No description available.

No description available.

Anhydrous proton conducting polymers are highly sought after for applications in high temperature polymer electrolyte membrane fuel cells (PEMFCs). N-heterocycles (eg. imidazole, triazole, and benzimidazole), owing to their amphoteric nature, have been widely studied to develop efficient anhydrous proton transporting polymers. The proton conductivity of N-heterocyclic polymers is influenced by several factors and the design and development of polymers with a delicate balance among various synergistic and competing factors to provide appreciable proton conductivities has been a challenging task. In this thesis, the proton transport (PT) characteristics of polymers functionalized with two diverse classes of functional groups - N-heterocycles and phenols have been investigated and efforts have been made to develop the molecular design criteria for the design and development of efficient proton transporting functional groups and polymers. The proton conduction pathway in 1H-1,2,3-triazole polymers is probed by employing structurally analogous N-heterocyclic (triazole, imidazole, and pyrazole) and benz-N-heterocyclic (benzotriazole, benzimidazole, and benzopyrazole) polymers. Imidazole-like pathway was found to dominate the proton conductivity of triazole and pyrazole-like pathway makes only a negligible contribution, if any. Polymers containing benz-N-heterocycles exhibited higher proton conductivity than those with the corresponding N-heterocycles. Pyrazole-like functional groups, i.e. the molecules with two nitrogen atoms adjacent to each other, were found not to be good candidates for PT applications. A new class of proton transporting functional groups, phenols, has been introduced for anhydrous PT. One of the highlighting features of phenols over N-heterocycles is that the hydrogen bond donor/acceptor reorientation can happen on a single -OH site, allowing for facile reorientational dynamics in Grotthuss PT and enhanced proton conductivities in phenolic polymers. Unlike the case of N-heterocycles, comparable conductivities were achieved between poly (3,4,5-trihydroxy) styrene and the corresponding small molecule, pyrogallol. This observation suggests that reorientation should be considered as a crucial design parameter for PT functional groups. The PT characteristics of phenol-based biaryl polymers are studied and compared with the analogous phenol-based linear styrenic polymers. The two-dimensional disposition of -OH moieties in biaryl polymers, although resulted in lower apparent activation energies (Ea), did not improve the net proton conductivity due to the accompanying increase in glass transition temperature (Tg). Thus, the ease of synthesis and lower Tg values of phenol-based styrene polymers make the styrenic polymer architecture preferable over the biaryl architecture. Finally, the synthesis of a series of poly(3,4-dihydroxy styrene)-b-polystyrene block copolymers has been demonstrated via anionic polymerization. These block copolymers will provide an opportunity to systematically investigate the effect of nanoscale morphology on proton transport.

Earth's climate is prone to natural and episodic cycles. The most recent period of climate change, the only one to be caused by humans, is significantly affecting species composition and landscapes. Northern expansion of the Boreal Forest in Canada is one of the expected outcomes, and tree line migration northward is one of the anticipated changes. Previous studies have found that many human activities like agriculture, grazing, and pastoralism can significantly affect tree line movement. Improving our ability to examine past tree line dynamics can be achieved using archival records in lake sediments. In this study, we focused on three sediment biomarkers that may be related to the presence of trees in a lake's catchment: n-alkanes, lignin-derived phenols, and stable isotopes of carbon. We examined the composition of these markers in sediment from 19 lakes in Saskatchewan spanning 4 ecoregions, from Prairie Grassland to Boreal Plain, to determine the biomarker signature for lakes in each ecoregion and relating them to land cover (trees vs herbaceous plants) in the catchments of each lake. The results showed that n-alkane composition was significantly correlated to the proportion of trees to herbaceous plants in a lake's catchment, raising the possibility that these can be used to infer the presence of trees in sediment records. The C/N ratio and δ¹³C were not effective in distinguishing ecoregions or land cover composition, likely due to algal production in the lake and agricultural activities in the surrounding farmland, while lignin-derived phenols appeared to be affected by unknown factors.

