Obesity and overweight have reached epidemic proportions and their prevalence has increased dramatically in the last decades worldwide. This has resulted in a dramatic increase in the incidence of obesity-associated metabolic alterations including type 2 diabetes, cardiovascular complications, and certain types of cancer. Evidences suggest that bioactive compounds present in fruit and vegetables, including polyphenols (or phenolic compounds), may exert beneficial effects against the development of obesity and associated alterations. Brazil is the world\'s third largest fruit producer and the seventh largest producer of tropical fresh fruits; however, only a few of them are being exploited commercially, perhaps due to the limited amount of information available about their chemical composition, and biochemical, nutritional and functional properties. Cagaita (Eugenia dysenterica DC.) and cambuci (Campomanesia phaea Berg.) are fruit species of the Myrtaceae family growing in the regions of the Brazilian Cerrado and Atlantic Coastal Forest biomes, respectively. Cagaita and cambuci fruits are used in various typical preparations, mainly jams, jellies, ice-cream, and liqueurs; whereas both fruit and leaves are used as popular alternative medicine by local communities to treat various disturbs such as diarrhea, diabetes, and jaundice. Previous studies have demonstrated the antioxidant and antidiabetic potential from cagaita and cambuci polyphenols in in vitro assays. Thus, in the present study, we investigated whether the administration of polyphenol-rich extracts from cagaita and cambuci, at two different doses, protect mice from diet-induced obesity and associated alterations. Two biological models, preventive and therapeutic, were designed for cagaita, and preventive for cambuci. For the preventive protocols, C57BL/6J mice fed either with a chow or a high-fat, high-sucrose (HFHS) diets were daily treated by gavage with water or polyphenols-rich extracts at two doses for 8 weeks. The findings demonstrate that polyphenols from cagaita prevented body weight and fat mass gains, attenuated fasting hyperglycemia and dyslipidemia, and reduced hepatic lipid accumulation. On the other hand, polyphenols from cambuci showed absence of changes in body weight and adiposity; however, an attenuation of adipose tissue inflammation was observed for both doses tested. Additionally, polyphenols from cambuci were effective in ameliorating glucose tolerance, as well as reducing fasting hyperglycemia, and improving dyslipidemia. For the therapeutic protocol, C57BL/6J obese mice induced by the intake of a HFHS diet for six weeks were treated with polyphenols from cagaita at two doses by oral gavage for further 8 weeks. Polyphenols from cagaita improved glucose homeostasis and attenuated dyslipidemia in obese mice, without affecting body weight and adiposity. Mechanistically, these beneficial actions seem to be mediated, at least in part, through a reduction in hepatic inflammation. In conclusion, polyphenols from cagaita and cambuci have a potential protective role in diet-induced obesity and their metabolic alterations. / A obesidade é considerada uma das grandes epidemias do século XXI, devido ao aumento de sua prevalência nos últimos anos e às diversas co-morbidades decorrentes destas alterações metabólicas como diabetes mellitus tipo 2, doenças cardiovasculares e alguns tipos de câncer. Evidências sugerem que compostos bioativos presentes em frutas e vegetais, incluindo os polifenóis (ou compostos fenólicos), podem exercer efeitos benéficos contra o desenvolvimento de obesidade e suas alterações associadas. O Brasil é o terceiro produtor mundial de frutas e o sétimo na produção de frutas tropicais, no entanto, um grande número de espécies frutíferas nativas permanece inexplorado em relação a seu potencial nutricional e funcional. Cagaita (Eugenia dysenterica DC.) e cambuci (Campomanesia phaea Berg.) são espécies frutíferas originárias das regiões do Cerrado e da Mata Atlântica, respectivamente, cujos frutos são usados na elaboração de diversos produtos alimentícios, e frutos e folhas de cagaita são usados na medicina popular. Estudos prévios têm demonstrado o potencial antioxidante e antidiabético in vitro dos polifenóis de ambas as frutas. Neste contexto, no presente estudo, foi investigado se a administração de extratos ricos em polifenóis de cagaita e cambuci, em duas doses diferentes, protegem camundongos de obesidade induzida por dieta a suas alterações associadas. Dois modelos biológicos, preventivo e terapêutico, foram desenvolvidos para cagaita, e preventivo para cambuci. Para os protocolos preventivos, foram usados camundongos da linhagem C57BL/6J alimentados com dieta rica em gorduras e sacarose (high-fat high-sucrose diet, HFHS), aos quais foram administrados água (controle) ou extratos ricos em polifenóis por gavagem em duas doses por 8 semanas. Os resultados demonstraram diferentes efeitos para os dois extratos. Os polifenóis de cagaita preveniram ganho de peso corporal e adiposidade, atenuaram hiperglicemia de jejum e dislipidemia, e reduziram acumulação de lipídeos hepáticos. Por outro lado, polifenóis de cambuci não contribuíram na prevenção do ganho de peso corporal e adiposidade, no entanto, foi observada uma atenuação na inflamação do tecido adiposo, em ambas as doses avaliadas. Adicionalmente, polifenóis de cambuci melhoraram a tolerância à glicose, assim como reduziram a hiperglicemia de jejum e atenuaram a dislipidemia. Para o protocolo terapêutico, camundongos da linhagem C57BL/6J foram induzidos à obesidade pela ingestão da dieta alta em gorduras e sacarose por 6 semanas e posteriormente foram tratados com polifenóis de cagaita, em duas doses, por gavagem por 8 semanas. Os polifenóis de cagaita melhoraram a homeostase glicêmica e atenuaram a dislipidemia em camundongos obesos, sem afetar peso corporal e adiposidade. Estes benefícios aparentam ser mediados, ao menos em parte, através da uma redução da inflamação hepática. Em conclusão, polifenóis de cagaita e cambuci têm um papel protetor potencial em obesidade induzida por dieta e suas alterações metabólicas.

