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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A novel iterative reducible ligation strategy for the synthesis of homogeneous gene delivery polypeptides

Ericson, Mark David 01 December 2012 (has links)
The ability to safely delivery efficacious amounts of nucleic acids to cells and tissues remains an important goal for the gene therapy field. Viruses are very efficient at delivering DNA, but safety concerns limit their clinical use. Nonviral vectors are not as efficient at DNA delivery, but have a better safety profile. Limiting the efficaciousness of nonviral vectors are the numerous extra and intracellular barriers that must be overcome for successful DNA delivery in vivo. While single polymers can successfully transfect immortalized cell lines in vitro, multicomponent gene delivery systems are required for delivery in vivo. Key in the development of multicomponent systems is their syntheses. Optimization of a nonviral gene delivery system requires the development of methodologies that incorporate the different components in a controlled fashion, generating homogeneous gene delivery vectors. Such syntheses ensure every polymer has the different components required for successful delivery. The amount of each component and location within the gene delivery system can also be varied systemically, allowing optimization of the vector. The overall scope of this thesis is to develop a chemical method to iteratively couple gene delivery peptides through reducible disulfide bonds. The synthesis of such polypeptides allows the triggered disassembly of a polypeptide polyplexed with DNA upon cellular uptake. To synthesize homogeneous gene delivery polypeptides, a novel iterative reducible ligation strategy was developed, based upon the use of a thiazolidine masked cysteine. Initial studies demonstrated that a thiazolidine could be unmasked to a cysteine in the presence of a disulfide bond without side reaction, though the reported thiazolidine hydrolysis conditions of aqueous methoxyamine were insufficiently robust for high yielding ligations. Discovery of a novel silver trifluoromethanesulfonate hydrolysis led to an efficient process for generating reducible polypeptides, as evidenced in the synthesis of a 4 component polypeptide. Due to the success of the thiazolidine mediated iterative ligation strategy, cysteines were replaced by penicillamines to produce more stable disulfide bonds. The mild thiazolidine hydrolysis and subsequent peptide conjugation reactions led to attempt the iterative ligation strategy on a solid support, eliminating purification steps that lowered the yields in the solution phase methodology. Initial progress at generating gene delivery peptides that could be incorporated into the synthetic strategy included the generation of a tri-orthogonal cysteine protecting scheme that allowed a third cysteine to be derivatized with a targeting ligand or stealthing polymer. Due to the use of terminal cysteines in the iterative ligation strategy, a PEG stealthing polymer could be placed in the center of a polyacridine gene delivery peptide with only a small decrease in the ability to condense and protect DNA during systemic circulation. A convergent synthesis was also developed that was able to synthesize large polypeptides in fewer linear steps. The synthetic methodology of thiazolidine mediated iterative reducible ligation developed in this thesis is important in the gene therapy field as it allows the construction of polypeptides that can be systemically optimized, potentially resulting in highly efficacious nonviral gene delivery.
2

Síntese, caracterização estrutural e avaliação antineoplásica de derivados 5-benzilideno-3-benzil-tiazolidina-2,4-diona