No / The Raman spectrum of scytonin, a novel derivative of the parent scytonemin, is predicted from DFT calculations of the most stable, lowest energy, conformational structure. The diagnostic importance of this study relates to the spectral ability to discriminate between scytonemin and its derivatives alone or in admixture with geological matrices from identified characteristic Raman spectral signatures. The successful interpretation of biosignatures from a wide range of cyanobacterial extremophilic colonization in terrestrial and extraterrestrial scenarios is a fundamental requirement of the evaluation of robotic spectroscopic instrumentation in search for life missions. Scytonemin is produced exclusively by cyanobacterial colonies in environmentally stressed habitats and is widely recognized as a key target biomarker molecule in this enterprise. Here, the detailed theoretical analysis of the structure of scytonin enables a protocol to be established for the recognition of characteristic bands in its Raman spectrum and to accomplish the successful differentiation between scytonin and scytonemin as well as other scytonemin derivatives such as the dimethoxy and tetramethoxy compounds that have been isolated from cyanobacterial colonies but which have not yet been characterized spectroscopically. The results of this study will facilitate an extension of the database capability for miniaturized Raman spectrometers which will be carried on board search for life robotic missions to Mars, Europa, and Titan.

M. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences) -- Vaal University of Technology / The widespread use of phenols and phenolic derivatives in industrial applications has resulted in their discharge as part of industrial wastewater. These chemicals are toxic and need to be removed from the aqueous environment. Amongst the available pollutant removal technologies, adsorption has been widely used due to its simplicity, ease of operation, cost-effectiveness and ability to sequester pollutants at very low concentrations. Different adsorbents have been applied for removal of phenols and their derivatives. Use of agricultural waste as adsorbents seems to offer a much cheaper alternative in pollutant removal. This study examines the synthesis of a hydrophobic biomaterial composite by cross-linking of Fenton treated pine cone and applying the prepared adsorbent for 2-nitrophenol removal from aqueous solution. Pine cone biomass, in its raw and modified forms was tested for its ability to remove 2-nitrophenol from simulated industrial wastewater. The experimental procedure is divided into two main parts: (1) pine cone modification using Fenton’s reagent and 1.6-hexamethylene diisocyanate and (2) application of the prepared hydrophobic adsorbent for 2-nitrophenol removal from wastewater. Fenton’s reagent was used to remove pigments, extractives and other soluble organic compounds from the raw pine. FTIR spectroscopy showed an increase in magnitude of oxygenated surface groups which resulted in a decrease in pHpzc. The effect of Fenton treatment on further modification of the pine biomass via cross-linking using 1.6-hexamethylene diisocyanate was investigated. Optimum reaction variables for the cross-linking using dibutyltin dilaurate as catalyst under an inert nitrogen gas atmosphere in anhydrous hexane solvent were determined using FTIR spectroscopy. Success of the cross-linking procedure was confirmed by use of analytical techniques (XRD, TGA, SEM, EDX and BET surface area) and weight percent gain calculations. Pine and modified pine biomass were tested for their ability to sequester 2-nitrophenol via batch adsorption technique. The effect of pine modification on affinity for the biosorbate was investigated. The mechanism of the adsorption process was determined via use of kinetic, diffusion and equilibrium isotherm models. Two error functions (coefficient of determination and percent variable error) were employed to substantiate the model showing a good fit to the experimental adsorption data. The experimental adsorption kinetic data was fit to the pseudo-first-order and pseudo-second-order kinetic models. Due to the large size of the pollutant molecules diffusion process analysis was also conducted. The effect of pine modification on kinetic and diffusion parameters was determined. The experimental equilibrium adsorption data was fit to the Freundlich, Redlich-Peterson and Hill isotherm models. The initial shapes of the adsorption isotherms for 2-nitrophenol adsorption onto pine