Poverty stricken areas of the world are affected by Neglected Tropical Diseases, with an estimated 1 billion sufferers. As well as inadequate living conditions and healthcare, there has been very little pharmaceutical incentive to tackle these diseases. As a result, the diseases are still spreading. Drugs available on the market suffer from poor efficacy, high toxicity, increasing resistance and inappropriate dosing for rural treatment. The nature of many NTDs prevents the use of vaccinations. Therefore, more efficacious and safe treatments are sought after. The folate pathway has been extensively studied in a number of organisms, with its essentiality exploited in a number of drugs and drug targets. The same cannot be said for the kinetoplastids. Drug discovery programmes have focused on targeting enzymes of the folate metabolism with very little clinical success. Despite showing significant inhibition of the parasitic enzymes, potency is seen to decrease in cellular and animal models. Understanding how the folate pathway operates in these organisms could provide insight into where and how anti-folate compounds bind. This information could then be used to facilitate better drug treatments for the kinetoplastids. This thesis describes a number of approaches undertaken to better understand folate metabolism in kinetoplastids. Clinical and literature anti-folate compounds were immobilized onto resins, followed by chemical proteomics, utilizing novel techniques (iTRAQ), to allow for target identification. Using competition studies, specific and non-specific targets were identified in parasitic lysate (T. brucei and L. major) for each anti-folate compound. This method was further exploited by creating a folate resin (Folate beads). The resin had the potential to pull down 9 proteins from the “folate-ome”. In future studies, the resin can be used to enrich for the folate proteins in kinetoplastids and related organisms. Alongside the studies of the folate proteins, it was also desired to study proteins involved in the essential pterin pathway. This pathway has not been extensively studied in kintoplastids, with the exception of PTR1 (by-pass protein for DHFR). The failure to synthesise pterin derivatives for bead coupling led to a fragment screening campaign being carried out on QDPR in leishmania major. Working through a triage workflow, two moderately potent fragments were identified, showing inhibition against LmQDPR. Through structure-free optimization strategies, greater than 100 optimized fragments were synthesised in a bid to understand SAR. Although this work remains incomplete, LmQDPR has been successfully crystalized with 23 hit fragments, which are awaiting further biophysical analysis to understand binding.

O estudo do processo de tradução no metabolismo celular atrai o interesse de vários grupos, em particular, o estudo do 21o aminoácido, a selenocisteína. A incorporação da selecisteína foi descrita em Escherichia coli e recentemente em eucariotos. O primeiro passo desta via é iniciado pela Seril-tRNA Sintetase que aminoacila o Ser-tRNASec (SelC) com uma serina. Em E. coli, o segundo passo é realizado pela Sec-sintetase (SelA) que remove o grupo hidroxil da cadeia lateral da serina, formando um intermediário aminoacrilil. Este serve como aceptor de seleno-fosfato gerando a selenocisteína. Em eucariotos, o processo análogo é realizado pela PSTK e pela SepSecS, que fosforila e seleniza a serina respectivamente. Interessados nesta parte da via, iniciamos estudos moleculares das enzimas Fosfoseril-tRNA Kinase de Trypanosoma brucei e Leishmania major e Seril-tRNA Sintetase de Trypanosoma brucei. Para o gene da enzima Fosfoseril-tRNA Kinase de T. brucei não foi possível obter um clone sem mutação. Já o gene da enzima Fosfoseril-tRNA Kinase de L. major foi clonado em vetor pET28 e a enzima foi expressa em células de E. coli porém com baixo rendimento impedindo a continuidade dos experimentos planejados. Portanto passou-se a investigar a enzima envolvida no primeiro passo da via, no caso, a Seril-tRNA Sintetase de T. brucei. Esta já se encontrava clonada e expressando em E. coli na fração solúvel. A proteína recombinante foi purificada com precipitação com 60% de sulfato de amônio e resinas de hidrofobicidade e de afinidade por níquel. Experimentos de gel nativo, DLS e fluorescência de anisotropia revelaram que, após a