Browsing by Author "Neves, Ana"
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- 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
- Metais pesados em pescado: caso de estudo num centro de distribuiçãoPublication . Gouveia, Hugo; Neves, Ana; Oliveira, Adelaide; Paulo, AnaO pescado é reconhecido como fonte de alimentação saudável e de elevada qualidade. A legislação da União Europeia assegura que os alimentos colocados nos mercados europeus são seguros para consumo. A legislação sobre contaminantes no pescado inclui, no caso dos metais pesados, os limites regulamentares e tem vindo a ser atualizada. O estudo foi realizado no âmbito de um trabalho de mestrado. Foi desenvolvido numa base logística, com recurso a informação recolhida nos boletins de análises de pescado, onde os metais pesados poderão estar presentes. Os metais pesados analisados foram o mercúrio, o chumbo e o cádmio. A base logística estabelece um plano de amostragem e as análises são realizadas por um laboratório externo. A amostragem é feita por espécies e, no caso dos metais pesados, existe um histórico de boletins de análises das várias espécies comercializadas, identificando os fornecedores e a origem do produto. A frequência de amostragem é mais elevada nos produtos em que já foi detetada a presença de metais pesados. O estudo incidiu sobre onze espécies de peixe, quatro espécies de moluscos, cinco espécies de bivalves e uma espécie de crustáceo, nos anos de 2017, 2018 e 2019. Após análise dos boletins e tratamento de dados verificou-se que apenas três espécies, duas de moluscos e uma de peixes, apresentam resultados superiores aos limites legais (EU Reg. 1881/2006, 629/2008), embora se detete a presença residual de metais pesados noutras espécies.
- Nutritional and microbial quality of edible insect powder from plant-based industrial by-product and fish biowaste dietsPublication . Andrade, R.; Martins, L.L.; Mourato, M.P.; Lourenço, H.; Ramos, A.C.; Roseiro, C.; Pereira, N.; Costa, G.J.; Lucas, R.; Alvarenga, N.; Reis, J.; Neves, Ana; Oliveira, Margarida; Dias, Igor; Abreu, M.Edible insect powder, particularly from the cricket Acheta domesticus L., is a promising sustainable alternative to traditional livestock-derived protein. Insects provide high protein content, fibre, and essential minerals, making them suitable for food applications. This study investigates the viability of alternative diets for rearing A. domesticus. Two experimental diets were tested: RI [50% horticultural by-products (HP) + 50% commercial diet (CD)] and RII (33% HP + 33% CD + 33% fish by-products). The results demonstrated that both diets were suitable for cricket rearing. Crickets reared on diets RI and RII produced, respectively, insect powders FI and FII, which were evaluated for their nutritional, bioactive, and microbiological attributes. Both powders exhibited high protein content (≈60%), all essential amino acids, higher mineral content than traditional protein sources, and met European Union food safety standards. Diet composition influenced powder characteristics: FI showed higher antioxidant activity and saturated fat content, while FII contained more protein, ash, minerals, and monounsaturated fatty acids. These findings underscore the potential of using industrial by-products to promote a circulareconomy in insect farming and suggest pathways for further research. However, since insects can bioaccumulate toxic elements, such as Hg, from diets, caution should be taken when considering fish by-products
- Sugar bislactones by one-step oxidative dimerisation with pyridinium chlorochromate versus regioselective oxidation of vicinal diolsPublication . Rauter, A. P.; Piedade, F.; Almeida, T.; Ramalho, R.; Ferreira, M.J.; Resende, R.; Amado, J.; Pereira, H.; Justino, Jorge; Neves, Ana; Silva, Filipa V.M.; Canda, T.Synthesis of 10-membered bislactones by PCC oxidation of methyl 2,6-di-O-pivaloyl-α-D-glucopyranoside and methyl 4,6-O-benzylidene-α-D-glucopyranoside is described, with emphasis on their structure elucidation using the information gained by combination of NMR spectroscopic techniques with X-ray diffraction data. In alternative, the use of PCC and PCC adsorbed on silica gel or alumina for the regioselective oxidation of vicinal diols in sugars is also reported. Both bislactones showed antifungal activity against Candida albicans, and were slightly active against the bacteria Bacillus subtilis. The bislactone presenting pivaloyl protecting groups also promoted some growth inhibition of Staphylococcus aureus.
- 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.