Oliveira, Albert Rocha de 27 February 2015 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-04-29T13:51:27Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação de Albert Rocha (versão final corrigida).pdf: 2822167 bytes, checksum: 2ad296bc0aaac078346eddd44a047b0f (MD5) / Made available in DSpace on 2016-04-29T13:51:27Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação de Albert Rocha (versão final corrigida).pdf: 2822167 bytes, checksum: 2ad296bc0aaac078346eddd44a047b0f (MD5) Previous issue date: 2015-02-27 / CAPEs / Câncer é o nome dado a uma grande variedade de doenças que possuem como principal característica um crescimento celular contínuo e desordenado. A quimioterapia é uma das alternativas terapêuticas no combate ao câncer, entretanto as atuais opções terapêuticas são frequentemente acompanhadas de fortes efeitos colaterais. Inúmeros trabalhos vêm sendo desenvolvidos nos últimos anos, relacionando as moléculas tiazolidínicas com atividades antineoplásicas. No presente trabalho, foram realizadas a síntese e a caracterização estrutural de cinco derivados da série 5-benzilideno-3-benzil-tiazolidina-2,4-diona, seguidas da avaliação da citotoxicidade de dois desses compostos sobre células mononucleares do sangue periférico (PBMCs) e sobre as linhagens de células neoplásicas DUO-145, HepG2, K562 e RAJI, utilizando ensaios de MTT. Inicialmente, realizou-se a síntese da tiazolidina-2,4-diona, a partir da reação entre ácido monocloroacético e tiouréia. Em seguida, realizaram-se N-alquilações, em uma solução equimolar de hidróxido de sódio, utilizando a tiazolidina-2,4-diona e diferentes haletos de benzila substituídos, obtendo-se intermediários 3-benzil-tiazolidina-2,4-diona substituídos. Os compostos finais foram sintetizados a partir de reações de condensação na posição 5 do anel tiazolidínico, reagindo-se os intermediários, anteriormente sintetizados, com benzaldeídos, obtendo-se os compostos tiazolidínicos finais, com rendimentos entre 52 e 70%. A estrutura química dos compostos sintetizados foi determinada por espectroscopia de ressonância magnética nuclear de 1H e de 13C, espectroscopia de infravermelho e por espectrometria de massas. A avaliação da seletividade citotóxica dos compostos 5-(3-cloro-benzilideno)-3-(2-cloro-6-flúor-benzil)-tiazolidina-2,4-diona (LPSF/GQ-103) e 5 - (2,4-dimetóxi-benzilideno) - 3 - (2-cloro-6-flúor-benzil)-tiazolidina-2,4-diona (LPSF/GQ-106) foi realizada sobre PBMC’s, através de ensaios MTT, apresentando resultados com viabilidade acima de 90%. Nos ensaios de citotoxicidade tumoral, a linhagem DUO-145 apresentou melhor suceptibilidade aos compostos testados, com valores de IC50 18,18 μM para o LPSF/GQ-103 e IC50 24,13 μM para o LPSF/GQ-106. / Cancer is the name given to a variety of diseases that have a major feature a continuous and disorderly cell growth. Chemotherapy is one of therapeutic alternatives to fight cancer, but the current therapeutic options are often accompanied by severe side effects. Numerous studies have been developed in recent years talking about the thiazolidine molecules with antineoplastic activities. In this study, we realized the synthesis and structural characterization of five derivatives of the series 5-benzylidene-3-benzyl-thiazolidine-2,4-dione, followed by evaluation of cytotoxicity of two such compounds on peripheral blood mononuclear cell (PBMCs) and on the tumor cell lines DUO-145, HepG2, K562 and RAJI, using MTT assays. Initially we realized the synthesis of thiazolidine-2,4-dione, from the reaction between monochloroacetic acid and thiourea. Then, it were realized N-alkylations using thiazolidine-2,4-dione and various substituted benzyl halides obtaining the intermediates 3-benzyl-thiazolidine-2,4-dione substituted. The final compounds were synthesized from condensation reaction in position 5 of the thiazolidine ring, by reacting intermediates previously synthesized with benzaldehydes obtaining tiazolidínicos final compounds in yields between 52 and 70%. The chemical structure of the synthesized compounds was determined by 1H and 13C nuclear magnetic resonance spectroscopy, by infrared spectroscopy and by mass spectrometry. The evaluation of selective cytotoxicity of the compounds 5-(3-chloro-benzylidene)-3-(2-chloro-6-fluoro-benzyl)-thiazolidine-2,4-dione (LPSF/GQ-103) and 5-(2,4-dimethoxy-benzylidene)-3-(2-chloro-6-fluoro-benzyl)-thiazolidine-2,4-dione (LPSF/GQ-106) was performed on PBMC’s by MTT assay, presenting results viability above 90%. In the tumor cytotoxicity assays, the tumor cell line DUO-145 had better cytotoxic susceptibility to the tested compounds, with 18.18 μM IC50 value for the compound LPSF/GQ-103 and 24.13 μM IC50 value for the LPSF/GQ-106.
3

