No / Background Plasmodium falciparum drug resistance is a major public health challenge in sub-Sahara Africa. Many people are now resorting to the use of herbs in managing malaria due to the increasing treatment failures with the conventional drugs. In this study the ethanolic extract of Polyalthia longifolia (Sonn) Thw. var. pendula, a variety fondly used in folklore medicine in Ghana was investigated for potential antimalarial drug development. Method The ethanolic extract of P. longifolia (Sonn) Thw. var. pendula stem bark was screened against the multidrug resistant, K1 strain of P. falciparum by the parasite lactate dehydrogenase (pLDH) assay and a good antiplasmodial activity (IC50 22.04 ± 4.23 µg/ml) was observed which led to further chromatographic analysis in search for actives. Results Bioassay guided fractionation of the extract yielded; three clerodane diterpenes [16-hydroxycleroda-3,13-dien-16,15-olide (1), 16-oxocleroda-3,13E-dien-15-oic acid (2) and 3,16-dihydroxycleroda-4(18),13(14)Z-dien-15,16-olide (3)], a steroid [beta-stigmasterol (4)] and two alkaloids [darienine (5) and stepholidine (6)]. While compounds 4, 5 and 6 exhibited weak antiplasmodial activity (IC50 22–105 µg/ml), the clerodane diterpenes exhibited significantly potent (p<0.005) blood schizonticidal activity (IC50: 3–6 µg/ml). This is the first report of the antiplasmodial activity of compounds 2 and 3. In combination assay with chloroquine, compounds 1, 2, 3 and 5 antagonized the antiplasmodial activity of chloroquine while 4 and 6 demonstrated a synergistic action. Conclusion The potent antiplasmodial activity of the extract of P. longifolia (Sonn) Thw. var. pendula and compounds therein strongly suggests its usefulness as an antimalarial agent and supports its inclusion or exploitation in formulations of herbal remedies for malaria in Ghana.

No / New antimalarial drugs are urgently needed to combat emerging multidrug resistant strains of malaria parasites. This Highlight focuses on plant-derived natural products that are of interest as potential leads towards new antimalarial drugs including synthetic analogues of natural compounds, with the exception of artemisinin derivatives, which are not included due to limited space. Since effective antimalarial treatment is often unavailable or unaffordable to many of those who need it, there is increasing interest in the development of locally produced herbal medicines; recent progress in this area will also be reviewed in this Highlight.

La plasmodione est une benzylmenadione (bMD) qui a été désignée comme inhibiteur subversif de flavoenzymes. Ces enzymes utilisent FAD comme co-facteur et sont impliquées dans de nombreux processus biologiques, et notamment dans le maintien de l’homéostasie redox par les systèmes thiorédoxine et glutathion. La plasmodione présente une forte activité contre P. falciparum in vitro, elle est actif sur tous les stades asexués, préférentiellement sur les stades anneaux, avec une vitesse d’élimination des parasites très rapide. Mon objectif a été de tester sa capacité à bloquer la transmission du parasite murin au moustique et de contribuer à déterminer son mode d’action. Pour ce faire, j’ai dans un premier temps mis au point de nouveaux protocoles. Mes résultats ont démontré que (i) la plasmodione réduit le développement du parasite in vivo et limite la transmission du parasite au moustique en agissant sur tous les stades parasitaires sexués infectieux pour le moustique ; (ii) qu’un dérivé de la même famille, plus soluble, est beaucoup plus efficace, notamment sur les stades sexués et la transmission ; (iii) que lorsqu’ils sont délivrés directement au moustique, il n’y a aucun effet du bleu de méthylène ou de la plasmodione sur la survie des moustique ; (iv) enfin en utilisant des parasites invalidés pour la GR, la GS, la γGCS ou la GluPho, mes résultats suggèrent que le modèle d’action proposé des bMDs est à revoir, et que d’autres flavoenzymes pourraient être la cible. / Plasmodione is a benzylmenadione, synthetized as a flavoenzyme inhibitor. These enzymes use FAD as a cofactor and are involved in numerous biologic processes, including the regulation of the redox equilibrium through thioredoxin and glutathione metabolisms. Plasmodione is very efficient in vitro against all stages of the human parasite P. falciparum, especially on ring stages, and is a fast killer. The aims of my PhD were to monitor the ability of Plasmodione to block parasite transmission to mosquitoes and to characterized its mode of action. For that, I had to implement new protocols. My results showed (i) that Plasmodione decrease both the parasite development in vivo and its transmission to mosquitoes while acting on every sexual stage infectious for the mosquito. (ii) A derivative from the same chemical family, more soluble, is more efficient than Plasmodione, especially on asexual stages and on transmission. (iii) When compounds are directly deliver into mosquitoes, neither methylene blue or Plasmodione have an effect on the survival. (iv) Finally, the use of knock out parasites for the GR, GS, γGCS or GluPho genes suggest that the proposed mode of action of the benzylmenadiones has to be corrected and other flavoenzymes could be targeted rather than GR.