O consumo de dieta hiperlipídica e consequente acúmulo de lipídios nos adipócitos é uma condição associada ao estresse oxidativo e à perpetuação de um quadro inflamatório de leve intensidade que leva ao desenvolvimento de doenças crônicas não transmissíveis. Uma vez que alguns componentes da dieta são reconhecidos como fortalecedores do sistema antioxidante exógeno dos organismos vivos, o objetivo deste trabalho foi investigar o efeito metabólico do extrato de sementes do gênero Passiflora sobre parâmetros bioquímicos, oxidativos e inflamatórios de camundongos submetidos a uma dieta hiperlipídica. Para tanto, inicialmente realizou-se um estudo de composição química (centesimal, teores de minerais e ácidos graxos) e de otimização da extração de sementes de P. edulis Flavicarpa para obtenção de maiores teores de compostos polifenólicos com expressiva capacidade antioxidante in vitro, segundo os parâmetros de processo tempo, temperatura e concentração de etanol. Determinada a condição ideal de extração, esta foi empregada para as demais espécies em estudo P. alata BRS Mel do Cerrado e BRS Doce Mel, P. tenuifila BRS Vita e P. edulis BRS Sol do Cerrado e BRS Gigante Amarelo e P. setacea BRS Pérola do Cerrado e foi realizada o estudo de composição química. Os extratos etanólicos obtidos possuíram interessante atividade antioxidante, com destaque para a espécie P. setacea. O composto piceatanol foi o polifenol majoritário (0,41-10,28 g/ 100 g de semente em base seca) nas sementes de Passifloras analisadas, com exceção para a amostra P. setácea BRS Vita, cujo composto de íon molecular m/z 747,2 não foi identificado. As sementes ainda apresentaram alto teor de óleo, com o ácido linoleico em sua composição, e proteína. Os extratos das sementes de P. setacea BRS Pérola do Cerrado e Passiflora edulis Flavicarpa, nas concentrações de 500 e 1000 mg/Kg de ração foram utilizados para a realização do ensaio biológico. O consumo dos extratos, dependendo da dose, apresentou efeitos biológicos importantes, tais como a diminuição das concentrações séricas de colesterol, glicose, insulina e leptina a níveis aproximados ao determinado para os animais em consumo de dieta normolipídica. Adicionalmente, verificou-se a atenuação do estresse oxidativo hepático, por elevação da atividade enzimática das enzimas catalase e glutationa peroxidase e diminuição da lipoperoxidação, e do processo inflamatório, por redução da concentração tecidual das citocinas IL-6 e MCP-1. Os resultados obtidos neste estudo contribuem para o conhecimento a respeito das passifloras brasileiras e na potencial utilização das sementes, consideradas subprodutos, na contribuição da manutenção da saúde. / The consumption of a high fat diet and consequent excessive lipid accumulation in adipocytes is a condition associated with oxidative stress and perpetuation of a mild inflammatory condition that leads to the development of chronic diseases. Since some dietary components are recognized as empowering exogenous antioxidant system defenses of living organisms, the aim of this study is to investigate the metabolic effects of passion fruit seeds that possess a high content of bioactive compounds and high antioxidant capacity in vitro on oxidative stress and inflammatory conditions in mice subjected to a high fat diet. For this purpose, initially were performed a chemical composition study (proximate, minerals and fatty acids content) and extraction optimization of P. edulis Flavicarpa seed for obtaining higher levels of polyphenolic compounds with expressive antioxidant capacity in vitro through process parameters such as time temperature and ethanol concentration. Once the optimum condition of extraction was determined, it was applied to others studied species P. alata BRS Mel do Cerrado e BRS Doce Mel, P. tenuifila BRS Vita e P. edulis BRS Sol do Cerrado e BRS Gigante Amarelo e P. setacea BRS Pérola do Cerrado and the chemical composition study was carried out. The obtained ethanolic extracts had high antioxidant activity, particularly the species P. setacea. The piceatannol compound was the major polyphenol (0.41 to 10.28 g / 100 g seed in dry basis) in the analyzed Passiflora, except for the sample P. setacea BRS Vita, which molecular íon m/z 747.2 was not identified. The seeds also showed high content of oil, with linoleic acid in its composition, and protein. P. setacea BRS Pérola do Cerrado and Passiflora edulis Flavicarpa seed extracts at concentrations of 500 and 1000 mg / kg of feed were used to carry out the biological assay. The consumption of the extracts, depending on the concentration, exhibited significant biological effects, such as the reduction of serum cholesterol, glucose, insulin and leptin levels to those one observed in animals with normolipidic diet consumption. Additionally, hepatic oxidative stress was attenuated by elevating enzymatic activity of catalase and glutathione peroxidase and decrease in the lipid peroxidation and inflammation by reducing the tissue concentrations of IL-6 and MCP-1 cytokines. The results obtained in this study contributes to the knowledge of the Brazilian passiflora and potential use of the seeds, considered a by-products, in health maintenance.