and modified pine biomass determined the type of equilibrium isotherm models to fit the experimental data to. Thermodynamic parameters were calculated to determine the spontaneity, feasibility and energy changes associated with the adsorption process. The degree of disorder at the solid/liquid interface after the adsorption was determined. The effect of temperature on the adsorption process was used to show whether the adsorption is physical or chemical. The effect of pine modification on equilibrium isotherm parameters was determined. The study is divided into seven chapters: Chapter 1: The chapter covers the introduction, problem statement, aim and objectives of the research. It gives an insight into the research project. Chapter 2: The literature review of pollutants in industrial wastewater and methods of their removal is dealt with in this chapter. Adsorption is introduced as an alternative technique for pollutant removal from aqueous systems. An in-depth review of various adsorbents (including pine cone), their merits and limitations are also discussed together with methods of modifying and use of modified adsorbents. Equilibrium, kinetic and thermodynamic models used to treat adsorption experimental data are presented. Chapter 3: The experimental procedures on the synthesis, characterization and application of the hydrophobic biosorbent in the removal of 2-nitrophenol from aqueous solution are presented. Kinetic and equilibrium experiments are described in detail. Chapter 4: It describes the first part of the results and discussions. The chapter focuses on optimization of reaction variables and characterization (using various analytical techniques) of the hydrophobic biomaterial composite. Chapter 5 The chapter discusses the second part of the results. It focuses on magnitude of surface charge, pHpzc and kinetic studies. Fitting of the adsorption experimental data to kinetic and diffusion models is presented together with the error functions. Chapter 6 The chapter discusses part three of the results on equilibrium studies. The adsorption experimental data is fitted to equilibrium isotherm equations and error determination is presented. Thermodynamic parameters are calculated and interpreted. Chapter 7: Conclusion and recommendations are presented. The optimum reaction variables for cross-linking of Raw and Fenton treated pine cone were determined using FTIR analysis and found to be: 0.2 g pine biomass, 3.5 cm3 1.6-hexamethylene diisocyanate cross-linker, 50 cm3 anhydrous hexane solvent, 1.5 cm3 dibutyltin dilaurate catalyst, temperature of 50 °C and a reaction time of 4 hours. The pine surface showed an increase in phenolic, lactonic and carboxylic acid groups due to the modification. The pHpzc showed a decrease due to modification of the pine cone biomass. The pHpzc values for the pine and modified pine cone biomass were found to be: Raw = 7.49, Raw-HMDI modified = 6.68, Fenton treated pine = 5.40 and Fenton-HMDI modified = 6.12. The optimum pH for the adsorption of 2-nitrophenol onto raw pine and modified pine cone biomass was determined to be 6. The optimum adsorbent dosage was determined as 1.5 g/dm3. The adsorption kinetics show a good fit with the pseudo-second-order model. This suggests that surface adsorption is the controlling step in the adsorption of 2-nitrophenol onto pine cone biomass. The analysis of diffusion processes showed that the initial rapid stage during the adsorption is due to external mass transfer processes. The adsorption experimental data also showed that pore diffusion was rate-limiting amongst the diffusion processes. Pine modification using Fenton’s reagent and 1.6-hexamethylene diisocyanate increased magnitude of kinetic and diffusion parameters. Experimental data for 2-nitrophenol adsorption onto pine and modified pine cone biomass showed better correlation with the Redlich-Peterson and Hill isotherm models and poor correlation with the Freundlich isotherm model. This suggests that the mechanism does not show complete multilayer coverage with cooperative phenomena between adsorbate molecules. Thermodynamic parameters showed that the adsorption is feasible, spontaneous, and exothermic and results in a decrease in degree of disorder at the solid/liquid interface. An increase in temperature resulted in a decrease in adsorption capacity showing that the adsorption is physical. Pine modification using Fenton’s reagent and 1.6-hexamethylene diisocyanate increased magnitude of kinetic, diffusion and isotherm parameters. The kinetic and equilibrium results show that the adsorption of 2-nitrophenol onto pine cone biomass follows the order: Fenton treated-HMDI > Fenton treated > Raw-HMDI > Raw. Hence, it can be concluded that Fenton treatment and HMDI cross-linking modification did increase the adsorptive capabilities of the pine cone biomass. / VUT Research Directorate

