A malária é uma doença que atinge 40% da população mundial e está entre as três maiores doenças infectantes do planeta, juntamente com a AIDS e a tuberculose. As crianças são as principais atingidas, uma vez que se estima que uma criança morra de malária a cada 40 segundos. As principais regiões atingidas são as que relacionam o clima tropical com altos índices de pobreza, como por exemplo a África sub-Sahariana. Este quadro agrava-se com o surgimento de cepas cloroquino-resistentes do Plasmodium falciparum, principal agente causador da malária grave. Muitos dos fármacos aplicados na terapêutica da malária apresentam inúmeros efeitos adversos, baixa biodisponibilidade e alta toxicidade, o que dificulta o emprego na terapêutica. Diante deste quadro urge o desenvolvimento de novos fármacos antimaláricos. A primaquina, fármaco desenvolvido na segunda guerra mundial, é o único esquizonticida tecidual disponível até o momento, porém apresenta baixa biodisponibilidade, em razão da meia-vida curta, e alta toxicidade. Estas características apresentadas pela primaquina podem ser atenuadas com o emprego da latenciação. O trabalho em questão visa ao desenvolvimento de pró-fármacos \"triglicerídicos\', também conhecidos com lipóides. Os pró-fármacos lipóides utilizam a digestão e absorção dos lipídeos para promover absorção, aumentando a biodiponibilidade e tempo de meia-vida, conseqüentemente, diminuindo a toxicidade. Serão sintetizados como transportadores os diglicerídicos dos ácidos palmítico, esteárico e decanóico. Estes ligar-se-ão à primaquina através dos espaçantes succnil, maleil e ftalil. / Abstract not available.

O núcleo quinolínico constitui uma das classes de heterociclos nitrogenados de maior destaque, pois são amplamente encontradas em produtos naturais, além de comporem a lista dos considerados esqueletos \"privilegiados\", relacionados com as diversas classes terapêuticas como: anticâncer, anticolinesterásicos, antimaláricos, etc. Diante das abordagens sintéticas de funcionalização de anéis heteroaromáticos, o uso de espécies organometálicas ocupa, hoje, uma posição central na química orgânica sintética, principalmente na formação de novas ligações carbono-carbono. Dessa forma, o presente trabalho explorou essencialmente a reatividade de quinolinas frente à reagentes organometálicos tais como alquil-lítio, amidetos de lítio, turbo-Grignard e amidetos mistos de magnésio e lítio. Inicialmente, foi estudada a funcionalização da 4,7- dicloroquinolina através da reação de metalação dirigida frente aos diferentes reagentes disponíveis. Em seguida, foi desenvolvida uma metodologia de troca iodo-magnésio para a 7-cloro-4-iodoquinolina visando a obtenção de derivados funcionalizados na posição C4 bastante estratégica para atividade antimalárica. Neste estudo foi utilizado o reagente turbo-Grignard para etapa de troca, seguida da reação com eletrófilos. Os compostos obtidos tiveram sua atividade antimalárica avaliada pelo grupo do Dr. Adrian M. Pohlit do Instituto Nacional de Pesquisas da Amazônia (INPA). A metodologia de troca iodomagnésio do turbo-Grignard frente à 7-cloro-4-iodoquinolina também foi aplicada para a obtenção de outros derivados por reações de acoplamento cruzado de Negishi, e na rota sintética de um híbrido molecular planejado com potencial atividade antimalárica. Além disso, foi estudada a reação de troca halogênio-metal da 3-bromoquinolina frente a reagentes de lítio seguida da reação com aldeídos. Por fim, algumas das estruturas sintetizadas também tiveram avaliação da atividade anticâncer realizada pelo grupo da Prof. Dra. Letícia Lotufo da Universidade Federal do Ceará. Portanto, foram demonstradas neste trabalho estratégias simples e eficientes utilizando reagentes organometálicos para funcionalização de quinolinas de interesse sintético e medicinal. / The quinoline unit is one of most important nitrogen heterocycle classes since it is found in a large number of natural products. Moreover, it is considered a privileged scaffold presenting a variety of pharmacologic activities such as: anti-cancer, anticholinesterase, antimalarial and others. Among the available aromatic heterocycle functionalization approaches, the organometallic chemistry have a prominent position mainly on the construction of new carbon-carbon bonds. In this context, this work have explored the quinoline reactivity against organometallic reagents like alkyl-lithium, lithium amides, turbo-Grignard and magnesium lithium amides. Initially, the functionalization of 4,7- dichloroquinoline was studied through the direct metalation reaction of the substrate with several available organometallic reagents. Afterwards, a new iodo-magnesium exchange methodology for the 7-chloro-4-iodoquinoline was developed in order to obtain C-4 functionalized quinoline derivatives. The turbo-Grignard was the reagent of choice in iodo-magnesium exchange reactions that were subsequently reacted with different electrophiles. The antimalarial activity of the compounds obtained in this study was evaluated by Dr. Adrian M. Pohlit group of National Institute of Amazon Research (INPA). The developed iodo-magnesium exchange methodology was further applied in Negishi cross-coupling reactions and on a synthetic study of a planned molecular hybrid with potential antimalarial activity. In addition, the halogen-metal exchange reaction on 3-bromoquinoline was studied using alkyl-lithium reagents with subsequent reaction with aldehydes. Finally, the anti-cancer activity of some of structures obtained in this work was evaluated by Prof. Dra Letícia Lotufo group of Federal University of Ceará

