Made available in DSpace on 2016-02-26T13:34:38Z (GMT). No. of bitstreams: 2 marianne_silva_ioc_mest_2015.pdf: 2399331 bytes, checksum: 4ca5147a85916a54e8f78b5504ea6ba3 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2016-02-23 / A doença de Chagas (DC), causada pelo protozoário Trypanosoma cruzi, é uma doença negligenciada endêmica em diferentes regiões empobrecidas da América Latina. O tratamento, baseado em dois nitroderivados, Nifurtimox e Benzonidazol (Bz), é insatisfatório, demandando a busca de novos fármacos com ação tripanocida que sejam mais seletivos e eficazes. Nesse âmbito, o presente trabalho busca a identificação de novos agentes antiparasitários para a DC, explorando a avaliação fenotípica de novas amidinas aromáticas sintéticas in vitro incluindo ensaios de combinação entre estes compostos. Dez novas amidinas foram testadas sobre tripomastigotas sanguíneos e amastigotas de diferentes cepas do T. cruzi (Y e Tulahuen) e também sobre células de mamífero hospedeiras (linhagem L929 e células cardíacas) para determinar seu perfil eficácia e de toxicidade, respectivamente. Dentre as moléculas testadas (apresentando um ou dois grupamentos catiônicos terminais), cinco foram mais ativas sobre tripomastigotas sanguíneos que o fármaco de referência (Bz), sendo uma delas, a DB2267 (molécula dicatiônica) a mais eficaz, exibindo EC50 de 0,23 \03BCM e um índice de seletividade (IS) de 417. Esta diamidina foi 28 vezes mais ativa e cerca de três vezes mais seletiva que Bz Para determinar se a combinação de duas amidinas teria um efeito tripanocida superior ao seu uso em monoterapia, tripomastigotas sanguíneos foram incubados com DB2267 e DB2236 em proporções fixas e os resultados mostraram apenas um efeito aditivo com \01A9FIC<4. Interessantemente, quando formas intracelulares foram expostas à DB2267, sua atividade foi relacionada à cepa do parasito, sendo eficaz (EC50 = 0.87 ± 0.05 \03BCM) contra DTU II (cepa Y), mas não contra um representante da DTU VI (Tulahuen), mesmo quando utilizamos veículo diferente do DMSO (\03B2-ciclodextrina). Esta divergência pode estar relacionada a diferenças inerentes aos alvos e/ou rotas metabólicas das cepas do parasito e que merecem ser mais investigadas visando conhecer melhor a relação entre as características estruturais e ação universal das moléculas sobre DTUs e formas do T. cruzi para o desenho de compostos mais promissores. Devido à fluorescência intrínseca apresentada pelas amidinas, a captação de duas delas foi avaliada. Os dados obtidos com a amidina não ativa (DB2236) e com a outra ativa (DB2267) sobre amastigotas da cepa Y revelaram que ambas foram localizadas intracelularmente, mas em compartimentos distintos: DB2236 no citoplasma, enquanto DB2267 no núcleo. Nossos dados são encorajadores a respeito da atividade antiparasitária das amidinas aromáticas, no tocante a futuras investigações de novos agentes promissores para o tratamento da DC / Chagas disease (CD), caused by the protozoan Trypanosoma cruzi, is a neglected disease endemic in different poor areas of Latin America. The treatment, based on two nitroderivatives, Nifurtimox and Benznidazole (Bz), is unsatisfactory, demanding the screening of new potential trypanocidal drugs more selective and potent. In this scope, the present work deals with the identification of new anti - parasitic agents for CD, exploring the phenotypic screening of novel synthetic aromatic amidines in vitro and also combination assays between these compounds. The novel ten amidines were tested against bloodstream trypomastigotes (BT) and amastigote forms of different T.cruzi strains (Y and Tulahuen) and were also evaluated on mammalian host cells (L929 cells and cardiac cells) to check their toxicity profile. Among these molecules, five were more active against BT than the reference drug (Bz), being one of them, the DB2267 (a dicationic molecule) the most potent, exhibiting an EC 50 value of 0.23 μM and a se lectivity index (SI) of 417. This diamidine was 28 - fold more active and about 3 times more selective than Bz. To ascertain if the combination of two amidines could improve their trypanocidal activity, BT were incubated with DB2267 and DB2236 in fixed - ratio proportions and the data showed only an additive effect with ƩFIC<4. Interest ingly, when intracellular forms were exposed to DB2267, its activity was related to the parasite strain, being effective (EC 50 = 0.87 ± 0.05 μM) against DTU II (Y strain) but not against one representative of DTU VI (Tulahuen) even using different vehicles (β - cyclodextrins and DMSO). This discrepancy might be related to differences concerning