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Caracterização de fitol e verificação de uma segunda via de biossíntese de filoquinona e tocoferol nos estágios intraeritrocíticos de Plasmodium falciparum. / Characterization of phyto and an alternative pathway for phylloquinone and tocopherol biosynthesis in intraerythrocytic stages of Plasmodium falciparum.Vega, Danielle da Silva Menchaca 24 February 2014 (has links)
Nosso grupo tem caracterizando diversos produtos da via de isoprenóides em Plasmodium falciparum que é promissora para o desenvolvimento de novas drogas. Dentre os compostos isoprenicos identificados estão as vitaminas K1 e E que apresentam uma cadeia isoprenica fitil. Em plantas o fitol é originado da degradação da clorofila. mas, como ainda não existem evidências da presença de clorofila no parasito, sugerimos que este possa ser formado pela degradação dessas vitaminas. Parte do fitol seria ligado a ácidos graxos utilizado como constituinte de membrana, e parte sofreria fosforilações, formando as vitaminas E e K1 como uma segunda via de biossíntese desse composto, assim como ocorre em Arabidopsis thaliana. Analises por HPLC e TLC utilizando o marcador [3H]GGPP, confirmaram a presença de fitol nos estágios intraeritrocíticos. Além disso, mostramos que o [3H]-fitol pode ser convertido em fitil-P e fitil-PP por uma atividade fitol quinase utilizando nucleotídeos como doador fosfato. / Our group has characterized differents products from isoprenoid pathway in Plasmodium falciparum which is promising for the development of new drugs. Among the isoprenics compounds identified there are the vitamins K1 and E which have a isoprenic phytyl side chain . In plants the phytol is obtained from the chlorophyll degradation. Until now theres no evidence that support its presence in the paraste. Our hypothesis that is phytol can be produced by the degradation of these vitamins E and K1. In the parasite phytol would fulfill to functions: used as a constituent of membrane, bounded to fatty acids and; be converted through phosphorylations vitamins E and K1 as a second biosynthetic pathway as well as in Arabidopsis thaliana. Analisys through and HPLC and TLC with radioactive [3H]GGPP confirmed the presence of phytol in intraerythrocytic stages. In addition, we showed that [3H]-phytol is converted into phytyl-P and phytyl-PP through a phytol kinasey using nucleotides as Phosphate donor.
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Caracterização bioquímica da biossíntese de tiamina (vitamina B1) em Plasmodium falciparum . / Biochemical characterization of the biosynthesis of thiamine (Vitamin B1) in Plasmodium falciparum.Jordão, Fabiana Morandi 18 September 2007 (has links)
Nesta dissertação, foi caracterizada a via de biossíntese de tiamina (Vitamina B1) nas três formas intraeritrocitárias de P. falciparum. Foram realizadas marcações metabólicas, utilizando diferentes precursores radioativos envolvidos na biossíntese de tiamina, já descritos para outros organismos. A utilização do precursor [1-14C] acetato de sódio demonstrou que a via de biossíntese de tiamina encontra-se ativa em todos os estágios intraeritrocitários de P. falciparum. Investigamos os precursores que poderiam estar envolvidos na biossíntese do intermediário tiazol, e nossos dados sugerem que a cistéina é a doadora do enxofre presente na molécula de tiamina; que o aminoácido tirosina pode ser o precursor da biossíntese de tiamina, e nicotinamida não é utilizada como precursor em P. falciparum. Também se avaliou o efeito da fosmidomicina e 3ClDHP e foi demonstrado que ambos propiciaram uma inibição no crescimento dos parasitas. Estes dados sugerem que a via de biossíntese de tiamina, pode ser explorada como alvo para drogas antimaláricas, devido ausência em humanos. / In the present work we have demonstrated the biosynthesis of thiamin (vitamin B1) in the intraerytrocytic stages of P. falciparum. We have demonstrated active biosynthesis of thiamine in the three parasite stages metabolically labeled with [1-14C] sodium acetate. We also investigated which precursors could be involved in the biosynthesis of the thiazole intermediate, by metabolic labelling with different precursors. Our data suggest that the sulphur present in the thiamine molecule is formed from cysteine white that tyrosine can be the precursor of thiamine biosynthesis. Nicotinamide is not utilized as a precursor in P.falciparum. We also investigated the effect of fosmidomycin (an inhibitor of the DOXP reductoisomerase in the MEP pathway) and 3CIDHP (an analogue of bacimethrin) in vitro cultures and both showed an inhibitory effect on parasite growth. These data suggest that the biosynthesis of thiamine can be an attractive target for the development of antimalarial drugs since this pathway is absent in humans.
