Browsing by Author "Gomes, Joana"
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- Differences in antimicrobial activity of natural compounds by drop diffusion or dilution methods on agarPublication . Gomes, Joana; Barbosa, Joana; Teixeira, Paula
- Effects of chitooligosaccharides on human red blood cell morphology and membrane protein structurePublication . Fernandes, João C.; Eaton, Peter; Nascimento, Henrique; Belo, Luís; Rocha, Susana; Vitorino, Rui; Amado, Francisco; Gomes, Joana; Santos-Silva, Alice; Pintado, Manuela E.; Malcata, F. XavierRecent studies of chitosan have increased the interest in its conversion to chitooligosaccharides (COSs) because these compounds are water-soluble and have potential use in several biomedical applications. Furthermore, such oligomers may be more advantageous than chitosans because of their much higher absorption profiles at the intestinal level, which permit their facilitated access to systemic circulation and potential distribution throughout the entire human body. In that perspective, it is important to clarify their effect on blood further, namely, on human red blood cells (RBCs). The aim of this work was thus to study the effect of two COS mixtures with different molecular weight (MW) ranges, <3 and <5 kDa, at various concentrations (5.0-0.005 mg/mL) on human RBCs. The interactions of these two mixtures with RBC membrane proteins and with hemoglobin were assessed, and the RBC morphology and surface structure were analyzed by optical microscopy (OM) and atomic force microscopy (AFM). In the presence of either COS mixture, no significant hemolysis was observed; however, at COS concentrations >0.1 mg/mL, changes in membrane binding hemoglobin were observed. Membrane protein changes were also observed with increasing COS concentration, including a reduction in both α- and β-spectrin and in band 3 protein, and the development of three new protein bands: peroxiredoxin 2, calmodulin, and hemoglobin chains. Morphologic evaluation by OM showed that at high concentrations COSs interact with RBCs, leading to RBC adhesion, aggregation, or both. An increase in the roughness of the RBC surface with increasing COS concentration was observed by AFM. Overall, these findings suggest that COS damage to RBCs was dependent on the COS MW and concentration, and significant damage resulted from either a higher MW or a greater concentration (>0.1 mg/mL).
- Effects of microencapsulated phenethyl isothiocyanate on gastrointestinal cancer cells and pathogenic bacteriaPublication . Abrantes, Rafaela; Ramos, Cátia C.; Coscueta, Ezequiel R.; Costa, João; Gomes, Joana; Gomes, Catarina; Reis, Celso A.; Pintado, Maria ManuelaGastrointestinal cancers remain a global health burden, demanding more effective prevention and treatments. Phenethyl isothiocyanate (PEITC), a compound derived from cruciferous vegetables, stands out as a promising nutraceutical agent due to its chemopreventive and therapeutic properties. However, its therapeutic translation remains limited mainly due to its poor water solubility and rapid metabolism. Herein, we encapsulated PEITC into biocompatible chitosan-based microparticles with an extra virgin olive oil core to improve its bioavailability and stability. Pure PEITC's biocompatibility and microencapsulated PEITC's stability and antibacterial activity were evaluated. The antibacterial activity analysis showed microencapsulated PEITC as a promising antibacterial agent against gastrointestinal pathogenic bacteria (two Gram-positive and two Gram-negative). The impact of both pure and microencapsulated PEITC was assessed on gastrointestinal cancer cells (MKN45 gastric cancer and SW48 colon cancer cell lines). PEITC exhibited threshold or hormetic dose-dependent toxicity in colon fibroblasts and decreased gastric cancer cells' migration capacity, enhanced upon encapsulation into microparticles. In addition, microencapsulated PEITC induced downregulation of phosphorylated AKT, FAK, and ERK1/2 proteins, disrupting motility signaling pathways and tubulin expression. These findings suggest that the delivery of PEITC via chitosan-based microparticles holds promise as a nutraceutical delivery strategy against gastrointestinal disorders that predispose to cancer.
- Influence of the nutritional growth conditions on the formation of biofilmsPublication . Gomes, Joana; Barbosa, Joana; Teixeira, PaulaIntroduction: Biofilm formation is influenced by many factors and varies between strains. Each strain uses different strategies and expresses different genes to promote biofilm formation and adherence. These processes are dependent on the environmental resources available. For some strains, the ability to form or not form a biofilm is strongly dependent on the biofilm growth conditions, such as the availability of nutrients. Listeria monocytogenes, Salmonella spp., and Escherichia coli are pathogenic bacteria associated with biofilm formation. Biofilm formation promotes the development and spread of infections difficult to treat, and contributes to antimicrobial resistance, which is a current concern. Purpose: This study aimed to evaluate the biofilm formation of Listeria monocytogenes (two serotypes), Salmonella enterica (four serotypes) and Escherichia coli strains on the surface of polystyrene under different nutrient conditions. Discussion and conclusions: Although this technique shows variability in results across different replicates, it remains possible to verify that: For three L. monocytogenes strains tested (2542, 12MOB047, and 12MOB050), the growth medium had a significant effect on biofilm formation (p < 0.05) (Figure 1); For two S. enterica strains tested (Typhimurium ESB9 and Senftenberg 775W), the growth medium also had a significant effect on biofilm formation (p < 0.05) (Figure 2); In contrast, no significant differences were observed for the E. coli strains (Figure 3). In conclusion, the greatest biofilm production of L. monocytogenes strains occurred in richer nutrient conditions (TSB with 1% glucose), in contrast to S. enterica strains (TSB).