purificação, a enzima permanece estável e livre de agregações, possuindo um raio hidrodinâmico de 4,32nm e massa molecular de 110kDa. Acima de 150nM de proteína, ela encontra-se inteiramente na forma dimérica. Estabelecidos estes parâmetros, informações sobre a ligação com o Ser-tRNASec poderão ser obtidos a partir da técnica de anisotropia de fluorescência visto que experimentos iniciais realizados com a SerRS adicionando-se o Ser-tRNASec mostraram-se promissores. / The translation process study is central role in the cellular metabolism and attracts the interest of several groups, in particular, the study of the 21º amino acid, the selenocystein. The selenocystein incorporation pathway was described in Escherichia coli and recently in eukaryotes. The first step of this pathway is initiated by Seryl-tRNA Synthetase that aminoacilates the Ser-tRNASec (SELC) with serine. In E. coli, the second step is performed by the Sec-synthase (SELA) that removes hydroxyl group of the serine side chain, forming an aminoacrylil intermediary. This serves as an acceptor of seleno phosphate generating the selenocystein. In eukaryotes, the similar process is performed by PSTK and SepSecS, which phosphorylate serine and adds the selenium, respectively. Interested in this pathway, we performed initial molecular studies of the Phosphoseryl-tRNA synthetase of Trypanosoma brucei and Leishmania major and Seryl-tRNA synthetase of Trypanosoma brucei. The gene that encodes T. brucei Phosphoseryl-tRNA synthetase was obtained with several mutations. However, the gene encoding the T. brucei Phosphoseryl-tRNA synthetase was cloned into pET28 vector and the enzyme was expressed in E. coli cells, however at low amounts hampering the intended experiments. Therefore we initiated the investigation of the enzyme involved in the first step of this pathway, the Seryl-tRNA Synthetase from T. brucei. The enzyme was already cloned and expressing in the soluble fraction of E. coli. The recombinant protein was purified using 60% ammonium sulfate precipitation, hydrophobic and nickel affinity chromatography. Native gel experiments, DLS and anisotropy fluorescence was performed and allowed to conclude that, after purification, the enzyme remains stable and free of aggregation, with a hydrodynamic radius of 4.32 nm, molecular weight of 110kDa. Above 150nM protein its entirely in the dimeric form. Information about Ser-tRNASec binding can now be obtained from the technique of anisotropy seen that initial experiments with SerRS add Ser-tRNASec be shown to be promising.

Umas das principais formas biológicas de incorporação do selênio é na forma de um aminoácido denominado selenocisteína (Sec, U), que é incorporado co-traducionalmente ao polipeptídio nascente em posições específicas do códon UGA, que normalmente é reconhecido como códon de parada. A incorporação de selenocisteína em E. coli já está completamente esclarecida, com a participação dos genes que codifica para selenocisteína sintase (SELA), seril-tRNA sintetase (SerRS), um tRNASec específico (SELC), selenofosfato sintetase (SELD) e um fator de elongação próprio (SELB). Entretanto em eucariotos não há homólogos para SELA e existem evidências de haver a necessidade de dois passos enzimáticos que substituem a atividade desempenhada por SELA, com uma fosforilação da serina seguida de uma selenilação através das enzimas Fosfo-Seril-tRNASec Kinase (PSTK) e Sep-tRNA:Sec-tRNA sintase (SepSecS), respectivamente. A via de biossíntese e incorporação de selenocisteína é muito estudada em alguns organismos, mas ainda pouco explorada em Kinetoplastida. Nesse sentido, realizaram-se estudos moleculares das enzimas envolvidas nessa via, mais especificamente em Trypanosoma brucei e Leishmania major. Foram identificados o elemento SECIS na região 3´ do mRNA que atua no reconhecimento do códon UGA interno e, em fase de leitura na inserção de selenocisteína em Leishmania major e Leishmania infantum; a incorporação de Se75 em proteínas de Leishmania; a ocorrência do tRNASec em Trypanosoma e Leishmania e, adicionalmente todos os genes necessários para a síntese de selenocisteína: SELB, SELD, PSTK e SECp43. Foram obtidos clones dos genes selB e selD em vetor de expressão pET28a(+) e as proteínas foram expressas em bactérias Escherichia coli cepa BL21 (DE3). A proteína recombinante SELD foi purificada em cromatografia de afinidade e seu pI e