Browsing by Author "Sousa, Clara"
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- Anthocyanins, carotenoids and chlorophylls in edible plant leaves unveiled by tandem mass spectrometryPublication . Sousa, ClaraNatural pigments are a quite relevant group of molecules that are widely distributed in nature, possessing a significant role in our daily lives. Besides their colors, natural pigments are currently recognized as having relevant biological properties associated with health benefits, such as anti‐tumor, anti‐atherogenicity, anti‐aging and anti‐inflammatory activities, among others. Some of these compounds are easily associated with specific fruits (such as blueberries with anthocyanins, red pitaya with betalain or tomato with lycopene), vegetables (carrots with carotenoids), plant leaves (chlorophylls in green leaves or carotenoids in yellow and red autumn leaves) and even the muscle tissue of vertebrates (such as myoglobin). Despite being less popular as natural pigment sources, edible plant leaves possess a high variety of chlorophylls, as well as a high variety of carotenoids and anthocyanins. The purpose of this review is to critically analyze the whole workflow employed to identify and quantify the most common natural pigments (anthocyanin, carotenoids and chlorophylls) in edible plant leaves using tandem mass spectrometry. Across the literature there, is a lack of consistency in the methods used to extract and analyze these compounds, and this review aims to surpass this issue. Additionally, mass spectrometry has stood out in the context of metabolomics, currently being a widely employed technique in this field. For the three pigments classes, the following steps will be scrutinized: (i) sample pre‐preparation, including the solvents and extraction conditions; (ii) details of the chromatographic separation and mass spectrometry experiments (iii) pigment identification and quantification.
- Assessing the potential of a sustainable bean leaf extract with abscisic acid in pear ripening restorationPublication . Dias, Cindy; Sousa, Clara; Ferrante, António; Pintado, Manuela; Vasconcelos, Marta W.Introduction: Rocha pear (Pyrus communis L. cv Rocha) is a Portuguese cultivar stored with 1-MCP in controlled atmosphere to extend storage life and prevent postharvest issues. However, 1-MCP obstructs the normal ripening, impacting pear quality for consumers. Several strategies have been applied to reboot the ripening of pear under 1-MCP effect, such as the application of higher temperatures, exogenous ethylene or a combination of both. However, these treatments demand high energy consumption. Some phytohormones, like abscisic acid (ABA), have been shown to accelerate ripening by stimulating ethylene production, firmness loss, coloring, among other ripening markers. Objective: In this study, leaves from bean plants derived from agri-food wastes were explored to extract phytohormones with focus on ABA, using a sustainable approach. Further the study aimed to investigate the potential of this green extract as a ripening inducer for pears under the 1-MCP effect. Time course physiological and biochemical analysis comparison with ‘Rocha’ pear treated with synthetic ABA was performed. Conclusions: The extraction approach developed in this study extracted ABA from bean leaves using only water under cold conditions. This suggests a sustainable approach by repurposing agricultural by-products; Bean leaves extract and synthetic ABA treatment of pears, under the influence of 1-MCP, resulted in increased respiration and ethylene production after 15 days. This was accompanied by higher SSC, color and firmness loss suggesting that ABA may be inducing the ripening process; Evaluating natural and synthetic ABA on pear ripening is essential to determine the effectiveness of the natural source relative to the conventional synthetic version. Despite lower ABA concentration in the natural extract, similar responses to synthetic ABA suggest the involvement of not only ABA but other bioactive compounds; The results of this study could have implications for the development of eco-friendly and sustainable practices in agri-food waste utilization and fruit post-harvest management.
- Bacillus invictae sp. nov., isolated from a health productPublication . Branquinho, Raquel; Sousa, Clara; Osório, Hugo; Meirinhos-Soares, Luís; Lopes, João; Carriço, João A.; Busse, Hans-Juergen; Abdulmawjood, Amir; Klein, Gunter; Kampfer, Peter; Pintado, Manuela E.; Peixe, Luísa V.
- Bacillus invictus SP. Nov., a new species isolated from medicinal products in PortugalPublication . Branquinho, Raquel; Sousa, Clara; Osório, Hugo; Meirinhos-Soares, Luís; Lopes, João; Abdulmawjood, Amir; Klein, Guenter; Pintado, M. E.; Peixe, Luísa V.