Leung, Yu Tim. / Thesis submitted in: November 2006. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 103-128). / Abstracts in English and Chinese. / Thesis Committee --- p.i / Acknowledgements --- p.ii / Abstract --- p.iii / 摘要 --- p.iv / Table of Contents --- p.v / List of Tables --- p.ix / List of Figures --- p.x / Abbreviations --- p.xiii / Chapter 1. --- Introduction / Chapter 1.1 --- Flower herbal teas --- p.1 / Chapter 1.2 --- R. rugosa --- p.3 / Chapter 1.2.1 --- The phytochemistry of R. rugosa --- p.3 / Chapter 1.3 --- Secondary metabolites --- p.4 / Chapter 1.4 --- Classification of secondary metabolites --- p.6 / Chapter 1.5 --- Phenolic compounds --- p.6 / Chapter 1.5.1 --- Phenylpropanoid compounds --- p.6 / Chapter 1.5.2 --- Lignins --- p.7 / Chapter 1.5.3 --- Coumarins --- p.7 / Chapter 1.5.4 --- Stilbenes --- p.8 / Chapter 1.5.5 --- Tannins --- p.8 / Chapter 1.5.6 --- Flavonoids --- p.9 / Chapter 1.6 --- Oxidative Stress --- p.13 / Chapter 1.6.1 --- Diseases related to ROS --- p.13 / Chapter 1.6.2 --- Significant chemical or biochemical conversion of ROS --- p.14 / Chapter 1.6.3 --- Sources of ROS --- p.15 / Chapter 1.7 --- Natural dietary antioxidants --- p.15 / Chapter 1.7.1 --- Vitamin C --- p.15 / Chapter 1.7.2 --- Vitamin E --- p.16 / Chapter 1.7.3 --- Carotenoids --- p.16 / Chapter 1.7.4 --- Phenolic compounds --- p.16 / Chapter 1.8 --- Cancinogenesis --- p.17 / Chapter 1.9 --- Cell cycle --- p.18 / Chapter 1.9.1 --- Cell cycle of eukaryotic cells --- p.18 / Chapter 1.9.2 --- Checkpoints of cell cycle --- p.18 / Chapter 1.10 --- Cancer cell lines --- p.19 / Chapter 1.11 --- The growth phases of cancer cell lines --- p.20 / Chapter 1.12 --- Antiproliferative effects of phenolic compounds --- p.21 / Chapter 1.13 --- Genotoxicity of phenolic compounds --- p.22 / Chapter 1.14 --- Objectives --- p.23 / Chapter 2. --- Methods and Materials / Chapter 2.1 --- Extraction of active substances --- p.40 / Chapter 2.2 --- Determination of antioxidant activities TEAC assay --- p.40 / Chapter 2.3 --- Determination of hydroxy 1 radical scavenging activity by the deoxyribose assay --- p.41 / Chapter 2.4 --- Determination of phenolic contents by Folin´ؤCiocalteu assay --- p.43 / Chapter 2.5 --- Determination of total flavonoid by aluminum chloride colorimetric method --- p.43 / Chapter 2.6 --- Determination of oxidative DNA damage by comet assay --- p.44 / Chapter 2.7 --- Cell lines propagation --- p.49 / Chapter 2.8 --- Determination of antiproliferative activities by MTT assay (colorimetric) --- p.50 / Chapter 2.9 --- Determination of antiproliferative activities by BrdU labeling assay --- p.52 / Chapter 2.10 --- Cell cycle analysis by flow cytometry --- p.55 / Chapter 2.11 --- Determination of genotoxicity by SOS chromotest --- p.57 / Chapter 3. --- Results / Chapter 3.1 --- Dermination of antioxidant activities by TEAC assay --- p.59 / Chapter 3.1.1 --- Trolox Standard Reference --- p.59 / Chapter 3.1.2 --- TEAC of the seven flower extracts --- p.59 / Chapter 3.2 --- Hydroxyl radical scavenging activity by deoxyribose assay --- p.60 / Chapter 3.3 --- Determination of phenolic contents by Folin´ؤCiocalteu assay --- p.60 / Chapter 3.4 --- Determination of total flavonoids by colorimetirc aluminium chloride assay --- p.61 / Chapter 3.5 --- "The Inter-correlation between the antioxidant activities, total phenolic and flavonoid contents of flower extraction powders" --- p.61 / Chapter 3.6 --- Determination of oxidative DNA damage by comet assay --- p.62 / Chapter 3.7 --- Determination of antiproliferative activities by MTT assay --- p.63 / Chapter 3.7.1 --- Antiporoliferative activities on HepG2 --- p.63 / Chapter 3.7.2 --- Antiproliferative activities on MCF7 --- p.63 / Chapter 3.7.3 --- IC50 of R. rugosa extract on both HepG2 and MCF7 --- p.64 / Chapter 3.8 --- "The Inter-correlation between antioxidant activities, total phenolic contents, flavonoid contents, and the antiproliferative activities of flower extraction Powders" --- p.64 / Chapter 3.9 --- Determination of DNA synthesis by BrdU labeling analysis --- p.65 / Chapter 3.10 --- Cell cycle analysis by flow cytometry --- p.65 / Chapter 3.11 --- Determination of genotoxicity by SOS chromotest --- p.66 / Chapter 4. --- Discussions / Chapter 4.1 --- Extraction method --- p.90 / Chapter 4.2 --- Comparison of TEAC of the dry flowers with other foods --- p.90 / Chapter 4.3 --- Correlation between ABTS+ and hydroxyl scavenging ability of flower extraction powder --- p.91 / Chapter 4.4 --- Comparison of phenolic contents of the fry flowers with other foods --- p.92 / Chapter 4.5 --- Correlation between total phenolic contents and flavonoid contents of flower Eextraction powders --- p.92 / Chapter 4.6 --- "Correlation between total phenolic, flavonoid content and antioxidant activities of flower extraction powders" --- p.93 / Chapter 4.7 --- Factors affecting the antioxidant power besides total phenolic contents --- p.94 / Chapter 4.8 --- Synergistic effect of phenolic compounds --- p.94 / Chapter 4.9 --- Toxicity of drinking flower herbal tea --- p.95 / Chapter 4.10 --- Recommended dose of flower herbal teas --- p.96 / Chapter 4.11 --- Antiproliferative activities of flower extracts by MTT assay --- p.97 / Chapter 4.12 --- Antiproliferation activities of flower extraction Powders by Brdu labeling assay --- p.98 / Chapter 4.13 --- Protective effects of flower extraction powder on oxidative DNA damage determined by comet assay --- p.99 / Chapter 4.14 --- Cell cycle analysis --- p.100 / Chapter 4.15 --- Further Studies --- p.101 / Chapter 5. --- Conclusion --- p.102 / Chapter 6. --- References --- p.103

Thesis (PhD (Genetics. Plant Biotechnology))--Stellenbosch University, 2008. / Wine quality is greatly influenced by the number of microorganisms, which occur throughout the winemaking process. These microorganisms are naturally present on the grapes and in the cellar from where they can be introduced to the winemaking process at any given time and consequently impart specific contributions to the wine quality. However, these microorganisms can be seen either as beneficial or as wine spoilage microorganisms, depending on the conditions under which they can proliferate during the winemaking process. Wine yeasts (Saccharomyces spp.) are typically responsible for the alcoholic fermentation; lactic acid bacteria (LAB) are responsible for malolactic fermentation (MLF), while acetic acid bacteria (AAB) and other wild yeasts (non-Saccharomyces spp.) are typically associated with the formation of off-flavours under poorly controlled winemaking conditions. In recent years, evidence from the wine industry has highlighted a specific group of non-Saccharomyces yeast species as a serious cause for wine spoilage that required more research investigations. Yeast of the genus Brettanomyces or its teleomorph Dekkera has been identified as one of the most controversial spoilage microorganisms during winemaking as they can produce several compounds that are detrimental to the organoleptic quality of wine. This has triggered the research initiative behind this doctoral study on the significance of Brettanomyces and Dekkera yeasts during winemaking. In this dissertation, various aspects of the detection, isolation and identification methods of Brettanomyces yeast from the winemaking environment were investigated. As a first objective, a culture collection of Brettanomyces bruxellensis wine isolates had to be established. This followed after the isolation of Brettanomyces yeasts from various red wine cultivars from South African wineries from different stages of the winemaking process. Different conventional microbiological methods such as plating on selective agar media and microscopy were investigated along with molecular identification techniques such as the polymerase chain reaction (PCR) in this regard. Other focus areas of this study aimed at performing genetic characterisation and differentiation studies of B. bruxellensis wine isolates. For this purpose, different intraspecific identification methods were investigated on several strains, including strains of European origin. The application of molecular techniques allowing strain identification aided in the selection of specific strains that were evaluated for volatile phenol production in synthetic media and wine. The results obtained from this work indicated that a large degree of genetic diversity exists among B. bruxellensis strains and that the volatile phenol production differed between the strains after evaluation in synthetic media and wine. In addition to the molecular intraspecific strain identification techniques that were investigated, a feasibility study was also performed that focused on evaluating Fourier transform infrared (FTIR) spectroscopy