A degradação oxidativa dos lipídeos é um fator preponderante que limita a vida útil dos alimentos, reduzindo suas qualidades nutricionais e organolépticas. A utilização de antioxidantes durante o processo de fabricação pode diminuir consideravelmente a extensão da oxidação lipídica, desencadeada pela reação de radicais livres. A crescente preocupação pelo consumo de alimentos mais saudáveis e livres de aditivos sintéticos tem recebido maior atenção pelas indústrias, que atualmente tem procurado por alternativas mais naturais, como o uso de antioxidantes provenientes de especiarias, como uma forma promissora de substituição dos compostos sintéticos. O objetivo deste trabalho foi estudar as condições de obtenção de extratos hidroalcoólicos de cravo (Syzygium aromaticum), canela (Cinnamomum verum) e pimenta dedo-de-moça (Capsicum annuum) e sua aplicação em óleos de soja refinado, armazenado em embalagens de vidro, em comparação com amostras adicionadas de antioxidante sintético TBHQ e amostras livres de antioxidantes (controle), durante sete meses, simulando a comercialização em supermercados. Foram verificados também as propriedades antioxidantes dos extratos de especiarias produzidos nas condições selecionadas através das metodologias de DPPH e ABTS. O estudo do efeito da temperatura de extração e do grau de hidratação do etanol sobre o rendimento de compostos fenólicos totais dos extratos destas especiarias foi realizado com aplicação de planejamento experimental e metodologia de superfícies de resposta. As condições para uma extração eficiente dos compostos fenólicos do cravo, da canela e da pimenta foram o emprego de etanol a 49,5 % (v/v). As melhores temperaturas estiveram entre 45 a 50 °C para o cravo e canela, e 60 °C para a pimenta. Os extratos de cravo, canela e pimenta dedo-de-moça preparados nas condições otimizadas, foram adicionados nas proporções de 50 mg kg-1, 100 mg kg-1, 150 mg kg-1 e 200 mg kg-1 às amostras de óleo de soja refinado e submetido a um teste acelerado em estufa a 65 °C juntamente com amostras adicionadas nas mesmas proporções de TBHQ e amostras isentas de antioxidantes (controle), para verificação da concentração mais eficiente no retardar a oxidação. Em seguida, após os resultados do teste de estufa, os óleos adicionados de 100 mg kg-1 de extratos, TBHQ, e isento de antioxidantes foram acondicionados em embalagens de vidro transparente de 250 mL e armazenados sob condições de comercialização (incidência de luz fluorescente por 15 horas / 24 horas e 331,71 Lux). Os resultados de Índice de Peróxido, Acidez e Absortividade na faixa do ultravioleta evidenciaram que os extratos foram capazes de oferecer proteção antioxidante ao óleo de soja refinado em diferentes níveis, sendo que o tratamento adicionado de extrato de cravo foi o que mais se destacou na inibição da oxidação lipídica do óleo de soja, seguido do extrato adicionado de canela e pimenta (p<0,05). / Lipid deterioration is a major cause of shorter food shelf life, reducing its nutritional and organoleptical quality. The use of antioxidants during the manufacturing process can significantly decrease the extent of lipid oxidation reactions triggered by free radicals. The growing concern about the consumption of healthier foods and free from synthetic additives has received increased attention by the industry, which is currently looking for more natural alternatives, such as the use of antioxidants from herbs and spices, as a promising replacement of synthetic compounds. The objective of this work was to study the conditions for obtaining hydroalcoholic extracts of cloves (Syzygium aromaticum), cinnamon (Cinnamomum verum) and red pepper (Capsicum annuum) and its application in soybean oil refined, stored in glass containers, compared with samples added of synthetic antioxidant TBHQ and samples free antioxidant (control) during 7 months simulating marketing conditions in supermarkets. Extracts were analyzed by DPPH and ABTS methods. The study of the effect of extraction temperature and the degree of hydration of ethanol on the yield of total phenolic compounds of the extracts of these spices was carried out with application of experimental design and response surface methodology. The best solvent concentration for efficient extraction of phenolic compounds from clove, cinnamon and pepper was 49.5% ethanol (v / v). The best temperatures were between 45 and 50°C for cloves and cinnamon, and 60 ° C for pepper. The extracts of clove, cinnamon and red pepper prepared under optimized conditions were added in concentration of 50 mg kg-1 , 100 mg kg-1, 150 mg kg-1 and 200 mg kg-1 to samples of refined soybean oil and subjected to an accelerated storage test at 65°C with samples containing the same concentrations of TBHQ and samples free of antioxidant (control) in order to check the most efficient concentrations to slow the oxidation. The best extracts concentration 100 mg kg-1 from the Schaal oven test was added to oil packed in glass containers against oil with 100 mg kg-1 of TBHQ, and oils free of antioxidants and stored under normal commercialization conditions (fluorescence light exposure for 15 hours / 24 hours and 333,71 Lux). Peroxide, acid values and absorptivity in the ultraviolet range showed that the extracts were able to offer antioxidant protection to soybean oil at different levels. Clove extract, showed the best performance in the inhibition soybean oil oxidation, followed by cinnamon and pepper (p<0,05).