massa molecular foram determinados usando as técnicas de sistema Phast de eletroforese e gel nativo. As proteínas SELB, SELD, SECp43 e Seril tRNA sintetase foram imunolocalizadas no citoplasma de células nativas de T. brucei. Uma nova metodologia \"PTP tagging\" foi utilizada para estudos de interação protéica com uso de proteínas alvos SECp43, SELB e PSTK na busca de novas proteínas ligantes na via de selenocisteínas em T. brucei. Futuras investigações moleculares e estruturais das enzimas envolvidas na via de selenocisteína em Kinetoplastida poderão trazer informações relevantes no entendimento da biossíntese desse aminoácido, assim como possibilitar o desenvolvimento de inibidores específicos visando o tratamento de doenças causadas pelos parasitas Trypanosoma brucei e Leishmania major. / One of the main biological forms of the selenium incorporation is the amino acid form named selenocysteine (Sec, U), which is incorporated co-translationally at the emerging new polypeptide in the specific positions at the UGA codon, that is usually recognized as stop codon. The incorporation of the selenocysteine in E.coli is already solved with the involvement of the genes that codify to selenocysteine synthase (SELA), seryl tRNA synthetase (SerRS), a specific tRNASec (SELC), selenophosphate synthetase (SELD) and a selenocysteine-specific translation elongation factor (SELB). However, in eukarya there is no SELA homologue, but there are evidences about the requirement of the two enzymatic steps that replace the activity performed by SELA, the fosforilation of the serine followed by selenocysteylation through the phosphoseryl-tRNASec kinase (PSTK) and Sep-tRNA:Sec-tRNA synthase (SepSecS) enzymes, respectively. Currently, the selenocysteine synthesis and its incorporation is more studied in many organisms, but less explored in Kinetoplastid. Subsequently, the molecular studies were done with the enzymes involved in this pathway, especially in Trypanosoma brucei and Leishmania major. The SECIS element was identified in the region 3´ of the mRNA, that acts in the recognition of the UGA codon positioned within a gene\'s open reading frame on the insertion of the selenocysteine in Leishmania major and Leishmania infantum; the incorporation of 75Se into Leishmania proteins, the occurrence of selenocysteine-tRNASec in both Leishmania and Trypanosoma; in addition, the finding of all genes necessary for selenocysteine synthesis, such as: SELB, SELD, PSTK, and SECp43. Clones were obtained from the selB and selD genes in the pET28a(+) expression vector and the enzymes were expressed in Escherichia coli BL21 (DE3). The recombinant SELD protein was purified by affinity chromatography and its pI and molecular mass were determined using: isoeletrophocusing electrophoresis and native gel. The proteins SELB, SELD, SECp43, and sery-tRNA synhetase were immune located in the cytoplasm in T. brucei native cells. A new methodology \"PTP tagging\" was utilized for protein interaction studies by using target proteins SECp43, SELB and PSTK to search new tagged proteins in selenocysteine T. brucei synthesis. Future molecular and structural investigation of the enzymes involved in Kinetoplastida selenocysteine biosynthesis will provide relevant information for understanding of the synthesis of this amino acid as well as the development of the specific inhibitors, focusing the treatment of the disease caused by Trypanosoma brucei e Leishmania major parasites.

Umas das principais formas biológicas de incorporação do selênio é na forma de um aminoácido denominado selenocisteína (Sec, U), que é incorporado co-traducionalmente ao polipeptídio nascente em posições específicas do códon UGA, que normalmente é reconhecido como códon de parada. A incorporação de selenocisteína em E. coli já está completamente esclarecida, com a participação dos genes que codifica para selenocisteína sintase (SELA), seril-tRNA sintetase (SerRS), um tRNASec específico (SELC), selenofosfato sintetase (SELD) e um fator de elongação próprio (SELB). Entretanto em eucariotos não há homólogos para SELA e existem evidências de haver a necessidade de dois passos enzimáticos que substituem a atividade desempenhada por SELA, com uma fosforilação da serina seguida de uma selenilação através das enzimas Fosfo-Seril-tRNASec Kinase (PSTK) e Sep-tRNA:Sec-tRNA sintase (SepSecS), respectivamente. A via de