Browsing by Author "Coelho, Marta"
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- 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.
- 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.
- Are olive pomace powders a safe source of bioactives and nutrients?Publication . Ribeiro, Tânia B.; Oliveira, Ana; Coelho, Marta; Veiga, Mariana; Costa, Eduardo M.; Silva, Sara; Nunes, João; Vicente, António A.; Pintado, ManuelaBACKGROUND Olive oil industry generates significant amounts of semi-solid wastes, namely the olive pomace. Olive pomace is a by-product rich in high-value compounds (e.g. dietary fibre, unsaturated fatty acids, polyphenols) widely explored to obtain new food ingredients. However, conventional extraction methods frequently use organic solvents, while novel eco-friendly techniques have high operational costs. The development of powdered products without any extraction step has been proposed as a more feasible and sustainable approach. RESULTS The present study fractionated and valorised the liquid and pulp fraction of olive pomace obtaining two stable and safe powdered ingredients, namely a liquid-enriched powder (LOPP) and a pulpenriched powder (POPP). These powders were characterized chemically, and their bioactivity was assessed. LOPP exhibited a significant amount of mannitol (141 g/ kg), potassium (54 g/ kg) and hydroxytyrosol/ derivatives (5 mg/g). POPP exhibited high amount of dietary fibre (620 g/ kg) associated to significant amount of bound phenolics (7.41 mg GAE/ g fibre DW) with substantial antioxidant activity. POPP also contained an unsaturated fatty acids composition similar to olive oil (76% of total fatty acids) and showed potential as a reasonable source of protein (12 %). Their functional properties (solubility, water‐holding and oil‐holding capacity), antioxidant capacity and antimicrobial activity were also assessed, and their biological safety was verified. CONCLUSION The development of olive pomace powders to apply in the food industry could be a suitable strategy to add-value to olive pomace and obtain safe multifunctional ingredients with higher health-promoting effects than dietary fibre and polyphenols itself.
- Avaliação das alterações provocadas pela maturação no conteúdo de ácidos fenólicos e flavonóides de mirtiloPublication . Coelho, Marta; Silva, Sara; Costa, Eduardo M.; Pintado, Mª Manuela
- Bioactive lipids in Dunaliella salina: implications for functional foods and healthPublication . Pais, Rita; Conde, Tiago; Neves, Bruna B.; Pinho, Marisa; Coelho, Marta; Pereira, Hugo; Rodrigues, Alexandre M. C.; Domingues, Pedro; Gomes, Ana Maria; Urbatzka, Ralph; Domingues, Rosário; Melo, TâniaDunaliella salina is a green microalga extensively explored for β-carotene production, while knowledge of its lipid composition is still limited and poorly investigated. Among lipids, polar lipids have been highlighted as bioactive phytochemicals with health-promoting properties. This research aimed to provide an in-depth lipidome profiling of D. salina using liquid and gas chromatography coupled with mass spectrometry. The lipid content was 6.8%, including phospholipids, glycolipids, betaine lipids, sphingolipids, triglycerides, diglycerides, and pigments. Among the total esterified fatty acids, 13.6% were 18:3 omega-3 and 14.7% were 18:1 omega-9. The lipid extract of D. salina showed anti-inflammatory activity by inhibiting cyclooxygenase-2 activity at 100 µg/mL, dose-dependent antioxidant scavenging activity, and antidiabetic activity by inhibiting α-glucosidase activity at 25 and 125 µg/mL. In conclusion, the lipid extract of D. salina has the potential to be used as a functional food ingredient or in the nutraceutical and cosmeceutical industries.
