Browsing by Author "Lucas, S."
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- Aclimatação ex vitro de pereira (Pyrus communis L.) microporopagada. Estudo de substratosPublication . Lucas, S.; Grego, José; Relelo, Maria; Lopes, Maria; Marques, António; Figueiredo, A.; Trindade, M.A pereira (Pyrus communis L.) é uma espécie frutícola de elevada importância na fruticultura Portuguesa. A produção nacional em 2005-6 foi de 129 mil toneladas para uma área cultivada de 12 mil hectares. Em 2010-11 a produção ascendeu às 220 mil toneladas. A cultivar “Rocha” é das mais importantes em termos de exportação com um volume de vendas em 2005 de 26 milhões de euros para 45 mil toneladas de pêra correspondente a 35 % da produção total. O presente estudo avaliou uma cultivar de pereira proveniente de uma “semente do acaso” originada numa quinta em Tábua, Distrito de Coimbra, Portugal entre 1990 e 2000. Foi testado o efeito do uso de diferentes substratos na aclimatação ex vitro de plantas micropropagadas. Usaram-se três tipos de substratos: substrato orgânico (SO); SO + perlite (½ + ½, v/v) e perlite. Fez-se a análise do desenvolvimento radicular e da parte aérea: número e comprimento das raízes; peso fresco e seco das raízes e parte aérea. Em todos os tratamentos obtiveram-se 100% de plantas aclimatadas. Os tratamentos com substrato orgânico e mistura SO + perlite deram origem a plantas mais vigorosas em termos de peso fresco das raízes e parte aérea.The common pear (Pyrus communis L.) is one of the most widely cultivated fruit crop in Portugal. The national production in 2005 was 129 thousand tons, to a cultivated area of 12 thousand ha. “Rocha” is the economically most important Portuguese cultivar accounting for 75% of pear production in Portugal, in 2005. Total exports amounted to 26 million euro, corresponding to approximately 45 thousand tons. This study was conducted with a pear-chance seedling originated on a farm located at Tábua, central Portugal, between 1999 and 2000. The main aim of the study was to determine the effects of three substrates: organic compost (SO); perlite + SO (½ + ½, v/v) and perlite on the ex vitro survival and development (roots and leaflets) of pear plantlets. All the treatments had a 100 % survival rate, and the highest ex vitro development was observed on SO and perlite + SO.
- Alkyl deoxy-arabino-hexopyranosides: synthesis, surface properties, and biological activitiesPublication . Silva, Filipa; Goulart, Margarida; Justino, Jorge; Neves, Ana; Santos, F.; Caio, J.; Lucas, S.; Newton, A.; Sacoto, D.; Barbosa, E.; Santos, M. S.; Rauter, A. P.Octyl and dodecyl glycosides possessing 2-deoxy-arabino-hexopyranoside moieties belonging to the D-and L-series in their alpha- and beta-forms were synthesized by reaction of an acetyl protected glycal with octanol or dodecanol, catalyzed by triphenylphosphine hydrobromide, followed by deprotection. Their surface properties were studied and discussed in terms of the adsorption and aggregation parameters, pC(20), CMC, and gamma(CMC). The antimicrobial activities were assessed using the paper disk diffusion and broth dilution methods. Both the octyl and dodecyl 2-deoxy beta-D-glycosides inhibited significantly Enterococcus faecalis, a microbe also highly susceptible to dodecyl 2,6-dideoxy-alpha-L-arabino-hexopyranoside. This compound was particularly active against Bacillus cereus and Bacillus subtilis, presenting for both Bacillus species a minimal inhibitory concentration of the same order of magnitude and a minimal lethal concentration even smaller than that obtained for chloramphenicol, a bioactivity which remained unaltered after 1 year solution storage at 4 degrees C. In addition, activity over Listeria monocytogenes was also observed. Direct cytotoxicity and genotoxicity of the glycosides were determined by proliferative index (mitotic index) evaluation in peripheral human lymphocytes of healthy donors. All compounds induced acute toxicity effects, and the response was dose dependent for the alpha-anomer of both the alkyl 2-deoxy-arabino-hexopyranosides and for the corresponding dodecyl beta-anomer, what suggests that non-toxic but still bioactive concentrations may be found for these compounds
- Synthesis, surface active and antimicrobial properties of new alkyl 2,6-dideoxy-L-arabino-hexopyranosidesPublication . Rauter, A. P.; Lucas, S.; Almeida, T.; Sacoto, D.; Ribeiro, V.; Justino, Jorge; Neves, Ana; V.M. Silva, Filipa; Oliveira, M.C.; Ferreira, M.J.; Santos, M.S.; Barbosa, E.Synthesis of alkyl 2,6-dideoxy-L-arabino-hexopyranosides was accomplished by the reaction of 1,5-anhydro-2,6-dideoxy-L-arabino-hex-1-enitol with fatty alcohols in dichloromethane, catalyzed by triphenylphosphine hydrobromide. Reaction with octanol and dodecanol gave the corresponding α-glycosides in 50% and 42% yield, the β-glycosides in 20% and 21% yield and the α-anomer of the Ferrier product in 10% and 9% yield, respectively.Deacetylation of the α-/β-glycosides with sodium methoxide in methanol afforded the amphiphilic L-arabino-hexopyranosides in 94–99% yield. The surface tension at the air–water interface of the octyl L-glycosides and of the dodecyl α-L-glycoside aqueous solutions at 35 °C was measured with a du Noüy ring tensiometer and surface properties such as critical micelle concentration (CMC), relative surface excess, molecular area at the interface and Gibbs micellization free energy were evaluated. The stereochemistry of the hexopyranoside ring in unimers and aggregates is correlated to the hydrophobicity and packing efficiency on the air–water interface. The antibacterial and antifungal activities of the surface-active glycosides were evaluated using the paper disk diffusion method. The dodecyl α-L-arabino-hexopyranoside was quite active over Bacillus cereus and Bacillus subtilis, while low activity was found for this glycoside over Enterococcus faecalis and Listeria monocytogenes. The octyl glycosides tested showed low activity over almost all the above-mentioned bacteria, and also over the fungus Candida albicans. No inhibition of Salmonella enteritidis and of the filamentous fungus Aspergillus niger was detected for any of the compounds tested.