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Etudes des mécanismes cellulaires et moléculaires de Plasmodium falciparum impliqués dans les résistances aux combinaisons à bases de dérivés de l’artémisinine / Study of cellular and molecular mechanisms of Plasmodium falciparum involved in Artemisinin-based Combination Treatment resistanceDuru, Valentine 15 December 2016 (has links)
Les combinaisons thérapeutiques à base d’artémisinine (ou CTAs) sont une des clés de voûte des stratégies actuelles de lutte contre le paludisme : ces thérapies ont en effet joué un rôle important dans la réduction de l’impact du paludisme au cours de la dernière décennie. Cependant, ces progrès sont aujourd’hui compromis par l’émergence de parasites Plasmodium falciparum résistants aux dérivés de l’artémisinine (ART). Les premiers parasites résistants ont été détectés pour la première fois en 2008 dans l’ouest du Cambodge, puis dans plusieurs pays avoisinants d’Asie du Sud-Est. Le problème de la multirésistance aux antipaludiques s’est récemment aggravé au Cambodge : plusieurs études ont rapporté l’émergence de parasites résistants à la pipéraquine (PPQ), la dernière génération de molécule partenaire utilisée en combinaison avec la dihydroartémisinine, entraînant des taux alarmants d’échecs cliniques. Pour préserver l’efficacité de ces combinaisons, la surveillance et la compréhension de ces deux types de résistance sont cruciales afin d’éviter la dissémination de parasites multirésistants en dehors d’Asie du Sud-Est, et particulièrement en Afrique où les conséquences sanitaires seraient désastreuses. À cette fin, le développement de nouveaux outils est nécessaire pour étudier les mécanismes biologiques et moléculaires impliqués dans la résistance aux CTAs et pour surveiller la distribution géographique des parasites multirésistants. Dans la première partie de cette thèse, axée sur la résistance à l’artémisinine, nous présentons tout d’abord la découverte de mutations au sein du gène K13, marqueur moléculaire pour la résistance à l'ART. Puis nous confirmons leur rôle comme déterminant majeur de cette résistance. Enfin, nous analysons l’étendue de cette résistance au travers d'une cartographie mondiale des polymorphismes de K13. Dans la seconde partie de cette thèse, nous présentons nos travaux portant sur l’émergence de la résistance à la pipéraquine au Cambodge, en confirmant dans un premier temps que des parasites multirésistants à l’ART et à la PPQ circulent désormais dans le pays. Puis en détaillant la mise en point d’un nouveau test phénotypique pour la détection des parasites PPQ-résistants, le Piperaquine Survival Assay ou PSA. Pour finir, nous exposons la découverte de l’amplification du gène PfPM2 comme marqueur moléculaire pour la résistance à la PPQ. / Artemisinin-based combination therapies (ACTs) are one of the pillars of the current strategies implemented for fighting malaria. Over the last decade, ACTs have played a major role in decreasing malaria burden. However, this progress is being jeopardized by the emergence of artemisinin-resistant Plasmodium falciparum parasites. Artemisinin (ART) resistance was first detected in western Cambodia in 2008 and has since been observed in neighboring countries in Southeast Asia. The problem of antimalarial drug resistance has recently worsened in Cambodia, with reports of parasites resistant to piperaquine (PPQ), the latest generation of partner drug used in combination with dihydroartemisinin, leading to worrying rates of clinical treatment failure. The monitoring and the comprehension of both types of resistance are crucial to prevent the spread of multi-drug resistant parasites outside Southeast Asia, and particularly to Africa, where the public health consequences would be catastrophic. To this end, new tools are required for studies of the biological and molecular mechanisms underlying resistance to antimalarial drugs and for monitoring the geographic distribution of the resistant parasites.In the first section of this thesis, centered on artemisinin resistance, we first present the discovery of mutations within the K13 gene as a molecular marker for ART resistance. Then we confirm their role as a major determinant of such a resistance. Finally, we analyze the extent of ART resistance through a global mapping of K13 polymorphisms. In the second section, we present our work on the emergence of piperaquine resistance in Cambodia, by initially confirming that multiresistant parasites now circulate in the country. Then we detail the development of a new phenotypical test for the detection of PPQ-resistant parasites, the Piperaquine Survival Assay or PSA. Lastly, we report the discovery of the PfPM2 gene amplification as a candidate molecular marker for PPQ-resistance.
