During the erythrocytic stage, the malaria parasite digests host cell haemoglobin into amino acids. Toxic haeme is released and is incorporated into an insoluble non-toxic crystal called haemozoin. Haemozoin is released into the blood stream along with the merozoites when the erythrocyte bursts and is phagocytosed by circulating monocytes and macrophages resident in tissues. Phagocytosed haemozoin impairs many functions of the monocytes, including antigen presentation and adhesion to T cells, differentiation and maturation to dendritic cells, erythropoiesis and thrombopoiesis, but stimulates the release of proinflammatory cytokines and activation of metalloproteinase 9 expression. In response to interferon-g secretion by T-helper cells subtype 1, monocytes secrete neopterin, which is used as a marker of a cell mediated immune response. Neopterin is an oxidation product of 7,8-dihydroneopterin, produced by the dephosphorylation of 7,8- dihydroneopterin triphosphate which results from the conversion of guanosine triphosphate that is catalysed by GTP-cyclohydrolase 1. Elevated plasma and urine neopterin levels have been detected in malaria infections and are associated with severe anaemia, respiratory distress, peak temperatures as well as fever- and parasite-clearance times. It has also been reported that monocytic U937 cells treated with P. falciparum-infected red blood cell lysate secrete elevated levels of neopterin. Antimalarial drugs are known to modulate the functions of monocytes, including inhibition of cytokine release, changes in phospholipid metabolism, decrease in expression of cytoadherance receptors as well as TNF receptors and MHC Class I and II molecules, changes in the production of reactive oxygen and nitrogen intermediates, and decreased phagocytosis. However, the effects of antimalarial drugs on haemozoin phagocytosis and GTP-cyclohydrolase 1 mRNA expression by monocytes are unknown. This study aimed to determine the effects of seven antimalarial drugs, amodiaquine, artemisinin, chloroquine, doxycycline, primaquine, pyrimethamine and quinine, on the phagocytosis of latex beads and b-haematin, a synthetic equivalent of haemozoin. Phagocytosis of b-haematin and latex beads by two monocytic cell lines, J774A.1 and U937, as well as peripheral blood mononuclear cells were monitored by enumeration and a novel spectrophotometric method. Patterns of inhibition and activation differed with each cell type investigated, due to the differing stages of cell differentiation. In general, artemisinin, primaquine, pyrimethamine and quinine activated the phagocytosis of b-haematin, whereas amodiaquine and chloroquine inhibited b-haematin phagocytosis. Doxycycline had different effects on each cell type investigated. Artemisinin, chloroquine, primaquine and quinine inhibited latex bead phagocytosis. The remaining drugs had minimal effects on latex bead phagocytosis. Thus, the effects of antimalarial drugs on monocyte phagocytosis appear to be dependent on the substance being phagocytosed. The effects of antimalarial drugs, b-haematin, latex beads, non-infected- and P. falciparuminfected cell lysates on interferon-g-induced neopterin secretion by U937 cells was monitored by GTP-cyclohydrolase 1 mRNA expression using quantitative PCR. Artemisinin, primaquine and quinine down-regulated the interferon-g-induced expression of GTPcyclohydrolase 1 mRNA, but by no greater than 1.7-fold. b-haematin up-regulated mRNA expression by 1.2-fold whereas P. falciparum-infected red blood cell lysate down-regulated the mRNA expression of GTP-cyclohydrolase 1 by 1.6-fold. Quinine and artemisinin, currently used to treat malaria, increased b-haematin phagocytosis suggesting that quinine and artemisinin might promote increased phagocytosis of infected red blood cells and enhance clearance of the parasite from circulation. Increased b- haematin phagocytosis also reduces ICAM-1 expression on the monocyte surface, thereby leading to reduced cytoadherance and sequestration, thus increasing the number of circulating monocytes to phagocytose infected red blood cells. Down regulation of GTPcyclohydrolase 1 mRNA expression by quinine and artemisinin suggested that the drugs reduce the responsiveness of the monocyte to interferon-g. Thus, quinine and artemisinin might also decrease the production of interferon-g-induced proinflammatory cytokines by monocytes, and potentially play a role in maintaining the balance between the pro- and antiinflammatory cytokines that determines the progression from acute to severe malaria. Therefore, in addition to the drug’s ability to kill the malaria parasite, the immunomodulatory effects of the antimalarial drugs may play a role in controlling the pathophysiology associated with the malaria infection. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2002. / Härtill 6 uppsatser.

Thesis (M.Sc. (Pharmacy))--Mahidol University, 1982.

Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [135]-144).

Thesis (M. S.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2006. / Fernandez, Facundo, Committee Chair ; Janata, Jiri, Committee Member ; Mizaikoff, Boris, Committee Member.