- Combined use of phosphonium-erythrosin B-based nanoGUMBOS, UV–Vis spectroscopy, and chemometrics for discrimination and quantification of proteinsPublication . Azevedo, Ana M. O.; Sousa, Clara; Rodrigues, S. Sofia M.; Chen, Mi; Ayala, Caitlan E.; Pérez, Rocío L.; Santos, João L. M.; Warner, Isiah M.; Saraiva, M. Lúcia M. F. S.Nanoparticles derived from a group of uniform materials based on organic salts (nanoGUMBOS) are considered promising candidates for protein analysis due to their facile synthesis in aqueous media and high tunability. In this study, a phosphonium-erythrosin B-based nanoGUMBOS (i.e., [P4444]2[EB]) was prepared using an ultrasound-assisted reprecipitation method, and its ability to discriminate and quantify proteins was evaluated. Sonication time (30 s, 5 min, and 15 min) and cyclodextrin templating (α-, 2-HP-β-, and γ-CD) were investigated for their effects on discrimination performance of synthesized nanomaterial. Six proteins (albumin, hemoglobin, trypsin, catalase, lysozyme, and cytochrome c) with different abundance levels and physicochemical properties were selected as target analytes. Absorbance response patterns generated from interactions between [P4444]2[EB] nanoGUMBOS and proteins were analyzed using partial least squares discriminant analysis. Percentages of correct protein discrimination ranged from 94.6 to 99.6%, with the latter being the best result obtained using non-templated nanoGUMBOS formed after 5 min sonication. Under optimized conditions, it was possible to discriminate all protein samples with percentages of correct assignments greater than 90% for concentrations as low as 2.0 μg mL−1. The discrimination capability of synthesized nanoGUMBOS was further evaluated using mixtures of different ratios of lysozyme, cytochrome c, and hemoglobin. Finally, partial least squares models were developed for protein quantification and the best performance was observed for albumin. Results support potential use of [P4444]2[EB] nanoGUMBOS in combination with ultraviolet–visible spectroscopy and chemometrics for qualitative and quantitative analyses of individual proteins and mixtures of proteins.
- Cyanobacteria as candidates to support mars colonization: growth and biofertilization potential using mars regolith as a resourcePublication . Macário, Inês P. E.; Veloso, Telma; Frankenbach, Silja; Serôdio, João; Passos, Helena; Sousa, Clara; Gonçalves, Fernando J. M.; Ventura, Sónia P. M.; Pereira, Joana L.Cyanobacteria are indicated as organisms that can possibly support Mars colonization, contributing to the production of oxygen and other commodities therein. In this general context, the aim of this work was to evaluate the ability of three species of cyanobacteria (Anabaena cylindrica, Nostoc muscorum, and Arthrospira platensis) and a green microalga (Chlorella vulgaris) to grow using only the resources existing in Mars, i.e., water and Martian regolith stimulant (MGS-1), under an Earth-like atmosphere. A Martian regolith extract was produced and used as a culture medium to grow these species. Their growth was assessed during a period of 25 days, using optical density and fluorometric parameters. After this period, the possible contribution of end-of-life cyanobacteria/microalga as biofertilizing agents was also assessed, using the macrophyte Lemna minor as a vegetable model. Among the three species, N. muscorum showed the best growth performance when compared to the other species, while A. platensis and C. vulgaris were not able to thrive on Mars regolith extract. Therefore, N. muscorum should be the target of future studies not only due to their role in oxygen production but also due to their possible use as a food source, as many members of the Nostoc genus. Cyanobacteria and microalgae (A. platensis and C. vulgaris) showed good abilities as biofertilizing agents, i.e., they stimulated biomass (i.e., dry weight) production at levels comparable to the plants that grew on standard synthetic medium. The highest yield was reached with A. platensis, while the lowest was achieved using the media with N. muscorum. FTIR-ATR (Fourier transform infrared with attenuated total reflectance) spectroscopy showed that the differences between the plants grown on media with or without Martian regolith seem to be related mainly to polysaccharides.
- Decellularized small intestine for burn wound treatment: a tissue engineering paradigm shift?Publication . Silva, Inês V.; Rosadas, Marta; Rodrigues, Ilda; Sousa, Clara; Ribeiro, Viviana; Costa, Raquel; Moroni, Lorenzo; Oliveira, Ana L.Introduction: Burn injuries are a significant global health issue, causing approximately 11 million injuries and 180,000 fatalities each year (1). Beyond physical trauma, burn injuries lead to complications such as infections and sepsis. Burn scars can also diminish quality of life by affecting joint mobility and daily activities (2,3). Conventional dressings and autografts have limitations, necessitating novel treatment strategies (4). Decellularized xenografts, particularly from porcine small intestine (SI), offer a promising alternative due to their content of growth factors and structural proteins essential for wound healing (5,6). Preserving these bioactive molecules while ensuring cost-effectiveness requires carefully designed decellularization processes. This study investigates a new decellularization protocol aimed at creating a safe and highly preserved extracellular matrix (ECM) from porcine SI for optimal functional wound dressing. Conclusion: Our results indicate that the protocol implemented effectively preserves essential ECM components and structure while removing cellular contaminants. The material demonstrates anisotropic preserved mechanical properties, adequate swelling capacity, and WTVR similar to skin. The treated samples present biocompatibility, as they do not hinder human fibroblast metabolic activity. This innovative strategy presents a promising approach to produce preserved ECM that could be further process to become a solution for wound healing and tissue regeneration, particularly in challenging cases like burns. Future research will focus on enhancing its antibacterial and anti-inflammatory properties to further improve its efficacy as a dressing for challenging wounds.
