.95, respectively) but less so for the maximum concentration of drug in serum (Cmax)/TRE ratio (R2 = 0.88). The present results suggest that for KAE609 and, supposedly, for its analogs, the dosing regimens covering a T>TRE of 100%, AUC0–48/TRE ratio of 587, and a Cmax/TRE ratio of 30 are likely to result in the maximum reduction in parasitemia in the P. berghei malaria mouse model. This information could be used to prioritize analogs within the same class of compounds and contribute to the design of efficacy studies, thereby facilitating early drug discovery and lead optimization programs.
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Akala HM, Achieng AO, Eyase FL, Juma DW, Ingasia L, Cheruiyot AC, Okello C, Omariba D, Owiti EA, Muriuki C, Yeda R, Andagalu B, Johnson JD, Kamau E. Five-year tracking of Plasmodium falciparum allele frequencies in a holoendemic area with indistinct seasonal transitions. J Multidiscip Healthc 2014; 7:515-23. [PMID: 25395861 PMCID: PMC4227620 DOI: 10.2147/jmdh.s67252] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND The renewed malaria eradication efforts require an understanding of the seasonal patterns of frequency of polymorphic variants in order to focus limited funds productively. Although cross-sectional studies in holoendemic areas spanning a single year could be useful in describing parasite genotype status at a given point, such information is inadequate in describing temporal trends in genotype polymorphisms. For Plasmodium falciparum isolates from Kisumu District Hospital, Plasmodium falciparum chloroquine-resistance transporter gene (Pfcrt-K76T) and P. falciparum multidrug resistance gene 1 (PfMDR1-N86Y), were analyzed for polymorphisms and parasitemia changes in the 53 months from March 2008 to August 2012. Observations were compared with prevailing climatic factors, including humidity, rainfall, and temperature. METHODS Parasitemia (the percentage of infected red blood cells per total red blood cells) was established by microscopy for P. falciparum malaria-positive samples. P. falciparum DNA was extracted from whole blood using a Qiagen DNA Blood Mini Kit. Single nucleotide polymorphism identification at positions Pfcrt-K76T and PfMDR1-N86Y was performed using real-time polymerase chain reaction and/or sequencing. Data on climatic variables were obtained from http://www.tutiempo.net/en/. RESULTS A total of 895 field isolates from 2008 (n=169), 2009 (n=161), 2010 (n=216), 2011 (n=223), and 2012 (n=126) showed large variations in monthly frequency of PfMDR1-N86Y and Pfcrt-K76T as the mutant genotypes decreased from 68.4%±15% and 38.1%±13% to 29.8%±18% and 13.3%±9%, respectively. The mean percentage of parasitemia was 2.61%±1.01% (coefficient of variation 115.86%; n=895). There was no correlation between genotype or parasitemia and climatic factors. CONCLUSION This study shows variability in the frequency of Pfcrt-K76T and PfMDR1-N86Y polymorphisms during the study period, bringing into focus the role of cross-sectional studies in describing temporal genotype trends. The lack of correlation between genotypes and climatic changes, especially precipitation, emphasizes the cost of investment in genotype change.
