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- The effect of alginate-based edible coatings enriched with essential oils constituents on Arbutus unedo L. fresh fruit storagePublication . Guerreiro, Adriana; Gago, Custódia; Faleiro, Leonor; Miguel, Maria Graça; Antunes, Maria DulceThe effect of coating Arbutus unedo fresh fruit with alginate-based edible coatings enriched with the essential oils compounds (EOC) eugenol (Eug) and citral (Cit) was studied. The minimum inhibitory concentrations (MIC) against the main postharvest pathogens were determined for Eug and Cit giving values of 0.10 and 0.15 (w/v), respectively. Twelve formulations of edible coatings were used: sodium alginate (AL) was tested at 1 and 2% (w/v) with incorporation of Eug and Cit at MIC and double MIC or their combination at MIC. Arbutus berries were dipped in those solutions for 2 min, and then stored at 0.5 degrees C. Control consisted of uncoated fruit. On days 0, 14 and 28, samples were taken to perform physicochemical and biochemical analysis [color CIE (L*, h degrees), firmness, soluble solids content (SSC), weight Loss, trolox equivalent antioxidant capacity (TEAC), microbial growth and taste panels]. Results showed that edible coatings of 1% AL were the best to maintain most quality attributes of the commodity through storage at 0.5 degrees C. The incorporation of Cit and Eug into the alginate edible coatings improved the coatings in most cases, AL 1% + Eug 0.20% and AL 1% + Cit 0.15% + Eug 0.10% being those that better preserved sensory and nutritional attributes and reduced microbial spoilage. Thus, these coatings may be useful for improving postharvest quality and storage life of fresh arbutus fruit. (C) 2014 Elsevier B.V. All rights reserved.
- Portuguese thymbra and thymus Species volatiles: Chemical composition and biological activitiesPublication . Figueiredo, A. C.; Barroso, J. G.; Pedro, L. G.; Salgueiro, L. R.; Miguel, Maria Graça; Faleiro, LeonorThymbra capitata and 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 present work reports on the state of the art on the information available on the taxonomy, ethnobotany, cell and molecular biology of the Portuguese representatives of these genera and on the chemotaxonomy and antibacterial, antifungal and antioxidant activities of their essential oils and other volatile-containing extracts.
- 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.
- Bioproducts from forest biomass: Essential oils and hydrolates from wastes of Cupressus lusitanica Mill. and Cistus ladanifer L.Publication . Tavares, Claudia S.; Martins, Alice; Faleiro, L; Miguel, Maria; Duarte, Luis C.; Gameiro, Jose A.; Roseiro, Luisa B.; Cristina Figueiredo, A.Unattended forest wastes are, among others, a potential source of wildfires, as well as a growth media for forest pests. As a way of lowering the detrimental effect of these wastes, it is important to convert these under-valued resources into a value-generating market forest wastes use. Essential oils (EOs) and hydrolates (Hs) from Cupressus lusitanica and Cistus ladanifer waste products, resulting from forest landscaping in Portugal, were evaluated for chemical composition and biological activity. Essential oils and Hs were obtained by steam-distillation (SD) and hydrodistillation (HD). Essential oils and Hs volatiles were analysed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC MS). The antimicrobial activity of EOs was studied by disk agar diffusion method against Escherichia coli, Staphylococcus aureus and Candida albicans. Antioxidant activity of EOs and Hs was evaluated by 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) free radical, superoxide anion radical formation, xanthine oxidase and chelating metal ions assays. Antiinflammatory activity of Hs was assessed by albumin denaturation assay. Monoterpene hydrocarbons and oxygen-containing monoterpenes dominated C. lusitanica EO (SD, 82-86 %, HD, 80-85 %) and Hs volatiles (SD, 93-94 %; HD 64-81 %), respectively. alpha-Pinene (14-36 %), limonene (8-21 %), delta-3-carene (8-19 %) and sabinene (6-18 %) were the main EO constituents. Hydrolates volatiles were dominated by cis-3-hexen-1-ol (0.1-13 %), camphor (1-11 %), umbellulone (t-48 %), p-cymene-8-ol (11-16 %) and terpinen-4-ol (21-31 %). C. ladanifer EOs were dominated by monoterpene hydrocarbons (SD, 48-80 % and HD, 29 %) and Hs by oxygen containing monoterpenes (SD, 38-43 %, HD, 39 %). The EO major constituents were alpha-pinene (13-28 %) and camphene (5-25 %), whereas 2,6,6-trimethyl cyclohexanone (2-12 %) and trans-pinocarveol (5-13 %) dominated the Hs volatiles. This study reports for the first time the chemical composition of the hydrolate volatiles of these two species and their anti-inflammatory properties. Among the studied biological activities, the EOs showed the best antioxidant properties while Hs demonstrated higher anti-inflammatory activity.
