Browsing by Author "Mendes, M. D."
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- 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.
- Propolis volatiles characterisation from acaricide-treated and -untreated beehives maintained at Algarve (Portugal)Publication . Miguel, Maria Graça; Nunes, S.; Cruz, C.; Duarte, J.; Antunes, Maria Dulce; Cavaco, A. M.; Mendes, M. D.; Lima, A. S.; Pedro, L. G.; Barroso, J. G.; Figueiredo, A. C.The variability of the volatile profile of 70 propolis samples from acaricide-treated and -untreated beehives maintained at Algarve (Portugal) was evaluated. Propolis samples were collected in three regions of Algarve at three different periods. Cluster analysis based on the propolis volatiles' chemical composition defined two main clusters, not related to the time of year, collection site, altitude, temperature or humidity ranges, and was based mainly on the relative amounts of viridiflorol, n-tricosane and n-nonadecane for cluster I. Cluster II was mainly characterised by the high thymol content, followed by viridiflorol, n-tricosane and n-nonadecane. The presence of higher thymol levels in propolis samples from cluster II may reflect the long use of an acaricide with thymol as main active ingredient. All samples showed an intense rock-rose aroma supported by the presence of characteristic Cistus and labdanum oil volatile components. Given the nowadays frequent propolis household use, volatiles thorough characterisation may assist in its quality assessment.