<p> Malaria, Human Immunodeficiency Virus (HIV) and tuberculosis (TB) are global health problems having their worst situation in sub-Saharan Africa. Consequently, concomitant use of antimalarial, antiretroviral and antitubercular drugs may be needed, resulting in a potential risk of drug-drug interactions.</p><p>Cytochrome P-450 (CYP) enzyme induction/inhibition may lead to drug-drug interactions and can be detected by probe drugs. An analytical method was developed for the quantitation of mephenytoin, CYP2B6 and CYP2C19 probe, and its metabolites. </p><p>Induction/inhibition of principal CYP enzymes by the antimalarials; artemisinin, dihydroartemisinin, arteether, artemether and artesunate, was evaluated using the 4-hour plasma concentration ratios of probe drugs and their metabolites along with modelling the population pharmacokinetics of S-mephenytoin and its metabolites. The extent of change in enzymatic activities was different among the antimalarials, with artemisinin having strongest capacity for induction and inhibition, consequently, the strongest potential risk for drug-drug interactions. </p><p>Drug-drug interactions between the antitubercular rifampicin and the antiretrovirals nevirapine and lopinavir were assessed, in TB/HIV patients, by developing population pharmacokinetic models. Rifampicin increased nevirapine oral clearance. Simulations suggested that increasing the nevirapine dose to 300 mg twice daily when co-administered with rifampicin, would result in nevirapine concentrations above subtherapeutic levels, with minimum exposure above the recommended maximum concentration. Lopinavir is co-formulated with ritonavir in the ratio of 4:1. In children, increasing ritonavir dose four times did not completely compensate the enhancement of lopinavir oral clearance caused by rifampicin. However, the predicted lopinavir trough concentration was above the recommended minimum therapeutic concentration.</p><p>The work presented in this thesis followed an investigation line though not done for a particular drug. First the CYP enzymes involved in the interaction are identified. Afterwards, the expected drug-drug interaction is investigated where the potentially interacting drugs are concomitantly administered and an adjustment in the dose regimen is proposed that is subsequently evaluated.</p>

Malaria, Human Immunodeficiency Virus (HIV) and tuberculosis (TB) are global health problems having their worst situation in sub-Saharan Africa. Consequently, concomitant use of antimalarial, antiretroviral and antitubercular drugs may be needed, resulting in a potential risk of drug-drug interactions. Cytochrome P-450 (CYP) enzyme induction/inhibition may lead to drug-drug interactions and can be detected by probe drugs. An analytical method was developed for the quantitation of mephenytoin, CYP2B6 and CYP2C19 probe, and its metabolites. Induction/inhibition of principal CYP enzymes by the antimalarials; artemisinin, dihydroartemisinin, arteether, artemether and artesunate, was evaluated using the 4-hour plasma concentration ratios of probe drugs and their metabolites along with modelling the population pharmacokinetics of S-mephenytoin and its metabolites. The extent of change in enzymatic activities was different among the antimalarials, with artemisinin having strongest capacity for induction and inhibition, consequently, the strongest potential risk for drug-drug interactions. Drug-drug interactions between the antitubercular rifampicin and the antiretrovirals nevirapine and lopinavir were assessed, in TB/HIV patients, by developing population pharmacokinetic models. Rifampicin increased nevirapine oral clearance. Simulations suggested that increasing the nevirapine dose to 300 mg twice daily when co-administered with rifampicin, would result in nevirapine concentrations above subtherapeutic levels, with minimum exposure above the recommended maximum concentration. Lopinavir is co-formulated with ritonavir in the ratio of 4:1. In children, increasing ritonavir dose four times did not completely compensate the enhancement of lopinavir oral clearance caused by rifampicin. However, the predicted lopinavir trough concentration was above the recommended minimum therapeutic concentration. The work presented in this thesis followed an investigation line though not done for a particular drug. First the CYP enzymes involved in the interaction are identified. Afterwards, the expected drug-drug interaction is investigated where the potentially interacting drugs are concomitantly administered and an adjustment in the dose regimen is proposed that is subsequently evaluated.