The goal of our research endeavor was to successfully employ modern lead discovery and optimization strategies towards the development and identification of compounds possessing antimalarial activity. Preliminary data from in vitro screening at the Walter Reed Army Institute of Research identified several chemotypes including 4(1H)-quinolones and 1,2,3,4-tetrahydroacridones to have potent antimalarial activities. Multiple synthetic routes were devised and implemented which enabled the rapid preparation and isolation of over 400 structurally diverse 4(1H)-quinolones and 1,2,3,4-tetrahydroacridones. Our research towards discovering and optimizing antimalarials was inspired from the severe impact malaria has had on our planet especially on impoverished countries. There are over 300 million cases annually and over one million deaths. The staggering mortality rates combined with the global emergence of chemical resistance that the parasite Plasmodium falciparum has developed towards many of the common antimalarials compelled us to extend our research efforts to this growing problem. The need for identifying and developing new antimalarial drugs is very important. However, our approach focuses on the optimization of historic antimalarials such as endochin, floxacrine, or ICI 56,780 which possess liabilities such as lack of poor solubility, poor in vivo activity or lingering toxicity issues. Through these optimization efforts using both SAR and structure-property relationship (SPR) studies, a more suitable candidate was developed that had superior physicochemical properties. Our drug design approach included not only the identification of liabilities of historic compounds but also the synthesis and optimization of numerous analogs guided by SAR. All compounds were tested in vitro for antimalarial activity and characterized in parallel for physicochemical properties such as solubility, permeability, and logD7.4. Insights from both the antimalarial activity as well as the physicochemical properties determined which analogs would be advanced in the design process. Based on our early investigations, 6-chloro-7-methoxy-3-phenyl-4(1H)-quinolone emerged as a promising hit. Compared to endochin, which possesses EC50s of 8.6 nM and 46.6 nM against drug resistant strains W2 and TM90C2B, and a solubility of less than 2 µM, 6-chloro-7-methoxy-3-pheny-4(1H)-quinolone was superior with a 4-fold improvement in solubility (6 µM) as well as slightly improved antimalarial activity (EC50s of 26.2 nM and 15.3 nM against W2 and TM90C2B, respectively). Unfortunately, this compound failed to reduce parasitemia levels in P. berghei infected mice. Hit-to-lead optimization lead to the discovery of 6-chloro-7-methoxy-2-methyl-3-o-tolyl-4(1H)-quinolone which was shown to reduce parasitemia levels by 41% at day 6 post-exposure (PE) in P. berghei infected mice at a 50 mg/kg dose. The observed in vivo activity of 6-chloro-7-methoxy-2-methyl-3-o-tolyl-4(1H)-quinolone was believed to relate to the 3-fold increase in solubility (19 µM) over the 3-phenyl-susbtituted analogue. Continuation of SAR and SPR studies identified additional 4(1H)-quinolones suggesting that the microsomal stability of the compounds is as important for in vivo efficacy as the aqueous solubility. Several of the analogs that showed minimal degradation in human microsomal stability studies demonstrated increased in vivo activity in the ranges of 72-98% parasitemia reductions on day 6PE in P. berghei infected mice at 50 mg/kg. These results helped refine the final SAR and SPR optimization identifying a compound with radical curative activity in mice (99% parasitemia reductions on day 6PE in P. berghei infected mice at 50 mg/kg with five out of five mice surviving beyond 30 days). Theses studies not only highlight the effectiveness of detailed SAR and SPR strategies used in drug discovery programs, but they also showcase the importance of re-evaluating historic antimalarials and exploiting their shortcomings. These studies have opened the doors to several possibilities regarding the 4(1H)-quinolone scaffold optimization for future antimalarial development. Several of the compounds described in this work are currently being subjected to stringent head-to-head comparative studies to determine the analog best suited for pre-clinical trials.