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Various antimalarial strategies in Indonesia to fight Plasmodium falciparum / Différentes stratégies en Indonésie pour combattre Plasmodium falciparumRamadani, Arba Pramundita 20 July 2017 (has links)
Le paludisme demeure un problème de santé publique mondial qui risque de s'aggraver avec la résistance de Plasmodium falciparum aux thérapies combinées à base d'artémisinine (ACT), médicaments antipaludiques les plus récents et les plus efficaces. Mon travail avait pour but de proposer différents axes d'élimination du paludisme en Indonésie. Une première partie a consisté à rechercher de nouveaux médicaments antipaludiques à partir de données ethnobotaniques indonésiennes. Parmi les 25 extraits bruts réalisés à partir de plantes médicinales indonésiennes utilisées traditionnellement dans le traitement du paludisme, sept ont montré une activité antipaludique intéressante (CI50 <5 µg/mL) et certains d'entre eux se sont révélés également actifs sur 2 autres pathogènes Babesia divergens et Leishmania infantum. La deuxième partie de ce travail était axée sur les composés organométalliques synthétiques. Les études de relations structure-activité de ces complexes organométalliques d'or (I) -NHC ont permis de sélectionner un composé actif sur P. falciparum avec une CI50 de 320nM. La troisième partie du travail a été consacrée à l'étude de la résistance de P. falciparum à l'artémisinine et à ses dérivés. La corrélation entre le polymorphisme de PfK13 et la résistance à l'artémisinine a été clairement établie grâce à des études de génétique inverse avec des souches de laboratoire résistantes et sensibles et des isolats cliniques Cambodgiens. Cette résistance a été mise en évidence in vitro par un test de survie parasitaire appelé RSA(0-3h). Par les mêmes méthodes génétique et phénotypique, la cartographie de la distribution du polymorphisme de PfK13 en Indonésie a été réalisée dans la zone de Kupang sur des patients infectés par P. falciparum. Cependant au moment de la collecte des échantillons de sang, la prévalence de P. falciparum a montré une diminution spectaculaire empêchant la poursuite de l'étude clinique. Face au faible nombre de patients admissibles avec un paludisme à P. falciparum, aucun résultat concluant n'a pu être obtenu. En conclusion, les plantes médicinales indonésiennes et les composés synthétiques sont potentiellement intéressants comme point de départ chimique pour de nouveaux médicaments antipaludiques. En ce qui concerne la résistance à l'artémisinine, aucun échec thérapeutique ou parasitologique après traitement par ACT n'a été signalé, pour le moment, en Indonésie. Cependant, les zones de résistance de P. falciparum aux ACT dans le Sud-Est asiatique sont relativement proches et nécessitent, en Indonésie, un suivi des variations de la chimiosensibilité du paludisme à P. falciparum et du polymorphisme de PfK13, responsable de la résistance à l'artémisinine. / Malaria remains a global public health problem and worsening with the resistance of Plasmodium falciparum to Artemisinin-based Combination Therapies (ACTs), the latest and most effective antimalarial drugs. My project aimed to provide insight into malaria elimination in Indonesia. The first part was to look for new antimalarial drugs based on Indonesian ethnobotanical data. Among 25 crude extracts realized on Indonesian traditional medicinal plants, seven showed a good antimalarial activity (IC50 < 5µg/mL) and some of them were also active against Babesia divergens and Leishmania infantum. The second part of the study focused on chemosynthetic organometallic compounds. The structure- activity relationships study on organometallic gold(I)-NHC complexes led to a very active compound on P. falciparum with an IC50 of 320nM. The third part of this work was dedicated to the study of P. falciparum resistance to artemisinin and its derivatives. The correlation between PfK13 polymorphism and artemisinin resistance has been clearly established thanks to reverse genetic with resistant and sensitive laboratory strains and clinical isolates from Cambodia. This resistance was evidenced in vitro throughout a parasite