Thesis (MSc)--Stellenbosch University, 2013. / Aminoquinolines are important class of drugs that have been used for malaria chemotherapy for centuries. However, long-term exposure to these drugs leads to extensive spread of drug resistance. As such, modified chloroquinoline derivatives are being studied as alternative antimalarial agents with the possibility to overcome drug resistance associated with chloroquine analogues. In this study, 15 aminoquinoline derivatives that are linked by a 1,4-disubstituted 1,2,3-triazole ring to an ethyl and propyl carbon spacer with a distal amine motif were designed and synthesized as novel antimalarial agents using the Cu(I)-promoted Huisgen reaction. The compounds have been synthesized from the 7-chloro-N-(prop-2-yn-1-yl)quinolin-4-amine alkyne precursor and the azides of ethyl and propyl amino moieties using a 1,3-dipolar cycloadditioncoupling in the presence of CuI catalyst to obtain moderate to good yields (53 – 85%). These compounds have been characterized by the combination of NMR, ESI+ HRMS and IR spectroscopic methods. The antiplasmodial activity of the compounds was investigated in vitro against P. falciparum strain NF54 using chloroquine as a reference drug together with a standard antimalarial drug artesunate. Of the 15 novel chloroquinoline derivatives, 11 have demonstrated to possess promising potency by way of the inhibition concentrations less than 250 nM with the lowest being 28 nM. The observed activities have been ascribed to the overall modifications such as the introduction of a triazole linker and changing of carbon chain length as these were the variables. The compounds are accordingly under further biological investigations and only the chloroquine sensitive results are reported in this work.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-10-03T14:02:51Z No. of bitstreams: 1 flaviamarciadecastroesilva.pdf: 1765527 bytes, checksum: 348a19d6219196394409151345b86399 (MD5) / Approved for entry into archive by Diamantino Mayra (mayra.diamantino@ufjf.edu.br) on 2016-10-03T15:17:30Z (GMT) No. of bitstreams: 1 flaviamarciadecastroesilva.pdf: 1765527 bytes, checksum: 348a19d6219196394409151345b86399 (MD5) / Made available in DSpace on 2016-10-03T15:17:30Z (GMT). No. of bitstreams: 1 flaviamarciadecastroesilva.pdf: 1765527 bytes, checksum: 348a19d6219196394409151345b86399 (MD5) Previous issue date: 2010-03-05 / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / As leishmanioses são doenças infecto parasitárias que atingem aproximadamente 12 milhões de pessoas em 88 países em todo o mundo, incluindo o Brasil. Esta doença é causada por diferentes espécies de Leishmania, as quais invadem e se multiplicam dentro de macrófagos no hospedeiro vertebrado. Ainda não existe vacina e a quimioterapia é baseada principalmente nos antimoniais pentavalentes, anfotericina B e pentamidina. Entretanto, estas drogas tem uso limitado devido a toxicidade, longo tempo de tratamento e alto custo. Portanto, existe uma necessidade urgente de desenvolvimento de novas drogas para as leishmanioses. O objetivo deste estudo foi avaliar a atividade leishmanicida de 12 derivados de aminoquinolinas, mais especificamente 4-amino-7-cloro-quinolinas, as quais apresentam grupos diaminas mono e di substituídas com alquil alcino. Em análise preliminar os compostos foram testados em formas promastigotas de L. amazonensis, L. major, L. chagasi e L. braziliensis e a atividade leishmanicida foi estabelecida pelo método do MTT. Nossos resultados mostraram variada sensibilidade das espécies de Leishmania aos compostos testados. Derivados com grupo das aminas-livre demonstraram melhor atividade leishmanicida do que outros compostos mono e di-alquil alcino substituídos. O composto 3 (4-amina-7-cloro-N-butilamina)quinolina mostrou o melhor CI50 (0,16 M para L. chagasi) demonstrando um CI50 ainda melhor do que o apresentado pela anfotericina-B (1,90 M para L. chagasi). Interessantemente, foi observada relação estrutura atividade principalmente em promastigotas de L. chagasi, sendo importante a presença do grupo amino-livre e o número de átomos de carbono. A maioria dos compostos não mostraram citotoxicidade para células de mamíferos, exceto os compostos com grupo amino-livre. O composto 5 (4-amina-7-cloro-quinolina-N-(prop-2-inil)quinolina