combined with chemometrics as an alternative approach for differentiating between B. bruxellensis strains. The two approaches of FTIR spectroscopy that were investigated involved the use of firstly, Fourier transform mid-infrared (FTMIR) spectroscopy to obtain spectral fingerprints of spoiled wines by different B. bruxellensis strains; and secondly, Attenuated total reflectance (FTIR-ATR) to obtain spectral fingerprints from whole cells of B. bruxellensis on microbiological agar media. The results of this study illustrated the potential of FTIR spectroscopy to become a reliable alternative to molecular based methods for differentiating between B. bruxellensis strains and for characterisation studies. The formation of volatile phenols in wine by species of the genera Brettanomyces and Dekkera is one of the primary reasons for their classification as wine spoilage yeasts. The enzymatic activities of this reaction have been identified and involve a phenyl acrylic (phenolic) acid decarboxylase (PAD) and a vinyl phenol reductase (VPR). However, only a limited amount of information is available about these enzymes from Brettanomyces/Dekkera yeasts and no genetic data have been described. It was therefore imperative that this dissertation should include a genetic investigation into the phenylacrylic (hydroxycinnamic) acid decarboxylase from the species B. bruxellensis involved in the formation of volatile phenols. Strategies that were investigated included various molecular DNA techniques and protein purification procedures to obtain either genetic or protein sequence data. The decarboxylase activity of this yeast species towards p-coumaric acid was demonstrated and substantial genetic sequence data was obtained. The results from this dissertation made a substantial contribution to the current available knowledge about Brettanomyces/Dekkera spp. and led to a better understanding of this wine spoilage yeast. This research developed a platform from which further investigations could follow and the knowledge gained will be invaluable for future Brettanomyces research projects at the Institute for Wine Biotechnology at Stellenbosch University.

A deterioração oxidativa de alimentos é o fator determinante na qualidade sensorial e nutricional do produto, podendo ocorrer em alimentos complexos tanto na fase contínua como na fase dispersa. Em geral, a formação de radicais e espécies reativas de oxigênio e nitrogênio é o evento primário que ocorre priori ao progresso da oxidação de componentes e estruturas sensíveis e está comumente associado a eventos na fase aquosa. A oxidação de lipídeos é frequentemente investigada em alimentos e em meio biológico separadamente dos eventos no meio aquoso e a proteção antioxidante somente avaliada na fase dispersa. Entretanto, a oxidação de proteínas e eventos na fase contínua vêm despertando considerável interesse e aparentemente antioxidantes eficientes na fase dispersa não protegem de forma eficaz as proteínas e os componentes na fase contínua. Um futuro progresso na proteção antioxidante de alimentos e sistemas biológicos origina de uma abordagem holística dos processos redox envolvidos em ambas as fases dispersa e contínua, bem como o uso combinado de espécies antioxidantes e antiredutoras para um superior efeito antiradical global. Neste sentido, foram preparados três novos compostos antiradicais de dupla função (antioxidante e antiredutor) com adequado balanço hidrofílico-lipofílico e aprimorada propriedade antiradical global. Os antiradicais diferulato de astaxantina, retinoato de quercetina e retinoato de epicatequina se mostraram melhores antioxidantes e antiredutores do que seus precursores isoladamente ou em misturas, apresentando superior eficiência na desativação do oxigênio singlete excitado, captação do radical 1-hidroxietila, menor efeito pró-oxidante em sistemas de oxidação catalisados por íons de ferro, e eficiência na redução do reativo estado triplete da safranina (E1/2 = 1,48 V vs. NHE). / The oxidative deterioration of foods is the determining factor in the sensory and nutritional quality of the product, which may occur in complex food both at the continuous and the dispersed phases. In general, the formation of radicals and reactive oxygen and nitrogen species is the primary event that occurs prior to the progress of oxidation of components and sensitive structures and is commonly associated with events in the aqueous phase. The oxidation of lipids is often investigated in food and biological media separately from the events in the