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- Microencapsulation of the Biocide Benzisothiazolinone (BIT) by Inclusion in Methyl-β-cyclodextrin and Screening of Its Antibacterial and Ecotoxicity PropertiesPublication . Silva, Vânia F. M.; Silva, Aurora; Garrido, Ermelinda M. P. J.; Borges, Fernanda; Gaspar, Alexandra; Garrido, Jorge P. M. J.; Garrido, E. Manuela; Soares da Silva, Maria Aurora; Garrido, Jorge; Liu, RutaoThe excessive use of biocides has considerable environmental and economic impacts; this is why new technologies have been sought to decrease the concentration levels applied in an effort to reduce the use of these substances. Microencapsulation using cyclodextrins has been widely used in the food and pharmaceutical industries as a way of reducing the concentrations of the active substance necessary to achieve a biological effect and/or eliminate its irritating or toxicological effects. In this study, the inclusion complexation behavior and binding ability of benzothiazolinone (BIT) with different β-cyclodextrins (β-CD, HP-β-CD, and Me-β-CD) was investigated. The intermolecular interactions were examined through UV and FTIR spectroscopy, DSC, 1D 1H NMR, and 2D ROESY. The highest stability constant was observed for the BIT/Me-β-CD inclusion complex (299.5 ± 2.9 M−1). Antibacterial activity was investigated against Staphylococcus aureus and Escherichia coli, and the results revealed that the BIT/Me-β-CD inclusion complex displays a higher antibacterial activity than BIT. The acute toxicity of the biocide and inclusion complex was also examined using the photobacterium Aliivibrio fischeri. Although BIT exhibited higher toxicity than the inclusion complex, further investigation is needed due to the quorum quenching effect of β-CDs. The data found suggest that BIT microencapsulation can increase its aqueous solubility and can be used as an effective tool to improve its chemical, biological, and ecotoxicological properties.
- Fucoxanthin’s Optimization from Undaria pinnatifida Using Conventional Heat Extraction, Bioactivity Assays and In Silico StudiesPublication . Lourenço-Lopes, Catarina; Fraga-Corral, Maria; Soria-Lopez, Anton; Nuñes-Estevez, Bernabe; Barral-Martinez, Marta; Silva, Aurora; Li, Ningyang; Liu, Chao; Simal-Gandara, Jesus; Prieto, Miguel A.Brown macroalgae are a potential source of natural pigments. Among them, Undaria pinnatifida is recognized for its high concentration of fucoxanthin (Fx), which is a pigment with a wide range of bioactivities. In this study, three independent parameters were optimized for conventional heat extraction (CHE) to maximize the recovery of Fx from Undaria pinnatifida. Optimal conditions (temperature = 45 °C, solvent = 70%, and time = 61 min) extracted 5.1 mg Fx/g dw. Later, the bioactivities of the Fx-rich extracts (antioxidant, antimicrobial, and neuroprotective) were assessed using in vitro and in silico approaches. In vitro assays indicated that Fx has a strong antioxidant capacity and even stronger antimicrobial activity against gram-positive bacteria. This data was supported in silico where Fx established a high binding affinity to DR, a Staphylococcus aureus protein, through aa ALA-8, LEU-21, and other alkane interactions. Finally, the in vitro enzymatic inhibition of AChE using Fx, was further supported using docking models that displayed Fx as having a high affinity for aa TYR72 and THR 75; therefore, the Fx extraction behavior explored in this work may reduce the costs associated with energy and solvent consumption. Moreover, this paper demonstrates the efficiency of CHE when recovering high amounts of Fx from Undaria pinnatifida. Furthermore, these findings can be applied in different industries.
- Recent advances in biological properties of brown algae-derived compounds for nutraceutical applicationsPublication . Silva, Aurora; Cassani, Lucia; Grosso, Clara; Garcia-Oliveira, Paula; Morais, Stephanie; Echave, Javier; Carpena, Maria; Xiao, Jianbo; Barroso, M. Fátima; Simal-Gandara, Jesus; Prieto, Miguel A.The increasing demand for nutraceuticals in the circular economy era has driven the research toward studying bioactive compounds from renewable underexploited resources. In this regard, the exploration of brown algae has shown significant growth and maintains a great promise for the future. One possible explanation could be that brown algae are rich sources of nutritional compounds (polyunsaturated fatty acids, fiber, proteins, minerals, and vitamins) and unique metabolic compounds (phlorotannins, fucoxanthin, fucoidan) with promising biological activities that make them good candidates for nutraceutical applications with increased value-added. In this review, a deep description of bioactive compounds from brown algae is presented. In addition, recent advances in biological activities ascribed to these compounds through in vitro and in vivo assays are pointed out. Delivery strategies to overcome some drawbacks related to the direct application of algae-derived compounds (low solubility, thermal instability, bioavailability, unpleasant organoleptic properties) are also reviewed. Finally, current commercial and legal statuses of ingredients from brown algae are presented, considering future therapeutical and market perspectives as nutraceuticals.