- Bioactive profile, bioaccessibility and antioxidant activity of diatoms: a comparative studyPublication . Rocha, Helena R.; Coelho, Marta; Coelho, Natacha; Morais, Rui M. S. C.; Pintado, Manuela E.; Gomes, Ana M.Diatoms are microalgae with significant biotechnological potential due to their richness in bioactive compounds, including carotenoids and phenolics, contributing to their antioxidant properties. This study aims to compare the bioactive profile and antioxidant activity of three diatom species: Chaetoceros calcitrans, Nannofrustulum shiloi, and Cylindrotheca fusiformis cultivated in closed Flat Panel photobioreactors by Necton S.A. The biomass was harvested via centrifugation, freeze-dried, milled, and vacuum-packed for subsequent analysis.Carotenoids were extracted using ethanolic extraction assisted by ultrasound and analyzed through HPLC-DAD. The Total phenolic content (TPC) was determined using the Folin-Ciocalteu method, considering both free and bound phenolics to provide a comprehensive understanding of their distribution. Antioxidant activity was evaluated using ABTS, ORAC, and DPPH assays, offering complementary insights into the radical-scavenging potential of the diatom species. Additionally, a bioaccessibility assessment was performed using the standardized INFOGEST in vitro model to evaluate the stability of these bioactive compounds.Carotenoid analysis revealed distinct profiles among the species. N. shiloi exhibited the highest levels of β-carotene and zeaxanthin, highlighting its strong potential as a source of antioxidant pigments, whereas C. fusiformis showed a balanced composition of β-carotene, zeaxanthin, and other carotenoids, suggesting a varied antioxidant capacity. In contrast, C. calcitrans contained comparatively lower levels of these carotenoids. In addition to carotenoids, phenolic compounds play a significant role in the antioxidant potential of these diatoms. The TPC varied significantly, with C. fusiformis presenting the highest levels, followed by N. shiloi and C. calcitrans. Besides the differences in the results of the antioxidant activity among species, all exhibited considerable antioxidant capacity, suggesting the presence of multiple bioactive compounds contributing to distinct yet effective mechanisms of action.These findings highlight the potential of diatoms as sources of natural bioactives, particularly for nutraceutical and pharmaceutical applications. The study underscores the importance of species selection in maximizing bioactive compound yield and antioxidant properties, paving the way for further exploration in functional food and cosmetic industries.
- Bioactivity and bioaccessibility of bioactive compounds in gastrointestinal digestion of tomato bagasse extractsPublication . Coelho, Marta; Oliveira, Carla; Coscueta, Ezequiel R.; Fernandes, João; Pereira, Ricardo N.; Teixeira, José A.; Rodrigues, António Sebastião; Pintado, Manuela E.A nutrient-rich diet is a key to improving the chemical signals, such as antioxidants, which modulate pathogens’ resistance in the gut and prevent diseases. A current industrial problem is the generation of undervalued by-products, such as tomato bagasse, which are rich in bioactive compounds and of commercial interest (carotenoids and phenolic compounds). This work analyzed the effect of gastrointestinal digestion on the bioactivity and bioaccessibility of carotenoids and phenolic compounds from tomato bagasse extracts. Thus, the extraction by ohmic heating (OH) technology was compared with conventional (organic solvents). The results showed that the main phenolic compounds identified by UPLC-qTOF-MS were p-coumaric acid, naringenin, and luteolin. A higher recovery index for total phenolic compounds throughout the gastrointestinal digestion was observed for OH while for carotenoids, a strong reduction after stomach conditions was observed for both extracts. Furthermore, colon-available fraction exhibited a prebiotic effect upon different Bifidobacterium and Lactobacillus, but a strain-dependent and more accentuated effect on OH. Thus, the extraction technology highly influenced bioaccessibility, with OH demonstrating a positive impact on the recovery of bioactive compounds and related health benefits, such as antioxidant, anti-hypertensive, prebiotic, and anti-inflammatory properties. Of these properties, the last is demonstrated here for the first time.
- 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.
- Carotenoid-microbiota dynamics: in vitro analysis of gut modulation and associated health benefitsPublication . Rocha, Helena R.; Coelho, Marta; Coelho, Natacha; Morais, Rui M.S.C.; Pintado, Manuela E.; Gomes, Ana M.Carotenoids are bioactive compounds with recognized health benefits, yet their full potential is limited by poor bioaccessibility and complex interactions within the gastrointestinal tract. This study aimed to investigate the digestion, absorption, and gut microbiota modulation of three carotenoids (β-carotene, lutein, lycopene), a mixed carotenoid solution, and the red alga Osmundea pinnatifida. Using a simulated gastrointestinal digestion model (INFOGEST), combined with dialysis and in vitro fecal fermentation, we evaluated carotenoid recovery, antioxidant capacity, antidiabetic and antimutagenic activities, and short-chain fatty acid (SCFA) production. Results demonstrated low carotenoid recovery and structural transformation during digestion, with the mixed carotenoid solution exhibiting the highest antioxidant activity. Lutein and the mixed group also showed significant α-glucosidase inhibition, suggesting antidiabetic potential. Fermented samples increased the production of SCFAs and significantly modulated the gut microbiota, enhancing beneficial taxa such as Lachnospiraceae. These findings highlight the potential of carotenoids and O. pinnatifida in supporting gut health and preventing noncommunicable diseases through microbiota-mediated mechanisms.
- Comparative analysis of two algae: impact on bioavailability, health benefits, and matrix variationsPublication . Coelho, Marta; Rocha, Helena; Morais, Rui; Gomes, Ana M.; Pintado, Manuela