Thesis (Ph.D.)--McMaster University, 2002. / Advisor: R.S. Gupta. Includes bibliographical references. Also available via World Wide Web.

Thesis (Ph.D.)--McMaster University, 2002. / Advisor: R.S. Gupta. Includes bibliographical references. Also available via World Wide Web.

Dissertation (Ph.D.) -- University of Texas Southwestern Medical Center at Dallas, 2008. / Vita. Bibliography: p.104-114

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [135]-147).

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2009. / Härtill 5 uppsatser.

Thesis (Ph.D.)--Virginia Commonwealth University, 2009. / Prepared for: School of Pharmacy. Title from title-page of electronic thesis. Bibliography: leaves 136-149.

Thesis (Ph.D.)--McMaster University, 2003. / Advisor: Gerard Wright. Includes bibliographical references. Also available via World Wide Web.

Made available in DSpace on 2014-08-13T14:50:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-12-06Bitstream added on 2014-08-13T18:01:04Z : No. of bitstreams: 1 000747336_20141206.pdf: 1912597 bytes, checksum: 84c5cc72a9058e08a4f2c5b561a0faa3 (MD5) / Nos últimos anos o interesse na obtenção de novos fármacos a base de metais vem aumentando consideravelmente. Desde a descoberta da atividade antitumoral da cisplatina na década de 60 inúmeros complexos de Pt(II) foram sintetizados, mas poucos chegaram aos testes clínicos. Por este motivo, o íon Pd(II) vem sendo usado sistematicamente no planejamento de novos compostos biologicamente ativos, pois apresenta a configuração eletrônica d8 e a mesma geometria quadrado planar dos compostos de platina, além de exibir outros modos de ação frente aos seus alvos biológicos. Neste trabalho foram sintetizados e caracterizados novos complexos de paládio(II) do tipo [PdX2(TAA)(PPh3)] e [PdX(L)(PPh3)]X [X = Cl-, Br-, I-, SCN-; TAA = tioacetamida; L = 4-metil-3-tiossemicarbazida (4-MeT) ou 4-fenil-3-tiossemicarbazida (4-PhT)]. Os complexos foram caracterizados pelas técnicas de IV, RMN, análise elementar e análise termogravimétrica. As estruturas moleculares dos complexos [PdI(4-MeT)(PPh3)]I (3), [Pd(SCN)(4-MeT)(PPh3)](SCN) (4) e [PdI(4-PhT)(PPh3)]I (7) foram determinadas via difração de raios X de monocristal, indicando um ambiente quadrático plano ao redor do metal, com seus sítios de coordenação ocupados pela trifenilfosfina, pela tiossemicarbazida coordenada de maneira bidentada e o I ou SCN. A citotoxicidade in vitro de todos os complexos foi avaliada pelo método do MTT, frente as culturas celulares de tumores murinos LM3 (adenocarcinoma mamário) e LP07 (adenocarcinoma pulmonar). Os compostos mais promissores tiveram sua capacidade de interação com o DNA investigada. Os resultados demostraram que o DNA não é o alvo principal, uma vez que os complexos só interagiram com a biomolécula em altas concentrações. Diante disto, outros possíveis alvos foram investigados. A capacidade dos complexos em inibir as enzimas topoisomerases foi avaliada pela técnica de eletroforese em gel de agarose e os dados mostraram que quase todos... / In the last years the interest in obtaining new metal drugs has increased considerably. Since the discovery of the antitumor activity of cisplatin in the 60's, many Pt(II) complexes were synthesized, but only few reached the clinical trials. For this reason, the Pd(II) ion has been used systematically in the design of new biologically active compounds. Palladium complexes display the same electron configuration and square planar geometry of platinum compounds, furthermore these complexes can interact through different way towards pharmacological targets. In this work new palladium(II) complexes of the type [PdX2(TA)(PPh3)] and [PdX(L)(PPh3)]X [X = Cl-, Br-, I-, SCN-; TAA = thioacetamide , L = 4-methyl-3-thiosemicarbazide (4-MeT) or 4-phenyl-3-thiosemicarbazide (4-PhT)], were synthesized and characterized. All the compounds were characterized by infrared, nuclear magnetic resonance spectroscopy, elemental analysis and thermogravimetric analysis. The structures of three complexes [(PdI(4-MeT)(PPh3)]I, [Pd(SCN)(4-MeT)(PPh3)](SCN) and [(PdI(4-PhT)(PPh3)]I were determined by single crystal X-ray diffraction and was observerd a square planar environment around the metal center, with the coordination sites occupied by triphenylphosphine, the N,S-donors ligand and iodine atom or thiocyanate group. The in vitro cytotoxicity of the complexes were evaluated against the murine tumor cells LM3 (breast adenocarcinoma) and LP07 (lung adenocarcinoma). The most promising compounds were further evaluated by their ability to interact with a purine base and the DNA. The results showed that DNA is not the primary target of these compounds because they only interacted with this biomolecule at high concentrations. Thus, others potential targets were investigated . The capacity of the complexes to inhibit topoisomerase enzymes was evaluated by electrophoresis, and the data showed that almost all the compounds inhibit this enzyme at a concentration rage...