Focused procedures which streamline and optimise plant prioritisation and selection in bioprospecting have the potential to save both time and resources. A variety of semiquantitative techniques were assessed for their ability to prioritise ethnomedicinal taxa in the Flora of Southern Africa (FSA) region. These techniques were subsequently expanded upon for application in plant selection for the Novel Drug Development Platform bioprospecting programme. Least squares regression analyses were used to test the hypothesis that ethnomedicinal plant use in southern Africa is strictly random, i.e. no order or family contains significantly more medicinal plants, than any other order or family. This hypothesis was falsified revealing several 'hot' plant orders. The distribution of southern African ethnomedicinal taxa was investigated, and revealed low ethnomedicinal plant usage in the Western Cape and Northern Cape. The historical settlement of Bantu tribes in the eastern regions of southern Africa was one explanation for this discrepancy. Growth forms of ethnomedicinal taxa in 'hot' orders (identified in the regression analysis) were analysed. The results indicated no clear preferences across orders, but rather a preference for particular growth forms in certain orders. With respect to distribution, endemism and Red Data List status of ethnomedicinal taxa, the Western Cape had the greatest proportion of endemics and Namibia had the highest proportion of Red Data Listed ethnomedicinal taxa. With respect to chemotaxonomy, the Asteraceae contained the highest proportion of terpenoids, the Rubiaceae the highest proportion of alkaloids and the Fabaceae the highest proportion of flavonoids. The predictive value of regression analyses was tested against an existing analysis of anti-malarials and the subsequent in vitro bioassays on Plasmodium falciparum. In particular, the ability of these analyses to identify plants with anti plasmodial IC50 values of [less than or equal to] 10 [micro]g/ml was assessed. Most species in 'hot' genera showed comparatively good antiplasmodial activities (IC50 [less than or equal to] 10 [micro]g/ml). Plant candidates were prioritised for screening anti-tuberculosis, anti-diabetes and immune-modulatory compounds, using a weighting system based on; their ethnomedicinal application, chemotaxonomic potential, frequency in ethnomedicinal trade, association with the relative disease, toxicity, Red Data status, indigenous or endemic status, and family selection in ethnomedicine (identified through regression analyses). Other taxa were short-listed due to their presence in biodiversity hotspots where few ethnomedicinal plant use records are documented, and still others were incorporated due to their taxonomic association with efficacious exotic allies. Statistical analyses of the weighting processes employed were not possible in the absence of screening results which are due only in December 2006. The legislation governing bioprospecting in South Africa is discussed and several recommendations are presented to minimise negative impacts on the industry. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

Malaria is one of the three most deadly diseases in Africa. Although there are available treatments, their efficacy has been greatly reduced over the past two decades due to the development of resistance to currently available drugs. This has necessitated the search for new and effective antimalarial agents. This project approached the search for new antimalarial compounds in two ways: (i) by screening natural products isolated from marine algae against the Plasmodium parasite and (ii) by modification of selected isolated active compounds to target 1-deoxY-đ-xylulose 5-phosphate reductoisomerase (DXR), an enzyme found in the nonmevalonate isoprenoid biosynthetic pathway of Plasmodium Jalciparum. It was envisaged that such a compound would exhibit dual action on the Plasmodium parasite. Extracts obtained from 22 marine algae were prefractionated by solvent partitioning and were screened for anti plasmodial activity against the chloroquine sensitive (CQS) P. Jalciparum D 10 strain. Overall, 50% of the algae screened produced at least one crude fraction with activity against P. Jalciparum. Extracts of the algae Sargassum heterophyllum, Plocamium cornutum, Amphiroa ephedrea and Pterosiphonia cloiophylla gave the most promising results. Fractionation of S. heterophyllum afforded three tetraprenyltoluquinols (3.1, 3.2 and 3.5) and an all-trans-fucoxanthin (3.6). Three new compounds (4.5, 4.6 and 4.7) and two known halogenated monoterpenes (4.1 and 4.4) were isolated from P. cornutum. Each of the isolated compounds from both S. heterophyllum and P. cornutum showed antiplasmodial activity with IC₅₀ values ranging from 2.0 - 15.3 μM for S. heterophyllum and 13 - 230 μM for P. cornutum. Attempts to synthetically modify halogenated monoterpene 4.4 by dihydroxylation and phosphorylation in order to inhibit the DXR enzyme was unsuccessful. However, the hemiterpene analogue (5.42) of the halogenated monoterpenes was successfully phosphorylated and dihydroxylated to give compound 5.45 which showed promising activity against DXR. The result obtained indicated that the proposed phosphorylation and dihydroxylation of the halogenated monoterpene 4.4 would result in the synthesis of a potent DXR inhibitor and therefore a potential antimalarial agent with dual mode of action on the Plasmodium parasite.