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Affiliation(s)
- Hoseah M Akala
- Global Emerging Infections Surveillance Program, United States Army Medical Research Unit-Kenya, Kenya Medical Research Institute, Walter Reed Project, Kisumu and Nairobi, Kenya
| | - Angela O Achieng
- Global Emerging Infections Surveillance Program, United States Army Medical Research Unit-Kenya, Kenya Medical Research Institute, Walter Reed Project, Kisumu and Nairobi, Kenya
| | - Fredrick L Eyase
- Global Emerging Infections Surveillance Program, United States Army Medical Research Unit-Kenya, Kenya Medical Research Institute, Walter Reed Project, Kisumu and Nairobi, Kenya
| | - Dennis W Juma
- Global Emerging Infections Surveillance Program, United States Army Medical Research Unit-Kenya, Kenya Medical Research Institute, Walter Reed Project, Kisumu and Nairobi, Kenya
| | - Luiser Ingasia
- Global Emerging Infections Surveillance Program, United States Army Medical Research Unit-Kenya, Kenya Medical Research Institute, Walter Reed Project, Kisumu and Nairobi, Kenya
| | - Agnes C Cheruiyot
- Global Emerging Infections Surveillance Program, United States Army Medical Research Unit-Kenya, Kenya Medical Research Institute, Walter Reed Project, Kisumu and Nairobi, Kenya
| | - Charles Okello
- Global Emerging Infections Surveillance Program, United States Army Medical Research Unit-Kenya, Kenya Medical Research Institute, Walter Reed Project, Kisumu and Nairobi, Kenya
| | - Duke Omariba
- Global Emerging Infections Surveillance Program, United States Army Medical Research Unit-Kenya, Kenya Medical Research Institute, Walter Reed Project, Kisumu and Nairobi, Kenya
| | - Eunice A Owiti
- Global Emerging Infections Surveillance Program, United States Army Medical Research Unit-Kenya, Kenya Medical Research Institute, Walter Reed Project, Kisumu and Nairobi, Kenya
| | - Catherine Muriuki
- Global Emerging Infections Surveillance Program, United States Army Medical Research Unit-Kenya, Kenya Medical Research Institute, Walter Reed Project, Kisumu and Nairobi, Kenya
| | - Redemptah Yeda
- Global Emerging Infections Surveillance Program, United States Army Medical Research Unit-Kenya, Kenya Medical Research Institute, Walter Reed Project, Kisumu and Nairobi, Kenya
| | - Ben Andagalu
- Global Emerging Infections Surveillance Program, United States Army Medical Research Unit-Kenya, Kenya Medical Research Institute, Walter Reed Project, Kisumu and Nairobi, Kenya
| | - Jacob D Johnson
- Global Emerging Infections Surveillance Program, United States Army Medical Research Unit-Kenya, Kenya Medical Research Institute, Walter Reed Project, Kisumu and Nairobi, Kenya
| | - Edwin Kamau
- Global Emerging Infections Surveillance Program, United States Army Medical Research Unit-Kenya, Kenya Medical Research Institute, Walter Reed Project, Kisumu and Nairobi, Kenya
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Bottieau E, Vekemans M, Van Gompel A. Therapy of vector-borne protozoan infections in nonendemic settings. Expert Rev Anti Infect Ther 2014; 9:583-608. [DOI: 10.1586/eri.11.32] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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14
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McGowan S. Working in concert: the metalloaminopeptidases from Plasmodium falciparum. Curr Opin Struct Biol 2013; 23:828-35. [PMID: 23948130 DOI: 10.1016/j.sbi.2013.07.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 07/24/2013] [Accepted: 07/24/2013] [Indexed: 01/05/2023]
Abstract
Malaria remains the world's most prevalent human parasitic disease. Because of the rapid spread of drug resistance in parasites, there is an urgent need to identify diverse new drug targets. One group of proteases that are emerging as targets for novel antimalarials are the metalloaminopeptidases. These enzymes catalyze the removal of the N-terminal amino acids from proteins and peptides. Given the restricted specificities of each of these enzymes for different N-terminal amino acids, it is thought that they act in concert to facilitate protein turnover. Here we review recent structure and functional data relating to the development of the Plasmodium falciparum metalloaminopeptidases as drug targets.
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Affiliation(s)
- Sheena McGowan
- Department of Biochemistry and Molecular Biology, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia.
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15
