Browsing by Author "Soares, Marta O."
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- Caracterização físico-química, teor em ácido ascórbico e compostos fenólicos do diospyrus kaki, provenientes de diferentes regiões geográficas de Portugal continentalPublication . Calhandro, Márcio; Coutinho, Filipe; Soares, Marta O.; Ferreira da Vinha, Ana; Machado, MarisaO conhecimento da composição química dos alimentos é fundamental para a implementação de uma dieta equilibrada na população portuguesa, com impacto positivo na saúde pública. O objectivo principal desta investigação foi estudar a cultivar caqui-chocolate (Diospyrus Kaki), caracterizando-o fisico-quimicamente e no teor em compostos fenólicos na pele e polpa do fruto, mediante a área geográfica de cultivo. Dos resultados obtidos verificou-se que o teor em compostos fenólicos e actividade antioxidante dos fenóis totais variam com a presença ou ausência de pele (p<0,05) e com a região geográfica (p<0,001). De uma forma geral, os compostos fenólicos são superiores em dióspiros com pele e cultivados na região Sul de Portugal.
- Caracterização química e antioxidante do tomate português (Lycopersicon esculentum Mill.) de cultura biológica e convencional: importância dos sistemas agrícolas no seu valor nutricionalPublication . Ferreira da Vinha, Ana; Coutinho, Filipe; Soares, Marta O.; Santos, António; Almeida-Dias, A.O principal objectivo deste estudo foi o de avaliar e caracterizar o perfil químico e o teor de compostos antioxidantes do tomate português cv. Redondo, cultivado por técnicas agrícolas diferentes (biológica e convencional). Atendendo ao impacto que a dieta mediterrânica tem na saúde pública, também foi estudado, por análise sensorial, o grau de aceitação e diferenciação organoléctica do fruto, produzido em diferentes sistemas agrícolas. Os tomates foram analisados, in natura, como inteiros, sem pele e sem semente. As amostras foram avaliadas quimicamente quanto à actividade de água, humidade, sólidos solúveis totais, pH, cor, teor de ácido ascórbico, teor de fenólicos totais e de licopeno. Para a análise estatística dos resultados, utilizou-se a análise univariada (ANOVA), teste de Tukey e o de t-Stdudent, adoptando-se um nível de significância 167 de 5%. Dos resultados obtidos verificou-se que os teores de compostos fenólicos e ácido ascórbico são superiores no tomate biológico (p<0,05), não existindo significância no teor de licopeno. De uma forma geral, o tipo de preparação doméstica (inteiro, sem pele, sem semente) influencia o valor nutricional do fruto, sendo o tomate inteiro o que apresenta maior valor de compostos bioactivos (p<0,05). O tomate biológico assumiu um papel preferencial na análise sensorial, evidenciando-se a importância dos produtos biológicos na promoção da saúde pública em geral.
- Evaluation of antioxidant and antimicrobial properties of the Angolan Cymbopogon Citratus essential oil with a view to its utilization as food biopreservativePublication . Soares, Marta O.; Ferreira da Vinha, Ana; Barreira, Sérgio; Coutinho, Filipe; Aires-Gonçalves, Sérgio; Oliveira, Maria B.P.P.; Pires, Pedro C.; Castro, AnaIt was studied the chemical composition, antioxidant, antibacterial and antifungal properties of the essential oil obtained from the Cymbopogon citratus of Angolan origin. Its major constituents analyzed by GC-MS were α-citral (40.55%), β-citral (28.26%), myrcene (10.50%) and geraniol (3.37%). The essential oil antioxidant capacity was statistically identical to that of synthetic antioxidants (DPPH IC50 of 41.7 μg/ml) and superior to that of extracts obtained from fresh leaves of the plant (DPPH IC50 of 55.7 μg/ml). The oil also demonstrated to possess high antibacterial activity even against multidrug resistant strains of Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Klebsiella pneumoniae and antifungal activity against Candida albicans and Non-Candida albicans, Candida parapsilosis and Candida tropicalis. The results of this study, in conjunction with already published data on the properties of other Cymbopogon citratus oils, provide evidence that it could have a potential application as food preservative.
- Phytochemical characterization and radical scavenging activity of aqueous extracts of medicinal plants from PortugalPublication . Ferreira da Vinha, Ana; Soares, Marta O.; Castro, Ana; Santos, António; Oliveira, Maria Beatriz P.P.; Machado, MarisaAims: The aim of this study was to evaluate the total phenolic and flavonoid contents of four medicinal plants from Portugal usually consumed as tea infusion, Melissa officinalis (Lamiaceae) – lemon balm, Matricaria chamomilla (Asteraceae) – chamomile, Olea europaea (Oleaceae) – olive leaves, and Aloysia triphylla (Verbenaceae) – lemon verbena. Place and Duration of Study: Air-dried leaves of four of the most consumed medicinal plants from Portugal were analyzed in the Department of Pharmacognosy (UFP) and Laboratory of Bromatology (FFUP) and, Department of Pharmacy, and Chemical Laboratory, Health Technology Research Center (CITS) between June 2010 and September 2011. Methodology: Qualitative phytochemical analysis was done for several phytoconstituents (alkaloids, steroids, terpenoids, flavonoids, and tannins). Total phenolic, flavonoid, and tannin contents were quantified by UV-Vis spectrophotometry. It was also analyzed the possible correlation between antioxidant activity (in vitro) and the synergistic effect between different phytochemicals, using the free radical 2,2’-diphenyl-1-picrylhydrazyl (DPPH•). Results: Steroids, terpenoids, flavonoids and tannin, were present in Melissa officinalis and Matricaria chamomilla. In Olea europaea leaves, all the chemical constituents were present except alkaloids, and terpenoids. Aloysia triphylla showed the presence of all the constituents. Total phenol contents ranged from 12.91mg.100g-1 to 87.25 mg.100g-1 and flavonoid contents ranged from 25.17mg.100g-1 to 57.28mg.100g-1. The screening of the leaf of the four selected medicinal plants indicates that the presence of high phenolic content may be due to the presence of tannins and flavonoids which are known to possess antioxidant activities. A slight correlation has been observed between total phenolics and antioxidant activity. Conclusion: Our findings provided evidence that aqueous extracts of these tested plants from Portugal contain medicinally important bioactive compounds. Results showed that plants from Portugal usually used as tea infusions are a good source of phytochemical compounds presenting antioxidant activity, so their consumption must be incremented in younger generations which usually consume other less beneficial drinks.
- Recent advances regarding the phytochemical and therapeutic benefits of diospyros kaki fruitPublication . Ferreira da Vinha, Ana; Soares, Marta O.; Machado, MarisaLately, several studies have demonstrated the health benefits associated with natural compounds consumption. Fruit phenolics, lycopene and ascorbic acid, have strong antioxidant, anti-inflammatory, antimugenic and anticarcinogenic activities. In the present study parameters related to fruit quality and climacteric conditions, such as color, moisture, pH, water activity, total phenolic compounds, ascorbic acid and lycopene content were analyzed. Diospyros kaki cv. chocolate fruits were extracted with different solvents, such as methanol, ethanol and water. Total polyphenolics of each extract determined by Folin-Ciocalteu method were found to be higher in methanolic extract and lower in ethanol considering Diospyros fruits with peel. Significant variations were found in the levels of these parameters according to different geographic regions. Results support the importance of Diospyros kaki cv. chocolate fruits, Portuguese cultivar, as a functional food with high antioxidant potential that may have beneficial effects against oxidative human damage.