biossíntese e incorporação de selenocisteína é muito estudada em alguns organismos, mas ainda pouco explorada em Kinetoplastida. Nesse sentido, realizaram-se estudos moleculares das enzimas envolvidas nessa via, mais especificamente em Trypanosoma brucei e Leishmania major. Foram identificados o elemento SECIS na região 3´ do mRNA que atua no reconhecimento do códon UGA interno e, em fase de leitura na inserção de selenocisteína em Leishmania major e Leishmania infantum; a incorporação de Se75 em proteínas de Leishmania; a ocorrência do tRNASec em Trypanosoma e Leishmania e, adicionalmente todos os genes necessários para a síntese de selenocisteína: SELB, SELD, PSTK e SECp43. Foram obtidos clones dos genes selB e selD em vetor de expressão pET28a(+) e as proteínas foram expressas em bactérias Escherichia coli cepa BL21 (DE3). A proteína recombinante SELD foi purificada em cromatografia de afinidade e seu pI e massa molecular foram determinados usando as técnicas de sistema Phast de eletroforese e gel nativo. As proteínas SELB, SELD, SECp43 e Seril tRNA sintetase foram imunolocalizadas no citoplasma de células nativas de T. brucei. Uma nova metodologia \"PTP tagging\" foi utilizada para estudos de interação protéica com uso de proteínas alvos SECp43, SELB e PSTK na busca de novas proteínas ligantes na via de selenocisteínas em T. brucei. Futuras investigações moleculares e estruturais das enzimas envolvidas na via de selenocisteína em Kinetoplastida poderão trazer informações relevantes no entendimento da biossíntese desse aminoácido, assim como possibilitar o desenvolvimento de inibidores específicos visando o tratamento de doenças causadas pelos parasitas Trypanosoma brucei e Leishmania major. / One of the main biological forms of the selenium incorporation is the amino acid form named selenocysteine (Sec, U), which is incorporated co-translationally at the emerging new polypeptide in the specific positions at the UGA codon, that is usually recognized as stop codon. The incorporation of the selenocysteine in E.coli is already solved with the involvement of the genes that codify to selenocysteine synthase (SELA), seryl tRNA synthetase (SerRS), a specific tRNASec (SELC), selenophosphate synthetase (SELD) and a selenocysteine-specific translation elongation factor (SELB). However, in eukarya there is no SELA homologue, but there are evidences about the requirement of the two enzymatic steps that replace the activity performed by SELA, the fosforilation of the serine followed by selenocysteylation through the phosphoseryl-tRNASec kinase (PSTK) and Sep-tRNA:Sec-tRNA synthase (SepSecS) enzymes, respectively. Currently, the selenocysteine synthesis and its incorporation is more studied in many organisms, but less explored in Kinetoplastid. Subsequently, the molecular studies were done with the enzymes involved in this pathway, especially in Trypanosoma brucei and Leishmania major. The SECIS element was identified in the region 3´ of the mRNA, that acts in the recognition of the UGA codon positioned within a gene\'s open reading frame on the insertion of the selenocysteine in Leishmania major and Leishmania infantum; the incorporation of 75Se into Leishmania proteins, the occurrence of selenocysteine-tRNASec in both Leishmania and Trypanosoma; in addition, the finding of all genes necessary for selenocysteine synthesis, such as: SELB, SELD, PSTK, and SECp43. Clones were obtained from the selB and selD genes in the pET28a(+) expression vector and the enzymes were expressed in Escherichia coli BL21 (DE3). The recombinant SELD protein was purified by affinity chromatography and its pI and molecular mass were determined using: isoeletrophocusing electrophoresis and native gel. The proteins SELB, SELD, SECp43, and sery-tRNA synhetase were immune located in the cytoplasm in T. brucei native cells. A new methodology \"PTP tagging\" was utilized for protein interaction studies by using target proteins SECp43, SELB and PSTK to search new tagged proteins in selenocysteine T. brucei synthesis. Future molecular and structural investigation of the enzymes involved in Kinetoplastida selenocysteine biosynthesis will provide relevant information for understanding of the synthesis of this amino acid as well as the development of the specific inhibitors, focusing the treatment of the disease caused by Trypanosoma brucei e Leishmania major parasites.