aqueous phase and the measurement of the antioxidant protection is only evaluated in the dispersed phase. However, the oxidation of proteins and the events in the continuous phase have attracted considerable interest and apparently, efficient antioxidants in dispersed phase do not effectively protect proteins and components in the continuous phase. A further progress in the antioxidant protection of food and biological systems arise from a holistic approach of the redox processes involved in both the dispersed and continuous phases as well as the combined use of antioxidant and antireductant species for a superior overall antiradical effect. In this sense three new antiradical compounds with dual function (antioxidant and antireductant) were prepared with proper hydrophilic-lipophilic balance and global antiradical properties. The antiradicals astaxanthin diferulate, epicatechin retinoate, and quercetin retinoate are shown to be better antioxidant and antireductant than their precursors, isolated or in mixture, exhibiting enhanced singlet excited oxygen deactivation, 1-hydroxyethyl radical scavenging, lower pro-oxidative effect in the oxidative system catalysed by iron ions and an efficient reduction of the reactive triplet state of safranine (E1 / 2 = 1.48 V vs. NHE).

Orientador: Rondinelli Donizetti Herculano / Coorientador: Matheus Carlos Romeiro Miranda / Banca: Mariana Nougalli Roselino / Banca: Darío Abel Palmieri / Resumo: O Brasil é o segundo maior produtor de soja do mundo, segundo dados da CONAB para o período 2017/2018, sendo que cerca de 47 milhões de toneladas do grão destinam-se ao consumo interno. A utilização da soja na alimentação humana tem aumentado por diversas razões, dentre elas o fato do grão possuir componentes importantes que conferem propriedades funcionais ao produto. Uma das formas de consumo é o extrato hidrossolúvel de soja (EHS), uma bebida obtida a partir de grãos hidratados de soja que, após a extração, recebe a adição de ingredientes que conferem sabor à bebida, permitindo ainda ser acrescentado de ingredientes que diversificam suas opções de consumo, como frutas e seus extratos, entre outros. A produção do EHS gera uma quantidade expressiva de resíduos, entre eles o okara, que é a massa coesa e úmida proveniente do processo de obtenção do EHS, um material que possui propriedades nutricionais interessantes, possibilitando sua uti-lização in natura e como matéria-prima para a produção de farinha de okara. No pre-sente trabalho foram avaliados a composição química, físico-química, nutricional, microbiológica e atividade antioxidante de grãos de soja, EHS, okara in natura e fa-rinha de okara. Os derivados de soja apresentaram valores nutricionais interessan-tes comparados aos grãos de soja e o EC50 do EHS foi 1,6 vezes menor que do grão de soja, podendo ter algum composto de interesse biológico. Os resultados obtidos pela técnica de EPR foram expressos em Equivalente em ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Brazil is the second largest soybean producer in the world, according to CONAB da-ta for the period 2017/2018, with about 47 million tons of grain destined for domestic consumption. The use of soybean in human food has increased for several rea-sons, among them the fact that the grain has important components that impart func-tional properties to the product. One of the forms of consumption is the water-soluble soy extract, a beverage obtained from soy-grained soybeans which, after extraction, receives the addition of ingredients that confers flavor to the beverage, allowing ad-dition of ingredients that diversify their consumption options, such as fruits and their extracts, among others. The production of EHS generates an expressive amount of residues, among them okara, which is the cohesive and moist mass coming from the process of obtaining EHS, a material that has interesting nutritional properties, ena-bling its in natura use as raw material for the production of okara flour. In the present work the chemical, physical-chemical, nutritional, microbiological and antioxidant properties of soybean, EHS, okara in natura and okara flour were evaluated. The soybean derivatives presented interesting nutritional values compared to soybeans and the EHS EC50 was 1.6 times lower than that of soybeans and could have some compound of biological interest. The results, which were obtained by the RPE tech-nique, were expressed in μg of ascorbic acid per mg of sample (Eq. μg ascorbic acid... (Complete abstract click electronic access below) / Mestre