Το φυσικό προϊόν αρτεμισινίνη και τα παράγωγά της αποτελούν σήμερα φάρμακα επιλογής για την αντιμετώπιση της ελονοσίας ενώ πολλά απ’αυτά παρουσιάζουν και ιδιαίτερα σημαντική αντικαρκινική δράση. Στο πλαίσιο της παρούσας διπλωματικής εργασίας έγινε χημική τροποποίηση του μορίου της αρτεμισινίνης, προκειμένου να συντεθούν διμερή συζεύγματά της με πολυαμίνες (πουτρεσκίνη, σπερμιδίνη, σπερμίνη). Αρχικά, η αρτεμισινίνη τροποποιήθηκε κατάλληλα έτσι ώστε, να φέρει συνδέτη με δεσμό C-O (10-oxo) στη θέση-10, προκειμένου στη συνέχεια να προσδεθεί στις πολυαμίνες μέσω δεσμού ουρεθάνης. Για το λόγο αυτό, συντέθηκε το ενεργοποιημένο ανάλογο(10-oxo , το οποίο μετά από αντίδραση με τις κατάλληλα προστατευμένες πολυαμίνες, έδωσαν τα διμερή συζεύγματα της αρτεμισινίνης 66-68. Επιπλέον, για προκαταρκτικές μελέτες βιολογικής δράσης, συντέθηκε ένα ασύμμετρο σύζευγμα της αρτεμισινίνης με το αντικαρκινικό χλωραμβουκίλη (69), χρησιμοποιώντας το 10-oxo ενεργοποιημένο ανάλογο και την πουτρεσκίνη ως πολυαμίνη. Όλα τα παραπάνω συζεύγματα, βρίσκονται στο στάδιο της αποτίμησης της βιολογικής τους δράσης, από συνεργαζόμενο εργαστήριο έναντι καρκινικών σειρών HL60. / The natural product Artemisinin and its derivatives are currently the drugs of choice for the treatment of malaria, with a large number of them showing important anticancer activity as well. In the context of the present dissertation, one chemical modification of artemisinin was accomplished towards the synthesis of several Artemisinin dimer conjugates with polyamines (putrescine, spermidine, spermine). Initially, artemisinin was modified at the 10- position, in order to synthesize analogue bearing suitable linkers, through C-O (10-oxo) bond, able to form urethane bonds with amino groups of polyamines. For this purpose, the activated intermediate(10-oxo) was synthesized, which upon reaction with suitably protected polyamines afforded the Artemisinin symmetric conjugates 66-68. In addition, for the sake of preliminary biological evaluation a new asymmetric conjugate (69) consisted of an 10-oxo Artemisinin and a chlorambucil moiety, using putrescine as a polyamine-type linker, was synthesized. All above conjugates are now under biological evaluation as anticancer agents, against HL60 cancer cells, by a collaborating research group. Further studies are underway, in order to evaluate the biological activity of the aforementioned analogues as antimalarials.

Malaria is an infectious disease caused by parasites of the Plasmodium genus with mortality rates of more than a million annually, hence a major global public health concern. Plasmodium falciparum (P. falciparum) accounts for over 90% of malaria incidence. Increased resistance to antimalarial drugs by the Plasmodium parasite, coupled with the lack of an effective malaria vaccine necessitates the urgent need for new research avenues to develop novel and more potent antimalarial drugs. This study focused on falcipains, a group of P. falciparum cysteine proteases that belong to the clan CA and papain family C1, that have emerged as potential drug targets due to their involvement in a range of crucial functions in the P. falciparum life cycle. Recently, falcipain-2 has been validated as a drug target but little is known of its Plasmodium orthologs. Currently, there are several falcipain inhibitors that have been identified, most of which are peptide based but none has proceeded to drug development due to associated poor pharmacological profiles and susceptibility to degradation by host cysteine proteases. Non-peptides inhibitors have been shown to be more stable in vivo but limited information exists. In vivo studies on falcipain-2 and falcipain-3 inhibitors have also been complicated by varying outcomes, thus a good understanding of the structural variations of falcipain Plasmodium orthologs at the active site could go a long way to ease in vivo results interpretation and effective inhibitor design. In this study, we use bioinformatics approaches to perform comparative sequence and structural analysis and molecular docking to characterize protein-inhibitor interactions of falcipain homologs at the active site. Known FP-2 and FP-3 small molecule nonpeptide inhibitors were used to identify residue variations and their effect on inhibitor binding. This was done with the aim of screening a collection of selected non-peptide compounds of South African natural origin to identify possible new inhibitor leads. Natural compounds with high binding affinities across all Plasmodium orthologs were identified. These compounds were then used to search the ZINC database for similar compounds which could have better binding affinities across all selected falcipain homologs. Compounds with high binding affinities across all Plasmodium orthologs were found.

