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- Natural resources with sweetener power: phytochemistry and antioxidant characterisation of Stevia Rebaudiana (Bert.), sensorial and centesimal analyses of lemon cake recipes with S. Rebaudiana incorporationPublication . Silva, Carla Sousa e; Oliveira, Adriana; Pinto, Sara Vanessa; Manso, M. Conceição; Ferreira da Vinha, AnaStevia rebaudiana leaf extracts are calorie-free sweeteners of natural origin, derived from the Stevia rebaudiana plant known as a natural sweetener, which contains steviol glycosides and others bioactive compounds recognized by their biological properties. The present study was designed to evaluate the total phenolics (26.0 mg gallic acid/g) and total flavonoids contents (9.7 mg catechin/g) of a hydroalcoholic extract of Stevia rebaudiana dried leaves. A similar hydroalcoholic extract of commercial powder steviol sweetener was also evaluated, showing lower contents of bioactive compounds (11.9 mg/g and 5.1 mg/g, for total phenolics and flavonoids, respectively). The hydroalcoholic extract of dried Stevia rebaudiana leaves also showed high in vitro antioxidant activity, besides a positive correlation between total phenolic compounds and the DPPH and FRAP assays. Moreover, Stevia rebaudiana leaves have sensory and functional properties superior to those of many other high-potency sweeteners and is likely to become a major source of natural sweetener for the growing food market. Thus, four different lemon cakes formulations were studied (a traditional cake control recipe with sugar, two cakes with incorporation of Stevia rebaudiana fresh leaf and a cake with commercial powder steviol), using a sensory analysis covering 100 untrained consumers. Centesimal composition analyses of the four lemon cakes showed significant differences in fat, ashes, proteins and carbohydrates contents (p<0.05). Also, the raised energy value observed for the cake control was superior to the cake with Stevia rebaudiana leaves incorporation (309.8 Kcal/100 g, 268.0 Kcal/100 g,142 respectively). Sensorial analysis results showed that Stevia rebaudiana leaves were accepted and, in the future, they can be a natural option to replace some or all the saccharose in cakes formulations.
- Novel tetradentate chelators derived from 3-hydroxy-4-pyridinone units: synthesis, characterization and aqueous solution propertiesPublication . Leite, Andreia; Silva, Ana M.G.; Nunes, Ana; Andrade, Mariana; Sousa, Carla; Cunha-Silva, Luís; Gameiro, Paula; de Castro, Baltazar; Rangel, MariaThe synthesis and characterization of three novel tetradentate ligands (T1, T2 and T3) based on 3-hydroxy-4-pyridinone chelating units are described. The three ligands exhibit different flexibility due to the use of two different anchor molecules, piperazine and 1,2-diaminobenzene, and to the diverse length of the 3-hydroxy-4-pyridinone arms. All reactions were performed using both conventional heating and microwave irradiation in order to evaluate the possibility of using greener methods in these synthetic procedures. The results showed that, in all cases, microwave irradiation provides the desired ligands reducing reaction time in ca. 97%. The structure of ligand T3 was resolved by X-ray crystallography, showing significant hydrogen bonding and interesting pep interaction between the benzene and pyridinone rings. The use of potentiometric and spectroscopic methods allowed determination of acidity constants and unequivocal assignment of proton loss for each pKa value. Interaction of the ligands with divalent metal ions was assessed by spectroscopic methods.
- Esteroisómeros na terapêutica com bloqueadores beta-adrenérgicosPublication . Moutinho, Carla; Matos, Carla; Magalhães, Joana; Castro, João; Silva, Carla Sousa eA maioria dos fármacos comercializados atualmente são estereoisómeros, podendo estes apresentarse na forma de enantiómeros ou diastereómeros. Desde que a talidomida causou inúmeros casos de malformações fetais, as indústrias química e farmacêutica aperceberam-se da importância do estudo da quiralidade dos fármacos e das suas propriedades estereoquímicas. A análise da correlação entre a quiralidade e as propriedades toxicológicas e farmacológicas dos compostos levou, não só à eliminação de efeitos adversos, como também a benefícios terapêuticos. Tem surgido uma tendência para a comercialização de novos fármacos sob a forma de enantiómeros puros, pois apresentam vantagens em relação às misturas racémicas. A escolha entre um enantiómero ou uma mistura racémica depende das vantagens terapêuticas, dos efeitos adversos e dos custos de desenvolvimento. Este trabalho evidência as diferenças a nível da atividade biológica e dos parâmetros farmacocinéticos entre os racematos e os estereoisómeros dos bloqueadores β-adrenérgicos. À semelhança do que acontece com outros fármacos, na sua maioria, os bloqueadores β são prescritos como racematos.Contudo, em humanos, os seus S-enantiómeros são muito mais eficazes que os seus antípodas, por exemplo, no tratamento de patologias cardíacas, podendo a purificação e administração do eutómero traduzir-se em benefício clínico para o doente.
