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Browsing by Author "Pedro, L. G."

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  • Acetylcholinesterase Inhibition Activity of Portuguese Thymus Species Essential Oils
    Publication . 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.
    2011Journal article Restricted access Show more
  • Ammoides pusilla (Apiaceae) and Thymus munbyanus (Lamiaceae) from Algeria essential oils: chemical composition, antimicrobial, antioxidant and antiproliferative activities
    Publication . Tefiani, C.; Riazi, A.; Youcefi, F.; S, Azza; Gago, Custódia; Faleiro, Leonor; Pedro, L. G.; Barroso, J. G; Figueiredo, A. C.; Megias, C.; Cortes Giraldo, I.; Vioque, J.; Miguel, Maria Graça
    The chemical composition, and antioxidant, antimicrobial and anti-proliferative activities of the essential oils of Ammoides pusilla (Apiaceae) and Thymus munbyanus (Lamiaceae), collected in Algeria, were studied. Cumin alcohol (44%), p-cymene (18%), limonene (14%), thymol (11%) and gamma-terpinene (7%) predominated in A.pusilla essential oil, whereas carvacrol (71%) was dominant in T.munbyanus essential oil. The antibacterial activity of A.pusilla and T.munbyanus essential oils was studied by the agar diffusion method against Escherichia coli, Salmonella enterica serovar Thyphimurium, methicillin-resistant Staphylococcus aureus and Listeria monocytogenes. The tested bacteria were more susceptible to T.munbyanus essential oil. Ammoides pusilla essential oil was the most effective for scavenging the free radicals. Ammoides pusilla essential oil also had the best reducing power as well as the highest lipid peroxidation inhibition. Thymus munbyanus essential oil showed the best anti-proliferative activity of human acute monocytic leukemia cell line (THP-1).
    2015Journal article Restricted access Show more
  • Antibacterial and antioxidant activities of essential oils isolated from Thymbra capitata L. (Cav.) and Origanum vulgare L.
    Publication . Faleiro, Leonor; Miguel, Maria Graça; Gomes, Sónia; Costa, L.; Venancio, F.; Teixeira, A.; Figueiredo, A. C.; Barroso, J. G.; Pedro, L. G.
    Antilisterial activities of Thymbra capitata and Origanum vulgare essential oils were tested against 41 strains of Listeria monocytogenes. The oil of T. capitata was mainly constituted by one component, carvacrol (79%), whereas for O. vulgare three components constituted 70% of the oil, namely, thymol (33%), gamma-terpinene (26%), and p-cymene (11%). T. capitata essential oil had a significantly higher antilisterial activity in comparison to O. vulgare oil and chloramphenicol. No significant differences in L. monocytogenes susceptibilities to the essential oils tested were registered. The minimum inhibitory concentration values of T. capitata essential oil and of carvacrol were quite similar, ranging between 0.05 and 0.2 mu L/mL. Antioxidant activity was also tested, the essential oil of T. capitata showing significantly higher antioxidant activity than that of O. vulgare. Use of T. capitata and O. vulgare essential oils can constitute a powerful tool in the control of L. monocytogenes in food and other industries.
    2005Journal article Restricted access Show more
  • Antimicrobial activity of essential oils isolated from Portuguese endemic species of Thymus
    Publication . Faleiro, Leonor; Miguel, Maria Graça; Ladeiro, F.; Venancio, F.; Tavares, R.; Brito, J. C.; Figueiredo, A. C.; Barroso, J. G.; Pedro, L. G.