Submitted by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2013-10-16T19:35:07Z No. of bitstreams: 1 Vinicius Pinto Costa Rocha. Avaliação da atividade antileishmania...2012.pdf: 1625526 bytes, checksum: 4407e0cb5e7b4ade8175d66ca2a59a34 (MD5) / Made available in DSpace on 2013-10-16T19:35:07Z (GMT). No. of bitstreams: 1 Vinicius Pinto Costa Rocha. Avaliação da atividade antileishmania...2012.pdf: 1625526 bytes, checksum: 4407e0cb5e7b4ade8175d66ca2a59a34 (MD5) Previous issue date: 2012 / Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / A leishmaniose compreende um complexo de doenças causadas por parasitos do gênero Leishmania, e é endêmica em 88 países, com uma população de 350 milhões de indivíduos sob o risco de contrair a infecção. O tratamento convencional da leishmaniose é realizado com antimoniais pentavalentes, e está associado a inúmeros efeitos adversos e falha terapêutica. Dessa forma, a busca por novas alternativas terapêuticas para esta doença é de extrema relevância. O presente estudo tem como objetivo avaliar a atividade antileishmania de fármacos antimaláricos in vitro e em modelo murino de leishmaniose tegumentar causada por Leishmania amazonensis. Os fármacos antimaláricos testados foram o artesunato, a cloroquina, a hidroxicloroquina, a mefloquina e a primaquina. Destes, a cloroquina e a hidroxicloroquina não reduziram, de forma significativa, o crescimento de formas promastigotas do parasito na concentração de 50 μM. Entretanto, estes dois fármacos foram eficazes em reduzir o número de amastigotas em macrófagos murinos, apresentando valores de IC50 de 0,78 ± 0,08 μM e 0,67 ± 0,12 μM, respectivamente. A mefloquina apresentou valor de IC50 de 8,4 ± 0,70 μM contra promastigotas do parasito, enquanto que, contra formas amastigotas o IC50 foi 1,56 ± 0,19 μM. A análise ultraestrutural de células infectadas e tratadas com a cloroquina ou com a mefloquina mostrou o acúmulo de corpos multivesiculares no citoplasma do parasito. Este resultado sugere o comprometimento da via endocítica da Leishmania após o tratamento com estas moléculas. O tratamento oral de camundongos CBA infectados com L. amazonensis reduziu a lesão e o parasitismo nos animais infectados. Diferente destes resultados, o tratamento com a mefloquina não reduziu o parasitismo nos animais infectados, apesar de ter reduzido o tamanho da lesão. Com base nestes resultados é possível concluir que a cloroquina pode representar uma alternativa terapêutica ao tratamento convencional da leishmaniose tegumentar. / Leishmaniasis comprises a complex of diseases caused by parasites of the genus Leishmania and is endemic in 88 countries, with a population of 350 million individuals at risk of contracting the infection. The conventional treatment of leishmaniasis based on pentavalent antimonials is associated with several adverse effects and treatment failure. Thus, the search for new therapeutic alternatives for this disease is extremely relevant. This study aims to evaluate the antileishmanial activity of antimalarial drugs in vitro and in a murine model of cutaneous leishmaniasis caused by Leishmania amazonensis. The antimalarial drugs tested were artesunate, chloroquine, hydroxychloroquine, mefloquine and primaquine. Of these, chloroquine and hydroxychloroquine did not reduce, significantly, the growth of promastigotes of the parasite at a concentration of 50 μM. However, these two drugs were effective in reducing the number of amastigotes in murine macrophages, with IC50 values of 0.78 ± 0.08 μM and 0.67 ± 0.12 μM, respectively. Mefloquine had an IC50 value of 8.4 ± 0.70 μM against promastigote forms, whereas the IC50 against amastigotes was 1.56 ± 0.19 μM. The ultrastructural analysis of infected cells and treated with chloroquine or mefloquine showed accumulation of multivesicular bodies in the cytoplasm of the parasite. This result suggests the involvement of the endocytic pathway of Leishmania after treatment with these molecules. Oral treatment of CBA mice infected with L. amazonensis reduced lesion size and parasitism in infected animals. In contrast, treatment with mefloquine did not reduce the parasite load in infected animals, although it did reduce the size of the lesion. Based on these results we conclude that chloroquine may represent a therapeutic alternative to conventional treatment of cutaneous leishmaniasis.

