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Pita Pegado Gonçalves Rodrigues Coelho, Maria Teresa
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- Adventitious rooting in microshoots of chestnut hybrid (Castanea sativa x C. crenata) in the presence of indole-3-butyric acid: The role of changes in endogenous indole-3-acetic acid, indole-3-acetylaspartic acid and indole-3- butyric acid levelsPublication . Gonçalves, José Carlos; Diogo, Maria da Graça; Coelho, Maria Teresa; Vidal, N.; Amâncio, SaraEndogenous levels of IAA, IAAsp and IBA were quantified during the first 8 days of in vitro rooting of the chestnut hybrid, clone M3 by high performance liquid chromatography. Rooting was induced either by dipping the basal ends of the shoots into 1 gl-1 IBA solution for 1 minute or by subculturing the shoots on agar rooting medium with 3 mgl-1 IBA for 5 days. For root development the induced shoots were transferred to auxin-free agar medium. Auxins were measured in the apical and basal parts of the shoots by means of high performance liquid chromatography. Endogenous levels of IAA and IAAsp were higher in IBA-treated shoots than in control shoots. In extracts of the basal parts of the shoots, the concentration of free IAA showed a transient peak at day 2, in both root inductive methods, a subsequent gradual decrease for the remainder of the time course was observed. The concentration of IAAsp peaked at day 6 in extracts of the basal parts of shoots induced with 3 mgl-1 IBA for 5 days, whereas shoots induced by dipping showed an initial increase until day 2, and then remained stable. In extracts from basal shoot portions induced by dipping and by IBA in the medium, IBA concentration showed a transient peak at 24 h and 48 h, respectively, remaining stable after day 4 for the dipping method, whilst showing a significant drop between day 4 and 6 for the other induction treatment. All quantified auxins remained at a relatively low level, virtually constant, in extracts from apical shoot portions, as well as in extracts from control of non-rooting shoots.
- Sugar composition, phenolic content and antioxidant activity of P. tridentatum aqueous extracts: micropropagated shoots vs wild plantsPublication . Coelho, Maria Teresa; Diogo, Maria da Graça; Martins, Vítor R.; Coimbra, Manuel A.; Alves, Vítor; Gonçalves, José Carlos; Martins, Margarida MoldãoSugar composition, phenolic content and antioxidant activity of P. tridentatum aqueous extracts: micropropagated shoots vs wild plants.
- Natural extracts from Pterospartum tridentatum at different vegetative stages: extraction yiels, phenolic content and antioxidant activityPublication . Coelho, Maria Teresa; Pimenta, Catarina; Gonçalves, José Carlos; Alves, Vítor; Martins, Margarida MoldãoThe aerial parts of Pterospartum tridentatum, a wild growing species in Portugal used in traditional medicine and gastronomy, were harvested at different stages (vegetative phase, flowering phase and beginning of dormancy) in two locations in Portugal (Malcata and Gardunha mountains), and the respective aqueous extracts have been studied. The influence of the seasonal variation in the extraction yield, total phenolic content and antioxidant activity was evaluated. The extraction was carried out in boiling water in consecutive steps. After each step, the aqueous extract was separated and fresh water was added maintaining the same plant material. The procedure was repeated seven times, within an overall time period of 180 minutes. Higher extraction yields were achieved with plant stems collected at the vegetative phases, either from Malcata or Gardunha regions. The total phenolic content of the extracts from Malcata plants ranged from 273 mg to 400 mg gallic acid equivalent/g dry matter, which was quite similar to that determined for extracts from Gardunha (245 to 394 mg gallic acid equivalent/g dry matter). The antioxidant activity was determined by the radical scavenging activity method using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). The greatest radical scavenging activity was observed in the flowers extracts, even though all extracts produced presented a good antioxidant activity. Furthermore, the antioxidant activity was not affected by the exposure of the plant material at 100ºC for long periods of time (180 min). The results show that Pterospartum tridentatum has a great potential to be used as a new source of natural antioxidants for the food industry.
