Browsing by Author "Faleiro, Maria Leonor"
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- Antioxidant activity of six Portuguese thyme species essential oilsPublication . Dandlen, S. Anahi; Lima, Ana Sofia; Mendes, Marta D.; Miguel, Maria da Graça; Faleiro, Maria Leonor; Sousa, Maria João; Pedro, Luís G.; Barroso, José G.; Figueiredo, Ana CristinaThe essential oils of Thymus caespititius, T. camphoratus, T. capitellatus, T. carnosus, T. pulegioides, T. zygis subsp. zygis and T. zygis subsp. sylvestris collected in diff erent 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 (IC50 = 0.030 ± 0.003 mg/ml), immediately followed by the oils isolated from T. zygis subsp. sylvestris collected in diff erent regions of Portugal. IC50 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 eff ective 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 IC50 < 0.5 mg/ml. The low oil amount did not allow IC50 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 Covão do Coelho, and of T. capitellatus from Sines. Copyright © 2010 John Wiley & Sons, Ltd.
- Avaliação de propriedades biológicas em mel dos Açores – atividade antioxidante e antimicrobianaPublication . Machado, Alexandra M.; Miguel, Maria da Graça; Vilas-Boas, Miguel; Faleiro, Maria Leonor; Figueiredo, Ana CristinaO mel e os seus produtos derivados são geralmente consumidos devido às suas características nutricionais e terapêuticas, bem como igualmente empregues em fragrâncias ou cosméticos [1]. Em Portugal, existem nove denominações de origem protegida de mel reconhecidas, entre as quais a do mel dos Açores [2], cujas propriedades biológicas estão pouco estudadas. O objetivo deste trabalho consistiu no estudo de oito méis dos Açores, provenientes das ilhas de São Miguel, Santa Maria, Terceira e Pico, relativamente à quantificação do teor em compostos fenólicos totais e flavonoides, à determinação da atividade antioxidante e anti-inflamatória por métodos espetrofotométricos, bem como o controlo de qualidade microbiológico e a avaliação da atividade antimicrobiana. O teor de fenóis totais variou entre 12 μg e 460 μg equivalentes de ácido gálico (EAG)/g de mel e para os flavonóides entre 0,6 μg e 55 μg equivalentes de quercetina (EQ)/g de mel. A atividade antioxidante determinada pelo método ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) foi relativamente baixa nos oito méis, comparativamente ao padrão utilizado (Trolox), sendo apenas possível determinar o IC50 (concentração de amostra necessária para diminuir ou reduzir a concentração inicial do radical ABTS em 50%) de uma amostra, cujo valor foi 8 mg/mL. Relativamente à capacidade quelante de iões ferro(II), esta foi somente detetada em três amostras de mel, cujas percentagens de inibição variaram entre 5 e 18%. A captação do radical superóxido foi também avaliada. Os valores de IC50 variaram entre 23 e 73 mg/L. A capacidade de inibição da enzima xantina oxidase foi observada em cinco amostras de mel, sendo particularmente elevada numa delas. No que diz respeito ao controlo de qualidade microbiológico dos méis analisados, não foi observada contaminação microbiana. A atividade antimicrobiana dos oito méis foi testada contra Escherichia coli, Staphylococcus aureus, Candida albicans e Pseudomonas aeruginosa, tendo sido verificada ação inibitória dos oito méis para Escherichia coli, de quatro méis em Staphylococcus aureus e de três méis em Pseudomonas aeruginosa. Não foi observada atividade inibitória contra Candida albicans.
- Chemical Characterization and Biological Properties Assessment of Euphorbia resinifera and Euphorbia officinarum Moroccan PropolisPublication . Boutoub, Oumaima; El-Guendouz, Soukaïna; Matos, Isabel; El Ghadraoui, Lahsen; Costa, Maria Clara; Carlier, Jorge D.; Faleiro, Maria Leonor; Figueiredo, Ana Cristina; Estevinho, Leticia M.; Miguel, Maria GraçaAlthough the plants of the genus Euphorbia are largely exploited by therapists in Morocco, the composition and antibacterial activities of propolis from these plants are still unknown. To address this gap, this study aimed to characterize the pollen type, the volatile compounds, and the phenolic and mineral profiles of three Euphorbia propolis samples collected in Morocco and evaluate their antimicrobial activities. The minimum inhibitory concentration of the propolis samples was determined by the microdilution method, and the anti-adherence activity was evaluated by the crystal violet assay. The examination of anti-quorum-sensing proprieties was performed using the biosensor Chromobacterium violaceum CV026. Pollen analysis revealed that Euphorbia resinifera pollen dominated in the P1 sample (58%), while E. officinarum pollen dominated in the P2 and P3 samples (44%). The volatile compounds were primarily composed of monoterpene hydrocarbons, constituting 35% in P1 and 31% in P2, with alpha-pinene being the major component in both cases, at 16% in P1 and 15% in P2. Calcium (Ca) was the predominant mineral element in both E. resinifera (P1) and E. officinarum (P2 and P3) propolis samples. Higher levels of phenols, flavonoids and dihydroflavonoids were detected in the E. officinarum P2 sample. The minimum inhibitory concentration (MIC) value ranged from 50 to 450 mu L/mL against Gram-positive and Gram-negative bacteria. Euphorbia propolis displayed the ability to inhibit quorum sensing in the biosensor C. violaceum CV026 and disrupted bacterial biofilm formation, including that of resistant bacterial pathogens. In summary, the current study evidences the potential use of E. officinarum propolis (P2 and P3) to combat important features of resistant pathogenic bacteria, such as quorum sensing and biofilm formation.
- Preliminary characterization of a Moroccan honey with a predominance of Bupleurum spinosum pollenPublication . Elamine, Youssef; Aazza, Smail; Lyoussi, Badiâa; Antunes, Maria Dulce; Estevinho, Leticia M.; Anjos, Ofélia; Resende, Mafalda; Faleiro, Maria Leonor; Miguel, Maria da GraçaHoney with Bupleurum spinosum (zandaz) as a main pollen source has not been the subject of previous detailed study. Therefore, twelve Moroccan samples of this honey were subjected to melissopalynological, physicochemical and microbiological quality characterization, as well as antioxidant activity assessment. From a quality point of view, almost all samples were within the limits established by Codex Alimentarius, and/or the European legislation. All samples presented predominance of B. spinosum pollen (more than 48%). Relatively high levels of trehalose (1.3–4.0 g/100 g) and melezitose (1.5–2.8 g/100 g) were detected. Those sugars, not common in monofloral honeys, could be used as an important factor to discriminate zandaz honey. Flavonoid content correlated positively with the honey color, melanoidin and polyphenol content, and negatively with the IC50values of scavenging ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) free radicals, while proline amount correlated negatively with IC50values of nitric oxide scavenging activity and chelating power. This correlation supports the use of anti-oxidant activities as important variables for PCA (principal component analysis). Both components explained 70% from the given data, and showed certain homogeneity upon analyzed samples independent of the region, suggesting the importance of B. spinosum nectar in the resulting honey characteristics.