Orientador: Francisco Carlos Lavarda / Banca: Ignez Caracelli / Banca: Alexandre Camilo Júnior / O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp / Resumo: Neste trabalho estudamos dois grupos de moléculas: as anilinoquinolinas e as sulfonamidas, inibidores do Plasmodium causador da malária, com o objetivo de correlacionar a estrutura eletrônica com a atividade antimalarial. Em nossas buscas utilizamos métodos empíricos e semi-empíricos para o estudo conformacional e obtenção dos descritores eletrônicos. Também aplicamos vários métodos estatísticos como: Regressão Linear Simples e Múltipla, Análise de Componentes Principais (PCA) e Análise Discriminante Linear (LDA), para verificar uma possível correlação estrutura-atividade dessas moléculas. Os resultados apontaram os descritores eletrônicos mais relevantes na classificação das moléculas antimalariais. / Abstract: In this work we study two groups of antimalarial compounds: the anilinoquinolines and sulfonamides, aiming the correlation of the electronic structure with the antimalarial activity. In our studies we employ empirical and semi empirical quantum chemistry methods for the geometry optimization and calculation of the electronic descriptors. Also we employed the statistical methods Simple and Multiple Linear Regression, Principal Component Analysis (PCA) and Linear Discriminating Analysis (LDA), to verify the existence of a possible structure-activity correlation for these compounds. The results of this work have pointed out the best electronic descriptors in the classification of the active compounds. / Mestre

Diferent classes of antimalarial drugs have been used to treat malaria, but the emergence of resistant strains of Plasmodium these drugs have decreased their efficiency, causing serious public health problem in tropical areas of the world. In this context, we carried out the preparation and antimalarial evaluation of eleven organic compounds: 7-Cl-MAQ, MAQPZ, 7-Cl-MAQPZ, 2-CF3-MAQ, 7-CF3-MAQ, 7-CF3-MAQPZ, 2-CF3-MAQPZ, 8-Cl-MAQ, 7-Cl-BAQ, 7-CF3-BAQ, 8-Cl-BAQ. These were obtained from the same synthetic strategy, via nucleophilic aromatic substitution reaction between 4-chloroquinoline derivatives and diethylenetriamine or 1,2-(aminoethyl) piperazine, reaching moderated to high yields. These compounds were designed based on the molecular structure of chloroquine, a classic antimalarial drug. As for antimalarial activity, only four substances (7-Cl-MAQ, BAQ, 2-CF3-MAQ and 7-CF3-MAQ) were evaluated. Note that the 7-Cl-MAQ was more active in in vitro and in vivo that the BAQ. The same behavior occurred in cytotoxicity assays, with higher values than the BAQ. In in vivo tests, the monoquinolínico derivative (7-Cl-MAQ) significantly reduced parasitemia. Have the 2-CF3-MAQ compounds and 7-CF3-MAQ, were active in vitro, but were inactive in vivo. Keywords: 4-aminoquinolinic derivatives, antimalarials, chloroquine. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Várias classes de antimaláricos têm sido utilizadas para o tratamento da malária, porém o surgimento de cepas de Plasmodium resistentes a esses fármacos têm diminuído suas eficácias, provocando graves problemas de saúde pública em áreas tropicais do mundo. Nesse contexto, realizou-se a preparação, caracterização e avaliação antimalárica de onze derivados aminoquinolínicos: 7-Cl-MAQ, MAQ, MAQPZ, 7-Cl-MAQPZ, 2-CF3-MAQ, 7-CF3-MAQ, 7-CF3-MAQPZ, 2-CF3-MAQPZ, 8-Cl-MAQ, 7-Cl-BAQ, 7-CF3-BAQ, 8-Cl-BAQ. Estes foram obtidos através da mesma estratégia sintética, via reação de substituição nucleofílica aromática, a partir da reação entre derivados de 4-cloroquinolinas com dietilenotriamina ou 1,2-(aminoetil)piperazina, chegando a rendimentos moderados altos a. Estes compostos foram elaborados baseados na estrutura molecular da cloroquina, um clássico fármaco antimalárico. Quanto à atividade antimalárica, apenas quatro substâncias (7-Cl-MAQ, BAQ, 2-CF3-MAQ e 7-CF3-MAQ) foram avaliadas. Vale destacar que a 7-Cl-MAQ foi mais ativa nos testes in vitro e in vivo que a BAQ. O mesmo comportamento ocorreu nos ensaios de citotoxicidade, apresentando valores maiores que a BAQ. Nos testes in vivo, o derivado monoquinolínico (7-Cl-MAQ) reduziu significativamente a parasitemia. Já os compostos 2-CF3-MAQ e 7-CF3-MAQ, mostraram-se ativos in vitro, porém foram inativos in vivo.