Os antioxidantes são substâncias capazes de inibir a oxidação lipídica, responsável pela produção de compostos de cor, aroma e sabor indesejáveis. Na busca por produtos naturais associada à crescente preocupação com a saúde do consumidor, à vista dos possíveis riscos que o uso irregular dos antioxidantes sintéticos pode acarretar ao homem, torna-se essencial verificar a viabilidade do emprego de compostos naturais, com poder antioxidante, em um óleo cuja suscetibilidade à oxidação é reconhecidamente elevada. Com esse objetivo, o presente trabalho avaliou a proteção antioxidante oferecida por extratos hidroalcoólicos de especiarias ao óleo de soja. Os resultados físico-químicos do teor de compostos fenólicos totais, do sequestro do radical livre DPPH (1,1-difenil-2-picrilidrazil), Trolox, da estabilidade oxidativa, através de teste acelerado em estufa e em Rancimat, e da qualidade oxidativa, como o índice de peróxido e a absortividade na faixa do UV, foram base para a seleção dos extratos de alecrim, sálvia, tomilho e orégano, os quais apresentaram maior potencial antioxidante. Os extratos de alecrim, sálvia e tomilho, adicionados ao óleo de soja, foram igualmente eficientes em sua ação antioxidante no teste acelerado em estufa. O óleo, adicionado destes extratos, foi avaliado sensorialmente para verificar o mais preferido pelos consumidores quanto às características de cor, aroma e sabor. Houve uma preferência pelo óleo de soja adicionado de extrato de alecrim. / Antioxidants are compounds able of inhibiting lipid oxidation, responsible for the production of compounds of undesirable color, aroma and flavor. The search for natural products associated with the growing concern over the health of the consumer, in view of the possible risks that the irregular use of synthetic antioxidants can lead to man becomes essential to checking the feasibility of employing natural compounds with antioxidant power, in oil whose susceptibility to oxidation is high. With this purpose, the present study aimed to evaluate the antioxidant protection offered by hydroalcoholic extracts of spices to soybean oil. Analytical results of total phenol compounds, content of kidnapping free radical DPPH (1,1-diphenyl-2-picrilidrazil) substances, Trolox, oxidative stability, through accelerated test in Schaal oven and Rancimat tests, oxidative status, as the acid value and peroxide and absorptivity in the UV range, had been the basis for the selection of extracts of rosemary, sage, thyme and oregano, which presented the highest antioxidant potential. Rosemary, sage and thyme extracts added to soybean oil were similarly efficient as antioxidant in the Schaal Oven Test. Oil added of these extracts were sensorially evaluated according to their colour and flavor. Based on these sensorial characteristics, consumers preferred soybean oil added of rosemary extract.