Isolée d'une bactérie, Streptomyces alboniger, la puromycine est un nucléoside antibiotique naturel présentant une analogie structurale avec l'adénosine terminale de l’extrémité 3’ de l'ARNt aminoacylé. Cette similarité confère à cette molécule la faculté de pouvoir s'insérer dans le site A (actif) du ribosome et d'inhiber la synthèse des protéines. Cependant, du fait de la formation d'un produit toxique lors de sa métabolisation, la puromycine n'a jamais été employée à des fins thérapeutiques chez l'homme. Néanmoins, utilisée en tant qu'outil synthétique, elle a largement contribué à une meilleure compréhension du mécanisme du transfert peptidique. Au travers de cette thèse, six analogues carbobicycliques (deux en série ribo et quatre en série 2'-désoxy), mimant de façon optimale les conformations extrêmes nord ou sud de la puromycine, ont été synthétisés puis testés dans le ribosome. Outre confirmer que la présence d'un groupement 2'-hydroxyle améliorait l'activité inhibitrice, ces expériences in vitro ont apporté une preuve que, dans le site actif, le déplacement de l'équilibre conformationnel du ribofuranose de l'adénosine terminale de l'ARNt aminoacylé – analogue structural de la puromycine – en faveur de son conformère nord pourrait être directement impliqué dans la catalyse ribosomale du transfert peptidique. Par ailleurs, un projet annexe sur le développement de nouveaux antipaludiques potentiels a permis la synthèse, en série xylo, de la puromycine et de son métabolite naturel le puromycine aminonucléoside. Ces composés ont été testés sur les souches 3D7 et Dd2 du parasite Plasmodium falciparum. / Puromycin, a natural antibiotic nucleoside isolated from the bacterium Streptomyces alboniger, has been used to approach and to clear up the understanding of the mechanism of protein biosynthesis. In fact, its structural similarity to the 3' terminal 3'-O-aminoacyl adenylate moiety of aminoacyl-tRNA explains its activity in the ribosomal A site causing the inhibition of the protein synthesis. Since its metabolism generates a toxic product, puromycin cannot be used as therapeutical purposes for humans. During this PhD work, six carbobicyclic analogues of puromycin, conformationally restricted into the northern or southern conformations with the help of a cyclopropane moiety, were synthesized (two ribo-derivatives and four in the 2'-deoxy ribo-series) then tested for pep¬tidyl transfer efficiency in ribosomes. In addition to confirming that the 2'-hydroxyl function is necessary to improve the inhibition properties, these enzymological tests brought an evidence that the conformational switching: southern to northern, occurring in the A site, could directly be involved in the ribosomal catalysis of the peptidyl transfer. Besides, a side project on the elaboration of potential antimalarial compounds provided new xylo-analogues of puromycin and its natural metabolite PAN. These derivatives were tested on the 3D7 and Dd2 strains of the Plasmodium falciparum parasite

Among the myriad of naturally occurring bioactive compounds are the aminocyclopentitol-containing natural products that represent a family of sugar-derived microbial secondary metabolites, such as the antibiotics pactamycin, allosamidin, and trehazolin. Pactamycin, a structurally unique aminocyclitol antibiotic isolated from Streptomyces pactum, consists of a 5-membered ring aminocyclitol (cyclopentitol) unit, two aromatic rings (6-methylsalicylic acid (6-MSA) and 1-(3-Amino-phenyl)-ethanone or 3-aminoacetophenone) and a 1,1-dimethylurea. It has pronounced antibacterial, antitumor, antiviral, and antiplasmodial activities, but its development as a clinical drug was hampered by its broad cytotoxicity. Efforts to modulate its pharmacological and toxicity properties by structural modifications using synthetic organic chemistry have been difficult due to the complexity of its chemical structure. As part of our ongoing studies on the biosynthesis of aminocyclitol-derived bioactive natural products, we have identified the biosynthetic gene cluster of pactamycin in S. pactum ATCC 27456, which paves the way for a better understanding of