Browsing by Author "Dandlen, S. A."
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- Acetylcholinesterase Inhibition Activity of Portuguese Thymus Species Essential OilsPublication . Dandlen, S. A.; Miguel, Maria Graça; Duarte, J.; Faleiro, Leonor; Sousa, M. J.; Lima, A. S.; Figueiredo, A. C.; Barroso, J. G.; Pedro, L. G.Thymus species are commonly known in Portugal as thyme and they are currently used as culinary herbs, as well as for ornamental, aromatizing and traditional medicinal purposes. The essential oils isolated from the Portuguese Thymus caespititius (Sect. Micantes), T. camphoratus and T. capitellatus (Sect. Thymus, Subsect. Thymastra), T. carnosus, T. zygis subsp. sylvestris and T. zygis subsp. zygis (Sect. Thymus, Subsect. Thymus) were evaluated for acetylcholinesterase inhibition capacity. A great variability in activity was detected in the assayed essential oils, even among oils isolated from a same species with different geographical origins, such as T. caespititius. T. zygis subsp. zygis essential oil showed the strongest acetylcholinesterase inhibition capacity with an IC50 = 1.1 mu g/ml.
- Antimicrobial activity, cytotoxicity and intracellular growth inhibition of Portuguese Thymus essential oilsPublication . Dandlen, S. A.; Lima, A. S.; Mendes, M. D.; Miguel, Maria Graça; Faleiro, Leonor; Sousa, M. J.; Pedro, L. G.; Barroso, J. G.; Figueiredo, A. C.Thyme essential oils are well recognized by their excellent biological activities and the antimicrobial activity of Portuguese thyme essential oils has been investigated with promising results, particularly against food borne pathogens. In this study the potential antimicrobial activity of the essential oils of five species of Thymus (Lamiaceae), namely Th. caespititius Brot., Th. camphoratus Hoffmanns. & Link, Th. capitellatus Hoffmanns. & Link., Th. carnosus Boiss. and Th. zygis L. was evaluated against Candida albicans, Haemophilus influenza, Helicobacter pylori, Listeria monocytogenes, Salmonella enterica and Streptococcus pneumoniae. H. pylori strains were the most susceptible bacteria, particularly to the essential oils of Th. caespititius (Planalto Central), Th. zygis (Rebordaos) and Th. caespititius (Pico) which minimum inhibitory concentration (MIC) values ranged from 0.05 to 0.08 mg. mL(-1). Th. caespititius essential oil from Planalto Central or its main component, carvacrol significantly (p<0.05) inhibited the intracellular growth of H. pylori, and showed no citotoxicity to the gastric cell line. Our results suggest the potential of this essential oil and its main component as a promising tool as anti-Helicobacter agent potentiating the eradication of this important gastroduodenal pathogen.
- Antioxidant activity of six Portuguese thyme species essential oilsPublication . Dandlen, S. A.; Sofia Lima, A. S.; Mendes, M. D.; Miguel, Maria Graça; Faleiro, Leonor; Sousa, M. J.; Pedro, L. G.; Barroso, J. G.; Figueiredo, A. C.The essential oils of Thymus caespititius, T. camphoratus, T. capitellatus, T. camosus, T. pulegioides, T. zygis subsp. zygis and T. zygis subsp. sylvestris collected in different regions of Portugal, including the Azores islands, were evaluated for preventing lipid peroxidation and scavenging free radicals, and hydroxyl and superoxide anions. T. zygis subsp. zygis oil possessed the best capacity for preventing lipid peroxidation (IC(50) = 0.030 +/- 0.003 mg/ml), immediately followed by the oils isolated from T. zygis subsp. sylvestris collected in different regions of Portugal. IC(50) values ranged from 0.066 +/- 0.003 to 0.087 +/- 0.001 mg/ml in oils isolated from samples from Alcanena and Duas Igrejas, respectively. The oils isolated from T. zygis subsp. sylvestris, independent of the harvesting region, were shown to be the most effective for scavenging free radicals (0.358- 0.453 mg/ml). The best capacity for scavenging hydroxyl radicals was found in the oils of T. camphoratus collected in Espartal and of T. caespititius of Lordelo, with IC(50) < 0.5 mg/ml. The low oil amount did not allow IC(50) values for the superoxide anion scavenging determination, therefore considering a unique oil concentration (5 mg/ml), the highest inhibition percentages (>50%) were registered with the essential oils of T. zygis subsp. sylvestris from Duas Igrejas and Covao do Coelho, and of T. capitellatus from Sines. Copyright (C) 2010 John Wiley & Sons, Ltd.
