Browsing by Author "Miranda, Isabel"
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- Bark anatomy, chemical composition and ethanol-water extract composition of Anadenanthera peregrina and Anadenanthera colubrinaPublication . Mota, Graciene S.; Sartori, Caroline J.; Miranda, Isabel; Quilhó, Teresa; Mori, Fábio Akira; Pereira, HelenaThe bark of Anadenanthera peregrina (L.) Speg and Anadenanthera colubrina (Vell.) Brenan were characterized in relation to anatomical and chemical features. The barks were similar and included a thin conducting phloem, a largely dilated and sclerified non-conducting phloem, and a rhyridome with periderms with thin phellem interspersed by cortical tissues. Only small differences between species were observed that cannot be used alone for taxonomic purposes. The summative chemical composition of A. peregrina and A. colubrina was respectively: 8.2% and 7.7% ash; 28.8% and 29.3% extractives; 2.4% and 2.6% suberin; and 18.9% lignin. The monosaccharide composition showed the predominance of glucose (on average 82% of total neutral sugars) and of xylose (9%). The ethanol-water extracts of A. peregrina and A. colubrina barks included a high content of phenolics, respectively: total phenolics 583 and 682 mg GAE/g extract; 148 and 445 mg CE/g extract; tannins 587 and 98 mg CE/g extract. The antioxidant activity was 238 and 269 mg Trolox/g extract. The barks of the Anadenanthera species are a potential source of polar extractives that will represent an important valorization and therefore contribute to improve the overall economic potential and sustainability of A. peregrina and A. colubrina
- Bark characterization of Tachigali guianensis and Tachigali glauca from the Amazon under a valorization perspectivePublication . Mota, Graciene S.; Sartori, Caroline J.; Ribeiro, Alessandra O.; Quilhó, Teresa; Miranda, Isabel; Ferreira, Gracialda C.; Mori, Fábio A.; Pereira, Helena
- Biochemical Characterization and Fuel Properties of Endemic Taurus Flowering Ash (Fraxinus ornus subsp. cilicica) Bark from TurkeyPublication . Sen, Ali Umut; Simões, Rita; Yüceda˘, Cengiz; Miranda, Isabel; Fernandes, Ângela; Pereira, HelenaTaurus flowering ash (Fraxinus ornus subsp. cilicica) is an endemic tree species in Turkey. The bark of the species was characterized for summative chemical composition, the monomeric composition of polysaccharides, phenolic content, in vitro and ex vivo antioxidant properties of hydrophilic extracts, the composition of lipophilic extractives and suberin, and thermal degradation. The bark has an elevated ash content (17%), primarily composed of calcium, and a noteworthy extractive content (38.9%), predominantly of hydrophilic compounds. The antioxidant activity of the bark extracts is moderate, with an IC50 value of 40 g/mL and an EC50 value of 230 g/mL by DPPH and TBARS methods. The lipophilic extractives principally contain fatty acids and diterpenoids. The suberin content is low (1%) and composed primarily of !-hydroxy acids with 9,10,18 trihydroxyoctadecanoic acid as the major suberin monomer. The lignin content is low (9.8%), and polysaccharides represent 33%. The ignition temperature of the bark is 190 C, the burnout temperature is 653 C, and the activation energy in combustion is 29 kJ mol1. A biorefinery concept was developed considering the bark’s chemical and thermal characteristics to convert approximately 90% of the bark mass into valuable chemicals, extracts, functional materials, and additives.
- Caracterização biométrica das fibras da madeira e casca da Acacia melanoxylon e Eucalyptus globulusPublication . Pereira, Helena; Tavares, Fátima; Quilhó, Teresa; Miranda, Isabel; Bessa, Fernanda; Santos, ClaúdiaNeste trabalho caracterizaram-se as fibras da madeira e da casca da Acacia melanoxylon, na árvore e entre árvores em diferentes condições ambientais. Os resultados compararam-se com os da Eucalyptus globulus. O comprimento e espessura da parede das fibras foram determinados em 20 árvores, provenientes de 4 povoamentos. A variação axial foi analisada em 3 níveis da altura total da árvore (5%, 35% e 65%) e a variação radial em 5 posições do raio (10%, 30%, 50%, 70% e 90%) de cada nível de altura. As medições efectuaram-se em elementos dissociados. O comprimento das fibras decresce da base para o topo da árvore e radialmente aumenta da medula para a periferia. A espessura da parede das fibras não apresentou um modelo específico de variação axial e radialmente aumentou da medula para o exterior com algumas fluctuações. O comprimento das fibras da casca e a espessura das fibras da madeira apresentaram diferenças significativas entre locais. As características biométricas das fibras da A. melanoxylon são semelhantes às das fibras da E. globulus.
