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HS-SPME/GC-MS methodologies for the analysis of volatile compounds in cork material

Publication . Moreira, Nathalie; Lopes, P.; Cabral, M.; Pinho, P. Guedes de

Two methods based on headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography– ion trap mass spectrometry (GC-IT/MS) were proposed for the analysis of volatile organic compounds (VOCs) in cork material used in the production of cork stoppers. The effect of various factors affecting the extraction efficiency was carried out by means of a 24 full factorial design. The first method allowed the extraction of 17 terpenes by using a divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber (50/30 μm). The optimal conditions were achieved when cork extract (5 mL) added with 2.3 g of NaCl was extracted during 35 min at 55 °C. The second method allowed the identification of 41 carbonyl compounds after in-solution (5 mL) derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA, 2.3 mg/mL), followed by an incubation period of 6 min at 52 °C and extraction during 36 min at the same temperature, using a PDMS/DVB (50/30 μm) fiber. Both methods are simple, solvent free and fast. These methods were applied to the analysis of different cork raw material showing significant differences in the amounts of volatile compounds analyzed. Alcanfor and α-terpineol were the terpenes compounds present at highest amounts, and within carbonyl compounds analyzed, some samples presented a high level of butanal, octanal, nonanal, and glyoxal.

2016Journal article

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New hydrophilic 3-hydroxy-4-pyridinone chelators with ether-derived substituents: synthesis and evaluation of analytical performance in the determination of iron in waters

Publication . Moniz, Tânia; Cunha-Silva, Luís; Mesquita, Raquel B.R.; Miranda, Joana L.A.; Silva, André M.N.; Silva, Ana M.G.; Rangel, António O.S.S.; Castro, Baltazar de; Rangel, Maria

Three new hydrophilic 3-hydroxy-4-pyridinone chelators containing ether-derived substituents were prepared by a more sustainable synthetic protocol that involves the use of microwave heating and commercially available amines, allowing the successful production of highly water soluble chelators with improved reaction yields and reaction times. Compared with parent 3-hydroxy-4-pyridinone ligands, the new compounds were obtained faster and in higher amounts, facilitating the scale up of the synthesis, which is crucial to produce these ligands and their respective iron(III) complexes for many biological, analytical and agricultural applications. Ligands were fully characterized by 1H and 13C Nuclear Magnetic Resonance, High Resolution Mass Spectrometry and Single Crystal X-Ray Diffraction and their performance in the analytical determination of iron(III) in water samples was evaluated by sequential injection methods. The results obtained are scientifically relevant, pointing out the potential of the new and straightforwardly synthesized ligands as analytical reagents for determination of iron(III).

2019Journal article

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Structure and function of a novel antioxidant peptide from the skin of tropical frogs

Publication . Barbosa, Eder Alves; Oliveira, Ana; Plácido, Alexandra; Socodato, Renato; Portugal, Camila C.; Mafud, Ana Carolina; Leite, José Roberto S.A.; Pintado, M. E.

The amphibian skin plays an important role protecting the organism from external harmful factors such as microorganisms or UV radiation. Based on biorational strategies, many studies have investigated the cutaneous secretion of anurans as a source of bioactive molecules. By a peptidomic approach, a novel antioxidant peptide (AOP) with in vitro free radical scavenging ability was isolated from Physalaemus nattereri. The AOP, named antioxidin-I, has a molecular weight [M+H]+ = 1543.69 Da and a TWYFITPYIPDK primary amino acid sequence. The gene encoding the antioxidin-I precursor was expressed in the skin tissue of three other Tropical frog species: Phyllomedusa tarsius, P. distincta and Pithecopus rohdei. cDNA sequencing revealed highly homologous regions (signal peptide and acidic region). Mature antioxidin-I has a novel primary sequence with low similarity compared with previously described amphibian's AOPs. Antioxidin-I adopts a random structure even at high concentrations of hydrophobic solvent, it has poor antimicrobial activity and poor performance in free radical scavenging assays in vitro, with the exception of the ORAC assay. However, antioxidin-I presented a low cytotoxicity and suppressed menadione-induced redox imbalance when tested with fibroblast in culture. In addition, it had the capacity to substantially attenuate the hypoxia-induced production of reactive oxygen species when tested in hypoxia exposed living microglial cells, suggesting a potential neuroprotective role for this peptide.

2018Journal article

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Fighting Helicobacter pylori: a specific antibiotic-free strategy

Publication . Pinho, A. S.; Nunes, C.; Reis, S.; Martins, M. C. L.; Seabra, C. L.; Parreira, P.

2020Conference object

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The potencial role of soil application of a tris (3-hydroxy-4-pyridinonate) iron (III) complex in iron deficiency chlorosis treatment

Publication . Rodrigues, Elsa; Ferreira, Sofia; Leite, Andreia; Moniz, Tânia; Rangel, Maria; Vasconcelos, Marta W.; Carvalho, Susana M. P.; Santos, Carla S.

2018Conference object

Open access