- Ascorbic acid and flavanone glycosides in citrus: Relationship with antioxidant activityPublication . Miguel, Maria Graça; Duarte, Amílcar; Nunes, S.; Sustelo, V.; Martins, D.; Dandlen, S. A.The effects of cultivar and orchard on the content of ascorbic acid and flavanone glycosides as well as on the antioxidant activity of citrus juices were studied. Ascorbic acid and flavanone glycosides were determined using HPLC method. For antiradicalar activity evaluation, TAEC and ORAC methods were used. Citrus of 'Valencia late' from Faro and 'D. Joao' presented the highest levels of hesperidin in contrast to the citrus of 'Valencia late' from Silves with 0.4 mg/ml, a value closer to those of Navel oranges 'Navelate' and 'Lanelate'. Citrus of 'Valencia late' from Silves and 'D. Joao' presented the lowest levels of narirutin. 'Ortanique' and 'Encore' cultivars were poorer in ascorbic acid compared with the oranges. When the TEAC method was used for the determination of antioxidant activity, 'Valencia late' from Faro presented the best activity. A good relation was observed between antiradical activity measured through the TEAC method and the amount of ascorbic acids in samples. None relation was found between the levels of flavanones and antiradical activity. When the ORAC method was applied, the best activity was found for 'Navelate' and 'Encore' samples and practically none relation between this method and the amounts of ascorbic acid and flavanones was found.
- Composition and biological activity of the essential oil peruvian lantana camaraPublication . Benites, J.; Moiteiro, C.; Miguel, Maria Graça; Rojo, L.; Lopez, J.; Venancio, F.; Ramalho, L.; Feio, S.; Dandlen, S. A.; Casanova, H.; Torres, I.The composition of the essential oil from Lantana camara L. (Verbenaccae) obtained by hydrodistillation of the aerial parts was examined by GC, GC/MS, and (13)C-NMR. The GC analysis showed that carvone is the most abundant monoterpene 75.9%, together with limonene 16.9%, accounting for 92.8% of the oil. The major components were also tested by (13)C-NMR analysis of the essential oil. The L. camara oil was assayed against several microorganisms, showing moderate antibacterial activity against the human pathogen Staphylococcus aureus (MIC 200 mu g/ml). High antioxidant activity evaluated by the Trolox equivalent antioxidant capacity assay (TEAC) was found (29.0 mmol Trolox/kg) and relative low anti-inflammatory activity due to its weak ability for inhibiting lipoxygenase (IC(50) = 81.5 mu g/ml).
- Effect of 1-Methylcyclopropene application prior to storage on fresh-cut kiwifruit qualityPublication . Antunes, Maria Dulce; Miguel, Maria Graça; Metelo, S.; Dandlen, S. A.; Cavaco, A. M.Kiwifruit is commercially important as fresh-cut. The purpose of this work was to study the effect of 1-methylcyclopropene (1-MCP) applied after harvest, before storage, on the posterior behaviour of ripe fruit prepared as fresh-cut. Harvested fruit where treated with 1 mu l L(-1) 1-MCP for 20 hours at room temperature, then stored at 0 C. After 3 months, fruit were removed from storage, peeled and cut longitudinally in quarters, then stored at 2 C for 8 days. Measurements of flesh colour, firmness, soluble solids content (SSC), electrolyte leakage and ascorbic acid were performed after 0, 4 and 8 days. Kiwifruit treated with 1-MCP showed higher firmness and lower a* value, electrolyte leakage and SSC than the control, after 3 months storage. Values of a* and electrolyte leakage increased through fresh-cut storage and after 8 days differences between treatments become almost nil. SSC did not change in fruit treated with 1-MCP, while it increased after 4 days and decreased on 8(th) day in the control. Firmness decreased through fresh-cut storage, being higher in 1-MCP treated fruit than control except on 8(th) day. Ascorbic acid which was higher in control, showed a higher decrease on those fruit and after 8 days was similar in both treatments. Panellists did not find significant differences between treatments, except that 1-MCP treated fruit had better appearance. The application of 1-MCP immediately after harvest showed beneficial effects in keeping kiwifruit quality during 3 months storage, and its effect lasted through shelf-life of those fruit when used as fresh-cut.
