Browsing by Author "Castro, Ana"
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- Comparison between the phytochemical and antioxidant properties of plants used in plant infusions for medicinal purposesPublication . Ferreira da Vinha, Ana; Barreira, Sérgio; Castro, Ana; Machado, MarisaIt has already been acknowledged among the medical community that plant based treatments represent an interesting contribution to modern therapeutics due to the presence in their composition of molecules with pharmacological and antioxidant action. The aim of this study was to evaluate the contents of total phenolics, flavonoids, and caffeine in six plants used traditionally by healers in Portugal and usually consumed as tea or infusion namely: Camellia sinensis, Melissa officinalis, Lippia citriodora, Cymbopogon citratus, Matricaria chamomilla, and Tilia cordata. Total phenolics ranged from 32.05 mg GAE/100g for aqueous extracts obtained from leaves of L. citriodora to 145.28 mg GAE/100g for aqueous extracts of C. sinensis. Significant variations in the flavonoid content were also found among analyzed plants and depending on the nature of the extract, with C. sinensis standing out again with the highest values (78.31 mg CE/100g) and the ethanolic extract obtained from the flowers of T. cordata exhibiting the lowest content (25.15 mg CE/100g). The concentration of caffeine was also very diverse and followed the sequence M. officinalis < T. cordata < C. citratus < M. chamomilla < L. citriodora < C. sinensis. The antioxidant activity of each plant was evaluated in vitro using a standard model system, the DPPH assay, and was found to vary according to C. citratus (90.9%) > C. sinensis (87.8%) > M. officinalis (50.7%) > M. chamomilla (45.3%) > T. cordata (32.2%) > L. citriodora (28.0%). The aqueous extracts presented lower antioxidant activity than the corresponding ethanolic ones.
- 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.
- Food preservative potential of lemongrass (Cymbopogon citratus) essential oilPublication . Soares, Marta De Oliveira; Ferreira da Vinha, Ana; Silva, Carla Sousa e; Castro, Ana; De Pina Catarino Pires, PedroThe economic charges and health implications of food spoilage and food waste handling are increasing. Contamination of food sources by different sources of contaminants remains a major public health concern. In the last decades, researches have focused on developing safer natural products and innovations to meet consumers' acceptance as alternatives to synthetic food preservatives. Many recent novel preservative techniques and applications of both natural and synthetic origin continue to proliferate in food and chemical industries. In particular, some essential oils of plant origin are potent food preservatives and are thus attractive alternatives to synthetic preservatives. For the reasons mentioned above, this studied aimed evaluate 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 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 high antibacterial activity even Aureus, Klebsiella pneumoniae and antifungal activity against Candida albicans and Non-Candida albicans, Candida parapsilosis and Candida tropicalis.
- 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.
- Variation in chemical composition and antioxidant activity of fresh tomato fruit: combined effect of cultivar and storagePublication . Ferreira da Vinha, Ana; Silva, Carla Sousa e; Castro, Ana; Soares, Marta De Oliveira; Oliveira, M. Beatriz P.P.; Costa, A.S.G.Tomato (Lycopersicon esculentum Mill.) is one of the most consumed vegetables in the world and probably the most preferred garden crop. It is a key component of the Mediterranean diet, commonly associated with a reduced risk of chronic degenerative diseases. Currently there are a large number of tomato cultivars with different morphological and sensorial characteristics. Its consumption brings health benefits, linked with its high levels of bioactive ingredients, including carotenoids such as β-carotene, a precursor of vitamin A, and mostly lycopene, which is responsible for the red colour, vitamins in particular ascorbic acid and tocopherols, phenolic compounds including hydroxycinnamic acid derivatives and flavonoids, and lectins. The content of these compounds is variety dependent. Besides, unlike unripe tomatoes, which contain a high content of tomatine (glycoalkaloid) but no lycopene, ripe red tomatoes contain high amounts of lycopene and a lower quantity of glycoalkaloids. Current studies demonstrate the several benefits of these bioactive compounds, either isolated or in combined extracts, namely anticarcinogenic, cardioprotective and hepatoprotective effects among other health benefits, mainly due to its antioxidant and anti-inflammatory properties. This study intended to evaluate the influence of different postharvest cooling conditions in the chemical composition, antioxidant activity and microbiological contamination of tomato cultivars namely: Cereja, Chucha, Rama and Redondo. Pink fruits were kept for 15 days under three different storage temperatures (6ºC, 12ºC and 25ºC) during which their lycopene, ascorbic acid contents, total phenolics and antioxidant activity were evaluated every three days. Counts of colony forming units of coliform bacteria, yeasts and molds and the presence of Escherichia coli, were determined before and after 15 days of storage. All studied parameters revealed that temperature and storage duration caused statistically significant differences in nutritional values of every cultivar. It was observed an increase in the lycopene concentration and antioxidant activity with temperature and storage duration. The phenolic and ascorbic acid contents showed a slight increase during storage at every temperature. Microbial contamination was only found in cultivars that grew in direct contact with the soil (Chucha and Redondo) and bacterial population increased exponentially with storage temperature. Our results indicate that the ideal temperature to maintain optimal physiological, biochemical and microbiological profiles of the cultivars studied is 12ºC and that the cv. Rama fruit is the most suited for consumption in natura.