Síntese, caracterização e atividade biológica de novos derivados e atividade biológica de novos derivados da 3-(acridina-9-imetil) tiazolidina-2,4-diona

ALMEIDA, Marcel Lucas de 19 February 2015 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-04-29T14:00:29Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Minha dissertação final para biblioteca.pdf: 6771552 bytes, checksum: cc238895a0629230ce30655a760f5a10 (MD5) / Made available in DSpace on 2016-04-29T14:00:29Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Minha dissertação final para biblioteca.pdf: 6771552 bytes, checksum: cc238895a0629230ce30655a760f5a10 (MD5) Previous issue date: 2015-02-19 / CAPEs / Estima-se que até 2030 o câncer será responsável por até 12 milhões de óbitos. Tendo em vista a necessidade de novos tratamentos para o câncer, este trabalho tem como objetivo sintetizar, caracterizar estruturalmente e avaliar a atividade anticâncer de sete novos derivados tiazacridínicos (LPSF AA-56, LPSF AA-57, LPSF AA-59, LPSF AA-60, LPSF AA-61, LPSF AA-62, LPSF AA-63). Estes derivados provém da hibridização molecular dos núcleos de tiazolidina e de acridina. As sínteses para obtenção destes compostos foram otimizadas para obtenção de um melhor rendimento. A síntese da tiazolidina-2,4-diona (TZD) foi feita por reação de ciclização. Uma posterior N-alquilação da TZD em presença de uma base e da 9-(bromo-metil)acridina, conduziu a formação do intermediário LPSF AA-1A. Os intermediários ésteres de Cope (IPs) foram obtidos a partir de uma reação de condensação Knoevenagel. A última etapa ocorreu por uma reação de adição de Michael através de reação entre a TZD N-alquilada com os ésteres de Cope, formando os derivados tiazacridínicos substituídos. A pureza e comprovação estrutural das moléculas sintetizadas foram obtidas através de cromatografia líquida acoplada a espectrômetro de massa (LC-MS), infravermelho (IV) e ressonância magnética nuclear (RMN) de hidrogênio. Ensaios de citotoxicidade dos derivados sintetizados foram realizados em células leucêmicas, fígado e próstata. Entre os compostos sintetizados, o LPSF AA-57 exibiu a atividade anti-cancerígena mais potente contra as linhagens celulares Jurkat (6,63 ± 2,65 μM), HL-60 (6,51 μM), K562 (3,97 ± 1,36 μM) e o LPSF AA-60 exibiu a atividade anti-cancerígena mais potente contra DU 145 (7,22 ± 3,12 μM). / It is estimated that cancer will be responsible for up to 12 million deaths by 2030. Given the need for new treatments for cancer this work aims to synthesize, characterize structurally and evaluate the anti-cancer activity of seven new thiazacridines derivatives (LPSF AA-56, LPSF AA-57, LPSF AA-59, LPSF AA-60, LPSF AA-61, LPSF AA-62, and LPSF AA-63). These derivatives derived of molecular hybridization from nucleus of thiazolidine and acridine. The syntheses for obtaining these compounds were optimized to obtain the best performance. Synthesis of thiazolidine-2,4-dione (TZD) was carried out by cyclization reaction. A further N-alkylation of the TZD in the presence of a base and 9-(bromomethyl)acridine, leading to formation of intermediate LPSF AA-1A. Intermediate esters of Cope (IPs) were obtained from a Knoevenagel condensation reaction. The last step was by a Michael addition, reaction between the N-alkylated TZD with ester of Cope, forming substituted thiazacridines derivatives. The purity and structural confirmation of the synthesized molecules were obtained from liquid chromatography coupled to mass spectrometry (LC-MS), infrared (IR) and Proton nuclear magnetic resonance (NMR). Assays of cytotoxicity of the synthesized products was conducted in leukemic cells, liver and prostate. Among the synthesized compounds, the LPSF AA-57 exhibited the most potent anti-cancer activity against cell lines Jurkat (6,63 ± 2,65 μM), HL-60 (6,51 μM), K562 (3,97 ± 1,36 μM) and the LPSF AA-60 exhibited the most potent anti-cancer activity against DU 145 (7,22 ± 3,12 μM).
4