- Evaluation of Fe deficiency effects on strawberry fruit qualityPublication . Gama, Florinda; Saavedra, T.; Miguel, Maria Graça; Dandlen, S. A.The effects of Fe deficiency on the antioxidant properties of strawberry juice was carried out with a day-neutral cultivar 'Selva'. Bare root transplants (without leaves) with approximately 18 cm, were transferred to Hoagland's nutrient solution with (Fe2.5) and without Fe (Fe0), using Fe-EDDHMA as the Fe source: 0 and 2.5 5 μM Fe. Plants were grown in 20 L containers in a glasshouse for 6 weeks (from April 27 to June 5) under natural light and air temperature ≤ 25°C. Twelve transplants were used per treatment, distributed in a complete randomized design. Plants grown in absence of Fe revealed chlorotic symptoms approximately after three weeks, based on SPAD values measured in young leaves (<20). The other treatments did not show any symptoms during the experiment. Fruits were harvested from each treatment, and juice was analysed for antioxidant activity by using the free radical α-α-diphenyl-β-picrylhydrazyl capacity (DPPH•), the Trolox equivalent antioxidant capacity (TEAC) and oxygen radical absorbance capacity (ORAC) assays. In addition, fruits were analysed for total phenols and some organic acids. The phenolic content varied between 1251 and 1514 mg gallic acid equivalents (GAE) L-1 juice, respectively, in Fe0 and Fe2.5 treatments, but with no significant differences. Despite the same total soluble solids values in both treatments, it was found that Fe depletion reduced significantly the anthocyanins and total phenols of the fruits. However, ascorbic acid increased as well as antioxidant activity expressed by both DPPH and TEAC methods.
- Identification of an RNA silencing suppressor encoded by Grapevine leafroll-associated virus 3Publication . Gouveia, P.; Dandlen, S. A.; Costa, A.; Marques, N T.; Nolasco, GustavoGLRaV-3, a member of the Closteroviridae family and type member of the genus Ampelovirus, is involved in the grapevine leafroll disease. Until now no RNA silencing suppressor has been found among viruses of this genus, contrary to what happens with a large number of other viral genera. In the sister genus Closterovirus, RNA silencing suppressors are present in the 3' end of the genome and have molecular weights close to 20 KDa. To test for RNA suppressing activity screening of p21, p19.6 and p19.7 proteins, coded for in an analogous genomic location of the GLRaV-3 was undertaken. Only p19.7 revealed suppressor activity demonstrated in diverse silencing inducing systems. This suppressor is able to overcome strong silencing inducers and shares several properties with the BYV p21-like family of suppressors of the closteroviruses. This is the first report of an RNA silencing suppressor in the genus Ampelovirus.
- Phenols and antioxidant activity of hydro-alcoholic extracts of propolis from Algarve, South of PortugalPublication . Miguel, Maria Graça; Nunes, S.; Dandlen, S. A.; Antunes, Maria DulcePropolis is a natural honeybee product known to be beneficial for human health, with a complex chemical composition, highly dependent on the collection site. The objective of the present research was to evaluate phenols and antioxidant activity of propolis samples collected in three main areas of Algarve, South of Portugal. Water revealed to be less effective for extracting phenolic compounds from propolis than the methanol and water/ethanol. The last two were good extraction solvents of phenols. Nevertheless water/ethanol was the solvent chosen because it was able to extract phenols in considerable amounts being less toxic than methanol. In spring, higher amounts of phenols (total phenols, flavones, flavonols, flavanones and dihydroflavonols) were detected in hydro-alcoholic extracts of propolis than in winter. Among the three main areas of Algarve where samples were collected, those from Barrocal had the highest levels of polyphenols, independent on the season (winter or spring). Within each area, the levels of phenols changed according to the zone. Concerning antioxidant activity, samples from Barrocal presented better radical scavenging abilities than those from the remaining areas, independent on the antioxidant method and collection season. Such results correlated closely with the levels of total phenols, flavones and flavonols in samples. (C) 2010 Elsevier Ltd. All rights reserved.
- Strawberry recovers from iron chlorosis after foliar application of a grass-clipping extractPublication . Pestana, M.; Domingos, I.; Gama, Florinda; Dandlen, S. A.; Miguel, Maria Graça; Pinto, J. C.; De Varennes, A.; Correia, P. J.Bare-root transplants of strawberry (Fragaria x ananassa Duch. cv. Selva) were transferred to nutrient solutions with or without iron. After 35 d of growth, plants in the solution without iron became chlorotic and had morphological changes in roots typical of iron-deficiency chlorosis (IDC). Acidification of the nutrient solution was also observed. We tested a grass-clipping extract to correct IDC in strawberry plants by foliar application to some chlorotic plants. We also assessed the effects of this product on plant growth, Fe allocation, as well as morphological and physiological parameters related with IDC. After the second spray, leaf chlorophyll increased in the youngest expanded leaves. The total content of iron in plants increased from 1.93 mg to 2.37 mg per plant after three sprays, accounting for 80% of the total iron supplied by the extract. Newly formed roots from sprayed plants had a normal morphology (no subapical swollen zone) but a higher ferric chelate-reductase (FC-R; EC 1.16.1.17) activity per root apex compared with roots from plants grown with iron or untreated chlorotic plants. Acidification of the nutrient solution continued in sprayed recovered plants. The results suggest an uncoupling of the regulation of morphological and physiological mechanisms related to IDC: FC-R activity seems to be controlled by roots on their own or together with shoots, while morphological changes in roots are apparently regulated only by the level of iron in shoots.