Percorrer por autor "Costa, Eduardo"
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- Alkaline extraction of phenolic compounds from Eucalyptus leaves: influence on antioxidant and antimicrobial activityPublication . Afonso, Tiago B.; Bonifácio-Lopes, Teresa; Costa, Eduardo; Macedo, Tiago; Moreira, Joana; Oliveira, Juliana; Pintado, ManuelaIntroduction: The valorization of agro-industrial by-products is a strategic approach to reducing biomass waste while advancing circular bioeconomy practices. Eucalyptus leaves, an abundant residue from the forestry and pulp industries, are particularly rich in phenolic compounds with well-known antioxidant and antimicrobial activities. These bioactivities highlight the potential of eucalyptus extracts for sustainable applications in the cosmetic and textile industries. However, their efficient recovery requires optimized extraction methodologies capable of disrupting the complex plant matrix and maximizing compound release. The aim of this study was to investigate how variations in eucalyptus particle size and alkali concentration can enhance the recovery of phenolic-rich extracts with bioactive potential. Conclusions: Alkaline extraction proved capable for recovering phenolic compounds from eucalyptus leaves, yielding extracts with relevant antioxidant and antimicrobial activities. However, the extracts showed cytotoxicity at the tested concentrations, highlighting the need for further optimization of extraction parameters and the establishment of safe concentration ranges before potential use in applications such as cosmetics or textiles.
- Alkaline extraction of phenolic compounds from Eucalyptus leaves: influence on antioxidant and antimicrobial activityPublication . Afonso, Tiago Barros; Bonifácio-Lopes, Teresa; Costa, Eduardo; Macedo, Tiago; Moreira, Joana; Oliveira, Juliana; Pintado, ManuelaBackground: The valorization of agro-industrial by-products is a strategic approach to reducing biomass waste while advancing circular bioeconomy practices. Eucalyptus leaves, an abundant residue from the forestry and pulp industries, are particularly rich in phenolic compounds with well- known antioxidant and antimicrobial activities. These bioactivities highlight the potential of eucalyptus extracts for sustainable applications in the cosmetic and textile industries. However, their efficient recovery requires optimized extraction methodologies capable of disrupting the complex plant matrix and maximizing compound release. In this work, we explored alkaline extraction, focusing on the influence of particle size and alkali concentration on the recovery of phenolic-rich extracts with bioactive potential. Methods: Eucalyptus leaves were processed at two particle sizes (4 mm and 10 mm) and extracted using NaOH at two concentrations (0.1 M and 0.3 M). Extracts were analyzed for total phenolic and flavonoid content as well as antioxidant capacity using ORAC assay. Phenolic composition was characterized by LC-ESI-QqTOF-HRMS. Furthermore, the antimicrobial efficacy of the extracts was tested against different Gram-negative and Gram-positive bacteria as well as the yeast Malassezia furfur. Additionally, the biocompatibility of the extracts was evaluated on a human keratinocyte cell line (HaCaT). Results: Smaller particle sizes (4 mm) combined with lower NaOH concentrations (0.1 M) yielded extracts with higher total phenolic and flavonoid content. In terms of antioxidant activity, no significant differences were observed between the different extracts. LC-ESI-QqTOF-HRMS analysis revealed the presence of phenolic acids (e.g., quinic and gallic acid) and flavonoids (e.g., quercetin-3-O-glucuronide) with compositional differences across conditions. All extracts displayed strong antimicrobial activity against Gram-positive bacteria and M. furfur, with MIC values below 1.25 mg/mL in most cases. However, cytotoxicity assays indicated reduced HaCaT viability at concentrations ? 500 ?g/mL. Conclusions: Alkaline extraction proved effective for recovering phenolic compounds from eucalyptus leaves, yielding extracts with strong antioxidant and antimicrobial activities. These findings support their potential for skin-related applications, including cosmetics and functional textiles, although further optimization of extraction conditions and safety thresholds is required.