Impact des ligands de PPARs, et leurs dérivés, sur les cellules cancéreuses coliques humaines : modifications des statuts redox et glycolytique / Impact of PPAR ligands treatment and their derivatives on human colorectal cancer cells : modifications of redox and glycolytic status

Huber-Villaume, Sophie 25 November 2014 (has links)
La Pioglitazone appartient à la famille des thiazolidinédiones et le Fénofibrate à la famille des fibrates. Ces molécules sont, respectivement, des agonistes synthétiques du récepteur activable par les proliférateurs de peroxysomes γ (PPARγ) et PPARα, membres de la famille des récepteurs nucléaires aux hormones. Le traitement de cellules cancéreuses humaines par ces molécules limite la croissance et peut induire leur apoptose. Cependant, l’impact de ces traitements sur les cellules cancéreuses est en partie dû à une action indépendante de l’activation du récepteur et met en cause la génération d'un stress oxydant. Au cours de ces travaux, un analogue de la Pioglitazone, la ΔPioglitazone, qui ne permet pas l’activation de PPARγ, a été synthétisé. Les effets de ces molécules ont été testés sur deux lignées cellulaires établies à partir de cancer colique, HT29 et HCT116. Ces traitements limitent la croissance des cellules cancéreuses sans induire de processus apoptotique. La production d’espèces réactives est responsable d’une diminution du contenu en glutathion intracellulaire. Le stress oxydant généré suite au traitement par la Pioglitazone et la ΔPioglitazone induit l’activation de la voie de signalisation antioxydante Nrf2/Keap1 et l’expression de ses gènes-cibles HO-1 et NQO1. En revanche, bien qu’il induise la production d’un stress oxydant, le Fénofibrate n’entraîne aucune activation de cette voie. De plus, ces trois composés sont responsables d’une modification du métabolisme cellulaire en faveur de la glycolyse. Parallèlement, l’impact de dérivés 4-thiazolidinones, analogues des thiazolidinédione, synthétisés au laboratoire, a été testé. L’effet de ces molécules a été évalué sur la survie cellulaire et le statut redox des cellules HT29. Plusieurs composés présentent une activité antiproliférative et sont capables de générer un stress oxydant sans activer la voie Nrf2/Keap1 / Peroxisome Proliferator-activated Receptors (PPAR) are members of the nuclear receptor family. Pioglitazone and Fenofibrate belong respectively to the thiazolidinedione and fibrate family. Pioglitazone is an agonist of PPARγ isotype whereas Fenofibrate is an agonist of PPARα isotype. Cancer cell exposure to each ligand inhibits cell growth and triggers apoptosis cell death. However, the effects of respective PPAR ligand on cell survival were found to be independent of receptor activation and were associated to redox changes within the cells. In order to discriminate PPAR independent from PPAR dependent activation, an analogue of Pioglitazone, Δ-Pioglitazone was synthesized. The molecule binds to PPARγ without activating it. Two cancer cell lines established from human colon adenocarcinoma, HT29 and HCT116 were tested. Cell exposure to each molecule inhibited cell growth but cells did not undergo apoptosis cell death. Cell treatment induced the production of reactive species and the decrease of intracellular glutathione content. Pioglitazone or [delta]-Pioglitazone-mediated oxidative stress triggered the activation of the Nrf2/Keap1 pathway as assessed by the increases of Nrf2 target genes expression such as HO-1 and NQO1. In contrast, Fenofibrate treatment increased reactive species production but did no activate this pathway. Moreover, cell exposure to Pioglitazone, Δ-Pioglitazone or Fenofibrate modulated cell metabolism, notably by enhancing glycolysis. In parallel, impact of 4-thiazolidinone derivatives synthesized in the laboratory was tested. These molecules are analogues of thiazolidinedione. Effect of 4-thiazolidinone treatments was assessed to cell growth arrest and redox changes within the HT29 cells. Several molecules have anti-proliferative effect and are able to generate oxidative stress without Nrf2/Keap1 pathway activation
5