- Depicting the suitability of FTIR to improve the differentiation of persistent and sporadic Listeria monocytogenesPublication . Meneses, Rui; Sousa, Clara; Teixeira, PaulaListeria monocytogenes is a ubiquitous Gram-positive pathogen that is particularly harmful to immunocompromised individuals. In food processing environments (FPEs), certain strains of L. monocytogenes are routinely isolated, while others are only encountered sporadically. One possible explanation for this recurrent isolation correlates with the presence of heterogeneous subpopulations, some of which can withstand adverse conditions encompassing high salinity, low temperature, and low pH, along with other FPEs-related stressors. We set out to evaluate the suitability of Fourier Transformed Infrared Atenuated Total Reflectance (FTIR-ATR) spectroscopy to discriminate between the fitest persistent specimens from the remaining sporadic subpopulations. 72 L. monocytogenes isolates, encompassing both persistent and sporadic L. monocytogenes, were grown in microtiter plates in the presence of different food-associated stressors (pH, T ºC, % NaCl), with growth curves obtained by measuring the optical density (OD600). After reaching the late exponential phase, the cell pellets were collected and analysed by FTIR-ATR spectroscopy. Additionally, infrared (IR) spectra of isolates grown in agar plates at 37ºC were collected. Partial Least-Squares Discriminant Analysis classification models based on collected IR spectra were developed to determine the viability of FTIR spectroscopy to discriminate persistence in different conditions. The gathered data showed no significant differences in growth rates and lag phases of persistent and sporadic L. monocytogenes in a planktonic state when grown at 37ºC or under the food-associated stressors tested. FTIR analysis has shown promising results in differentiating persistent and sporadic isolates belonging to the same serogroup, achieving correct assignment rates of over 70%.
- Differentiation of Bacillus pumilus and Bacillus safensis Using MALDI-TOF-MSPublication . Branquinho, Raquel; Sousa, Clara; Lopes, João; Pintado, Manuela E.; Peixe, Luísa V.; Osório, HugoMatrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) despite being increasingly used as a method for microbial identification, still present limitations in which concerns the differentiation of closely related species. Bacillus pumillus and Bacillus safensis, are species of biotechnological and pharmaceutical significance, difficult to differentiate by conventional methodologies. In this study, using a well-characterized collection of B. pumillus and B. safensis isolates, we demonstrated the suitability of MALDI-TOF-MS combined with chemometrics to accurately and rapidly identify them. Moreover, characteristic species-specific ion masses were tentatively assigned, using UniProtKB/Swiss-Prot and UniProtKB/TrEMBL databases and primary literature. Delineation of B. pumilus (ions at m/z 5271 and 6122) and B. safensis (ions at m/z 5288, 5568 and 6413) species were supported by a congruent characteristic protein pattern. Moreover, using a chemometric approach, the score plot created by partial least square discriminant analysis (PLSDA) of mass spectra demonstrated the presence of two individualized clusters, each one enclosing isolates belonging to a species-specific spectral group. The generated pool of species-specific proteins comprised mostly ribosomal and SASPs proteins. Therefore, in B. pumilus the specific ion at m/z 5271 was associated with a small acid-soluble spore protein (SASP O) or with 50S protein L35, whereas in B. safensis specific ions at m/z 5288 and 5568 were associated with SASP J and P, respectively, and an ion at m/z 6413 with 50S protein L32. Thus, the resulting unique protein profile combined with chemometric analysis, proved to be valuable tools for B. pumilus and B. safensis discrimination, allowing their reliable, reproducible and rapid identification.
- Discriminating Fe deficient soybean plants by fourier transform infrared spectroscopyPublication . Bagheri, Maryam; Santos, Carla S.; Sousa, Clara; Vasconcelos, Marta W.
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