pactamycin biosynthesis and generating novel pactamycin analogs through biosynthetic engineering. Through gene inactivations, feeding experiments, and in vitro enzymatic assay, we studied the biosynthesis of pactamycin, which include the modes of formation of the unique cyclopentitol unit, the 3-aminoacetophenone and the 6-methyl salicylic acid moieties. Armed with the tools needed to genetically engineer target strains of S. pactum, we were able to produce novel analogs of this untapped-class of natural products. TM-026 was generated from a ΔptmH (a radical SAM C-methyltransferase gene) mutant, whereas TM-025 was generated from a ΔptmH/ΔptmQ (a polyketide synthase gene) double knockout mutant. Both compounds show potent antimalarial activity, but lack significant antibacterial activity, and are about 10-30 times less toxic than pactamycin toward mammalian cells. The results suggest that distinct ribosomal binding selectivity or new mechanism(s) of action may be involved in their plasmodial growth inhibition, which may lead to the discovery of new antimalarial drugs and identification of new molecular targets within malarial parasites. TM-035 was also isolated from a ΔptmH mutant. However, we found that TM-035 showed no activity against bacteria, malarial parasites, and most tested mammalian cells, but it has potent growth inhibitory activity against two well-established human head and neck squamous cell carcinomas (SCC025 and SCC104) (IC₅₀ 725 nM) in an in vitro assay. More intriguingly, the compound is significantly less active against human primary epidermal keratinocytes (HPEK), demonstrating an interesting biological phenomenon and outstanding cell type selectivity, which may lead to the development of new anticancer chemotherapy. The production yield of pactamycin and its congeners under laboratory conditions is relatively low. This has hampered both mechanistic and preclinical studies of these promising compounds. To deepen our understanding of pactamycin biosynthesis and engineer mutant strains with improved production yields, we investigated pathway specific regulatory genes, ptmF and ptmE. Based on gene inactivation and RT-PCR studies, we found that the PtmF-PtmE system controls the transcription of the whole biosynthetic gene cluster. The results provide important insight into regulation of pactamycin biosynthesis and will contribute to future studies that aim at engineering high producing strains of S. pactum. / Graduation date: 2012 / Access restricted to the OSU Community at author's request from Feb. 28, 2012 - Feb. 28, 2013

Conselho Nacional de Desenvolvimento Científico e Tecnológico / A malária é uma doença infecciosa causada por protozoários do gênero Plasmodium, transmitidos ao homem, principalmente, através da picada do mosquito infectado. O tratamento é realizado por meio do uso de drogas, como a cloroquina, uma vez que não há vacina eficiente contra a doença. Porém, a resistência dos parasitos aos medicamentos tem levado à busca por novas substâncias com atividade antimalárica, inclusive de origem vegetal. Nesse contexto, o presente trabalho teve por objetivo avaliar a atividade antimalárica de extratos metanólicos de Norantea brasiliensis cultivada sob condições in vivo e in vitro, espécie nativa ocorrente em restingas, com potencial medicinal já comprovado para várias atividades. Foram desenvolvidos protocolos de calogênese e cultura de raízes da espécie visando à definição de um sistema de produção de metabólitos. Para a cultura in vitro, explantes foram inoculados em meio líquido e sólido contendo diferentes fitorreguladores e concentrações. A partir da cultura de tecidos, foram testados extratos do material produzido biotecnologicamente para comparação com o material botânico cultivado no campo. Os testes sobre o potencial antimalárico foram realizados in vivo, utilizando-se camundongos infectados pelo Plasmodium berghei ANKA, e in vitro utilizando o Plasmodium falciparum. Em seguida foram administrados a cloroquina e os extratos vegetais. A parasitemia foi observada seguindo os protocolos já estabelecidos pelo Laboratório de Imunofarmacologia do Instituto Oswaldo