none

No description available.

No description available.

No description available.

Made available in DSpace on 2016-06-02T20:34:49Z (GMT). No. of bitstreams: 1 5686.pdf: 10016184 bytes, checksum: e6a42772f0db7983f4cc9525851f9c5b (MD5) Previous issue date: 2014-01-17 / Universidade Federal de Sao Carlos / O foco principal desse trabalho foi a implementação, otimização e aplicações práticas de métodos de ressonância magnética nuclear (RMN) com o propósito de avaliar as interações entre moléculas de diferentes massas molares, sendo que essas técnicas foram implementadas pela primeira vez no laboratório de RMN do DQ-UFSCar. Existem várias abordagens que podem ser utilizadas com esse propósito, e dentre elas, destacamos: STD NMR, Tr-NOESY, WaterLOGSY, SALMON, INPHARMA, DOSY, SAR. Esses métodos são muito úteis para detectar mudanças de comportamento, a nível molecular, quando adicionamos macromoléculas em um meio contendo somente micromoléculas. O entendimento desse comportamento molecular ajuda a desvendar sistemas complexos de interações moleculares existentes no corpo humano, e que, são muito importantes para o descobrimento de novos medicamentos. O primeiro passo para a implementação das técnicas foi a utilização da proteína de soro bovino (do inglês BSA) e proteína de soro humano (do inglês HSA) como fonte de macromoléculas e micromoléculas orgânicas isoladas da fração etanólica do extrato bruto (1 mg) de Rauia resinous e da fração acetato de etila de Strypnodendron polyphyllum, utilizando cromatografia líquida de alta eficiência, extração por fase sólida e a ressonância magnética nuclear (CLAE-EFS/RMN) para a completa elucidação estrutural quando necessário. As técnicas utilizadas foram: saturation transfer difference (STD), transfer nuclear Overhauser spectroscopy (Tr-NOESY) e STD-TOCSY (total correlation spectroscopy). Essa mesma metodologia além de representar um importante mecanismo para avaliar as interações entre moléculas, também pode ser utilizada para outras matrizes variando tanto as macro quanto as micromoléculas. / The main focus of this work was the implementation, optimization and practical applications of nuclear magnetic resonance (NMR) methods for the purpose of evaluating the interactions between molecules of different masses, and these techniques were implemented for the first time in the laboratory NMR DQ - UFSCAR. There are a number of ligand-based screening approaches available, such that, STD NMR, Tr-NOESY, WaterLOGSY, SALMON, INPHARMA, DOSY, SAR by NMR etc. These methods are sensitive towards the perturbations as results of the macromolecular addition in a medium containing the small molecules. The molecular understanding of this behavior helps to uncover the complex systems of molecular interactions existing in the human body, which are very important for the discovery of new medicines. In the first step while implementing these techniques, Bovine Serum Albumin (BSA) and Human Serum Albumin (HSA) as a source of organic macromolecules were used. While, for the small organic molecules, a 1 mg crude extract from the hydroethanolic fraction of the Rauia resinous and ethyl acetate fraction of Strypnodendron polyphyllum was utilized, however, for the complete structural characterization, solid phase extraction following high-pressure liquid chromatography in an integrated fashion and then nuclear magnetic resonance (LC-SPE/NMR) was employed when necessary. On the other hand, the ligand screening techniques used were the saturation transfer difference (STD), Nuclear Overhauser Transfer Effect SpectroscopY (Tr- NOESY), Diffusion-Order Spectroscopy (DOSY) and STD- TOCSY (TOtal Correlation SpectroscopY). More importantly, this methodology also represents an important mechanism to evaluate the interactions between molecules or the first hand detection of the active constituents/inhibitors, which can also be used for other matrices varying both the macro and the small molecules.

4, 4'-Dihydroxybenzophenone-2, 4-dinitrophenylhydrazone (A-007) has recently completed a phase-I clinical trial, and objective responses were seen in advanced breast cancer, lung cancer, ovarian cancer, melanoma, skin cancer and non-Hodgkin's lymphoma. Despite the promising results in the clinical trials, the major disadvantage to using A-007 as a broad-scale therapeutic is its poor water solubility. To make use of this promising anticancer drug either orally or intravenously, the short-term obstacle must be to overcome the limited solubility of A-007 in water. There are several approaches to overcome this obstacle. The first approach is to make hydrolysable prodrugs of A-007. The second approach is to make an A-007 complex with a water soluble host, such as cyclodextrin. We used a combination of these two previously described methods, i.e. transforming A-007 into a more water soluble prodrugs and then further increasing the prodrug water solubility by making their cyclodextrin inclusion complexes. Our syntheses and spectroscopic explorations of A-007 prodrugs are presented in this dissertation. Tetramic acid (2, 4 pyrrolidine-2, 4-dione ring system) containing compounds have been found to display a remarkable diversity of biological activities and have attracted the interest of medicinal and synthetic chemists. Magnesidin (1-acetyl-3-octanoyl-5-ethylidene tetramic acid) has strong antimicrobial activity against bacteria that cause gingivitis and dental plaque. Current efforts toward the synthesis of Magnesidin are discussed along with the plans for the completion of synthesis.