O buriti (Mauritia flexuosa L.) é um fruto rico em carotenoides, ácidos graxos e compostos fenólicos com grande potencial de industrialização. Entretanto, sua vida útil reduzida dificulta a comercialização e um maior aproveitamento. Dessa forma, tecnologias de processamento podem ser empregadas para que haja maior utilização e expansão do buriti. Este trabalho teve como objetivo caracterizar polpa de buriti congelada, liofilizada e atomizada, quantificando os compostos bioativos (carotenoides e ácidos graxos), a composição centesimal e mineral, além de avaliar a estabilidade química e funcional da polpa submetida a esses tratamentos ao longo do tempo de armazenamento. Polpas de buriti oriunda da Comunidade Boa Vista, zona rural do município de Arinos, MG, foram submetidas a três processamentos: congelamento (eleito como controle), liofilização e atomização (com adição de maltodextrina como coadjuvante de tecnologia). Após o processamento, as polpas foram acondicionadas em embalagens laminadas compostas por poliéster, alumínio e polietileno (25 x 25 cm), com capacidade para 100 g cada, e armazenadas a -23 °C para o congelamento e a temperatura ambiente para as polpas desidratadas. As análises físicas, químicas, nutricionais e funcionais foram realizadas logo após o processamento, para caracterização das polpas e nos períodos: 1, 14, 28, 42 e 56 dias, para avaliação da estabilidade. O delineamento experimental empregado constituiu-se de dois fatores (processamento e período) e a interação entre eles. Os dados foram analisados estatisticamente por meio da Análise de Variância Univariada (ANOVA) com nível de significância de 5 %. Constatou-se que durante a estocagem a polpa liofilizada apresentou maior brilho, menor opacidade, valores inferiores para o pH, menor variação da atividade de água e maior acidez titulável. Esses parâmetros são importantes indicadores de qualidade da polpa durante a sua estocagem, visto que dificultam o desenvolvimento microbiano. A adição da maltodextrina no processo de atomização acarretou maiores teores de sólidos solúveis em relação aos demais tratamentos. Os resultados demonstraram que, ao longo do armazenamento, a liofilização contribuiu para a melhor preservação dos carotenoides totais. A quantificação dos carotenoides e dos ácidos graxos na polpa congelada demonstrou que houve melhor preservação de carotenoides do tipo alfa e beta caroteno, dos ácidos graxos oleico, indicando maior valor nutricional para a alimentação humana. Apesar dos resultados satisfatórios para a polpa congelada, durante o tempo analisado a polpa congelada apresentou maiores perdas em relação à polpa liofilizada. Para a classe dos compostos fenólicos, a liofilização apresentou melhores resultados ao longo da estocagem. O uso de baixas temperaturas foi mais efetivo para a preservação dos compostos bioativos analisados. Portanto, pode-se concluir que o emprego da liofilização é a alternativa mais adequada entre as avaliadas, para o aproveitamento da polpa de buriti na indústria de alimentos, uma vez que esse tratamento preservou todos os constituintes avaliados durante a estocagem. / The Buriti (Mauritia flexuosa L.) is a fruit rich in carotenoids, fatty acids and phenolic compounds with great potential for industrialization. However, its limited life difficults commercialization and better use. Thus, processing technologies can be employed for greater use and expansion of Buriti. This study aimed to characterize frozen, lyophilized and atomized pulp of Buriti, quantifying the bioactive compounds (carotenoids and fatty acids), the centesimal and mineral composition, as well as evaluating the chemical and functional stability of the pulp subjected to these treatments over the time of storage. Pulps of Buriti coming from the Community of Boa Vista, countryside of Arinos, MG, were subjected to three processing: freezing (chosen as a control), lyophilization and atomization (with the addition of maltodextrin as a supporting technology). After processing, the pulps were stored in laminated packages composed of polyester, aluminum and polyethylene (25 x 25 cm) with a capacity of 100 grams each, and stored at -23 ° C for freezing and at room temperature for dehydrated pulps.The effects of the treatments of frozen pulp (control), lyophilized and atomized obtained from fruits of buriti palm (Mauritia flexuosa L.), associated with temperature and storage periods were analysed in order to evaluate the effect of atomization and lyophilization, comparing them to the effects of the freezing process, elected as control and quantify bioactive compounds (carotenoids and fatty acids), the chemical composition, mineral, presence of phenolic compounds and their variations over time. The physical, chemical, nutritional and functional analysis were performed in the periods: 1, 14, 28, 42 and 56 days. The experimental design consisted of two factors (processing and period of storage) and the interaction between them. Data were statistically analyzed by Analysis of Variance (ANOVA) with 5% of significance level. During storage of the freeze-dried pulp the results showed higher brightness, lower opacity, lower values for pH, smaller variation of aw and higher titratable acidity. These parameters are important indicators of pulp quality during storage. The addition of maltodextrin in the atomization process led to higher soluble solids compared to other treatments. The results showed that, during storage, lyophilization contribute to the better preservation of carotenoids. The quantification of carotenoids and fatty acids in frozen pulp showed that there were better preservation of alpha carotenoids, beta carotene, and oleic fatty acids, indicating a higher nutritional value for human consumption. Although the results for the frozen pulp were satisfactory, during the time, examined frozen pulp showed greater losses compared to the lyophilized pulp. For the group of phenolic compounds, lyophilization showed better results over storage. The use of low temperatures was more effective for the preservation of bioactive compounds that were analysed. Therefore, it can be concluded that the use of lyophilization is the most appropriate alternative among the other ones for the use of burity pulp in the food industry, since this treatment preserved all constituents evaluated during storage.