- BBr3-assisted cleavage of most ethers does not follow the commonly assumed mechanismPublication . Silva, Carla Sousa e; Silva, Pedro J.Density‐functional computations were used to probe the reaction mechanism of BBr3‐assisted ether cleavage. After the initial formation of an ether–BBr3 adduct, secondary and tertiary alkyl ethers are cleaved through Br– transfer from the activated BBr3 to the alkyl moiety, as postulated in the literature. In contrast, all other ethers studied react through a novel pathway involving two ether–BBr3 adducts, one of which acts as Br– donor, and the second as the reaction substrate. The identification of the novel bimolecular mechanism for this classical reaction has further applications, because it implies that BBr3‐assisted ether cleavage may become impossible if the ether is surrounded by bulky portions of the molecule that prevent the approach of the attacking BBr3 adduct. Our data also allow the construction of an order of reactivity of alkyl ether deprotection: isopropyl, benzyl, tertiary alkyl, allyl, isobutyl and ethyl can be removed sequentially as their bromo derivatives; phenyl, cyanomethyl and chloromethyl groups can be sequentially removed as their corresponding alcohols.
- Ultra-trace elements in human health: selenium, chromium, molybdenum, cobalt, boron and iodinePublication . Silva, Carla Sousa e; Moutinho, Carla; Ferreira da Vinha, Ana; Matos, CarlaEssential ultra-trace elements have an essential role in many physiological processes, regulating enzymes and metabolic pathways, being fundamental for growth, development, muscle and nerve function, normal cellular functioning, and synthesis of some hormones and connective tissue. Nevertheless, excessive levels of these elements can also lead to health problems, as neoplastic diseases. Another field of interest, that has been capturing researcher’s attention for several years, is the possibility of development of pharmacologically active compounds base in these ultra-trace minerals, as anticancer, anti-inflammatories, antidiabetic or antimicrobial agents. This article aims to review the main effects of ultra-trace elements in human health, namely selenium, chromium, molybdenum, cobalt, boron and iodine, focusing on the physiopathology and consequences of deficiency and/or excess of these elements. Also, it offers an overview of research information published in recent years concerning the use of these metals in compounds that show promising pharmacological activities.
- Edible flowers of ornamental plants: a food promise in the sustainability sectorPublication . Pinto, Sara; Oliveira, Adriana; Silva, Carla Sousa e; Ferreira da Vinha, AnaThe growing interest in nutraceutical ingredients and functional foods has increased research into new foods that provide beneficial health. Although flowers were already used as food in ancient times, they have only recently sparked off nutraceutical research focusing on new agronomic and economic horizons, which are part of the concept of sustainability. OBJECTIVES: Having in mind the potential of edible flowers as source of bioactive compounds and related antioxidant activity, this work evaluated the contents of total phenolics and flavonoids, in aqueous extracts of rose (Rosa canina L.), marigold (Calendula officinalis L.) and camellia (Camellia L.). Additionally, the antioxidant activity of all the extracts was evaluated.
- Antioxidant activity of the garlic (Allium sativum L.) submitted to different technological processesPublication . Silva, Carla Sousa e; Novo, Catarina; Ferreira da vinha, Ana
- Coffee industrial waste as a natural source of bioactive compounds with antibacterial and antifungal activitiesPublication . Silva, Carla Sousa e; Gabriel, Carla; Cerqueira, Fátima; Manso, M. Conceição; Vinha, A. F.Coffee is one of the most popular and consumed beverages in the world, which leads to a high contents of solid residue known as spent coffee grounds (SCG). As is known, coffee beans contain several classes of health related chemicals, including phenolic compounds, melanoidins, diterpenes, xanthines and carotenoids which are associated with therapeutic and pharmaceutical effects, due to antimicrobial, antioxidant, anti-infectious and antitumour activities. Considering that this coffee industrial waste has no commercial value and are currently disposed as a solid waste or employed as fertilizers, we intend to highlight the use of SCG as a raw material with potential interest to the food and pharmaceutical industries. Moreover, this work seems to be valuable to promote the use of SCG as natural and an inexpensive food supplements or pharmaceutical additive. The phytochemical compounds content among the crude aqueous extracts of SCG followed this order: phenolics > flavonoids > carotenoids (mg/ g dry waste), respectively. Caffeine content found in SCG was ~ 0.82 g/100 g dry waste, 70 % lower than coffee roasting beans. Coffee ground extracts showed inhibition to S. aureus and E. coli growth for concentrations of 1.0 mg/ mL and a stronger inhibition was also observed against C. albicans, C. krusei and C. parapsilosis growth using lower concentration (0.5 mg/ mL).