The sialidases/neuraminidases represent a family of enzymes whose function is important in the pathogenicity of bacteria and the virulence of influenza. Relenza and Tamiflu represent two drugs that were developed using structure-based drug design (SBDD) and computational-assisted drug design (CADD). These drugs target the active site of the influenza neuraminidase A and B (GH-34 family). Sialidases in the GH-33 family could represent novel drug targets for the treatment of bacterial or parasitic infection. SBDD was employed to develop chemical tools of two GH-33 sialidases, NanB and TcTS. NanB is a potential drug target for S. pneumoniae. The chemical tool developed for NanB follows on from work within the Taylor and Westwood research groups, in which a molecule of CHES and a glycerol were found serendipitously bound within a water channel at an allosteric site. Using this information as a basis for SBDD an allosteric inhibitor of NanB, Optactin was developed. Within this work, synthesis of this inhibitor was achieved and optimised. Optactin was then modified to improve potency. This proceeded through an amide analogue and addition of an arene resulting in a mid- micromolar inhibitor (IC50: 55.4±2.5 μM). Addition of polar substituents improved potency further resulting in a low micromolar inhibitor of NanB, Optactamide (IC50: 3.0±1.7 μM). Application of this tool in vitro demonstrated that NanB and NanA have a role in invasion of S. pneumoniae into lung epithelial cells. TcTS is a potential drug target for the treatment of Chagas disease. A CADD approach using a fragment library was unsuccessful at identifying an allosteric inhibitor of TcTS despite structural similarity with NanB. A re-task of the CADD approach towards the active site was successful in identifying an inhibitor of TcTS and a fragment useful for further development. This work sets the groundwork for the development of a chemical tool targeting TcTS.

Molecular docking technologies enable the extraordinary structural diversity of natural products to be harnessed in an efficient manner. In this thesis, in silico techniques were used to discover and develop c-myc oncogene down-regulators and JAK2 inhibitors from databases of natural products and approved drugs. In Chapter 1, current literature on the use of molecular docking in virtual screening for the identification of bioactive molecules from natural product databases are reviewed. Chapter 2 provides an overview of the experiments performed during the course of this work, including molecular docking, PCR stop assay, absorption spectroscopy, CD spectroscopy, FID assay, mass spectrometry, SPR spectroscopy, ELISA assay, MTT assay, luciferase assay and Western blot analysis. The mechanisms, applications and protocols of these experiments are detailed. A unique intramolecular G-quadruplex c-myc NHE IIIi loop isomer model developed by our group was employed to design and screen 30 flavone derivatives in silico. The highest-scoring flavone derivatives 3.5, 3.6 and 3.7 containing cationic pyridinium side chains that could interact with the G-quadruplex grooves were synthesized. The flavone derivatives could stabilize the c-myc G-quadruplex in the PCR-stop assay, and induce the G-quadruplex structure in guanine-rich sequences as revealed by CD spectroscopy. The binding affinity of the derivatives towards various DNA structures was examined using UV-visible spectroscopy. The most promising derivative 3.7 was further subjected to surface plasmon resonance spectroscopy, in silico molecular modeling and luciferase reporter assay to determine its selectivity, binding interaction mode and c-myc G-quadruplex promoter inhibitory activity in cancer cells. This compound also displayed promising cytotoxic behavior against human cancer cell lines. This part of work is detailed in chapter 3. Chapter 4 describes the application of computer-aided techniques for the repurposing of FDA-approved drugs as c-myc oncogene G-quadruplex stabilizers. Methylene blue (MB) emerged as a promising scaffold after virtual screening of 3,000 FDA-approved drugs. A structure-based lead optimization approach was used to generate and screen 50 MB derivatives, containing side chains that could interact with the G-quadruplex grooves, in silico. The highest-scoring compounds 4.10, 4.11 and 4.12 were synthesized and their ability to interact with the c-myc G-quadruplex was investigated using FID assay. The most promising compound 4.11 stabilized c-myc G-quadruplex DNA in a PCR-stop assay. The selectivity of 4.11 for the c-myc G-quadruplex over duplex DNA and other G-quadruplexes was demonstrated using UV-visible spectroscopy and mass spectrometry. Compound 4.11 could induce or stabilize c-myc G-quadruplex formation in cellular models, and displayed higher cytotoxicity against human hepatocarcinoma cells compared to the parent compound, MB. The application of the DOLPHIN kinase model to discover natural product scaffolds as Type II JAK2 inhibitors is presented in chapter 5. Amentoflavone, a biflavonoid from the Chinese plant Gingko biloba, emerged as a promising candidate after biological verification of the hit structures. Amentoflavone was optimized in silico, and the top scoring derivatives were synthesized. The activity of the amentoflavone analogues against JAK2 activity in HEL cells was evaluated using a Western blot assay. Two derivatives, 5.3 and 5.7, showed low-micromolar activity against JAK2 phosphorylation in cellulo. Analogue 5.2 inhibited total JAK2 content in HEL cells and also displayed potent anti-proliferative activity against HEL cells in the MTT assay. This chapter also describes the total synthesis of amentoflavone.