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A head-to-head comparison of four artemisinin-based combinations for treating uncomplicated malaria in African children: a randomized trial. PLoS Med 2011; 8:e1001119. [PMID: 22087077 PMCID: PMC3210754 DOI: 10.1371/journal.pmed.1001119] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Accepted: 09/30/2011] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Artemisinin-based combination therapies (ACTs) are the mainstay for the management of uncomplicated malaria cases. However, up-to-date data able to assist sub-Saharan African countries formulating appropriate antimalarial drug policies are scarce. METHODS AND FINDINGS Between 9 July 2007 and 19 June 2009, a randomized, non-inferiority (10% difference threshold in efficacy at day 28) clinical trial was carried out at 12 sites in seven sub-Saharan African countries. Each site compared three of four ACTs, namely amodiaquine-artesunate (ASAQ), dihydroartemisinin-piperaquine (DHAPQ), artemether-lumefantrine (AL), or chlorproguanil-dapsone-artesunate (CD+A). Overall, 4,116 children 6-59 mo old with uncomplicated Plasmodium falciparum malaria were treated (1,226 with AL, 1,002 with ASAQ, 413 with CD+A, and 1,475 with DHAPQ), actively followed up until day 28, and then passively followed up for the next 6 mo. At day 28, for the PCR-adjusted efficacy, non-inferiority was established for three pair-wise comparisons: DHAPQ (97.3%) versus AL (95.5%) (odds ratio [OR]: 0.59, 95% CI: 0.37-0.94); DHAPQ (97.6%) versus ASAQ (96.8%) (OR: 0.74, 95% CI: 0.41-1.34), and ASAQ (97.1%) versus AL (94.4%) (OR: 0.50, 95% CI: 0.28-0.92). For the PCR-unadjusted efficacy, AL was significantly less efficacious than DHAPQ (72.7% versus 89.5%) (OR: 0.27, 95% CI: 0.21-0.34) and ASAQ (66.2% versus 80.4%) (OR: 0.40, 95% CI: 0.30-0.53), while DHAPQ (92.2%) had higher efficacy than ASAQ (80.8%) but non-inferiority could not be excluded (OR: 0.35, 95% CI: 0.26-0.48). CD+A was significantly less efficacious than the other three treatments. Day 63 results were similar to those observed at day 28. CONCLUSIONS This large head-to-head comparison of most currently available ACTs in sub-Saharan Africa showed that AL, ASAQ, and DHAPQ had excellent efficacy, up to day 63 post-treatment. The risk of recurrent infections was significantly lower for DHAPQ, followed by ASAQ and then AL, supporting the recent recommendation of considering DHAPQ as a valid option for the treatment of uncomplicated P. falciparum malaria. TRIAL REGISTRATION ClinicalTrials.gov NCT00393679; Pan African Clinical Trials Registry PACTR2009010000911750
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16
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Gutteridge CE, Hoffman MM, Bhattacharjee AK, Milhous WK, Gerena L. In vitro efficacy of 7-benzylamino-1-isoquinolinamines against Plasmodium falciparum related to the efficacy of chalcones. Bioorg Med Chem Lett 2011; 21:786-9. [DOI: 10.1016/j.bmcl.2010.11.099] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Revised: 11/17/2010] [Accepted: 11/22/2010] [Indexed: 11/28/2022]
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17
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Gutteridge CE, Thota DS, Curtis SM, Kozar MP, Li Q, Xie L, Zhang J, Melendez V, Asher CO, Luong TT, Gerena L, Nichols DA, Montip G. In vitro Biotransformation, in vivo Efficacy and Pharmacokinetics of Antimalarial Chalcones. Pharmacology 2011; 87:96-104. [DOI: 10.1159/000322532] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Accepted: 10/18/2010] [Indexed: 11/19/2022]
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18
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Müller IB, Hyde JE. Antimalarial drugs: modes of action and mechanisms of parasite resistance. Future Microbiol 2010; 5:1857-73. [DOI: 10.2217/fmb.10.136] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Malaria represents one of the most serious threats to human health worldwide, and preventing and curing this parasitic disease still depends predominantly on the administration of a small number of drugs whose efficacy is continually threatened and eroded by the emergence of drug-resistant parasite populations. This has an enormous impact on the mortality and morbidity resulting from malaria infection, especially in sub-Saharan Africa, where the lethal human parasite species Plasmodium falciparum accounts for approximately 90% of deaths recorded globally. Successful treatment of uncomplicated malaria is now highly dependent on artemisinin-based combination therapies. However, the first cases of artemisinin-resistant field isolates have been reported recently and potential replacement antimalarials are only in the developmental stages. Here, we summarize recent progress in tackling the problem of parasite resistance and discuss the underlying molecular mechanisms that confer resistance to current antimalarial agents as far as they are known, understanding of which should assist in the rational development of new drugs and the more effective deployment of older ones.