survival assay called RSA(0-3h). By the same genotypic and phenotypic methods, mapping of PfK13 polymorphism distribution in Indonesia was performed in Kupang on P. falciparum malaria patients. However, at the time of P. falciparum blood samples collection, prevalence showed a dramatic decrease hindering the continuation of the clinical study. Facing to the very small number of eligible patients with a P. falciparum malaria, no conclusive results has been obtained. In conclusion, medicinal plants and synthetic compounds are potentially interesting as chemical starting point for new antimalarial drugs. Concerning artemisinin resistance, any treatment failure or delayed cure with ACTs has yet to be reported in Indonesia. However, because Indonesia is relatively close to the Southeast Asian areas of resistance, the possible occurrence of such cases in Indonesia must be anticipated by determining the variations of P. falciparum malaria chemo-sensitivity and by following PfK13 polymorphism, responsible for artemisinin resistance.
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Análise do catabolismo da hemoglobina de Plasmodium falciparum. / Analysis of the haemoglobin catabolism of Plasmodium falciparum.Lindner, Jasmin 07 June 2017 (has links)
O metabolismo de nutrientes abriga um alto potencial para o desenvolvimento de novos alvos quimioterápicos para o tratamento do parasita da malária Plasmodium falciparum. A partir de ensaios de crescimento do parasita dentro de eritrócitos geneticamente diferentes, concentrando-se na via catabólica da hemoglobina plasmodial usando parasitas transgênicos, a natureza protetora das variantes da hemoglobina foi investigada. Sendo que Falcipain 2 (FP2) prolifera três vezes mais elevada no sangue de células falciformes do que o Mock, a célula de controle. Adicionalmente, estudos de inibidores indicam que FP2 é uma proteína essencial para o parasita. Em cooperação com o DESY em Hamburgo, Alemanha a estrutura cristalina da amino peptidase P foi resolvida difratando até 1,7 Å. / The metabolism of nutrients harbors a high potential for the development of new chemotherapeutic targets for the treatment of the malaria parasite Plasmodium falciparum. From parasite growth assays within genetically different erythrocytes, concentrating on the catabolic pathway of plasmodial hemoglobin using transgenic parasites, the protective nature of hemoglobin variants was investigated. Since Falcipain 2 (FP2) proliferates three times higher in sickle cell blood than the Mock, the control cell. In addition, inhibitor studies indicate that FP2 is an essential protein for the parasite. In cooperation with DESY in Hamburg, Germany the crystalline structure of the amino peptidase P was resolved diffracting up to 1.7 Å.
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Plasmodium Falciparum response to chloroquine and artemisinin based combination therapy (Act) in Guinea BissauUrsing, Johan, January 2009 (has links)
Diss. (sammanfattning) Stockholm : Karolinska institutet, 2009. / Härtill 6 uppsatser.
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Drug resistance in Plasmodium falciparum : the role of point mutations in dihydropteroate synthase and dihydrofolate reductase analyzed in a yeast model /Hankins, Eleanor Gray. January 2001 (has links)
Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 92-99).
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Genetic diversity of Plasmodium falciparum infections : influence on protective malaria immunity /Bereczky, Sándor, January 2005 (has links)
Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 5 uppsatser.
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Identification of putative Plasmodium falciparum mefloquine resistance genes /Jeffress, Mara L., January 2004 (has links)
Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 135-171).
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Analysis of resistance to inhibitors of Plasmodium falciparum dihydrofolate reductase in yeast /Wooden, Jason, January 1996 (has links)
Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [135]-144).
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