- The effect of abiotic stress pre-treatments on quality attributes of fresh-cut carrot cv. NantesPublication . Alegria, Carla; Pinheiro, Joaquina; Duthoit, Margarida; Gonçalves, Elsa; Coelho, Maria Teresa; Martins, Margarida Moldão; Abreu, MartaThe aim of this study was to evaluate the effects of heat-shock and UV-C radiation stress treatments, applied in whole carrots, on the overall quality of fresh-cut carrot cv. Nantes during storage (5º C).
- Microencapsulation of natural antioxidants from Pterospartum tridentatum in different alginate and inulin systemsPublication . Isailović, B.; Kalušević, Ana; Žuržul, Nataša; Coelho, Maria Teresa; Đorđević, Verica; Alves, Vítor; Sousa, Isabel; Martins, Margarida Moldão; Bugarski, Branko; Nedović, ViktorThe bioactivity of natural antioxidants from plant extracts is well known. Still, the effectiveness of these natural antioxidants, namely polyphenols, depends on preserving their stability, which can be increased by microencapsulation. The aim of this study was to protect natural antioxidants from the aqueous extract of Portuguese wild herb Pterospartum tridentatum by encapsulation in alginate hydrogel microbeads. Microbeads were prepared by electrostatic extrusion technique: plain Ca-alginate microbeads and Ca-alginate microbeads with 10 and 20 mass% of inulin as a filler substance. Total polyphenol content (TPC) and the radical scavenging activity using ABTS and DPPH cations were determined. The release studies of polyphenols from microbeads were performed. The microbeads were analysed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and optical microscopy (OM). Encapsulation efficiency (EE) was in the range from 49 to 73%. Antioxidant assays and release studies showed that alginate-inulin microbeads appeared to be suitable dosage forms. The inclusion of inulin contributes to improved microbeads structure, as well as to nutritional values of food. Thereby, potential applications of these microbeads could be functional food products, an increasingly valued market.
- Efeitos da conservação in vitro a 4ºC na sobrevivência e proliferação da cerejeira (Prunus avium L.)Publication . Gonçalves, José Carlos; Coelho, Maria TeresaA utilização de técnicas in vitro para o armazenamento e conservação de germoplasma, apresenta-se hoje como uma alternativa de valor potencial aos tradicionais métodos de conservação. De facto, a possibilidade de manter partes vegetativas de plantas em condições limitadas de espaço e manutenção por longos períodos de tempo, tornam essas técnicas suficientemente atractivas para constituírem no futuro uma garantia da manutenção de recursos genéticos escassos e limitados. Neste estudo referem-se os resultados obtidos na conservação pelo frio de rebentos axilares de cerejeira com 1 ± 0.2 com de comprimento, obtidos a partir de culturas com 1 ano de idade e mantidos a 4ºC em meio de MS com diferentes concentrações de sacarose e de reguladores de crescimento, quer na sobrevivência, quer nas taxas de proliferação, durante três subcultivos sucessivos após o período de conservação de 3, 6, 9 e 12 meses. A presença de sacarose mostrou ser determinante para a sobrevivência dos explants, o mesmo já não acontecendo às diferentes combinações dos reguladores de crescimento utilizados, BAP e AIA. Decréscimos na sobrevivência começaram a registar-se a partir dos 9 meses de conservação, apesar dos explants sobreviventes continuarem a apresentar capacidade proliferativa. As taxas de multiplicação e alongamento dos rebentos foram em geral afectadas no primeiro subcultivo após a conservação, mas estes valores normalizaram ao longo do segundo e terceiro subcultivo.
- Comparative study between in vitro and in vivo developing root systems in micropropagated chestnutPublication . Gonçalves, José Carlos; Coelho, Maria Teresa; Diogo, Maria da GraçaThe aim of this study was to compare two rooting environmental conditions for root development, in vitro and ex vitro, and their influence in anatomical differentiation.
