Made available in DSpace on 2017-07-21T14:13:06Z (GMT). No. of bitstreams: 1 BRUNA MIKULIS LEMES.pdf: 2339856 bytes, checksum: 090063d94222c9d5a81d2f53dd692a81 (MD5) Previous issue date: 2016-02-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The abusive use of anti-inflammatory drugs entails health risks and this fact has increasingly led researchers to seek alternative new drugs and safer formulations.Consequently the development of new, modified drug delivery systems and the search for new drugs, presents itself as a great research field. The extracts from plant species stand out as a matrix of interest due to the presence of possible active compounds. These compounds include the class of phenolic compounds, which is a structurally diversified class whose antioxidant and anti-inflammatory activity have already been well-studied and recognised. The species Euphorbia umbellata has attracted attention in recent years in relation to its ethnopharmacological use for the treatment of cancer and inflammation and it presents as candidate to be used in formulations with antiinflammatory activity, which is especially present among in its metabolites, i.e. phenoliccompounds. Consequently, this study developed, characterised and evaluated chitosan membranes containing the methanol fraction of E. umbellata for topical application in relation to their antioxidant and antimicrobial potential. Initially, the quantitative determination of phenolic compounds (total flavonoids and phenolics) present in the crude extract and its fractions (hexane, chloroform, ethyl acetate and methanol) were performed using UV-VIS, and a qualitative chromatographic evaluation of the methanolic fraction was performed using UHPLC-MS. The physicochemical characterisation of the membranes was performed using SEM and EGF techniques,density, XRD, FTIR, DSC, TGA, colour measurements, and pharmacological evaluation in vitro by determining the scavenging (DPPH and ABTS) and antimicrobial potential, in addition to ex vivo permeation testing. The quantification of phenolic compounds demonstrated that the methanolic fraction contained the highest amount ofthese compounds (225.205 mg.g-1) and the chromatographic evaluation of themethanolic fraction made it possible to suggest 23 molecules of phenolic substances belonging to the classes of simple phenolic acids, tannins and flavonoids. The characterisation tests showed variations related to the addition of the methanolic fraction of the chitosan matrix, which showed interaction between the chitosan matrix and the polymer structure. The antioxidant and antimicrobial tests indicated the positive potential of the membranes in relation to the studied models. Similarly, these formulations also stood out in the antimicrobial assay. There was no permeation of the Franz cell model, suggesting a local activity. Thus, it was possible to demonstrate that interactions occurred between the methanolic fraction and the polymer. These formulations show promising potential for topical application in relation to antiinflammatory action. / O uso abusivo de medicamentos anti-inflamatórios traz riscos à saúde da população e tal fato preocupa e instiga cada vez mais os pesquisadores a buscar alternativas de novos fármacos e formulações mais seguros. Neste sentido o desenvolvimento de novas formas farmacêuticas de liberação modificada e a busca de novos fármacos, apresentase como um campo de pesquisa de grande importância. Os extratos de espécies vegetais se destacam com uma matriz de interesse em decorrência da presença de possíveis moléculas bioativas. Entre estes compostos destacam-se os fenólicos, que se destacam como uma classe bastante diversificada estruturalmente e cuja atividade antioxidante e anti-inflamatória são bem estudadas e reconhecidas. A espécie Euphorbia umbellata tem despertado interesse nos últimos anos quanto ao seu uso etnofarmacológico para tratamento de quadros de câncer e inflamação, e apresenta-se como candidata a ser empregada em formulações com atividade anti-inflamatória, especialmente por apresentar entre seus metabólitos, os compostos fenólicos. Sendo assim, no presente estudo, membranas de quitosana contendo a fração metanólica de E. umbellata para aplicação tópica foram desenvolvidas, caracterizadas e avaliadas quanto ao seu potencial antioxidante e antimicrobiano. Para tanto, inicialmente foram realizadas a determinação quantitativa dos compostos fenólicos (fenólicos e flavonoides totais) presentes no extrato bruto e suas frações (hexano, clorofórmio, acetato de etila e metanol) por UV-VIS e a avaliação cromatográfica qualitativa da fração metanólica por UHPLC-MS. A caracterização físico-química das membranas foi desenvolvida por meio de técnicas de MEV, FEG, densidade, DRX, FTIR, DSC, TGA, determinação de cor e avaliação farmacológica in vitro mediante a determinação do potencial scavenger (DPPH e ABTS) e antimicrobiano, além do teste de permeação ex vivo. A quantificação de fenólicos revelou que a fração metanólica é a que possui maior quantidade desses compostos (225,205 mg.g-1) e a avaliação cromatográfica da mesma permitiu sugerir 23 moléculas de substâncias fenólicas pertencentes as classes dos ácidos fenólicos simples, taninos e flavonoides. Os testes de caracterização evidenciaram variações relacionadas à adição da fração metanólica à matriz de quitosana, o que demonstra a interação desta com a estrutura do polímero. Os ensaios antioxidante e antimicrobiano indicaram favorável potencial das membranas M50FM e M100FM, nos modelos estudados. Da mesma forma, estas formulações também se destacaram no ensaio antimicrobiano. Não foi observada permeação cutânea o modelo de célula de Franz, o que aponta para uma atividade local. Deste modo, foi possível indicar que ocorrem interações entre a fração metanólica e o polímero, entretanto as formulações são candidatas promissoras à aplicação tópica para ação anti-inflamatória.

M. Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / Fuel cell technology is a promising clean energy source compared to internal combustion engines and electricity generating plants which are associated with high emissions of greenhouse gases. The aim of this study was to modify chitosan into polymer electrolyte membranes suitable for use in PEMFC and DMFC fuel cells. Chitosan modification was done with 2-aminoethanesulfonic acid (2-AESA), dimethylformamide (DMF) and silica nanoparticles. The effect of the modification on the properties of the developed chitosan membranes was studied using FTIR, XRD, SEM-EDS and TGA. The performance of the membrane electrode assemblies was investigated. The formation of electrostatic interactions in the developed sulfonated chitosan membranes was confirmed via the Fourier transform infrared (FTIR) analysis, indicating a shift in the wavenumber of the N-H bonds from 1581 cm-1 on the chitosan spectrum to a lower wavenumber of 1532 cm-1 in the FTIR spectra of the membranes and by the new peak at the wavenumber of ~1260 cm-1 attributed to the asymmetric O=S=O stretching vibrations of the sulphate groups and sulfonic acid groups from the cross-linking sulphuric acid solution and 2-aminoethanesulfonic acid incorporated on the chitosan polymer chain during the modification. Notably, the FTIR spectra of the developed sulfonated chitosan membranes lacked the peak at the wavenumber of ~1153 cm-1 attributed to the stretching of C-O-C bonds of the polysaccharide ring of chitosan. A reaction mechanism was proposed in this study illustrating the possible conversion of the polysaccharide rings of chitosan into a poly (cyclohexene-oxide) thermoplastic rings in the developed membranes. The TGA/DTGA results of the developed sulfonated chitosan membranes showed three degradation stages. The initial weight loss occurred at temperatures ˂100 °C due to the evaporation of volatile components and water molecules inside the membranes. The second degradation phase of the membranes occurred at 208 ℃ with a loss in weight of >30% resulting from the decomposition of cross-linking networks. The third degradation stage was associated with the decomposition of the main polymer backbone of the membranes and occurred at 263°C for the chitosan membranes modified with 2-aminoethanesulfonic acid and at 266 °C for the chitosan membrane modified with silica nanofiller. The TGA/DTGA curves of Nafion 117 showed a small loss in weight of ~ 5% before a sharp decomposition that occurred between 346–505 °C. The XRD diffractograms of the developed sulfonated chitosan membranes showed amorphous phases, the crystal peaks of chitosan at 2theta of 10° and 20° were flattened on the membranes. The SEM images showed a homogenous surface morphology for the sulfonated chitosan membrane with a higher weight percentage of 2-aminoethanesulfonic acid (13,6 wt.%). The SEM images performed on the surface of the sulfonated chitosan membrane modified silica nanoparticles showed a slight agglomeration associated with the migration of the unbonded silica to the surface. The methanol permeability coefficient of the developed sulfonated chitosan membrane modified with 2-aminoethanesulfonic acid was calculated to be 2.29x10-6 cm2/s. This value was close to the methanol permeability coefficient of 2.33x10-6 cm2/s associated with unfavourable depolarisation at the cathode in direct methanol fuel cells when using Nafion 117. The proton diffusion coefficient of Nafion 117 was calculated to be 1.64x10-5 cm2/s and that of the developed sulfonated chitosan membrane modified with 2-aminoethanesulfonic acid was found to be 6.56x10-6 cm2/s, respectively. The fuel cell performance of the developed sulfonated chitosan membrane modified with 2AESA was investigated in a hydrogen fuel cell (PEMFC) supplied with H2 and O2 directly from the electrolyser. The sulfonated chitosan membrane modified with 2-aminoethanesulfonic acid (13.6 wt.%) achieved an open-circuit voltage of ~0.9 V and a maximum power output of 64.7 mW/cm2 at a maximum current of 70 mA. The current produced by the developed chitosan membrane was applied into the load and was able to turn (power) the electric fan. The sulfonated chitosan membrane modified with silica nanoparticles (2 wt.%) yielded an open-circuit voltage of ~0.9 V and attained a maximum power output of 58 mW/cm2 at a maximum current output of 60 mA/cm2. The current generated by the membrane was also able to turn the electric fan. The Nafion 117 membrane was also investigated under similar conditions and obtained an open-circuit voltage of 0.6 V and a maximum power output of 130 mW/cm2 at the maximum current output of 308 mA. The current produced by Nafion 117 was supplied into the load and was able to turn the electric fan.