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Previous issue date: 2017-03-03 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The high incidence of tuberculosis is a great concern worldwide. Different strategies are
being developed by the World Health Organization to fight tuberculosis. Amongst the three
pillars that are part of the End TB Strategy, we can highlight the intensive research and
innovation pillar. In this extent, the development of new drugs for tuberculosis treatment is a
field that is gaining importance. The 2(quinolin-4-yloxy) acetamides are molecules that showed
promising bactericidal effects in Mycobacterium tuberculosis, which motivated us to continue
studying to improve their mycobactericidal activity and also perform their chemical and
biological characterization. In order to continue the 2(quinolin-4-yloxy) acetamides derivatives
development, the target identification of these molecules is a keystone and is also the focus of
this study. Initially, it was hypothesized that DNA gyrase was their molecular target due to the
great chemical similarities between the 2(quinolin-4-yloxy) acetamides and the
fluoroquinolones. Despite our results that the 2(quinolin-4-yloxy) acetamides have diminished
effects in ofloxacin resistant clinical isolates, the results obtained with the gyrA point mutant
and with DNA gyrase protein revealed that this enzyme is not the molecular target of these
compounds. The new target identification strategy involved the selection of spontaneous
mutants for our lead compound 12L, characterization of this mutant strain against other
2(quinolin-4-yloxy) acetamides derivates and whole genome sequencing. Whole genome
sequencing data allowed the identification of a single mutation (T313A) in the QcrB protein,
which is the B subunit of cytochrome bc1 complex. This mutation was confirmed by Sanger
sequencing and molecular docking results confirmed the importance of this residue for proteindrug
interaction. The cytochrome bc1 complex is involved in the electron transport of the
bacilli?s respiratory chain, and therefore it appears to be an interesting target, especially to treat
the latent form of the disease. We hope that this work contributes to the 2(quinolin-4-yloxy)
acetamides development for tuberculosis treatment. / A alta incid?ncia da tuberculose, em ?mbito mundial, ? de grande preocupa??o. Para
combater esta doen?a, diferentes estrat?gias v?m sendo desenvolvidas pela Organiza??o
Mundial da Sa?de (OMS). Dentre os pilares que comp?em a End TB strategy, podemos destacar
a pesquisa intensiva e a inova??o. Neste ?mbito, o desenvolvimento de novos f?rmacos para
tuberculose vem ganhando destaque. As 2(quinolin-4-il?xi) acetamidas s?o mol?culas que
demonstraram resultados bactericidas promissores frente ao Mycobacterium tuberculosis, o que
nos motivou a realizar novos estudos para melhorar a atividade e realizar a caracteriza??o
qu?mica e biol?gica destas mol?culas. A fim de continuar o desenvolvimento da s?rie
quinol?nica, a identifica??o do seu alvo molecular foi o foco deste trabalho. Inicialmente,
levantou-se a hip?tese de que a DNA girase seria o alvo molecular, uma vez que as 2(quinolin-
5-il?xi) acetamidas possuem grande similaridade estrutural com as fluoroquinolonas. Apesar
das 2(quinolin-4-il?xi) acetamidas terem apresentado menor atividade frente a isolados cl?nicos
resistentes a ofloxacino, os resultados de atividade obtidos frente a uma mutante pontual de
gyrA e frente ? prote?na indicam que a DNA girase n?o ? o alvo destas mol?culas. A nova
estrat?gia para identifica??o de alvo envolveu a sele??o de mutantes espont?neos para o
composto l?der 12L, caracteriza??o desta cepa frente aos demais compostos da s?rie e
sequencimento total do genoma. Este permitiu a identifica??o de uma ?nica muta??o (T313A)
localizada na prote?na QcrB, que ? a subunidade B do complexo citocromo bc1. Esta muta??o
foi confirmada por sequenciamento de Sanger e o docking molecular aferiu a import?ncia deste
res?duo na intera??o prote?na-composto. O complexo citocromo bc1 est? envolvido no
transporte de el?trons na cadeia respirat?ria do bacilo, e por isso ? um alvo molecular
interessante, principalmente para combater a forma latente da doen?a. Esperamos que este
trabalho contribua no processo de desenvolvimento das 2(quinolin-4-il?xi) acetamidas para o
tratamento da tuberculose.
| Identifer | oai:union.ndltd.org:IBICT/oai:tede2.pucrs.br:tede/7359 |
| Date | 03 March 2017 |
| Creators | Subtil, Fernanda Teixeira |
| Contributors | Santos, Di?genes Santiago, Villela, Anne Drumond |
| Publisher | Pontif?cia Universidade Cat?lica do Rio Grande do Sul, Programa de P?s-Gradua??o em Biologia Celular e Molecular, PUCRS, Brasil, Faculdade de Bioci?ncias |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da PUC_RS, instname:Pontifícia Universidade Católica do Rio Grande do Sul, instacron:PUC_RS |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 8198246930096637360, 600, 600, 600, 600, 36528317262667714, -1634559385931244697, 2075167498588264571 |
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