- Common myrtle in vitro propagation : establishment and multiplication stagesPublication . Coelho, Maria Teresa; Diogo, Maria da Graça; Reis, R.; Ribeiro, M.M.A.The use of medicinal plants for the extraction of active pharmacological agents and precursors for chemical-pharmaceutical chemosynthesis has recently increased. The aim of this work was to study the establishment and multiplication phases of the in vitro propagation of common myrtle (Myrtus communis L.). In the establishment phase, the most suitable disinfection method was found by using increasing concentrations of commercial bleach (10%, 15% and 20%). It was discovered that commercial bleach at 15% allowed better results in the shoots survival rate (87%). The concentrations used to establish the explants from adult plant material did not allow however that all of them survived. This was possibly due to the some release of phenolic substances, and, also, to a certain toxicity of the disinfectant used, especially at the highest concentration. During the multiplication phase it was intended to assess the influence of light, through coloured bottle caps, on the shoots growth rate parameters, but we observed that it had no influence on the average of the longest shoot, on the average of the smaller shoot, and also, on the parameters related to the multiplication rate, the number of shoots and the number of shoot segments.
- Inventariação e propagação de Thymus mastichina na Beira InteriorPublication . Vila Boa, H.; Coelho, Maria Teresa; Silva, M.C.A.; Silva, Isabel Castanheira; Delgado, F.M.G.; Jacinto, Paulo; Oliveira, Maria do Rosário; Caldeira, RaquelIntegrado no Programa Agro, Medida 8.1, Projecto nº 800, foram elaborados estudos de distribuição e propagação da espécie Thymus mastichina L., existentes espontaneamente na Beira Interior. Foram avaliadas seis zonas ecológicas distintas denominadas Vale do Tejo, Beira Interior Sul, Cova da Beira, Beira Interior Norte, Serra da Estrela e Serra da Gardunha. Durante dois anos fez-se prospecção no campo em cada zona ecológica e recolheu-se material vegetal. Realizaram-se ensaios de germinação em laboratório em condições de temperatura alterna 10º/20ºC (dia) e temperatura constante 23ºC (dia), com fotoperíodo de 8 e 16 horas/dia, respectivamente. Testou-se ainda a capacidade germinativa em estufa, na Primavera e efectuaram-se ensaios de enraizamento, com estacas terminais, em condições de Outono/Inverno e Primavera/Verão. Na Beira Interior foram encontrados 36 locais onde se verificou a ocorrência de Thymus mastichina. Em cada zona ecológica onde foram encontrados indivíduos da espécie em estudo, foi seleccionado um local para recolha de 20 plantas-mãe, que foram posteriormente instaladas no campo de caracterização/demonstração da ESACB. Nos ensaios de germinação verificaram-se taxas entre os 80% e 94% em laboratório e entre os 76% e 84%, em viveiro. Nos ensaios de propagação vegetativa de estacas terminais obtiveram-se taxas de enraizamento entre os 20% e 100%.
- Antioxidant activity and phenolic content of extracts from different Pterospartum tridentatum populations growing in PortugalPublication . Coelho, Mara Teresa; Gonçalves, José Carlos; Alves, Vítor; Martins, Margarida MoldãoIn the present study, aerial parts of Pterospartum tridentatum plants, collected in three locations in Portugal, at different vegetative stages, were evaluated for their total phenolic content and the antioxidant activity of aqueous extracts. The influence of the seasonal variation in the yield and composition of the extracts was evaluated, in order to select the most appropriate harvest season. Among the populations assayed, the extraction yields have some differences with the harvest period but the highest yield extraction was obtained in the flowering season, using flowers (19.4g/100g plant dry mass) and the lowest extraction yield was also obtained in the same period but using stems. The antioxidant activity of the solid extracts of Pterospartum tridentatum aerial parts, was determined by the radical scavenging activity method using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). The greatest DPPH radical scavenging activity was observed in the flowering period (3.6 mMTrolox/Kg dry mater), but no significant differences for the dormancy period. According to these results, we can choose the harvest season more favorable. The total phenolic content (TP) of the extracts was evaluated by measuring the absorbance at 280 nm and the values ranged from 270.7 to 402.9 mg gallic acid equivalents per g dry matter. The vegetative stage did not influence this total phenolic content. From preliminary experiments, it is also anticipated a significant antimicrobial activity of the solid extracts against bacteria and fungus.