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Affiliation(s)
- Ingrid B Müller
- Department of Biochemistry, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - John E Hyde
- Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
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Nhu D, Duffy S, Avery VM, Hughes A, Baell JB. Antimalarial 3-arylamino-6-benzylamino-1,2,4,5-tetrazines. Bioorg Med Chem Lett 2010; 20:4496-8. [DOI: 10.1016/j.bmcl.2010.06.036] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Revised: 06/04/2010] [Accepted: 06/07/2010] [Indexed: 11/26/2022]
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20
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Structure of the Plasmodium falciparum M17 aminopeptidase and significance for the design of drugs targeting the neutral exopeptidases. Proc Natl Acad Sci U S A 2010; 107:2449-54. [PMID: 20133789 DOI: 10.1073/pnas.0911813107] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Current therapeutics and prophylactics for malaria are under severe challenge as a result of the rapid emergence of drug-resistant parasites. The human malaria parasite Plasmodium falciparum expresses two neutral aminopeptidases, PfA-M1 and PfA-M17, which function in regulating the intracellular pool of amino acids required for growth and development inside the red blood cell. These enzymes are essential for parasite viability and are validated therapeutic targets. We previously reported the X-ray crystal structure of the monomeric PfA-M1 and proposed a mechanism for substrate entry and free amino acid release from the active site. Here, we present the X-ray crystal structure of the hexameric leucine aminopeptidase, PfA-M17, alone and in complex with two inhibitors with antimalarial activity. The six active sites of the PfA-M17 hexamer are arranged in a disc-like fashion so that they are orientated inwards to form a central catalytic cavity; flexible loops that sit at each of the six entrances to the catalytic cavern function to regulate substrate access. In stark contrast to PfA-M1, PfA-M17 has a narrow and hydrophobic primary specificity pocket which accounts for its highly restricted substrate specificity. We also explicate the essential roles for the metal-binding centers in these enzymes (two in PfA-M17 and one in PfA-M1) in both substrate and drug binding. Our detailed understanding of the PfA-M1 and PfA-M17 active sites now permits a rational approach in the development of a unique class of two-target and/or combination antimalarial therapy.
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Orhan I, Şener B, Kaiser M, Brun R, Tasdemir D. Inhibitory activity of marine sponge-derived natural products against parasitic protozoa. Mar Drugs 2010; 8:47-58. [PMID: 20161970 PMCID: PMC2817922 DOI: 10.3390/md8010047] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Revised: 01/05/2010] [Accepted: 01/14/2010] [Indexed: 11/23/2022] Open
Abstract
In this study, thirteen sponge-derived terpenoids, including five linear furanoterpenes: furospinulosin-1 (1), furospinulosin-2 (2), furospongin-1 (3), furospongin-4 (4), and demethylfurospongin-4 (5); four linear meroterpenes: 2-(hexaprenylmethyl)-2-methylchromenol (6), 4-hydroxy-3-octaprenylbenzoic acid (7), 4-hydroxy-3-tetraprenyl-phenylacetic acid (8), and heptaprenyl-p-quinol (9); a linear triterpene, squalene (10); two spongian-type diterpenes dorisenone D (11) and 11 beta-acetoxyspongi-12-en-16-one (12); a scalarane-type sesterterpene; 12-epi-deoxoscalarin (13), as well as an indole alkaloid, tryptophol (14) were screened for their in vitro activity against four parasitic protozoa; Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani and Plasmodium falciparum. Cytotoxic potential of the compounds on mammalian cells was also assessed. All compounds were active against T. brucei rhodesiense, with compound 8 being the most potent (IC(50) 0.60 microg/mL), whereas 9 and 12 were the most active compounds against T. cruzi, with IC(50) values around 4 microg/mL. Compound 12 showed the strongest leishmanicidal activity (IC(50) 0.75 microg/mL), which was comparable to that of miltefosine (IC(50) 0.20 microg/mL). The best antiplasmodial effect was exerted by compound 11 (IC(50) 0.43 microg/mL), followed by compounds 7, 10, and 12 with IC(50) values around 1 microg/mL. Compounds 9, 11 and 12 exhibited, besides their antiprotozoal activity, also some cytotoxicity, whereas all other compounds had low or no cytotoxicity towards the mammalian cell line. This is the first report of antiprotozoal activity of marine metabolites 1-14, and points out the potential of marine sponges in discovery of new antiprotozoal lead compounds.
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Affiliation(s)
- Ilkay Orhan
- Department of Pharmacognosy, Faculty of Pharmacy, Gazi University, TR-06330 Ankara, Turkey; E-Mails:
(I.O.);
(B. Ş.)
| | - Bilge Şener
- Department of Pharmacognosy, Faculty of Pharmacy, Gazi University, TR-06330 Ankara, Turkey; E-Mails:
(I.O.);
(B. Ş.)
| | - Marcel Kaiser
- Department of Medical Parasitology and Infection Biology, Swiss Tropical Institute, CH-4002 Basel, Switzerland; E-Mails:
(M.K.);
(R.B.)
| | - Reto Brun
- Department of Medical Parasitology and Infection Biology, Swiss Tropical Institute, CH-4002 Basel, Switzerland; E-Mails:
(M.K.);
(R.B.)