Cruz (IOC). Resultados mostraram que explantes foliares e caulinares de plantas germinadas in vitro, inoculados em meio sólido B5 suplementado com 2,0 mg.mL-1 de ANA, são as melhores fontes para a produção de raízes, apresentando maiores valores de peso fresco e peso seco, mostrando-se um sistema promissor para a produção in vitro de metabólitos da espécie. A avaliação da atividade antimalárica in vivo revelou seu potencial a partir de extrato de raízes de planta cultivada in vivo, na concentração de 50 mg/kg apresentando redução significativa da parasitemia quando comparada com o controle não tratado. Paralelamente, nos testes in vitro a concentração de 100 &#956;g/kg do extrato de raízes de planta cultivada in vivo apresentou diferença significativa quando comparada com as outras concentrações testadas e o controle negativo. Além disso, há uma tendência de aumento do efeito inibitório conforme o aumento da concentração do extrato. Os resultados indicam o potencial de atividade antimalárica em raízes de N. brasiliensis, sendo este estudo o primeiro realizado para a espécie / Malaria is an infectious disease caused by protozoa of the genus Plasmodium, transmitted to humans primarily through the bite of an infected mosquito. The treatment is accomplished through the use of drugs such as chloroquine, since there is no effective vaccine against the disease. However, the resistance of parasites to drugs has led to the search for new antimalarial substances, including vegetable. In this context, this study aimed to evaluate the antimalarial activity of methanol extracts of Norantea brasiliensis grown under conditions in vivo and in vitro, native species occurring in salt marshes, with proven medicinal potential for various activities. Protocols were developed callus and culture of roots of species in order to define a system for production of metabolites. For in vitro culture, explants were inoculated in liquid and solid media containing different growth regulators and concentrations. From the tissue culture material were tested extracts biotechnologically produced for comparison with plant material grown in the field. Tests on the potential in vivo antimalarial were performed using mice were infected by Plasmodium berghei ANKA, and in vitro using the Plasmodium falciparum. They were then administered chloroquine and plant extracts. The parasitemia was observed following the protocols established by the Laboratory of Immunopharmacology of the Oswaldo Cruz Institute (IOC). Results showed that stem and leaf explants of in vitro germinated seedlings were inoculated on B5 solid medium supplemented with 2.0 mg.mL-1 ANA, are the best sources for the production of roots, with highest values of fresh weight and dry weight and proved to be a promising system for in vitro production of metabolites of the species. The assessment of antimalarial activity in vivo has shown its potential to extract from plant roots grown in vivo at a concentration of 50 mg/kg showing significant reduction of parasitemia when compared with the untreated control. Similarly, in in vitro tests the concentration of 100 &#956;g/kg of extract of roots of plants grown in vivo showed a significant difference when compared with other tested concentrations and negative control. Furthermore, there is a tendency to increase the inhibitory effect with increasing extract concentration. The results indicate the potential for antimalarial activity in roots of N. brasiliensis, which is the first study conducted for the species.