Esta tese descreve a preparação, caracterização e desenvolvimento de biossensores baseados na imobilização de enzimas em filmes nanoestruturados. Os filmes foram obtidos pela técnica de automontagem do inglês Layer-by-Layer (LbL) ou pela técnica de Langmuir-Blodgett (LB). A tese se divide em três partes: a primeira parte teve como objetivo o estudo e a aplicação de filmes finos nanoestruturados, contendo enzima tirosinase (Tyr), em biossensores para detecção de moléculas antioxidantes (polifenóis), visando sua aplicação na indústria de alimentos, em especial a de vinhos tintos. Foi utilizada a técnica LB para a imobilização da enzima Tyr sobre substratos sólidos (ITO ou Pt) sem que a enzima perdesse sua atividade. A enzima foi incorporada a filmes LB mistos de ácido araquídico (AA) e bisftalocianina de lutécio (LuPc2) pela injeção na subfase aquosa. A LuPc2 foi usada como mediadora de transferência de cargas. Foi possível a detecção do composto fenólico representativo pirrogalol. Estudos de voltametría cíclica demonstraram que o biossensor possui uma boa reprodutibilidade com desvio padrão de ca. 2% (n = 4), limite dinâmico de até 400 \'mü\'M (potencial aplicado de 0,4 V; R2: 0,993), sensibilidade de 1,54 \'mü\'A.\'mü\'M POT.-1/\'CM POT.2\' e limite de detecção (critério 3\'sigma\'0/m) de 4,87 x \'10 POT.-2\' \'mü\'M (n = 10). A segunda parte do trabalho descreve o desenvolvimento de sensores eletroquímicos baseados em filmes automontados LbL de hidrocloreto de polialilamina (PAH) e LuPc2. A motivação para o estudo foi a troca do material biológico (Tyr) pela LuPc2, a qual possui poder catalítico e relativa seletividade, capaz de mimetizar algumas proteínas. A LuPc2 foi utilizada como enzima artificial na quantificação de catecol e pirogalol como representantes de compostos fenólicos. Em medidas de voltametria, o sensor automontado de PAH/LuPc2 apresentou boa linearidade (R2 = 0,992) na faixa de até 500 \'mü\'M, com uma sensibilidade de 90 nA/\'mü\'M e limite de detecção de 8 \'mü\'M. Nas medidas cronoamperométricas, os sensores apresentaram uma ampla faixa linear (R2 = 0,994; tempo de resposta de 60 s) de até 900 \'mü\'M e limite de detecção (LD) de 37,5 x \'10 POT.-8\' M (sensibilidade de 20 nA/\'mü\'M) para o catecol. Por fim, estudou-se a fabricação de filmes LbL baseados em dendrímero poli(propileno imina) (PPID) e metaloftalocianina tetrasulfonada de níquel (NiTsPc) em sensores baseados em transistores de efeito de campo (FET). Neste caso, os filmes foram utilizados como membranas sensíveis na aplicação de sensores de pH e \'H IND.2\'O IND.2\'. Também se demonstra a importância de se utilizar estruturas dendríticas nesse tipo de filme, comparando estes filmes com aqueles contendo um polieletrólito fraco linear (PAH). Foi dada ênfase à fabricação dos filmes pela técnica LbL e sua aplicação em sensores do tipo FET de porta estendida e separada (SEGFET). Filmes LbL baseados em enzimas artificiais se mostram bastante promissores em aplicações reais por serem relativamente baratos e simples, possibilitando o uso de variados tipos de materiais. A utilização desses filmes em dispositivos baseados em estruturas SEGFET possibilita a miniaturização dos sensores bem como sua produção unindo técnicas convencionais de fabricação microeletrônica. / This thesis describes the preparation, characterization and development of biosensors based on nanostructured films containing immobilized enzymes and metallophthalocyanines. The films were obtained using the Layer-by-Layer (LbL) or Langmuir-Blodgett (LB) techniques. In the first part of the thesis we describe the development of nanostructured thin films containing the enzyme tyrosinase (Tyr) and their use as biosensors for detection of antioxidants molecules (polyphenols), which find applications in the food industry, specialy red wines. The enzyme was incorporated into the mixed LB films of arachidic acid (AA) and lutetium bisphthalocyanine (LuPc2) by injection into the aqueous subphase followed by transference to ITO or Pt electrodes. The representative phenolic compound molecule to be detected was pyrogallol. Cyclic voltammetry studies shown that the biosensor response is highly reproducible with a standard deviation of ca. 2% (n = 4), dynamic range up to 400 \'mü\'M (applied potential of 0.4 V; R2: 0.993), sensitivity of 1.54 \'mü\'A/\'mü\'M.\'CM POT.2\' and detection limit (3 \'sigma\'0/m criteria) of 4.87 x \'10 POT.-2\' \'mü\'M (n = 10). The second part of this thesis focus on the development of electrochemical sensors based on LbL films of poly(allylamine hydrochloride) (PAH) and LuPc2. The purpose of the study was to change the biological material (Tyr) by LuPc2. LuPc2 was used as an artificial enzyme in the quantification of catechol and pyrogallol as representative of phenolic compounds. In voltammetric measurements, the LbL PAH/LuPc2 sensors presented good linearity (R2 = 0.992) in the range up to 500 \'mü\'M with a sensitivity of 90 nA/\'mü\'M and detection limit of 8 \'mü\'M. As revealed by chronoamperometry measurements, the sensors exhibited a wide linear range (R2 = 0.994; response time of 60 s) up to 900 M and detection limit of 37.5 × \'10 POT.-8\' \'mü\'M (sensibility of 20 nA/\'mü\'M) for catechol. Finally, we investigated the fabrication of LbL films based on poly(propylene imine) dendrimer (PPID) and nickel tetrasulfonated phthalocyanine (NiTsPc) as active elements in devices based on field effect transistors (FET). The films were used as sensitive membranes applied as pH and \'H IND.2\'O IND.2\' sensors. It was shown the importance on the LbL technique and its application in FET-based sensors such as the separated and extended gate FET (SEGFET). LBL films based on artificial enzymes exhibit great promise in real applications due to their low cost and simplicity. The use of these films in devices based on SEGFET structures allows miniaturization of the sensors and their production combining conventional microelectronics fabrication and nanotechnological tools.