- Chemical composition and biological activities of Algerian Thymus oilsPublication . Hazzit, M.; Baaliouamer, A.; Verissimo, A. R.; Faleiro, Leonor; Miguel, Maria GraçaThe compositions of essential oils isolated from nine samples of three Thymus species (Thymus algeriensis, Thymus pallescens and Thymus dreatensis) were analysed by GC and GC-MS, and a total of 114 components were identified. T. pallescens collected from various regions showed a great similarity in their compositions and were characterised by carvacrol (44.4-57.7%), p-cymene (10.3-17.3%) and gamma-terpinene (10.8-14.2%) as the major components for four samples; only one sample was thymol-rich (49.3t) with a small amount of carvacrol (9.0%). On the other hand, T. algeriensis showed a chemical polymorphism, even for samples from the same location, and two new chemotypes for this species were proposed. Oxygen-containing monoterpenes were the predominant class (76.3%) in T. dreatensis oil, with linalool (30.4%), thymol (20.2%) and geraniol (19.6%) as the principal constituents. The oils were screened for their possible antioxidant activities by four complementary assays, namely DPPH free radical scavenging, hydroxyl radical scavenging, inhibition of lipid peroxidation and reducing power. The two new chemotypes of T algeriensis exhibited strong hydroxyl radical scavenging (IC(50) = 2.2-3.3 mu g/ml), but were not or only slightly active against the other radicals and exhibited a weak reducing power. Despite their chemical similarity, T. pallescens oils sometimes produced significant differences in their antioxidant activities. The essential oils were also screened for their antimicrobial activity against five bacteria (three Gram-positive and two Gram-negative) and one yeast (Candida albicans). The tested essential oils showed antimicrobial activity against the microorganisms used, in particular against two important pathogens, C. albicans and Helicobacter pylori. (C) 2009 Elsevier Ltd. All rights reserved.
- Mechanism of uranium (VI) removal by two anaerobic bacterial communitiesPublication . Martins, Mónica; Faleiro, Leonor; Rosa da Costa, Ana; Chaves, Sandra; Tenreiro, Rogério; Matos, António Pedro; Costa, Maria ClaraThe mechanism of uranium (VI) removal by two anaerobic bacterial consortia, recovered from an uncontaminated site (consortium A) and other from an uranium mine (consortium U), was investigated. The highest efficiency of U (VI) removal by both consortia (97%) occurred at room temperature and at pH 7.2. Furthermore, it was found that U (VI) removal by consortium A occurred by enzymatic reduction and bioaccumulation, while the enzymatic process was the only mechanism involved in metal removal by consortium U. FTIR analysis suggested that after U (VI) reduction, U (IV) could be bound to carboxyl, phosphate and amide groups of bacterial cells. Phylogenetic analysis of 16S rRNA showed that community A was mainly composed by bacteria closely related to Sporotalea genus and Rhodocyclaceae family, while community U was mainly composed by bacteria related to Clostridium genus and Rhodocyclaceae family.