    Aims: Thymus species are wild species mostly found in the arid lands of Portugal. Possible antimicrobial properties of Thymus essential oils have been investigated. The chemical composition of the essential oils and the antimicrobial activity of Thymus mastichina (L) L. subsp. mastichina , T. camphoratus and T. lotocephalus from different regions of Portugal were analysed. Methods and Results: Hydrodistillation was used to isolate the essential oils and the chemical analyses were performed by gas chromatography (GC) and GC coupled to mass spectrometry. The antimicrobial activity was tested by the disc agar diffusion technique against Candida albicans , Escherichia coli , Listeria monocytogenes , Proteus mirabilis , Salmonella spp. and Staphylococcus aureus . Pure linalool, 1,8-cineole and a mixture (1:1) of these compounds were included. Linalool, 1,8-cineole or linalool/1,8-cineole and linalool/1,8-cineole/linalyl acetate were the major components of the essential oils, depending on the species or sampling place. The essential oils isolated from the Thymus species studied demonstrated antimicrobial activity but the micro-organisms tested had significantly different sensitivities. Conclusions: The antimicrobial activity of essential oils may be related to more than one component. Significance and Impact of the Study: Portuguese endemic species of Thymus can be used for essential oil production for food spoilage control, cosmetics and pharmaceutical use. Further studies will be required to elucidate the cell targets of the essential oil components.
    2003Journal article Restricted access Show more
  • Antimicrobial activity, cytotoxicity and intracellular growth inhibition of Portuguese Thymus essential oils
    Publication . 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.
    2011Journal article Open access Show more
  • Antioxidant activity of six Portuguese thyme species essential oils
    Publication . 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.
    2010Journal article Restricted access Show more
  • Antioxidant activity of thymbra capitata essential oil in meat-treated oil
    Publication . Mohammed, A. D.; Miguel, Maria Graça; Antunes, Maria Dulce; Figueiredo, A. C.; Pedro, L. G.; Barroso, J. G.
    Several synthetic antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and tertiary butyl hydroquinone (TBHQ), have been used to preserve meat. Nevertheless they are considered toxic and to have carcinogenic effects. Natural products, such as those present in essential oils, have been the target of studies as alternative antioxidants, showing promising results. In addition, these natural compounds have the advantage of having consumer's acceptance. Thymbra capitata is a perennial, herbaceous shrub commonly used as a spicy herb. The essential oils isolated from this plant showed antimicrobial and antioxidant activities. The main goal of the present work was to evaluate the capacity of T. capitata oil to prevent lipid oxidation in bovine meat. Different concentrations of essential oil (0, 50, 75 and 100 mg/5 g of meat) were used in two types of bovine meat samples purchased in the local market. The protein content of both types of meat samples was 21%, and lipid content ranged from 9% to 15%. After covering with the oil, the two types of meat samples were stored at -17 degrees C, for one month. After 1 day, 15 days and 30 days, meat samples were taken and cooked at 85 degrees C for 90 min. The samples were then submitted to the TBARS modified method, for antioxidant activity evaluation. The essential oil was able to prevent meat oxidation even after one month of storage and showed a dose-dependent activity.
    2010Conference object Open access Show more
  • Antioxidant Capacity of the Essential Oils From Lavandula luisieri, L. stoechas subsp lusitanica, L. stoechas subsp lusitanica x L. luisieri and L. viridis Grown in Algarve (Portugal)
    Publication . Matos, F.; Miguel, Maria Graça; Duarte, J.; Venancio, F.; Moiteiro, C.; Correia, A. I. D.; Figueiredo, A. C.; Barroso, J. G.; Pedro, L. G.
    The antioxidant capacity of the essential oils isolated from the aerial parts of Lavandula luisieri, L. stoechas subsp. lusitanica, the hybrid L. stoechas subsp. lusitanica x L. luisieri, and L. viridis collected in different regions of Algarve (Portugal), its well as that of butylated hydroxytoluene (BHT), was evaluated using three different methods: free radical scavenging activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) method, thiobarbituric acid reactive substances assay (TBARS) and reductive potential. The chemical composition of the essential oils wits analyzed by GC and GC/MS. The oils of L. luisieri were mainly constituted by 1,8-cineole (26-34%) and trans-alpha-necrodyl acetate (11-18%), only present in this lavender species. The oils of Lavandula stoechas subsp. lusitanica and the hybrid L. stoechas subsp. lusitanica x L. luisieri were dominated by fenchone (42-44%) and camphor (35-36%). Despite of the morphological resemblances of the L. stoechas subsp. lusitanica x L. luisieri with L. luisieri, no necrodane derivatives were detected ill the hybrid, showing instead a major chemical similarity with L. stoechas oil. Lavandula viridis oil mainly comprised 1,8-cineole (33%) and camphor (20%). The oils of L. luisieri were the most effective as antioxidants, independent of the evaluation method used, although showing always lower antioxidant ability than BHT.