Philosophiae Doctor - PhD / Fusarium verticil/ioides (Sacc) Nirenberg a common phytopathogen of maize and maize-based products produces fumonisin B (FB) mycotoxins that have been related to several diseases such as equine leukoencephalomalacia (ELEM), porcine pulmonary edema (PPE), liver toxicity in several animals and esophageal and liver cancer in humans. In one of our studies we hypothesize that aqueous extracts of indigenous South African wild garlic species (Tulbaghia violacea, T. alliacea and T. simmleri) may enhance the efficacy of the fungicides, SporekilPu, Thiram, Itraconazole and Fluconazole against F. verticil/ioides (MRC 826). Data analysis from in vitro results indicates that for the 16 different mixtures of each plant extract and fungicide combination, several significantly (P<O.05) higher growth inhibition responses were produced. More synergistic interactions were observed for the combinations of sporekill with T. violacea (62%) and T. alliacea (75%) than for T. simmleri (25%) .. Mixtures between the azole fungicides and T. simmleri produced 94 % synergistic interactions. Combination of fungicides and plant compounds offers the opportunity to find synergistic mixtures and may validate disease control strategies with increased biological activity and low dose rate application. Modulation studies of hepatic drug metabolizing enzymes and oxidative properties of AI/ium sativum, Tulbaghia violacea and T. alliacea in male Fischer rats were also evaluated. Due to its complex phytochemical composition a battery of assays were used to evaluate antioxidant potential. The extracts exhibited no adverse effects in the liver and kidneys of the rats. Total plasma iron was not affected showing no evidence for iron catalyzed lipid peroxidation. An increase was noted in hepatic ORAC values for rats consuming T. violacea and T. al/iacea. However, no correlation was observed between the phenolic intake by the rats and the increased hepatic ORAC levels. In this study, pre-treatment with aqueous extracts of T. violacea, T. al/iacea and A. sativum resulted in a significant elevation in GSH levels, induction of GST -IJ and UDP-GT and modulation of CAT and SOD. This modulated oxidative status and phase II drug metabolizing enzymes in the liver may protect the liver against the adverse effects related to oxidative damage and mutagenesis. The chemoprotective properties of crude aqueous extracts of A. sativum, T. violacea and T. alliacea were investigated on preneoplastic foci formation promoted by culture material of F. verticil/ioides MRC 826 utilizing diethylnitrosamine (DEN) as cancer initiator. Clinical chemical parameters related to liver and kidney function and decreased body weight gain suggesting that severe, acute liver injury had been induced in the positive control (DEN-eMF) rats, while the levels were mostly reduced by the garlic treatments. This study further indicates that T. alliaceae (2 % w/v) and A. sativum (1% w/v) treatment suppressed GST-P+ foci formation with the modulation of GST-0 phase II detoxification enzymes, as well as the antioxidant enzyme, SOD (T. alliaceae) and decreased GSH levels as being possible mechanisms of protection. These results provide new evidence showing the modulation of phase II drug metabolizing enzymes and the oxidative status in the liver of rats by the wild garlic species as well as A. sativum.