O estudo do processo de tradução no metabolismo celular atrai o interesse de vários grupos, em particular, o estudo do 21o aminoácido, a selenocisteína. A incorporação da selecisteína foi descrita em Escherichia coli e recentemente em eucariotos. O primeiro passo desta via é iniciado pela Seril-tRNA Sintetase que aminoacila o Ser-tRNASec (SelC) com uma serina. Em E. coli, o segundo passo é realizado pela Sec-sintetase (SelA) que remove o grupo hidroxil da cadeia lateral da serina, formando um intermediário aminoacrilil. Este serve como aceptor de seleno-fosfato gerando a selenocisteína. Em eucariotos, o processo análogo é realizado pela PSTK e pela SepSecS, que fosforila e seleniza a serina respectivamente. Interessados nesta parte da via, iniciamos estudos moleculares das enzimas Fosfoseril-tRNA Kinase de Trypanosoma brucei e Leishmania major e Seril-tRNA Sintetase de Trypanosoma brucei. Para o gene da enzima Fosfoseril-tRNA Kinase de T. brucei não foi possível obter um clone sem mutação. Já o gene da enzima Fosfoseril-tRNA Kinase de L. major foi clonado em vetor pET28 e a enzima foi expressa em células de E. coli porém com baixo rendimento impedindo a continuidade dos experimentos planejados. Portanto passou-se a investigar a enzima envolvida no primeiro passo da via, no caso, a Seril-tRNA Sintetase de T. brucei. Esta já se encontrava clonada e expressando em E. coli na fração solúvel. A proteína recombinante foi purificada com precipitação com 60% de sulfato de amônio e resinas de hidrofobicidade e de afinidade por níquel. Experimentos de gel nativo, DLS e fluorescência de anisotropia revelaram que, após a purificação, a enzima permanece estável e livre de agregações, possuindo um raio hidrodinâmico de 4,32nm e massa molecular de 110kDa. Acima de 150nM de proteína, ela encontra-se inteiramente na forma dimérica. Estabelecidos estes parâmetros, informações sobre a ligação com o Ser-tRNASec poderão ser obtidos a partir da técnica de anisotropia de fluorescência visto que experimentos iniciais realizados com a SerRS adicionando-se o Ser-tRNASec mostraram-se promissores. / The translation process study is central role in the cellular metabolism and attracts the interest of several groups, in particular, the study of the 21º amino acid, the selenocystein. The selenocystein incorporation pathway was described in Escherichia coli and recently in eukaryotes. The first step of this pathway is initiated by Seryl-tRNA Synthetase that aminoacilates the Ser-tRNASec (SELC) with serine. In E. coli, the second step is performed by the Sec-synthase (SELA) that removes hydroxyl group of the serine side chain, forming an aminoacrylil intermediary. This serves as an acceptor of seleno phosphate generating the selenocystein. In eukaryotes, the similar process is performed by PSTK and SepSecS, which phosphorylate serine and adds the selenium, respectively. Interested in this pathway, we performed initial molecular studies of the Phosphoseryl-tRNA synthetase of Trypanosoma brucei and Leishmania major and Seryl-tRNA synthetase of Trypanosoma brucei. The gene that encodes T. brucei Phosphoseryl-tRNA synthetase was obtained with several mutations. However, the gene encoding the T. brucei Phosphoseryl-tRNA synthetase was cloned into pET28 vector and the enzyme was expressed in E. coli cells, however at low amounts hampering the intended experiments. Therefore we initiated the investigation of the enzyme involved in the first step of this pathway, the Seryl-tRNA Synthetase from T. brucei. The enzyme was already cloned and expressing in the soluble fraction of E. coli. The recombinant protein was purified using 60% ammonium sulfate precipitation, hydrophobic and nickel affinity chromatography. Native gel experiments, DLS and anisotropy fluorescence was performed and allowed to conclude that, after purification, the enzyme remains stable and free of aggregation, with a hydrodynamic radius of 4.32 nm, molecular weight of 110kDa. Above 150nM protein its entirely in the dimeric form. Information about Ser-tRNASec binding can now be obtained from the technique of anisotropy seen that initial experiments with SerRS add Ser-tRNASec be shown to be promising.

No description available.

No description available.