- Caracterização da composição química da madeira de Quercus fagineaPublication . Pereira, Helena; Sousa, Vicelina; Cardoso, Sofia; Miranda, IsabelNeste estudo fez-se a caracterização da composição química somativa (cinzas, extractivos, lenhinas e polissacáridos) da madeira de cerne e de borne de Quercus faginea proveniente de um local do Nordeste Transmontano (Macedo de Cavaleiros). Foram seleccionadas e abatidas 10 árvores de Quercus faginea e retiradas amostras de discos a 1,30 m de altura da árvore. As árvores de Quercus faginea estudadas apresentaram todas formação de cerne, com um contorno regular e cor castanha amarelada bem distinto do borne de cor castanha mais clara. A área de cerne variou entre 15% e 64% da área total da secção transversal da madeira, e a espessura de borne entre 1,5 e 4,9 cm. A madeira de Quercus faginea apresentou a seguinte composição química: cinzas 0,8%, extractivos totais 14,5% e lenhina total 24,5%. Os polissacáridos são constituídos principalmente por glucose e xilose (respectivamente em média 59,5% e 31,0% dos monómeros).
- Characterization of crop residues from false banana/Ensete ventricosum/in Ethiopia in view of a full-resource valorizationPublication . Berhanu, Hanna; Kiflie, Zebene; Miranda, Isabel; Lourenço, Ana; Ferreira, Joana; Feleke, Sisay; Yimam, Abubeker; Pereira, HelenaFalse banana /Ensete ventricosum [Welw.] Cheesman/ is exploited as a food crop in Ethiopia where it represents an important staple food. The plant is harvested and large amounts of biomass residues are originated, mainly from the pseudo stem (i.e., fiber bundles obtained from the leaf sheaths after being scrapped to produce starchy food) and the inflorescence stalk. These materials were studied in relation to their summative chemical composition, composition of lignin, lipophilic and polar extracts. Moreover, their structural characteristics, in view of their valorization, were scrutinized. The analytical studies were performed with the aid of FTIR, GC/MS, Py-GC/MS and SEM. The fiber bundles are aggregates of mainly long and slender fibers with low ash, extractives and lignin contents (3.8%. 4.4% and 10.5% respectively) and high holocellulose and α-cellulose contents (87.5% and 59.6% respectively). The hemicelluloses in the fibers are mostly highly acetylated xylans and the lignin is of the H-type (H:G:S, 1:0.7:0.8). This lignin composition is in line with the FTIR peaks at 1670 cm-1 and 1250 cm-1.The inflorescence stalk has high ash content (12.3% in the main stalk and 24.6% in fines) with a major proportion of potassium, high extractives (25.9%), and low lignin and α-cellulose contents (5.8% and 17.9% respectively). The stalk includes numerous starch granules in the cellular structure with the predominant presence of parenchyma. The potential valorization routes for these materials are clearly different. The fiber bundles could be used as a fiber source for paper pulp production with the possibility of a prior hemicelluloses removal while the inflorescence stalk has nutritional value for food and fodder. Furthermore, it can also be used for sugar fermentation products
- Chemical and fuel properties of stumps biomass from Eucalyptus globulus plantationsPublication . Gominho, Jorge; Lourenço, Ana; Miranda, Isabel; Pereira, HelenaEucalyptus globulus Labill. is managed in commercial plantations for the pulp and paper industry as a coppice system. For stand reforestation the stumps are uprooted and at present used as biofuel. In this study, the biomass of stumps collected in six eucalypt stands in Portugal was evaluated in terms of physical, chemical and fuel properties. Stumps had basic density between 0.55 g cm−3 and 0.71 g cm−3, and the chemical composition showed 15.1% total extractives (mainly ethanol soluble extractives, 10.5%), 24.8% lignin and 67.0% holocellulose. In terms of thermal properties the stumps presented 18.9 MJ kg−1 for higher heating value (HHV) and 0.6%, 81.1% and 18.3% respectively for ash, volatile matter and fixed carbon. The elemental composition (C = 51.0%; H = 5.8%; O = 45.3%; Cl = 0.04%) has adequate values for use as woodfuel.