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / A malária é uma doença infecciosa causada por protozoários do gênero Plasmodium, transmitidos ao homem, principalmente, através da picada do mosquito infectado. O tratamento é realizado por meio do uso de drogas, como a cloroquina, uma vez que não há vacina eficiente contra a doença. Porém, a resistência dos parasitos aos medicamentos tem levado à busca por novas substâncias com atividade antimalárica, inclusive de origem vegetal. Nesse contexto, o presente trabalho teve por objetivo avaliar a atividade antimalárica de extratos metanólicos de Norantea brasiliensis cultivada sob condições in vivo e in vitro, espécie nativa ocorrente em restingas, com potencial medicinal já comprovado para várias atividades. Foram desenvolvidos protocolos de calogênese e cultura de raízes da espécie visando à definição de um sistema de produção de metabólitos. Para a cultura in vitro, explantes foram inoculados em meio líquido e sólido contendo diferentes fitorreguladores e concentrações. A partir da cultura de tecidos, foram testados extratos do material produzido biotecnologicamente para comparação com o material botânico cultivado no campo. Os testes sobre o potencial antimalárico foram realizados in vivo, utilizando-se camundongos infectados pelo Plasmodium berghei ANKA, e in vitro utilizando o Plasmodium falciparum. Em seguida foram administrados a cloroquina e os extratos vegetais. A parasitemia foi observada seguindo os protocolos já estabelecidos pelo Laboratório de Imunofarmacologia do Instituto Oswaldo Cruz (IOC). Resultados mostraram que explantes foliares e caulinares de plantas germinadas in vitro, inoculados em meio sólido B5 suplementado com 2,0 mg.mL-1 de ANA, são as melhores fontes para a produção de raízes, apresentando maiores valores de peso fresco e peso seco, mostrando-se um sistema promissor para a produção in vitro de metabólitos da espécie. A avaliação da atividade antimalárica in vivo revelou seu potencial a partir de extrato de raízes de planta cultivada in vivo, na concentração de 50 mg/kg apresentando redução significativa da parasitemia quando comparada com o controle não tratado. Paralelamente, nos testes in vitro a concentração de 100 &#956;g/kg do extrato de raízes de planta cultivada in vivo apresentou diferença significativa quando comparada com as outras concentrações testadas e o controle negativo. Além disso, há uma tendência de aumento do efeito inibitório conforme o aumento da concentração do extrato. Os resultados indicam o potencial de atividade antimalárica em raízes de N. brasiliensis, sendo este estudo o primeiro realizado para a espécie / Malaria is an infectious disease caused by protozoa of the genus Plasmodium, transmitted to humans primarily through the bite of an infected mosquito. The treatment is accomplished through the use of drugs such as chloroquine, since there is no effective vaccine against the disease. However, the resistance of parasites to drugs has led to the search for new antimalarial substances, including vegetable. In this context, this study aimed to evaluate the antimalarial activity of methanol extracts of Norantea brasiliensis grown under conditions in vivo and in vitro, native species occurring in salt marshes, with proven medicinal potential for various activities. Protocols were developed callus and culture of roots of species in order to define a system for production of metabolites. For in vitro culture, explants were inoculated in liquid and solid media containing different growth regulators and concentrations. From the tissue culture material were tested extracts biotechnologically produced for comparison with plant material grown in the field. Tests on the potential in vivo antimalarial were performed using mice were infected by Plasmodium berghei ANKA, and in vitro using the Plasmodium falciparum. They were then administered chloroquine and plant extracts. The parasitemia was observed following the protocols established by the Laboratory of Immunopharmacology of the Oswaldo Cruz Institute (IOC). Results showed that stem and leaf explants of in vitro germinated seedlings were inoculated on B5 solid medium supplemented with 2.0 mg.mL-1 ANA, are the best sources for the production of roots, with highest values of fresh weight and dry weight and proved to be a promising system for in vitro production of metabolites of the species. The assessment of antimalarial activity in vivo has shown its potential to extract from plant roots grown in vivo at a concentration of 50 mg/kg showing significant reduction of parasitemia when compared with the untreated control. Similarly, in in vitro tests the concentration of 100 &#956;g/kg of extract of roots of plants grown in vivo showed a significant difference when compared with other tested concentrations and negative control. Furthermore, there is a tendency to increase the inhibitory effect with increasing extract concentration. The results indicate the potential for antimalarial activity in roots of N. brasiliensis, which is the first study conducted for the species.