- Use of Essential Oils and Their Components against Multidrug-Resistant BacteriaPublication . Faleiro, Leonor; Miguel, Maria GraçaAromatic and medicinal plants, through their secondary metabolism, provide a complex mixture of volatile molecules known as essential oils. These volatile molecules exert antibacterial activity that has been used in folk medicine for centuries. During the last few decades, the emergence of antibacterial resistance has forced us to search for new and efficient antimicrobial agents. The significant number of studies on the use of essential oils and their components against multidrug-resistant bacteria, such as Acinetobacter baumannii, methicillin-resistant Staphylococcus aureus, Mycobacterium tuberculosis, and Pseudomonas aeruginosa show the exceptional potential of these natural products to curb the development of antibacterial resistance. Moreover, the use of essential oils and their components in combination with antibiotics may increase bacterial susceptibility, thus limiting resistance. © 2013 Elsevier Inc. All rights reserved.
- Foeniculum vulgare Essential Oils: Chemical Composition, Antioxidant and Antimicrobial ActivitiesPublication . Miguel, Maria Graça; Cruz, Claudia; Faleiro, Maria Leonor; Simoes, M. T. F.; Figueiredo, A. C.; Barroso, J. G.; Pedro, L. G.The essential oils from Foeniculum vulgare commercial aerial parts and fruits were isolated by hydrodistillation, with different distillation times (30 min, I h, 2 h and 3 h), and analyzed by GC and GC-MS. The antioxidant ability was estimated using four distinct methods. Antibacterial activity was determined by the agar diffusion method. Remarkable differences, and worrying from the quality and safety point of view, were detected in the essential oils. trans-Anethole (31-36%), alpha-pinene (14-20%) and limonene (11-13%) were the main components of the essentials oil isolated from F. vulgare dried aerial parts, whereas methyl chavicol (= estragole) (79-88%) was dominant in the fruit oils. With the DPPH method the plant oils showed better antioxidant activity than the fruits oils. With the TBARS method and at higher concentrations, fennel essential oils showed a pro-oxidant activity. None of the oils showed a hydroxyl radical scavenging capacity >50%, but they showed an ability to inhibit 5-lipoxygenase. The essential oils showed a very low antimicrobial activity. In general, the essential oils isolated during 2 h were as effective, from the biological activity point of view, as those isolated during 3 h.
- Poly(butylene succinate)-based composites with technical and extracted lignins from wood residuesPublication . Melro, Elodie; Duarte, Hugo; Eivazi, Alireza; Costa, Carolina; Faleiro, Maria Leonor; Rosa Da Costa, Ana; Antunes, Filipe E.; Valente, Artur J. M.; Romano, Anabela; Norgren, Magnus; Medronho, BrunoPoly(butylene succinate) (PBS) has been drawing attention as a reliable biodegradable and sustainable alternative to synthetic petroleum-based polymers. In this study, PBS-lignin composites were developed using a recently extracted lignin (LA-lignin) from pine wood residues employing an innovative sustainable approach. These composites were systematically compared with PBS-based composites formed with commonly used technical lignins. The molecular weight of the lignins was evaluated, along with various structural and performance-related properties. The LA-lignin/PBS composites display a remarkably low water solubility (ca. < 2%), water uptake (ca. 100 degrees). Moreover, the rigidity and thermal stability of the LA-lignin-PBS composites were higher than those of the systems formed with technical lignins. Although all composites studied present remarkable antioxidant features, the novel LA-lignin-PBS systems stand out in terms of antiadhesion activity against both Gram-positive and Gram-negative bacteria. Overall, the systematic analysis performed in this work regarding the impact of various lignins on the formed PBS composites enables a better understanding of the essential structural and compositional lignin features for achieving biobased materials with superior properties.
- Changes in the chemical parameters during the production of água-mel from PortugalPublication . Miguel, Maria; AAZZA, Smail; Antunes, Maria Dulce; Faleiro, Maria LeonorAgua-mel is a honey-based traditional product typically produced in southern Portugal. The evolution of some parameters during its production using two distinct containers (aluminium and stainless steel with a water cooling system) and two heating sources (gas heating and electricity) were evaluated. All parameters, except moisture, increased over time, reaching a 'plateau' after 8 h of heating. Moisture, free acidity, HMF (hydroxymethylfurfural), colour, melanoidins, phenols and glucose depended on the producer and procedure for obtaining agua-mel. Kinetic parameters and correlation coefficients were determined. In general, changes in parameters during agua-mel production followed zero- and/or first-order kinetics, depending on the producer and heating system.