Planejamento de potenciais inibidores de enzimas do parasito Trypanosoma cruzi: síntese, docking e avaliação biológica / Design of potential enzyme inhibitors from Trypanosoma cruzi paraite: synthesis, docking and biological evaluation

Silva Júnior, Edeildo Ferreira da 10 March 2015 (has links)
Neglected diseases constitute a major public health problem worldwide, quantifying a total of 1 billion people suffering from some kind of infection of bacterial, viral or parasitic origin. Among them, we can highlight Chagas disease, caused by the parasite Trypanosoma cruzi, which affects more than 8 million people around the world. In order to discover new active compounds against T. cruzi, developed herein the synthesis of new prototypes of thiophene-2- thioureic and 2-iminothiazolidine rationally designed with potential antichagasic activity, biological evaluation and study docking. Initially, the start material was the polysubstituted thiophene derivatives synthesized via Gewald reaction, which were converted into thioureic derivatives and then cyclized with five different electrophiles, generating thiophene-2- iminothiazolidine derivatives. The intermediates and final compounds were synthesized in yields between 40 and 98%, and characterized by NMR. For docking study was initially performed by minimizing the energy of the ligands by ArgusLab® software, using AM1, and applying the software AutoDock Tools® and AutoDock Vina®, using the Gasteiger method. All compounds were evaluated in the anti-T. cruzi assays, in vitro, and the most active serie was selected for the cytotoxicity assay (MTT) in J774 cell line. It was possible to determine the enzymes involved in the probable mechanisms of action for the ligands. It has been observed that in 50% of cases, TcDHFR enzyme is the main target of the new compounds, in amastigotes. The pharmacological tests in amastigotes and trypomastigotes, line of C2C12 and MK2 cells was established as validation for the theoretical studies. The compound 3d probably develops its mechanism of action by inhibition of the enzyme TcTS (IC50= 10.3 µM) in trypomastigotes of the parasite. Since the compound 7c possibly acts by inhibition of the enzyme TcDHFR (IC50= 9.2 µM) in amastigotes. In additional, it was proposed that the compound 7b carries out its activity by inhibition of the enzyme TcDHFR (IC50 = 5.0 µM). Finally, it was observed that the most active compounds obtained in this study were more effective than the benznidazole, gold standard drug used in pharmacotherapy clinical of the Chagas disease, additionally has a low cytotoxicity (CC50> 100 µM). / As doenças negligenciadas configuram um grande problema de saúde pública mundial, quantificando um total de 1 bilhão de pessoas acometidas por algum tipo de infecção de origem bacteriana, viral ou parasitária. Dentre elas, podemos destacar a Doença de Chagas, causada pelo parasito Trypanosoma cruzi, a qual acomete mais de 8 milhões de pessoas em todo o mundo. No intuito de se descobrir novos compostos ativos capazes de combater o T. cruzi de maneira eficaz, desenvolvemos neste trabalho a síntese de novos protótipos de fármacos tiofeno-2-tioureicos e 2-iminotiazolidínicos racionalmente planejados com potencial atividade antichagásica, avaliação biológica e estudo de docking. Para a síntese dos compostos planejados, partiu-se de derivados tiofenos polissubstituídos, sintetizados via reação de Gewald, os quais foram convertidos em derivados tioureicos e, em seguida, ciclizados com cinco diferentes di-eletrófilos, gerando derivados tiofeno-2- iminotiazolidínicos. Os intermediários e compostos finais foram sintetizados com rendimentos entre 40 e 98%, e caracterizados por RMN. Para o estudo de docking, inicialmente foi realizada a minimização das energias dos ligantes pelo software ArgusLab®, usando o método AM1, e aplicando os softwares AutoDock Tools® e AutoDock Vina®, empregando o método de Gasteiger. Todos os compostos foram submetidos à avaliação in vitro de suas atividades anti-T. cruzi, e a série mais ativa foi selecionada para ensaio de citotoxicidade (MTT) em células da linhagem J774. Foi possível determinar as enzimas envolvidas nos prováveis mecanismos de ação para os ligantes. Foi observado que, em 50% dos casos, a enzima TcDHFR é o principal alvo dos novos composto, em formas amastigotas. Os ensaios farmacológicos em formas amastigotas e tripomastigotas, linhagem de células C2C12 e MK2 funcionaram como métodos de validação dos estudos teóricos. O composto 3d, provavelmente desenvolve seu mecanismo de ação através da inibição da enzima TcTS (IC50= 10.3 µM), em formas tripomastigotas do parasito. Já o composto 7c,possivelmente atua por meio da inibição da enzima TcDHFR (IC50= 9.2 µM) em formas amastigotas. Em adicional, foi proposto que o composto 7b desenvolve sua atividade através da inibição da enzima TcDHFR (IC50= 5.0 µM). Por fim, foi verificado que os compostos mais ativos obtidos neste trabalho se mostraram mais eficientes do que o fármaco benznidazol, padrão-ouro utilizado na clínica farmacológica da doença de Chagas, além destes apresentarem baixa citotoxicidade (CC50> 100 µM).
6