foi escolhido para avaliação da atividade em amastigotas intracelulares e a atividade leishmanicida foi a partir da contagem dos parasitos após coloração por Giemsa. O tratamento com o composto em macrófagos infectados com L. major e L. amazonensis não demonstrou atividade leishmanicida para a primeira espécie deste parasito. Em L. amazonensis, o tratamento mostrou significante atividade nas formas intracelulares, reduzindo o número de amastigotas/macrófagos, número de células infectadas e a carga parasitária acima de 90% após 72 horas. O efeito antiamastigota foi dose e tempo dependente. Nenhuma alteração nos níveis de óxido nítrico pelos macrófagos infectados tanto com L. amazonensis quanto por L. major foi observada após tratamento com o composto 5. Entretanto, esta aminoquinolina significativamente aumentou e inibiu a produção de TNF- em células infectadas com as respectivas espécies. Conjuntamente, estes resultados sugerem que a atividade leishmanicida do composto 5 pode atuar diretamente no parasito ou através de mecanismos imunomodulatórios. Este estudo indica que derivados de aminoquinolinas tem promissoras propriedades leishmanicidas sendo bons candidatos para alvos de pesquisas para desenvolvimento de novas drogas anti-protozoários. / The leishmaniasis are parasitic-infection diseases that affect 12 million people in 88 countries, it remains a serious public health problem worldwide, including in Brazil. This disease is caused by different Leishmania species, which invade and multiply within macrophages in vertebrate host. No vaccine exists yet and chemotherapy has been based mainly in pentavalent antimonials, amphotericinB e pentamidina. However, these drugs have limited use due to their toxicities, long term treatment and high costs. Therefore, there is an urgent need for development of new drugs for leishmaniasis. The aim of this study was to evaluate the leishmanicidal activity in twelve aminoquinolines derivatives, but specifically, 4-amino-7-chloro-quinoline, those present diamine with amine-free, mono-alkyne or di-alkyne groups. In a previous analysis the compounds were tested in promastigote forms of L. amazonensis, L. major, L. chagasi and L. braziliensis and the leishmanicidal activities was established by MTT method. Our results showed varied sensibility of the Leishmania species to the tested compounds. Derivatives with amine-free groups demonstrated better leishmanicidal activity than the others compounds and the compound 3(4-amine-7-cloro-N-butilamine)quinoline showed the best IC50 (=0,16 M for L. chagasi) displaying an IC50 better than anfothericin B (1,90 M para L. chagasi) Interestingly, it was observed structure-activity relationships (SAR) mainly in promastigotes of L. chagasi, being important the presence of amine-free group and number of carbon atoms. The majority of compounds didn’t showed citotoxicity for the mammalian cells, except compounds containing amine-free groups. The compound 5 (4-amine-7- chloro-quinoline-N-prop-2-ynil)quinoline was chosen for antileishmanial evaluation in an intramacrophage amastigotes model and the leishmanicidal activity was achieved from the count of parasites after coloration by Giemsa. The treatment with this compound from infected macrophages with L. major e L. amazonensis didn’t show leishmancidal activity for the first specie of this parasite. In L. amazonensis, the treatment showed a significant activity against intracellular forms, reducing the number of amastigotes/macrophage, the infected cells and the parasite burden above 90% after 72 hours. The antiamastigote effect was dose and time response. No alteration in nitric oxide levels by infected macrophages as for L. amazonensis as well for L. major was observed after treatment with the compound 5. However, this aminoquinoline significantly enhanced and inhibit the TNF- production in infected cells with the respective Leishmania species. Together, these results suggest strongly that leishmanicidal acitivity from compound 5 can be directly in parasites or through the immune modulatory mechanism. This study indicate that aminoquinolines have promising leishmanicidal properties being a good candidates for further research to develop of new anti-protozoan drugs.

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