Demonstramos que o P. falciparum dentro do eritrócito é capaz de usar a via de sinalização celular dependente do inositol trifosfato (IP3). Investigamos os estoques de Ca2+ intracelular sensíveis ao IP3 neste parasita e a sensibilidade ao IP3 em diferentes estágios no ciclo intraeritrocítico. Demonstramos que o hormônio melatonina é capaz de aumentar a concentração de IP3 neste parasita. Com o uso de uma coluna de afinidade ao IP3 tentamos encontrar proteínas candidatas ao receptor de IP3 em P. falciparum. Este trabalho também estuda a enzima heme oxigenade de P. falciparum (PfHO). Testamos a capacidade desta enzima em converter biliverdina (BV) em bilirubina (BR), a modulação desta atividade na presença de diversas metaloprotoporfirinas e o potencial destes compostos como antimaláricos. Reportamos que a biliverdina é capaz de modular o ciclo intraeritrocítico de P. falciparum e apresentamos a proteína enolase de P. falciparum como candidato ao sensor de BV neste parasita. / We demonstrate that P. falciparum within the erythrocyte is able to use the cellular signaling pathway dependent on inositol triphosphate (IP3). We investigated the intracellular Ca2+ stores sensitive to IP3 and explore parasite sensitivity to IP3 at different stages in the intraerythrocytic cycle. We demonstrate that melatonin hormone is capable of increasing the IP3 concentration on this parasite. Using an IP3 affinity column, we tried to find candidate proteins for IP3 receptor in P. falciparum. This work also studies the enzyme P. falciparum heme oxygenase (PfHO). We tested the ability of this enzyme to convert biliverdin (BV) in bilirubin (BR), the modulation of this activity in the presence of various metalloprotoporphyrins and the potential of these compounds as antimalarials. We reported that biliverdin is capable of modulating the intraerythrocytic cycle of P. falciparum and present P. falciparum enolase as candidate for BV sensor on this parasite.

Early diagnosis and prompt treatment is one of the malaria control strategies used to minimize malaria morbidity and mortality. One of the mechanisms to implement early diagnosis and prompt treatment is community access to diagnostic services and effective antimalarial drugs. However, in Ethiopia the health system is underdeveloped and much of the rural population has limited access to modern health services. Therefore, the Ethiopian government introduced the Health Extension Programme(HEP) which is a community-based health care delivery system aimed at accessing essential health services through its health extension workers (HEWs). Involvement of the HEWs in prescribing and dispensing antimalarial drugs is shown to have improved community access to antimalarial drugs. However, there is insufficient knowledge of HEWs compliance to malaria treatment guidelines and patient adherence of patients treated by HEWs. The objectives of this study has been to describe the HEWs practice in malaria treatment, to evaluate adherence of patients to antimalarial drugs, to explore the factors influencing the HEWs malaria treatment practice and patient adherence, and to develop the guidelines to support the HEWs in malaria treatment practice. A qualitative study design was used to study the HEWs practice in malaria treatment along with patient adherence. Data were collected using in-depth face-to-face interviews, focus group discussion and patient medical record review and were analysed according to Tesch’s steps. The study revealed that the HEWs adequately comply with malaria treatment guidelines during diagnosis of malaria, as well as during the prescribing and dispensing of antimalarial drugs. However, there are some factors influencing the performance of HEWs. These are: shortage of diagnostic kit/RDT, shortage of antimalarial drugs, patient pressure to obtain coartem, work load, and community beliefs with regard to antimalarial drugs effectiveness. This study also revealed that the HEWs follow up after treatment of patients and good community support systems improved patient adherence to antimalarial drug use. Factors negatively influencing patient adherence were identified to include: forgetfulness, fear of shortage of drugs, adverse drug effects, duration of treatment, rapid relief of malaria symptoms and inadequate awareness of the consequence of incomplete dosage. Guidelines were developed to support the HEWs in malaria treatment practice with the aim to improve patient adherence to antimalarial drugs / Health Studies / D. Litt. et Phil. (Health Studies)