Latent Cysteine Residues from Polymers Prepared via Free and Controlled Radical Polymerizations

Amato, Douglas Vincent 01 June 2013 (has links) (PDF)
One less commonly used “click” reaction is thiazolidine chemistry. Thiazolidine chemistry is a commonly used reaction used in biological systems because the reaction requires the presence of both cysteine (a common amino acid) and an aldehyde or ketone. If cysteine residues could be incorporated into a polymer then a variety of applications could be developed. Polymers containing free thiols (aka thiomers) have developed in the last decade to become great mucoadhesives. If there was a facile route to control the amount of free thiols along the polymer then more fine-tuned and potentially stronger adhesives could be made. For these reasons the attachment of cysteine residues in a facile way via reversible addition fragmentation chain transfer (RAFT) polymerization or small molecule synthesis was researched. The incorporation of latent cysteine residues into the polymer via post polymerization modification proved to be less successful. However protected cysteine molecules have been successfully ligated onto polymerizable monomers and have been show to be easily deprotected in the presence of an acid source.
7

Adição de enolatos de titanio derivados de N-acil-(4S)-4-isopropil-1,3-tiazolidin-2-tiona a ions N-aciliminios ciclicos : sintese assimetrica dos alcaloides (+)-isoretronecanol e (+)-5-epi-tashiromina / Addition of the titanium enolates derived from N-acyl-(4S)-4-isopropyl-1,3-thiazolidine-2-thione to cyclic N-acyliminium ion : assymetric synthesis of alkaloids (+)-isoretronecanol and (+)-5-epi-tashiromine

Pereira, Elaine 23 February 2005 (has links)
Orientador: Ronaldo Aloise Pilli / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-04T15:31:59Z (GMT). No. of bitstreams: 1 Pereira_Elaine_M.pdf: 9380147 bytes, checksum: a608a978d005928c3df671eb93be3ed9 (MD5) Previous issue date: 2005 / Mestrado / Quimica Organica / Mestre em Química
8

Identification of novel scaffolds for Monoamine oxidase B inhibitors

Odhar, Hasanain 21 March 2014 (has links)
No description available.

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