- Anthocyanin recovery from grape by-products by combining ohmic heating with food-grade solvents: phenolic composition, antioxidant, and antimicrobial propertiesPublication . Coelho, Marta; Silva, Sara; Costa, Eduardo; Pereira, Ricardo N.; Rodrigues, António Sebastião; Teixeira, José António; Pintado, ManuelaUsually, wine-making by-products are discarded, presenting a significant environmental impact. However, they can be used as a source of bioactive compounds. Moreover, consumers’ increasing demand for naturally nutritious and healthy products requires new formulations and food product improvement, together with sustainable, environmentally friendly extraction methods. Thus, this work aimed to compare ohmic heating (OH) with conventional methodology (CONV), using food-grade solvents, mainly water, compared to standard methanol extraction of anthocyanins. No significant differences were found between the CONV and OH for total phenolic compounds, which were 2.84 ± 0.037 and 3.28 ± 0.46 mg/g DW gallic acid equivalent, respectively. The same tendency was found for antioxidant capacity, where CONV and OH presented values of 2.02 ± 0.007 g/100 g and 2.34 ± 0.066 g/100 g ascorbic acid equivalent, respectively. The major anthocyanins identified were malvidin-3-O-acetylglucoside, delphinidin-3-O-glucoside, petunidine-3-O-glucoside, cyanidin-3-O-glucoside, and peonidine-3-O-glucoside. These extracts displayed antimicrobial potential against microorganisms such as Yersinia enterocolitica, Pseudomonas aeruginosa, Salmonella enteritidis, methicillin-sensitive Staphylococcus aureus, a methicillin-resistant Staph. aureus (MRSA), and Bacillus cereus. In conclusion, OH provides similar recovery yields with reduced treatment times, less energy consumption, and no need for organic solvents (green extraction routes). Thus, OH combined with water and citric acid allows a safe anthocyanin extraction from grape by-products, thus avoiding the use of toxic solvents such as methanol, and with high biological potential, including antimicrobial and antioxidant activity.
- Antiadhesive and antibiofilm effect of Malvidin -3- glucoside and Malvidin -3- glucoside/neochlorogenic acid mixtures upon staphylococcusPublication . Silva, Sara; Costa, Eduardo; Veiga, Mariana; Morais, Rui; Calhau, Conceição; Pintado, Manuela
- Antibiofilm properties of quercus ilex acorn extracts against MRSA and MSSAPublication . Silva, Sara; Costa, Eduardo; Costa, Maria do Rosário; Pereira, Miguel; Coelho, Marta; Pintado, M. E.Biofilms are complex structures that grant microorganisms some survival advantages namely nutrient availability and antimicrobial resistance. As such, the need to find new antimicrobial compounds that are active against these structures is in great demand. Phenolic compounds are described as capable of interfering with the cellular membrane and interact with both intracellular and extracellular proteins, thus they may present an alternative to traditional biofilm control. Acorns have been reported as a rich source of phenolic compounds, particularly tannins, and thus are likely to exhibit some of the properties that are associated with these compounds, namely antimicrobial properties. As such, the present work aimed to assess the antibiofilm properties of hydroethanolic, phenolic rich, acorn extracts against two Staphylococcus aureus strains, one sensitive (MSSA) and one resistant (MRSA) to methicillin. To do so, both microorganisms were exposed to two different sub-MIC concentrations of extracts produced using acorn shells (fresh and roasted) and cotyledons (fresh or roasted). The amount of biofilm produced in the presence of the extracts, after 48 h, was then determined using the microtiter - crystal violet based assay. The results obtained showed that MRSA was the most sensitive strain, with biomass inhibition percentages ranging from 60 to 70%, while for MSSA all inhibition percentages ranged between 29 to 57%. No significant differences between shell and cotyledon were found when considering the results obtained for MRSA. The same was not observed for MSSA where biomass production was significantly higher for roasted cotyledon (2.5 to 20.6%). For this microorganism, it was interesting to note that lower concentrations of the extracts appeared to possess a higher antibiofilm activity (0.7 times more active for fresh or roasted shell extract and 0.6 times more active for fresh cotyledon extracts). Overall, these results indicate that Quercus ilex acorns possess the potential to be an effective means of biofilm control though further studies are still required to fully ascertain their true potential.