- Alimentos funcionais: uma tendência de mercadoPublication . Silva, Carla Sousa e; Passos, Ana Rita; Pereira, Ana Filipa; Ferreira da Vinha, Ana; Ana, NunesA mudança dos hábitos e costumes da sociedade moderna que tem vindo a acontecer nas últimas décadas, conduziu a uma alteração dos padrões alimentares e, consequentemente, a consumidores mais exigentes e atentos aos benefícios que cada género alimentício aporta. Como resposta a esta situação, a indústria alimentar reforçou a sua política de investigação, surgindo um novo tipo de alimentos, denominados alimentos funcionais, os quais são caracterizados como alimentos comuns, integrados na dieta e capazes de produzir benefícios específicos para a saúde. As substâncias biologicamente ativas presentes nos alimentos funcionais podem ser classificadas em: probióticos e prebióticos, alimentos sulfurados e azotados, pigmentos naturais e vitaminas, compostos fenólicos, ácidos gordos polinsaturados e fibras alimentares. Este trabalho teve como objetivo realizar uma revisão bibliográfica fundamentada que sustente a importância dos alimentos funcionais como géneros alimentícios integrantes da dieta alimentar, apresentando as diferentes classes de compostos bioativos que os integram e divulgando os seus efeitos benéficos à saúde. A pesquisa de informação para a realização deste trabalho foi efetuada recorrendo aos motores de busca PubMed, Science Direct, Google Scholar e Scielo. As palavras-chave utilizadas foram, maioritariamente, alimento funcional, ingrediente funcional, componentes bioativos, prebióticos, consumo. A pesquisa bibliográfica teve por base artigos de revisão e estudos experimentais publicados, relacionados com o tema deste trabalho, limitando-se a procura a textos escritos em inglês, espanhol e português. Uma vez que esta revisão pretendeu abranger a evolução dos alimentos funcionais, desde o aparecimento do conceito dos mesmos, no Japão, na década de 80, até aos dias de hoje, a pesquisa realizada teve como limites temporais os anos de 1995 até à atualidade.
- Propriedades biológicas das sementes do mamão (Carica papaya L.): valorização de um resíduo alimentar - reaproveitamento e valorização de subprodutos alimentaresPublication . Maia, Mariana; Silva, Carla Sousa e; Ferreira da Vinha, AnaO interesse pelo reaproveitamento das diferentes partes das frutas e dos vegetais tem vindo a aumentar, não só com o intuito de promover a sustentabilidade ambiental, como também pelas demais propriedades benéficas que têm sido reconhecidas pela comunidade científica. O teor em compostos bioativos das sementes de mamão, que são quase sempre desperdiçadas, levou ao estudo de usos alternativos das mesmas. Neste âmbito, quantificou-se o teor de compostos não-nutritivos das sementes da Carica papaya L., nomeadamente, fenólicos e flavonoides totais, avaliando-se também a atividade antioxidante das mesmas. Os resultados obtidos permitiram concluir que o teor de compostos bioativos extraídos está diretamente relacionado com a natureza do solvente extrator utilizado. Assim, o extrato aquoso obteve maior teor de flavonoides totais, enquanto o extrato etanólico continha maior concentração de fenólicos totais. A atividade antioxidante foi, igualmente, avaliada, usando-se o ácido ascórbico como controlo. Apesar da atividade antioxidante do ácido ascórbico ter sido superior à observada nos dois extratos estudados, estes últimos poderão ser utilizados como antioxidantes naturais, sendo o extrato etanólico o que permitiu obter maior atividade antioxidante. Apesar das evidências de que as sementes de mamão podem ser utilizadas como antioxidantes naturais, nas indústrias alimentar e farmacêutica, torna-se necessário aprofundar a investigação no sentido de avaliar a toxicidade das mesmas.
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