| | - Deniz Tasdemir
- Department of Pharmaceutical and Biological Chemistry, School of Pharmacy, University of London, London WC1N 1AX, UK
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Progress in the development of piperaquine combinations for the treatment of malaria. Curr Opin Infect Dis 2010; 22:588-92. [PMID: 19773652 DOI: 10.1097/qco.0b013e328332674a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Dihydroartemisinin-piperaquine is a new and extremely promising artemisinin-containing fixed-combination antimalarial, about to be registered with international regulatory authorities such as the European Medicines Agency. A formulation produced according to good manufacturing practices should be available soon. RECENT FINDINGS Piperaquine is characterized by a slow absorption, long mean terminal elimination half-life and large mean volume distribution. However, children, compared to the population mean profile, tend to have a smaller central volume of distribution, a shorter distribution half-life and a more rapid fall in early piperaquine plasma concentrations, suggesting that an increase of the weight-adjusted dosage in children may be required. In addition, the oral bioavailability of piperaquine improves when given with a high-fat meal, though this does not necessarily translate into a higher efficacy. Several clinical trials have repeatedly shown that dihydroartemisinin-piperaquine is well tolerated and efficacious, with the only exception of one trial recently carried out in Papua New Guinea. Patients treated with dihydroartemisinin-piperaquine may have a higher rate of person-gametocyte-weeks, though it is unclear whether this translates into a higher infectiousness to biting anophelines. SUMMARY The dosage recommended for children may need to be reviewed and the usefulness of the coadministration with food should be determined. Establishing safety and efficacy of this treatment in pregnancy remains a priority.
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Srinivasan V, Spence DW, Moscovitch A, Pandi-Perumal SR, Trakht I, Brown GM, Cardinali DP. Malaria: therapeutic implications of melatonin. J Pineal Res 2010; 48:1-8. [PMID: 20025640 DOI: 10.1111/j.1600-079x.2009.00728.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Malaria, which infects more than 300 million people annually, is a serious disease. Epidemiological surveys indicate that of those who are affected, malaria will claim the lives of more than one million individuals, mostly children. There is evidence that the synchronous maturation of Plasmodium falciparum, the parasite that causes a severe form of malaria in humans and Plasmodium chabaudi, responsible for rodent malaria, could be linked to circadian changes in melatonin concentration. In vitro melatonin stimulates the growth and development of P. falciparum through the activation of specific melatonin receptors coupled to phospholipase-C activation and the concomitant increase of intracellular Ca2+. The Ca2+ signaling pathway is important to stimulate parasite transition from the trophozoite to the schizont stage, the final stage of intraerythrocytic cycle, thus promoting the rise of parasitemia. Either pinealectomy or the administration of the melatonin receptor blocking agent luzindole desynchronizes the parasitic cell cycle. Therefore, the use of melatonin antagonists could be a novel therapeutic approach for controlling the disease. On the other hand, the complexity of melatonin's action in malaria is underscored by the demonstration that treatment with high doses of melatonin is actually beneficial for inhibiting apoptosis and liver damage resulting from the oxidative stress in malaria. The possibility that the coordinated administration of melatonin antagonists (to impair the melatonin signal that synchronizes P. falciparum) and of melatonin in doses high enough to decrease oxidative damage could be a novel approach in malaria treatment is discussed.
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Hyde JE. Mapping the origins and spread of antifolate-resistant malaria parasites. Future Microbiol 2009; 4:953-8. [PMID: 19824787 DOI: 10.2217/fmb.09.66] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Evaluation of: Pearce RJ, Pota H, Evehe MSB et al.: Multiple origins and regional dispersal of resistant dhps in African Plasmodium falciparum malaria. PLoS Med. 6(4), e1000055 (2009). Widespread resistance to current antimalarial drugs is a major factor in the extremely high levels of mortality and disabling illness that still prevail in many developing countries. It is important to understand how frequently resistant malaria parasite strains arise and their patterns of propagation and dispersal across borders and continents. By studying the DNA sequences of both the gene encoding the drug target and its flanking regions, it is possible to collect and map such data, providing a considerable asset in devising and evaluating future strategies of drug use and deployment. In this article, Pearce et al. analyze a large number of parasite samples collected over a decade from countries across Africa, allowing them to present for the first time a detailed picture of the origins and relatively recent spread of resistance to sulfa-drugs, key components of antifolate drug combinations that have been used extensively as part of the antimalarial armory.
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Affiliation(s)
- John E Hyde
- Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, Manchester M1 7ND, UK.
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