Since the middle of the 20th century, significant interest has evolved from the scientific community towards the polypropionate family of marine natural products. A number of these compounds have been shown to possess significant biological activity, and this property, as well as their structural complexity, has driven numerous efforts towards their synthesis. The first chapter provides an introduction into the world of polypropionates, with a discussion on synthetic studies into a number of members of the tridachiapyrone family. Fundamental synthetic concepts utilised in this thesis towards the preparation of polyketides are also described, with a focus on their application towards the synthesis of 9,10-deoxytridachione, anti tridachiahydropyrone and syn tridachiahydropyrone. Chapter 2 describes the work undertaken towards the total synthesis of 9,10-deoxytridachione. The novel tandem conjugate addition-Dieckmann condensation of complex enones developed previously in the Perkins group was used to generate anti methylated cyclohexenones as key synthetic intermediates. The conversion of the cyclohexenones into the corresponding cyclohexadienes via allylic alcohols was attempted, utilising a Grignard-mediated reaction to achieve the selective 1,2-reduction. Studies into the Grignard-mediated reduction were also undertaken on seven additional cyclohexenones, in order to investigate the utility and scope of the reaction. The extension of the methodology previously developed for the synthesis of cyclohexenones is the subject of Chapter 3. This section describes investigations into the synthesis of stereochemically-diverse cyclohexenones from complex enones. The conjugate addition-Dieckmann condensation strategy was extended successfully towards the synthesis of a syn methylated cyclohexenone, which allowed the synthesis of the proposed true structure of tridachiahydropyrone to be pursued. The methodology developed in Chapter 3 was utilised in Chapter 4 to synthesise a model system of syn tridachiahydropyrone. A comparative analysis of the NMR data of the syn model, an anti model and anti tridachiahydropyrone with the natural product indicated that the true structure of tridachiahydropyrone may indeed have syn stereochemistry. The synthesis of syn tridachiahydropyrone was attempted, and to this end a suitable cyclohexanone was successfully synthesised. However, the subsequent methylation-elimination cascade failed to furnish the desired syn methylated cyclohexenone, producing only an anti methylated cyclohexanone. The stereochemistry of the methylation was deduced using high and low variable temperature NMR coupled with selective irradiation NOESY.

Host–guest complexes are widely investigated because of their importance in many industrial applications. The investigation of their physico–chemical properties helps understanding the inclusion phenomenon. The hosts investigated in this work are cryptophane molecules possessing a hydrophobic cavity. They can encapsulate small organic guests such as halo–methanes (CH2Cl2, CHCl3). The encapsulation process was investigated from both the guest and the host point of view. With the help of Nuclear Magnetic Resonance (NMR), the kinetics of complex formation was determined. The information was further used to obtain the activation energies of the processes. Having done this on five different cryptophanes, it is possible to relate the energies to structural differences between the hosts. Via the dipolar interaction between the guest’s and host’s protons, one can get information on the orientation of the guest inside the cavity. Moreover, the dynamics of the guest can be further investigated by its relaxation properties. This revealed restricted motion of the guest inside the host cavity. Not only the nature of the guest plays an important role. The host is also changing its properties upon encapsulation. All the cryptophanes investigated here can exchange rapidly between many conformers. These conformers have different–sized cavities. Quantum chemical optimization of the structure of the conformers makes volume estimation possible. Not only the cavity volumes, but also the quantum-chemically obtained energies and the calculated chemical shifts of the carbon–13 atoms can be helpful to follow the changes of the host upon complex formation. The host cannot be considered as a rigid entity. Analysis of variable temperature proton and carbon-13 spectra shows that the encapsulation can be considered as a mixture of conformational selection and induced fit. The structures of the formed complexes are further investigated by means of two-dimensional nuclear Overhauser spectroscopy (NOESY). The complex formation, its kinetics and thermodynamics are found to be a complicated function of structure elements of the host, the cavity size and the guest size and properties. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Accepted. Paper 5: Manuscript.</p><p> </p>

No description available.

Stimuli-responsive (stimuli-sensitive, intelligent, or smart) polymers are polymer materials which, after small external stimuli, evidently change their physical or chemical properties. Smart polymers can be classified according stimuli they respond to such as: temperature changes, mechanical stress, light irradiation, ultrasonic treatment, application of external magnetic as well as electric field, changes of pH, ionic strength, addition of the chemical agents and presence of biomolecules and bioactive molecules. Stimuli-responsive synthetic polymer systems has attracted considerable attention due to wide range of applications, i.e. controlled drug delivery and release systems, diagnostics, tissue engineering and 'smart' optical systems, as well as biosensors, microelectromechanical systems, coatings, and textiles. Among the types of stimuli for this dissertation temperature, pH and reactive oxygen species (ROS) responsive polymer systems were studied. In case of thermoresponsive polymers, when polymer chains are molecularly dissolved in a good solvent, changes (increasing or decreasing) of temperature result in insolubility (globular nanoparticles formation) of polymer chains, called temperature induced phase-separation. pH responsive polymers change properties such as: solubility, volume (gels),...