- Antimicrobial and antibiofilm activity of chitosan on the oral pathogen Candida albicansPublication . Costa, Eduardo; Silva, Sara; Tavaria, Freni; Pintado, ManuelaOral candidiasis is particularly evident, not only in cancer patients receiving chemotherapy, but also in elderly people with xerostomy. In general, Candida is an opportunistic pathogen, causing infections in immunocompromised people and, in some cases, when the natural microbiota is altered. Chitosan, a natural derivative of chitin, is a polysaccharide that has been proven to possess a broad spectrum of antimicrobial activity that encompasses action against fungi, yeast and bacteria. While recent studies have revealed a significant antibiofilm activity upon several microorganisms, including C. albicans, little is known regarding the impact of chitosan upon the adhesive process or mature biofilms. With that in mind, the purpose of this work was to evaluate, in vitro, the capability of chitosan to inhibit C. albicans growth and biofilm formation. The results obtained showed that chitosan is capable of inhibiting C. albicans planktonic growth (HMW, 1 mg/mL; LMW, 3 mg/mL). Regarding biofilm growth, chitosan inhibited C. albicans adhesion (ca. 95%), biofilm formation (percentages above 90%) and reduced mature biofilms by ca. 65% and dual species biofilms (C. albicans and S. mutans) by ca. 70%. These results display the potential of this molecule to be used as an effective anti-Candida agent capable of acting upon C. albicans infections.
- Antioxidant-loaded nanocarriers for drinksPublication . Veiga, Mariana; Costa, Célia; Carvalho, Maria João; Costa, Eduardo; Silva, Sara; Pintado, Manuela
- Bioavailability of phenolic compounds from blueberry leaf infusions (Vaccinium Corymbosum L.) In caco-2 cellsPublication . Silva, Sara; Norberto, Sónia; Costa, Eduardo; Pereira, Miguel; Costa, Maria do Rosário; Coelho, Marta; Faria, Ana; Pintado, M. E.; Calhau, ConceiçãoPhenolic compounds are widespread in plant-derived foodstuffs and therefore abundant in our diet. There are evidences regarding the positive association of their intake with several diseases prevention. Blueberry leaves are of particular interest as they have been described as being rich in phenolic compounds such as chlorogenic acid and quercetin glicosides. Bioavailability is a major issue regarding the biological impact of these compounds in vivo and remains unclear, with few data available on this matter. Studies in CaCo-2 cells (entrocyte cell line) tested the transport of blueberry leaf infusion (optimized to yield the highest amount total phenolics) across this cell line for different incubation times. From the different compounds originally identified only rutin (9%), quercetin-3- glucoside (Q3glu), chlorogenic (7%) and neochlorogenic acids (23%) were transported across the epithelia cells, after 60, 90 and 120 min. From these compounds, neochlorogenic acid and Q3glu exhibit the highest transport rates (23 and 22%, respectively of the original concentration) while for rutin and chlorogenic acid the transport was lower than 10% of the original amount of compound. It was interesting to note that two metabolites, that were not originally present, caffeic and p-coumaric acids were detected after 30 and 60 min, respectively. From this work it was possible to conclude that neocholorogenic acid and Q3glu are more efficiently transported through the CaCo-2 membrane and that this process resulted in the detection of some metabolites that were not originally present.
- Biocompatibility of salix viminalis, salix atrocinerea and salix fragilisPublication . Silva, Sara; Veiga, Mariana; Costa, Eduardo; Costa, Célia; Faustino, Margarida; Ramos, Patricia A. B.; Santos, Sónia A. O.; Freire, Carmen S. R.; Silva, Artur M. S.; Silvestre, Armando J. D.; Pintado, M. Manuela
- Cellulose from sugarcane bagasse as a potential prebiotic agentPublication . Freixo, Ricardo; Bastos, Francisca; Costa, Eduardo; Ribeiro, Alessandra B.; Pereira, Carla F.; Pintado, Manuela E.; Ramos, Oscar L.