Browsing by Author "Miguel, Maria Graça"
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- Accumulation of stress metabolites in cell-suspension cultures of hyoscyamus-albusPublication . Miguel, Maria Graça; Barroso, J. G.Cell suspension cultures of Hyoscyamus albus treated with freeze-dried Phytophthora cinnamomi autoclaved mycelium of freeze-dried Candida albicans autoclaved cells accumulated mainly lubimin and 10-epilubimun, along with small amounts of rishitin and solavetivone. Cultures treated with cellulase did not accumulate any of the reported compounds. The pattern and the amount of sesquiterpenoids produced were dependent on cell growth stage, incubation time with the elicitor and elicitor concentration. Higher yields of lubimin and 10-epilubimin occurred in cultures inoculated two days after subculturing and incubated for 48 hr. Some elicitor-treated cultures and old untreated ones accumulated acetophenones: acetovanillone, acetosyringone and hydroxyacetosyringone.
- 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.
- Ammoides pusilla (Apiaceae) and Thymus munbyanus (Lamiaceae) from Algeria essential oils: chemical composition, antimicrobial, antioxidant and antiproliferative activitiesPublication . 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 GraçaThe 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).
- Analysis by gas chromatography-mass spectrometry of the volatile components of Teucrium lusitanicum and Teucrium algarbiensisPublication . Cavaleiro, C.; Salgueiro, L. R.; Miguel, Maria Graça; Da Cunha, A. P.The essential oils from four samples of Teucrium lusitanicum and one sample of Teucrium algarbiensis, grown in Algarve (southern Portugal) were analyzed by gas chromatography (GC) and gas chromatography-mass spectroscopy (GC-MS). Seventy-one volatile compounds were identified. Major compounds of T. algarbiensis oil were alpha-pinene (8.3%), sabinene (7.2%), beta-pinene (10.2%), limonene (11.8%) and germacrene D (7.6%). Concerning T. lusitanicum, some quantitative differences were found with regards to the major constituents of the oils from four populations: alpha-pinene (0.8-8.5%), sabinene (2.1-9.6%), beta-pinene (2.5-11.9%), limonene (1.2-11.5%) and elemol (2.6-12.0%). (C) 2004 Elsevier B.V. All rights reserved.
- Anthocyanin concentration of "Assaria" pomegranate fruits during different cold storage conditionsPublication . Miguel, Maria Graça; Fontes, C.; Antunes, Maria Dulce; Neves, Alcinda; Martins, D.The concentration of anthocyanins in fruits of "Assaria" pomegranate, a sweet Portuguese cultivar typically grown in Algarve (south Portugal), was monitored during storage under different conditions. The fruits were exposed to cold storage (5 degrees C) after the following treatments: spraying with wax; spraying with 1.5% CaCl2; spraying with wax and 1.5% CaCl2; covering boxes with 25 mu c thickness low-density polyethylene film. Untreated fruits were used as a control. The anthocyanin levels were quantified by either comparison with an external standard of cyanidin 3-rutinoside (based on the peak area) or individual calculation from the peak areas based on standard curves of each anthocyanin type. The storage time as well as the fruit treatment prior to storage influenced total anthocyanin content. The highest levels were observed at the end of the first month of storage, except for the fruits treated with CaCl2, where the maximal values were achieved at the end of the second month. The anthocyanin quantification method influenced the final result. When total anthocyanin was calculated as a sum of individual pigments quantified based on standard curves of each anthocyanin type, lower values were obtained.
- Anthocyanins: Antioxidant and/or anti-inflammatory activitiesPublication . Miguel, Maria GraçaAnthocyanins are polyphenols with known antioxidant activity which may be responsible for some biological activities including the prevention or lowering the risk of cardiovascular disease, diabetes, arthritis and cancer. Nevertheless such properties, their stability and bioavailability depend on their chemical structure. In the present work a brief review is made on chemical structures, bioavailability and antioxidant/anti-inflammatory of anthocyanins.
- Anti-oxidant, Anti-inflammatory and Anti-proliferative Activities of Moroccan Commercial Essential OilsPublication . S, Azza; Lyoussi, B.; Megias, C.; Cortes Giraldo, I.; Vioque, J.; Figueiredo, A. C.; Miguel, Maria GraçaEssential oils (EO) possess antimicrobial, anti-inflammatory, insect repellent, anti-cancer, and antioxidant properties, among others. In the present work, the antioxidant, anti-inflammatory and anti-proliferative activities of Moroccan commercial EOs (Citrus aurantium, C. union, Cupressus sempervirens, Eucalyptus globulus, Foeniculum vulgare and Thymus vulgaris) were evaluated and compared with their main constituents. T. vulgaris EO showed the best free radicals scavenging capacity. This EO was also the most effective against lipid peroxidation along with C. limon and F. vulgare EOs. C. sempervirens EO was the most effective in scavenging NO free radicals, whereas C. limon EO showed the best chelating power. Not all of the major compounds of the EO were responsible for the whole activity of the EOs. T. vulgaris EO showed the best anti-proliferative activity against THP-1 cells in contrast to that of F. vulgare. The antioxidant and anti-inflammatory activities of the EOs were plant species dependent and not always attributable to the EOs main components. Nevertheless, the EOs anti-proliferative activities were more related to their main components, as with T. vulgaris, C. limon, E. globulus and C. sempervirens.
- 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.
- Antimicrobial activity of essential oils isolated from Portuguese endemic species of ThymusPublication . 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.
- Antimicrobial activity of the essential oils of Dittrichia viscosa subsp viscosa on Helicobacter pyloriPublication . Silva, D.; Denham, E.; Faleiro, Leonor; Miguel, Maria Graça; Cavaleiro, C.; Salgueiro, L. R.Dittrichia viscosa subsp. viscosa (Compositae) is found on edges, wood clearings and in waste places of the Iberian Peninsula. Aerial parts of D. viscosa were collected at flowering phase in September-October 2001 around Lisbon, Portugal and the essential oils isolated by hydro-distillation for 4 h using a Clevenger-type apparatus. The oils were analyzed by gas chromatography and gas chromatography-mass spectrometry. Preliminary examination of the essential oils allowed the identification of 32 components. Only four components reached percentages over 5%: fokienol (11.8%), T-muurorol (7.9%), (E)-nerolidol (5.5%) and delta-cadinene (5.0%). The essential oils were tested against Helicobacterpylori and Listeria monocytogenes. Essential oils did not have antimicrobial activity against L. monocytogenes. The essential oil at 0.88 to 22.22 mu g.ml(-1) did not inhibit the growth of H. pylori, affected the growth slightly at 44.40 mu g.ml(-1), and completely inhibited the growth at 88.80 to 133.20 mu g.ml(-1) Results show that use of D. viscosa essential oil in the treatment of gastric disorders caused by H. pylori can be effective.