No presente trabalho avaliamos fenotípica e molecularmente isolados de P. vivax da Amazônia Ocidental Brasileira. A avaliação fenotípica de sensibilidade à cloroquina (CQ) foi realizada por meio do ensaio de maturação de esquizonte. A avaliação molecular efetuou-se por tipagem de cinco polimorfismos de nucleotídeo único (SNPs) não-sinônimos do gene pvmdr-1 (A266G, A1498G, A2722C, A2927T e T3226C) e variações no número de cópias deste gene. Em decorrência, o fenótipo de susceptibilidade à CQ nos 36 isolados analisados não foi estabelecido devido ao escasso desenvolvimento ex-vivo dos parasitos. Mutações na posição Y976F, potencialmente associada à resistência à CQ, não foram observadas nos 80 isolados testados. Além disso, 10% das amostras apresentaram a mutação F1076L, que frequentemente acompanha a mutação Y976F. Finalmente, apenas dois isolados (0,9%) dos 215 analisados apresentaram duas cópias do gene pvmdr-1, sugerindo que a duplicação gênica, potencial mecanismo de resistência à mefloquina, ainda não está disseminada nas populações de parasitos desta região. / In this study, we performed a molecular and phenotypic evaluation of isolates of P. vivax from Brazilian Western Amazon. The phenotypic evaluation of chloroquine (CQ) sensitivity was performed using the schizont maturation assay. The molecular evaluation was made by typing of five non-synonymous single nucleotide polymorphisms (SNPs) of the pvmdr-1 gene (A266G, A1498G, A2722C, T3226C and A2927T) and variations of the copy number of this gene. As a result, the CQ susceptibility phenotype in 36 isolates of P. vivax analyzed was not established, due to the scarce ex-vivo development of the parasites. Mutations at position Y976F, potentially associated with CQ resistance, were not observed in 80 isolates tested. In addition, 10% of the isolates had the mutation F1076L, which often accompanies the mutation Y976F. Finally, two isolates (0,9%), from a total of 215 had two copies of the pvmdr-1 gene, suggesting that the gene duplication, a potential mechanism of mefloquine resistance, is not spread in the parasites populations of this region.

No presente trabalho avaliamos fenotípica e molecularmente isolados de P. vivax da Amazônia Ocidental Brasileira. A avaliação fenotípica de sensibilidade à cloroquina (CQ) foi realizada por meio do ensaio de maturação de esquizonte. A avaliação molecular efetuou-se por tipagem de cinco polimorfismos de nucleotídeo único (SNPs) não-sinônimos do gene pvmdr-1 (A266G, A1498G, A2722C, A2927T e T3226C) e variações no número de cópias deste gene. Em decorrência, o fenótipo de susceptibilidade à CQ nos 36 isolados analisados não foi estabelecido devido ao escasso desenvolvimento ex-vivo dos parasitos. Mutações na posição Y976F, potencialmente associada à resistência à CQ, não foram observadas nos 80 isolados testados. Além disso, 10% das amostras apresentaram a mutação F1076L, que frequentemente acompanha a mutação Y976F. Finalmente, apenas dois isolados (0,9%) dos 215 analisados apresentaram duas cópias do gene pvmdr-1, sugerindo que a duplicação gênica, potencial mecanismo de resistência à mefloquina, ainda não está disseminada nas populações de parasitos desta região. / In this study, we performed a molecular and phenotypic evaluation of isolates of P. vivax from Brazilian Western Amazon. The phenotypic evaluation of chloroquine (CQ) sensitivity was performed using the schizont maturation assay. The molecular evaluation was made by typing of five non-synonymous single nucleotide polymorphisms (SNPs) of the pvmdr-1 gene (A266G, A1498G, A2722C, T3226C and A2927T) and variations of the copy number of this gene. As a result, the CQ susceptibility phenotype in 36 isolates of P. vivax analyzed was not established, due to the scarce ex-vivo development of the parasites. Mutations at position Y976F, potentially associated with CQ resistance, were not observed in 80 isolates tested. In addition, 10% of the isolates had the mutation F1076L, which often accompanies the mutation Y976F. Finally, two isolates (0,9%), from a total of 215 had two copies of the pvmdr-1 gene, suggesting that the gene duplication, a potential mechanism of mefloquine resistance, is not spread in the parasites populations of this region.