the targets and/or metabolic pathways of the parasite that deserve to be more investigated aiming to better understand the relationship between the structural characte ristics and universal action of the molecules against DTUs and forms of the T.cruzi for the design of more promising compounds . Due to the intrinsic fluorescence presented by the amidines, the uptake of two of them was assessed. The data obtained with the non - active amidine (DB2236) and the other active one (DB2267) against amastigotes of the Y strain showed that both were localized intracellular ly , but in distinct compartments : DB2236 in the cytoplasm , while DB2267 in the nucleus . Our results are encouragi ng regarding the antiparasitic activity of the a romatic amidines , referring to future investigations of new promising agents for the treatment of CD / Chagas disease (CD), caused by the protozoan Trypanosoma cruzi, is a neglected disease endemic in different poor areas of Latin America. The treatment, based on two nitroderivatives, Nifurtimox and Benznidazole (Bz), is unsatisfactory, demanding the screening of new potential trypanocidal drugs more selective and potent. In this scope, the present work deals with the identification of new anti - parasitic agents for CD, exploring the phenotypic screening of novel synthetic aromatic amidines in vitro and also combination assays between these compounds. The novel ten amidines were tested against bloodstream trypomastigotes (BT) and amastigote forms of different T.cruzi strains (Y and Tulahuen) and were also evaluated on mammalian host cells (L929 cells and cardiac cells) to check their toxicity profile. Among these molecules, five were more active against BT than the reference drug (Bz), being one of them, the DB2267 (a dicationic molecule) the most potent, exhibiting an EC 50 value of 0.23 μM and a se lectivity index (SI) of 417. This diamidine was 28 - fold more active and about 3 times more selective than Bz. To ascertain if the combination of two amidines could improve their trypanocidal activity, BT were incubated with DB2267 and DB2236 in fixed - ratio proportions and the data showed only an additive effect with ƩFIC<4. Interest ingly, when intracellular forms were exposed to DB2267, its activity was related to the parasite strain, being effective (EC 50 = 0.87 ± 0.05 μM) against DTU II (Y strain) but not against one representative of DTU VI (Tulahuen) even using different vehicles (β - cyclodextrins and DMSO). This discrepancy might be related to differences concerning the targets and/or metabolic pathways of the parasite that deserve to be more investigated aiming to better understand the relationship between the structural characte ristics and universal action of the molecules against DTUs and forms of the T.cruzi for the design of more promising compounds . Due to the intrinsic fluorescence presented by the amidines, the uptake of two of them was assessed. The data obtained with the non - active amidine (DB2236) and the other active one (DB2267) against amastigotes of the Y strain showed that both were localized intracellular ly , but in distinct compartments : DB2236 in the cytoplasm , while DB2267 in the nucleus . Our results are encouragi ng regarding the antiparasitic activity of the a romatic amidines , referring to future investigations of new promising agents for the treatment of CD

Submitted by Anderson Silva (avargas@icict.fiocruz.br) on 2012-09-17T17:49:32Z No. of bitstreams: 1 cristiane_f_silva_ioc_bp_0051_2011.pdf: 4625689 bytes, checksum: 9b9576a91ed1d5f8dcd03755634e513e (MD5) / Made available in DSpace on 2012-09-17T17:49:32Z (GMT). No. of bitstreams: 1 cristiane_f_silva_ioc_bp_0051_2011.pdf: 4625689 bytes, checksum: 9b9576a91ed1d5f8dcd03755634e513e (MD5) / Fundação Carlos Chagas Filho de Amparo, Conselho Nacional Desenvolvimento Científico e Tecnológico,PAPES V/FIOCRUZ,Consortium for Parasitic Drug Development / Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Departamento de Ultra-Estrutura e Biologia Celular. Rio de Janeiro, RJ, Brasil / O atual tratamento da doença de Chagas (DC) se baseia em dois compostos nitroderivados, o Nifurtimox (Nf) e benznidazol (Bz), ambos introduzidos na clínica médica há cerca de 40 anos e que têm sido considerados insatisfatórios principalmente devido à baixa atividade, sobretudo na fase crônica, além de alta toxicidade e/ou ocorrência de isolados do parasito resistentes a ambos nitroderivados. Assim como um dos principais desafios ainda a serem enfrentados há mais de cem anos depois da descoberta da DC diz respeito a identificação de novas terapias alternativas para o tratamento