<p>Entomophagy, which is the habit of eating insects, has become relevant in the past few years as it could potentially help reduce current and future food insecurity, due to the highly nutritious and sustainable characteristics of edible insects. In addition to the nutritional content of insects, research on the potential bioactive components of insect extracts has also gained popularity. In this study, extracts from house cricket (<i>Acheta domesticus</i>) from two farms and their corresponding feeds were obtained using a microwave-assisted extraction. Further phenolic characterization led to the identification and quantification of 4-hydroxybenzoic acid, <i>p</i>-coumaric acid, ferulic acid and syringic acid as major phenolic compounds in both <i>A. domesticus </i>extracts as well as both feed extracts. Additionally, <i>in vitro</i> antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl radical cation (DPPH) and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical assays. In both <i>in vitro</i> assays, <i>A. domesticus</i> extracts showed higher antioxidant activity compared to the feeds. Antibacterial activity against <i>E. coli</i> and <i>L. innocua</i> was also evaluated using the microwell method. The <i>A. domesticus </i>extracts showed a selective inhibition (p<0.05) towards the gram-positive bacteria <i>L. innocua </i>between a period of 4 to 8 h. This inhibition is thought to have occurred as a result of the presence of phenolic acids and antimicrobial peptides, while the feed extracts did not exhibit any inhibitory activity towards any of the bacteria. The finding of the same phenolic acids in <i>A. domesticus</i> and their corresponding feed could imply the capacity of <i>A. domesticus</i> to absorb and sequester dietary phenolics that may provide additional health benefits when the insect is consumed, unveiling new benefits of entomophagy. </p>

Presented thesis deals with the complex characterization of extracts from medical plants using spectroscopic and chromatographic techniques, with emphasis on the influence of solvent, post-harvest treatment of the sample, location and year of production on selected parameters. Part of the work is devoted to application of selected extracts from medical plants in suitable form into beverages. The thesis is divided into two parts. At the first part of the work combination of electron paramagnetic resonance, ultraviolet visible spectroscopy, liquid chromatography and inductively coupled plasma optical emission spectrometry was applied for characterization of aqueous, ethanol and dimethylsulfoxide extracts from 10 selected medical plants, which were collected from two different locations during two years (2015, 2016) and post-harvestly treated by two ways (freezing, drying). In total, 39 parameters were determinated: namely total phenolic compounds content, total flavonoids content, 14 specific phenolic compounds, colour characteristics in the CIE L*a*b* system (L *, a*, b *, C*, h°, BI), radical-quenching activity using the cation radical of the 2,2'-azino-bis- (3-ethylbenzothiazoline-6-sulfonic acid), antioxidant/pro-oxidant activity using the spin trapping technique in the presence of 5,5-dimethyl-1-pyrrolin-N-oxide (DMPO)/potassium peroxodisulphate and content of 15 minerals (Al, As, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, P, Pb, Zn). The results confirmed that the studied parameters of medical plants are influenced by the extraction system, post-harvest treatment of samples, year of production, origin of samples (locality) and species composition. It has been shown that the type of extraction solvent significantly affects the composition of the extracts. On the basis of these analyzes, for food application – the isolation of the main functional components (phenolic compounds, flavonoids) –50% ethanol, post harvest treatment by drying and samples of Mentha piperita, Melissa officinalis, Hypericum perforatum and Salvia officinalis were selected. The second part of the thesis was focused on the application of selected extracts of medical plants to beverages (syrups). The above mentioned plants, 25% ethanol instead of 50% ethanol (due to the limitation of the ethanol content in final raw material), were selected for the application. At first, extraction of medical plants was optimized. Suitable ratio of material and solvent (1:10), extraction time (8 h) and herb absorbency (50–62 %) were determined. The prepared extract after filtration was applied to the syrup concentrate in different ratios to produce one-species syrups and further sensorially tested to select the suitable recipe, the best flavour and basis for the production of two-species syrups. The mint syrup was the most tasty and generally the most acceptable one-species syrup, and sage syrup was selected as the basis for two-species syrups. Further, the most appropriate recipes of the two-species syrups were chosen, the most sensorially acceptable one was selected and further tested if it would be appropriate to colour them. Preferentially, it has been found that it is not necessary to colour two-species syrups. On the basis of the sensory analysis, it has been found that peppermint and sage-peppermint syrups were the most tasty and acceptable syrups, which could be, after further testing, produced industrially to enrich the food market.

Presented diploma thesis deals with the analysis of juices of selected red and white currant varieties. The theoretical part is dedicated to the characteristics of a currant, biologically active substances of its fruits, its growing proces and the utilization of currants in the food industry. The analyzed parameters of currants - phenolics, anthocyanins and vitamin C are also characterized in the theoretical part with possibůe methods of their determination. The experimental part is devoted to the preparation of samples and the working practices of individual analysis. Six selected varieties of white and eleven varieties of red currant from Research and Breeding Institute of Pomology Holovousy Ltd. and six varieties of white and ten varieties of red currant from private grower were used for the analysis. Total phenolics and anthocyanins were determined spectrophotometrically, the content of vitamin C was determined by HPLC. Higher values of these compounds were measured mainly in the varieties of Research and Breeding Institute of Pomology Holovousy Ltd. Varieties of red currants contained higher amounts of total phenolics and anthocyanins while white currants contained higher amounts of vitamin C.