- Chemical characterization and extractives composition of heartwood and sapwood from Quercus fagineaPublication . Miranda, Isabel; Sousa, Vicelina; Ferreira, Joana; Pereira, HelenaHeartwood and sapwood of Quercus faginea were evaluated in relation to summative chemical composition and non-polar and polar extracts composition, including an assessment of antioxidant properties (DPPH and FRAP). Twenty trees from two sites in Portugal were analysed. Heartwood had approximately two times more solvent extractible compounds than sapwood (on average 19.0% and 9.5%). The lipophilic extractible compounds were below 1%, and most of them were polar e.g. ethanol-soluble compounds corresponded to 65% of total extractives in heartwood and 43% in sapwood. Lignin content was similar in sapwood and heartwood (28.1% and 28.6% of extractive-free wood respectively) as well as the sugar composition. Site did not influence the chemical composition. The lipophilic extractible compounds from both sapwood and heartwood included mainly saturated fatty acids (23.0% and 36.9% respectively) and aromatic compounds were also abundant in sapwood (22.9%). The ethanol-water extractibles had a high content of phenolic substances (558.0 and 319.4 mg GAE/g extract, respectively of heartwood and sapwood). The polyphenolic composition was similar in heartwood and sapwood with higher content of ellagitannins (168.9 and 153.5 mg tannic acid/g of extract in sapwood and heartwood respectively) and very low content of condensed tannins. The antioxidant activity was very high with IC50 of 2.6 μg/ml and 3.3 μg/ml for sapwood and heartwood respectively, as compared to standard antioxidants (IC50 of 3.8 μg/ml for Trolox). The ferric reducing ability was 2.8 and 2.0 mMol Trolox equivalents/ g extract of heartwood and sapwood respectively. The variability between trees was low and no differences between the two sites were found. Q. faginea showed a very good potential for cooperage and other applications for which a source of compounds with antioxidant properties is desirable
- Chemical composition of barks from Quercus faginea trees and characterization of their lipophilic and polar extractsPublication . Ferreira, Joana P.A.; Miranda, Isabel; Sousa, Vicelina; Pereira, HelenaThe bark from Quercus faginea mature trees from two sites was chemically characterized for the first time. The barks showed the following composition: ash 14.6%, total extractives 13.2%, suberin 2.9% and lignin 28.2%. The polysaccharides were composed mainly of glucose and xylose (50.3% and 35.1% of all monosaccharides respectively) with 4.8% of uronic acids. The suberin composition was: ω-hydroxyacids 46.3% of total compounds, ɑ,ω-alkanoic diacids 22.3%, alkanoic acids 5.9%, alkanols 6.7% and aromatics 6.9% (ferulic acid 4.0%). Polar extracts (ethanol-water) had a high phenolic content of 630.3 mg of gallic acid equivalents (GAE)/g of extract, condensed tannins 220.7 mg of catechin equivalents (CE)/g extract, and flavonoids 207.7 mg CE/g of extract. The antioxidant activity was very high corresponding to 1567 mg Trolox equivalents/g of extract, and an IC50 of 2.63 μg extract/ml. The lipophilic extracts were constituted mainly by glycerol and its derivatives (12.3% of all compounds), alkanoic acids (27.8%), sterols (11.5%) and triterpenes (17.8%). In view of an integrated valorization, Quercus faginea barks are interesting sources of polar compounds including phenols and polyphenols with possible interesting bioactivities, while the sterols and triterpenes contained in the lipophilic extracts are also valuable bioactive compounds or chemical intermediates for specific high-value market niches, such as cosmetics, pharmaceuticals and biomedicine
- Chemical composition of cuticular waxes and pigments and morphology of leaves of Quercus suber trees of different provenancePublication . Simões, Rita; Rodrigues, Ana; Ferreira-Dias, Suzana; Miranda, Isabel; Pereira, HelenaThe chemical composition of cuticular waxes and pigments and the morphological features of cork oak (Quercus suber) leaves were determined for six samples with seeds of di erent geographical origins covering the natural distribution of the species. The leaves of all samples exhibited a hard texture and oval shape with a dark green colour on the hairless adaxial surface, while the abaxial surface was lighter, with numerous stomata and densely covered with trichomes in the form of stellate multicellular hairs. The results suggest an adaptive role of leaf features among samples of di erent provenance and the potential role of such variability in dealing with varying temperatures and rainfall regimes through local adaptation and phenotypic plasticity, as was seen in the trial site, since no significant di erences in leaf traits among the various specimens were found, for example, specific leaf area 55.6–67.8 cm2/g, leaf size 4.6–6.8 cm2 and photosynthetic pigment (total chlorophyll, 31.8–40.4 ug/cm2). The leaves showed a substantial cuticular wax layer (154.3–235.1 ug/cm2) composed predominantly of triterpenes and aliphatic compounds (61–72% and 17–23% of the identified compounds, respectively) that contributed to forming a nearly impermeable membrane that helps the plant cope with drought conditions. These characteristics are related to the species and did not differ among trees of different seed origin. The major identified compound was lupeol, indicating that cork oak leaves may be considered as a potential source of this bioactive compound
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