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-06-28T11:14:22Z No. of bitstreams: 1 antonioviniciusdoriguettoferreira.pdf: 2820060 bytes, checksum: 3ecff4ce032ebee730a9907d3248b98a (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-06-28T12:25:03Z (GMT) No. of bitstreams: 1 antonioviniciusdoriguettoferreira.pdf: 2820060 bytes, checksum: 3ecff4ce032ebee730a9907d3248b98a (MD5) / Made available in DSpace on 2016-06-28T12:25:03Z (GMT). No. of bitstreams: 1 antonioviniciusdoriguettoferreira.pdf: 2820060 bytes, checksum: 3ecff4ce032ebee730a9907d3248b98a (MD5) Previous issue date: 2013-07-30 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / As espécies do gênero Andira (Fabaceae), popularmente conhecidas como “angelins”, destacam-se pelo uso popular como febrífugas, vermífugas e antimaláricas. Apesar das evidências da atividade antimalárica das espécies do gênero, existe uma carência de estudos químicos e biológicos em torno da espécie Andira nitida. Desta forma, este trabalho objetivou estabelecer o perfil químico e avaliar o potencial biológico de A. nitida, a fim de encontrar uma possível opção de novos alvos terapêuticos para o tratamento da malária. O perfil químico foi estabelecido por cromatografia em camada delgada (CCD) e cromatografia em fase líquida de alta eficiência (CLAE), após a análise dos cromatogramas constatou-se a presença de derivados fenólicos, especialmente, flavonoides como as isoflavonas e de derivados de catequina. O conteúdo de derivados fenólicos totais variou de 100-320 mg de equivalente em catequina/g amostra e de 90-280 mg de equivalente em ácido gálico/ g amostra, já o de isoflavonoides de 6,24-11,15 mg de equivalente em biochanina A/g amostra e o de flavonoides totais de 1,20-4,55 mg de equivalente em quercetina/g amostra. As CE50 para o método DPPH variaram de 5,99-31,90 μg/mL. Os valores da atividade antioxidante equivalente ao Trolox (TEAC) para as amostras foram de 0,161-0,693. Foi encontrada forte correlação entre atividade antioxidante por DPPH e o conteúdo de derivados fenólicos (Pearson > 0,9) e entre TEAC e o teor de flavonoides expressos em quercetina (Pearson > 0,83). A fração em hexano e em clorofórmio apresentaram CE50 de 40,5 μg/mL e 136,2 μg/mL, respectivamente, no ensaio de quantificação de substâncias reativas ao ácido tiobarbitúrico (SRAT). As amostras mais ativas no ensaio antiplasmodial (Teste LDH) foram as frações em hexano e em clorofórmio com 31% de inibição do crescimento de P. falciparum. Já no ensaio de inibição da polimerização da ferriprotoporfirina (FBIT) as CE50 variaram de 0,41-1,12 mg/mL sendo as frações em hexano, clorofórmio e em acetato de etila ativas, juntamente com o extrato lipofílico. In vivo, estas amostras a 200 mg/kg/dia foram ativas no teste de Peters com inibições da parasitemia de 39-75% no sétimo dia após a infeccção. Os resultados indicaram que A. nitida apresenta perfil químico predominante em isoflavonas, corroborado pela quantificação de isoflavonoides, dessa forma ratifica-se o papel das isoflavonas como possíveis marcadores quimiossistemáticos do gênero Andira, além de responsáveis, em parte, pela atividade antimalárica das espécies estudadas até o presente momento. Além disso, as amostras provenientes dos galhos de A. nitida podem ser fontes de substâncias bioativas com pronunciada atividade antioxidante, além de interessante atividade antimalárica. / The Andira species (Fabaceae), popularly known as "Angelins" stand out for popular use as febrifugue, vermifuge and antimalarial. Chemically they are characterized by the presence of phenolic derivatives such as isoflavones. However, despite evidence of antimalarial activity of the genus, there is a lack about chemical and biological studies of Andira nitida. So the present study aimed to establish the chemical profile and assess