desta negligenciada parasitose, esta temática representou o principal objetivo da presente tese. Assim, estudos in vitro e in vivo foram conduzidos visando avaliar a eficácia de amidinas aromáticas, incluindo diamidinas e arilimidamidas (AIAs) sobre o T.cruzi, analisando ainda a localização e distribuição dos compostos aromáticos assim como seus alvos celulares. Nossos dados revelaram a ação tripanocida de diamidinas e AIAs sobre formas sanguíneas e amastigotas do parasito, em faixa micro e nanomolar, respectivamente. Alguns dos compostos estudados, em especial as AIAs DB745 e DB1831 exibiram excelente efeito sobre formas sanguíneas na presença de sangue a 4oC, demonstrando seu potencial uso também na profilaxia de bancos de sangue. De modo geral, as amidinas testadas, incluindo as AIAs, apresentaram superior eficácia que as drogas de referencia, incluindo o Bz e a violeta de genciana. AIAs como a DB745 foram ativas sobre diferentes cepas do T.cruzi, incluindo YuYu e Colombiana, que apresentam resistência natural a nitroderivados. Estudos ultra-estruturais e por ensaios fluorescentes (microscopia e citometria de fluxo) revelaram que o núcleo e a mitocôndria do parasito representam potenciais alvos dos compostos estudados. No entanto, não foi observada correlação entre atividade e maior acúmulo destes agentes na mitocôndria (kDNA) do T.cruzi. Os ensaios in vivo demonstraram que estes compostos aromáticos são ativos sobre modelos experimentais de infecção aguda pelo T.cruzi, reduzindo carga parasitária e a inflamação, oferecendo 100% de proteção na mortalidade dos animais tratados. A AIA DB1965 revelou eficácia semelhante ao Bz e a sua combinação com esta droga de referência resultou em 100% de sobrevida e níveis superiores a 99% de supressão de parasitemia, sem alcançar cura parasitológica avaliada pelo hemocultivo e PCR. O excelente efeito de amdinas, em especial de AIAs contra o T. cruzi, reforça o rastreamento por novos análogos que possam ser usados sozinhos ou em combinações com outras drogas, para o tratamento da doença de Chagas. / The current treatment of Chagas disease (CD) is based on two old drugs, the Nifurtimox (Nf) and benznidazole (Bz), both introduced in clinical medicine for nearly 40 years ago. Both are not considered adequate mainly due to their low activity, especially in the chronic phase, and high toxicity and/or occurrence of parasite strains naturally resistant to both nitro-derivatives. Then, one of the main challenges still to be faced after more than a century after the discovery of CD is respect to need of identifying new alternative therapies for the treatment of this neglected illness, and this issue represents the main objective of the present thesis. Thus, in vitro and in vivo studies were conducted to evaluate the efficacy of aromatic amidines, including diamidines and arylimidamides (AIAs), and to evaluate the localization and distribution of these compounds as well as their potential cellular targets upon T. cruzi. Our data revealed trypanocidal activity of diamidines and AIAs against bloodstream and intracellular amastigotes under micro and nanomolar range, respectively. Some of the studied compounds, especially AIAs, DB745 and DB1831, exhibited an outstanding effect on bloodstream forms even in the presence of blood at 4oC, also demonstrating their potential prophylactic use in blood banks. In general, amidines mainly AIAs, showed higher efficacy than the reference drugs, including Bz and gentian violet. AIAs, as DB745, were active on different strains of T. cruzi, including Colombian and YuYu, which have natural resistance to nitro-derivatives. Ultrastructural studies and fluorescent tests (microscopy and flow cytometry) revealed that the nucleus and mitochondria of the parasite are potential targets of the compounds studied. However, there was no correlation between activity and greater accumulation of these agents in the mitochondria (kDNA) of T. cruzi. In vivo testing demonstrated that these aromatic compounds are active on experimental models of acute infection of T. cruzi, by reducing cardiac parasite load and inflammation, and offering 100% of protection upon the mortality of treated animals. The AIA, DB1965, also showed similar efficacy of Bz and its combination with this reference drug resulted in 100% survival and >99% of parasitemia suppression, without achieving, parasitological cure assessed by blood culture and PCR. The excellent effect of amidines (especially of AIAs) against T. cruzi, justify the screening of novel amidine analogues that could be used alone or in combination with other drugs to treat Chagas disease.