- Natural antimicrobial agents and their potential on the preservation of foodPublication . Gomes, Joana; Barbosa, Joana; Teixeira, Paula
- Natural antimicrobial agents as an alternative to chemical antimicrobials in food preservationPublication . Gomes, Joana; Barbosa, Joana; Macieira, Ariana; Teixeira, PaulaIntroduction: Microbiological quality of food is of considerable concern to the food industry, since the activity of microorganisms can cause deterioration and, more seriously, affect the health of consumers [1]. Therefore, chemical additives are added to most of the foods with the purpose of maintaining certain properties or prolonging their shelf life [2]. However, there are several health-related problems associated with the use of these additives. Due to the problem of demonstrated or potential toxicity to the consumers, the number of chemical compounds allowed as food preservatives is limited [3]. Although, currently, most preservatives have no side effects and are classified as safe, there have been problems with the safety of some of these chemicals. The objective of this work was to determine the minimum inhibitory concentrations of three natural antimicrobial agents (ethanolic extract of propolis, chitosan and nisin) against 32 microorganisms (15 Gram-positive and 15 Gram-negative bacteria and two fungi) in order to compare with the minimum inhibitory concentrations of the chemical compound sodium nitrite, alone and in combination with sodium chloride. The inhibition of microorganisms was also tested at different pH values and temperatures of incubation to simulate the presence of the pathogens in different foods stored at different conditions. Conclusions: The natural compounds tested had greater inhibitory effect against the various microorganisms compared with the sodium nitrite alone and in combination with sodium chloride, in the different conditions of pH and temperature. Chitosan at 0.65% (w/v) inhibited most of the tested microorganisms. At 10 mg/mL of propolis, fungi, most of the Gram-positive and some of the Gram-negative bacteria were inhibited. At 25 μg/mL of nisin it was possible to inhibit most of the Gram-positives. Sodium nitrite, individually or in combination with sodium chloride, did not inhibit most microorganisms. The minimum inhibitory concentrations of several microorganisms were different depending on the methodology. With these in vitro results, it seems that the natural compounds investigated are good alternatives to chemical antimicrobials used in food production.
- Noite europeia dos investigadores em Armamar: palco da ciência em ambientes ruraisPublication . Branquinho, Raquel; Duarte, Joaquim; Sarabando, Cândida; Damião, Cláudia; Ambrósio, Susana; Barbosa, Joana Cristina; Barbosa, Joana Bastos; Rezende, Lourenço; Carocho, Márcio; Fernandes, Mariana; Marques, Richard; Friães, Sofia; Santos Carvalho, Ana; Teixeira, Bruno; Ribeiro, Daniela; Grosso, Filipa; Duarte, Inês; Teixeira, José Carlos; Saavedra, Maria José; Alvim, Mariana; Lúcio, Marlene; Oliveira, Mónica; Cardoso Santos, Nuno; Cardoso, Paula; Nunes, Paulo; Cruz, Pedro; Bartolomeu, Raul; Cardoso, Ricardo; Ferreira, Sónia; Carvalho, Teresa; Teixeira, Sofia; Fonseca, Joana; Duarte, Hernâni; Sá-Pinto, Xana; Gomes, Joana; Soares, Luís
- Ozone and UVC radiation as disinfection strategies of textile substratesPublication . Gomes, Joana; Rezende, Lourenço; Barbosa, Joana; Neto, Cláudia; Carvalho, Marta; Coelho, Nuno; Ferreira, João; Costa, Ana Filipa; Pintado, Manuela; Teixeira, PaulaThe emergence of COVID-19 triggered changes in routines and other concerns, such as the disinfection of textile clothing, to avoid the transmission of the disease. The application of ozone and UV radiation to textiles are interesting disinfection methodologies that do not use harmful chemicals. Ozone has been used for several years as a disinfectant, and UVC radiation has been shown to destroy viruses and bacteria. These technologies can be applied in hospitals, clinics, clothing stores, hotels, among others. This study aimed to investigate the impact of ozone (at different concentrations) and UVC radiation treatments and their combination (at different treatment times) in the elimination of pathogenic microorganisms (Acinetobacter ESB260 and Escherichia coli ATCC 8739) applied to different textile substrates. These treatments were applied in a prototype of the MTEX PHYS Sterilizer. The results demonstrated that ozone is more effective than UVC radiation. The highest bacterial inactivation with UVC radiation was that lasting 60 minutes. The best results with ozone treatments were obtained at concentrations of 50 and 60 ppm for 60 minutes, and log reductions of up to 5 log cycles were obtained. Apparently, the treatment time is more relevant than the ozone concentration. The combined treatment triggered a synergy of the treatments, in which values of logarithmic reduction were identical to those of the ozone treatment, but in a shorter time. The effectiveness of the treatments depends on the type of fabric and the bacterial species/strain.
- Risk associated with water contaminated with listeria monocytogenes and used for irrigation of sproutsPublication . Gomes, Joana; Barbosa, Joana; Teixeira, PaulaListeria monocytogenes is a foodborne pathogen that has been associated with outbreaks of listeriosis caused by the consumption of contaminated vegetables 1 Once in contact with plant tissue, the bacteria can adhere and persist for a significant period of time Moreover, the quantity of cells can influence their dissemination and survival within plants 2.
- Spore resistance to disinfection treatments by ozone and UV radiation in textilesPublication . Gomes, Joana; Rezende, Lourenço; Barbosa, Joana; Neto, Cláudia; Carvalho, Marta; Coelho, Nuno; Ferreira, João; Costa, Ana Filipa; Pintado, Manuela; Teixeira, Paula