Trypanosomatid protozoan parasites are the causative agents of a number of diseases responsible for the death of thousands of people in developing countries. There is currently little hope for the development of vaccines and existing treatment regimens are associated with high toxicity. Trypanosoma brucei is the etiological agent of devastating parasitic disease in humans and livestock in sub-saharan Africa. The pathogenicity and growth of these parasites are intimately linked to their shape and form which are in turn derived from a highly ordered microtubule-based cytoskeleton. Here I have investigated some of the critical structures of the cytoskeleton in terms of their molecular composition with a view toward interrogating their functions. I have used a combined reverse genetics/comparative proteomics approach to identify over 20 novel components of the paraflagellar rod, an essential structure for the mammalian infective form of the parasite. I have iterated this approach to define interdependent sub-groups within the cohort which provide clues to the function of the paraflagellar rod. I next applied the same comparative proteomics techniques to investigate the differences between the protein composition of two life-cycle stages of the parasite. I have identified novel components of a unique mobile transmembrane junction called the flagella connector, and of the flagellum attachment zone, a structure that is essential for cell division. In addition I have defined a pair of paralogous cytoskeletal proteins that show life-cycle stage specificity. Finally, I have used electron tomography, reverse genetics and in situ protein tagging to define the morphology of the flagellar pocket collar, a critical structure required for parasite viability, and provide new insights into its molecular composition, function and biogenesis.

The membrane trafficking system mediates delivery of macromolecules and metabolites to discrete intracellular compartments from their site of uptake or synthesis. For many pathogens the trafficking system has a special relevance as it is responsible for maintaining the host-pathogen interface, i.e., the cell surface. Both the surface and the underlying trafficking apparatus are intimately connected with immune evasion in many parasites including those belonging to the highly divergent order Kinetoplastida. Kinetoplastid parasites are etiological agents of several neglected tropical diseases such as African sleeping sickness, Chagas disease, and Leishmaniasis. Newly available sequences of many kinetoplastid genomes were used to reconstruct evolution of trafficking across this lineage, using three central paralogous trafficking families: Rabs, SNAREs and Rab-GAPs, which have defined roles in specific trafficking events. Further, proteomics was used to analyse a representative SNARE complex to explore compositional conservation between kinetoplastids and Opistokhonts. Overall there is little evidence for large scale expansions or contractions of these protein families, excluding a direct association with parasitism or changes to host range, host immunosophistication or transmission mechanisms. The data indicate a stepwise sculpting of the trafficking system where the large repertoire of the basal bodonids is mainly retained by the cruzi group, while extensive lossses characterise other lineages, particularly the African trypanosomes and phytomonads. Kinetoplastids possess several lineage-specific Rabs but all retain a core canonical Rab set; by contrast there is little novelty within the SNARE family even though certain canonical endosomal SNAREs appear to show a considerable degree of sequence divergence. Proteomics suggests that SNARE complex composition is largely conserved. The major changes in Rab and SNARE repertoires are associated with endosomal and late exocytic pathways, which is consistent with the considerable evolution of surface proteomes. Therefore, despite the absence of a transition per se associated with parasitism, adaptation of membrane trafficking is likely under active selection where it meets the host environment.

Ce projet d’interface Chimie/Biologie repose sur les expertises complémentaires de deux équipes. Il concerne la conception et le développement d’inhibiteurs dirigés contre les Kinétoplastidés (trypanosomes, leishmanies). Il est en effet urgent de développer de nouvelles stratégies thérapeutiques pour répondre à la chimiorésistance et à la toxicité des médicaments actuellement utilisés contre ces parasites. Le métabolisme et le transport des polyamines étant essentiel chez les parasites, ils constituent des cibles thérapeutiques d’intérêt contre les Kinétoplastidés. Le projet intègre la synthèse de nouveaux dérivés polyamines spécifiques des parasites, l’évaluation sur des modèles in vitro de leishmaniose et de trypanosomose africaine, ainsi qu’une évaluation sur trypanothione réductase. La mise au point d’une méthode de quantification du transport de polyamine a également été initiée. Cinquante-quatre composés, répartis en trois séries chimiques, ont été synthétisés et évalués. Un grand nombre d’entre eux présentent des activités antiparasitaires de l’ordre du micromolaire et des évaluations in vivo sont actuellement en cours avec le composé le plus prometteur. / This project is at the interface of chemistry and biology and relies on the expertise of two different teams. This thesis involves the design and development of inhibitors directed against Kinetoplastids. It is urgent to develop new therapeutic strategies to respond to drug resistance and toxicity of currently used drugs against these parasites. Polyamine metabolism and transporter have been demonstrated as essential for parasite growth. Therefore, these systems are potential drug targets for development of antikinetoplastid compounds. We chose to synthesize polyamine derivatives and evaluate their biological activity against Kinetoplatids. Fifty-four compounds, divided into three chemical series, have been synthesized and evaluated. Many have shown a micromolar biological activity in vitro against parasite. In vivo evaluation is foreseen for the most promising derivative.