the biological potential of A. nitida, to find a possible option for new therapeutic targets for the malaria treatment. The chemical profile was established by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC), after analysis of the chromatograms; they showed the predominant presence of phenolic derivatives, especially flavonoids such as isoflavones and catechin derivatives. The contents of phenolic derivatives ranged from 100 to 320 mg catechin equivalent/g sample and from 90 to 280 mg gallic acid equivalent/g sample. The isoflavonoids content ranged from 6.24 to 11.15 mg equivalent biochanin A/g sample and flavonoids content ranged from 1.20 to 4.55 mg quercetin equivalent/g sample. The EC50 for DPPH ranged from 5.99-31.90 μg/mL.Trolox equivalent antioxidant activity (TEAC) values for the samples were 0.161 to 0.693. Strong correlation was found between oxidant activity by DPPH and content of phenolic derivatives (Pearson > 0.9) and between TEAC and the flavonoids content expressed in quercetin (Pearson > 0.83). The fraction in hexane and in chloroform showed EC50 of 40.5 μg/mL and 136.2 μg/mL, respectively; in the quantification of thiobarbituric acid reactive substances assay (TBARS). The more active samples in antiplasmodial assay (LDH testing) were the fractions in hexane and in chloroform with 31% inhibition of P. falciparum growth. In the ferriprotoporphyrin polymerization inhibition assay (FBIT) the EC50 ranging from 0.41 to 1.12 mg/ml and the fractions in hexane, in chloroform and in ethyl acetate were actives along with the lipophilic extract. In vivo, these samples at 200 mg/kg/day (Peters testing) showed parasitaemia inhibitions of 39-75 % in day 7 after infection. The results indicated that A. nitida presents chemical profile composed of isoflavones, corroborated by quantification of isoflavones, and thus confirms the role of isoflavones as potential chemosystematic markers of Andira genus. Futhermore, the samples from A. nitida can be a source of bioactive substances with pronounced antioxidant activity, as well as interesting antimalarial activity thus can be an alternative for future therapeutic applications.

Le paludisme reste une des maladies infectieuses les plus importantes au monde. Récemment, le laboratoire de Dr E. Davioud-Charvet a conçu des 3-Benzyl-Ménadiones substituées (benzylMD) comme agents antipaludiques prometteurs. Les études sur le mode d'action ont mis en évidenceque ces molecules déstabilisent l'équilibre redox des érythrocytes infectés en agissant comme agent catalytique redox (redox-Cycler), une stratégie prometteur pour le développement de nouveaux agents antipaludiques. Le travail de thèse présenté a caractérisé l'activité in vitro et le mécanisme d'action de tête de série, la 3-[4-(trifluorométhyl)-Benzyl]-Ménadione 1c, ce qui représente une partie principale du développement des benzylMDs. Une deuxième partie explorait les relations structure-Activité de benzylMD dérivés. Dans l'ensemble, les résultats démontrent l'activité in vitro très prometteuse de la benzylMD 1 cet soutiennent l'amélioration de benzylMDs comme nouveaux candidats-Médicaments antipaludiques. / Malaria is still one of the most important infectious diseases worldwide. Previously, the laboratory of Dr. E. Davioud-Charvet presented the chemical design of very promising antimalarial agents, 3-[substituted-Benzyl]-Menadiones (benzylMD). Studies on the mode of action evidenced that these agents disturb the redox balance of the parasitized erythrocyte by acting as redox-Cyclers - a promising strategy for the development of new antimalarial agents. The presented PhD work characterized the in vitro potency and the mechanism of action of the lead agent, the 3-[4-(trifluoromethyl)benzyl]-Menadione 1 c, which represents an essential part of the lead optimization stage of the benzylMD drug development process. A second part of this work focused on the structure-Activity relationships benzylMD derivatives. Overall, the presented findings demonstrate the promising in vitro potency of lead benzylMD 1c and highly support the further development of benzylMDs as antimalarial drug candidates.