    2009Journal article Restricted access Show more
  • Antioxidant, Anti-5-lipoxygenase and Antiacetylcholinesterase Activities of Essential Oils and Decoction Waters of Some Aromatic Plants
    Publication . Albano, Sílvia; Lima, A. S.; Miguel, Maria Graça; Pedro, L. G.; Barroso, J. G.; Figueiredo, A. C.
    The scavenging of free radicals and superoxide anion, the inhibition of 5-lipoxygenase and the antiacetylcholinesterase activities of essential oils and decoction waters of eight aromatic plants (Dittrichia viscosa, Foeniculum vulgare, Origanum vulgare, Salvia officinalis, Thymbra capitata, Thymus camphoratus, Thymus carnosus and Thymus mastichina) were studied. The essential oils were dominated by 1,8-cineole in S. officinalis (59%), T. mastichina (49%) and T. camphoratus (21%); borneol (20%) in T. carnosus; carvacrol in Thymbra capitata (68%); gamma-terpinene (49%) in O. vulgare; alpha-pinene (26%) in F. vulgare; and trans-nerolidol (8%) + beta-oplopenone (7%) in D. viscosa. O. vulgare decoction waters had the highest amount of phenols (45 +/- 3mg GAE/mL) while F. vulgare only had 5 +/- 0mg GAE/mL. The decoction waters showed higher radical scavenging activity than the essential oils. O. vulgare decoction water showed the best antioxidant activity (IC(50) = 3 +/- 0 mu g/mL), while the most effective essential oils were those of Thymbra capitata (IC(50) = 61 +/- 2 mu g/mL) and O. vulgare (IC(50) = 156 +/- 5 mu g/mL). Thymbra capitata (IC(50) = 6 +/- 0 mu g/mL) decoction water showed the best superoxide anion scavenging activity. F. vulgare decoction water and essential oil revealed the best 5-lipoxygenase inhibition capacity (IC(50) = 27 +/- 1 mu g/mL and IC(50) = 68 +/- 2 mu/mL, respectively). T. mastichina (IC(50) = 46 +/- 4 mu g/mL), S. officinalis (IC(50) = 51 +/- 4 mu g/mL), Thymbra capitata (IC(50) = 52 +/- 1 mu g/mL) and T. camphoratus (IC(50) = 137 +/- 2 mu g/mL) essential oils showed the best antiacetylcholinesterase activity.
    2012Journal article Open access Show more
  • Assessment of the antioxidant ability of Thymus albicans, T mastichina, T camphoratus and T carnosus essential oils by TBARS and micellar model systems.
    Publication . Miguel, Maria Graça; Costa, L. A.; Figueiredo, A. C.; Barroso, G. B.; Pedro, L. G.
    The essential oils isolated by hydrodistillation from different populations of Thymus albicans, T mastichina, T carnosus and T. camphoratus, collected during the vegetative phase, were analysed by GC and GC-MS. The same oils were used in the antioxidant activity evaluation using.the TBARS assay and the micellar model systems. T albicans oils and two of the oils from T. mastichina populations were 1,8-cineole-rich. The third T mastichina oil was linalool-rich. trans-Sabinene hydrate, bomeol and linalool in similar amounts, and 1,8-cineole were the main components of the oils from each of the three populations of T camphoratus. T carnosus oils were mainly composed of borneol. All essential oils revealed some degree of antioxidant activity either in the presence or absence of ABAP in the TBARS method. The micellar model system showed higher antioxidant indices than those obtained by the TBARS method.
    2007Journal article Restricted access Show more