- Antibacterial Use of Macroalgae Compounds against Foodborne PathogensPublication . Silva, Aurora; Silva, Sofia A.; Lourenço-Lopes, C.; Jimenez-Lopez, C.; Carpena, M.; Gullón, P.; Fraga-Corral, M.; Domingues, Valentina; Barroso, M. Fátima; Simal-Gandara, J.; Prieto, M. A.The search for food resources is a constant in human history. Nowadays, the search for natural and safe food supplies is of foremost importance. Accordingly, there is a renewed interest in eco-friendly and natural products for substitution of synthetic additives. In addition, microbial contamination of food products during their obtaining and distribution processes is still a sanitary issue, and an important target for the food industry is to avoid food contamination and its related foodborne illnesses. These diseases are fundamentally caused by certain microorganisms listed in this review and classified according to their Gram negative or positive character. Algae have proven to possess high nutritional value and a wide variety of biological properties due to their content in active compounds. Among these capabilities, macroalgae are recognized for having antimicrobial properties. Thus, the present paper revises the actual knowledge of microbial contaminants in the food industry and proposes antimicrobial algal compounds against those pathogenic bacteria responsible for food contamination as valuable molecules for its growth inhibition. The capacity of algae extracts to inhibit some major food pathogen growth was assessed. Moreover, the main applications of these compounds in the food industry were discussed while considering their favorable effects in terms of food safety and quality control
- A HPLC‐DAD method for identifying and estimating the content of fucoxanthin, β‐carotene and chlorophyll a in brown algal extractsPublication . Lourenço-Lopes, C.; Fraga-Corral, M.; Garcia-Perez, P.; Carreira-Casais, A.; Silva, Aurora; Simal-Gandara, J.; Prieto, M.A.Seaweeds are photosynthetic organisms that have high contents of pigments. The coloration of each alga is defined by the content and combination of pigments synthesized, which varies among species and environmental conditions. The most abundant pigments in algae are chlorophylls and carotenoids, lipophilic molecules that can be used as natural colorants and have high acceptance by consumers. In this work, a simple and short hands-on time HPLC-DAD method for identifying and estimating the pigment content of algal extracts, specifically fucoxanthin, β-carotene and chlorophyll a was carried out. Using this optimized method, a pigment screening was performed on the ethanolic extracts obtained by ultrasound-assisted extraction from nine brown algal from the Atlantic coastline: Ascophyllum nodosum, Bifurcaria bifurcata, Fucus spiralis, Himanthalia elongata, Laminaria saccharina, Laminaria ochroleuca, Pelvetia canaliculata, Sargassum muticum and Undaria pinnatifida. HPLC results permitted to highlight L. saccharina and U. pinnatifida as promising sources of these three target pigments containing a total amount of 10.5 – 11.5 mg per gram of dry weight. Among them, the most abundant one was fucoxanthin, an added-value compound with a high potential to be commercially exploited by different industries, such as the food, cosmetic, and pharmaceutical sectors.
- Macroalgae as a Source of Valuable Antimicrobial Compounds: Extraction and ApplicationsPublication . Silva, Aurora; Silva, Sofia A.; Carpena, M.; Garcia-Oliveira, P.; Gullón, P.; Barroso, M. Fátima; Prieto, M.A.; Simal-Gandara, J.n the last few decades, attention on new natural antimicrobial compounds has arisen due to a change in consumer preferences and the increase in the number of resistant microorganisms. Macroalgae play a special role in the pursuit of new active molecules as they have been traditionally consumed and are known for their chemical and nutritional composition and their biological properties, including antimicrobial activity. Among the bioactive molecules of algae, proteins and peptides, polysaccharides, polyphenols, polyunsaturated fatty acids and pigments can be highlighted. However, for the complete obtaining and incorporation of these molecules, it is essential to achieve easy, profitable and sustainable recovery of these compounds. For this purpose, novel liquid–liquid and solid–liquid extraction techniques have been studied, such as supercritical, ultrasound, microwave, enzymatic, high pressure, accelerated solvent and intensity pulsed electric fields extraction techniques. Moreover, different applications have been proposed for these compounds, such as preservatives in the food or cosmetic industries, as antibiotics in the pharmaceutical industry, as antibiofilm, antifouling, coating in active packaging, prebiotics or in nanoparticles. This review presents the main antimicrobial potential of macroalgae, their specific bioactive compounds and novel green extraction technologies to efficiently extract them, with emphasis on the antibacterial and antifungal data and their applications.
- Pigment Composition of Nine Brown Algae from the Iberian Northwestern Coastline: Influence of the Extraction SolventPublication . Garcia-Perez, Pascual; Lourenço-Lopes, Catarina; Silva, Aurora; Pereira, Antia G.; Fraga-Corral, Maria; Zhao, Chao; Xiao, Jianbo; Simal-Gandara, Jesus; Prieto, Miguel A.Brown algae are ubiquitously distributed in the NW coastline of the Iberian Peninsula, where they stand as an underexploited resource. In this study, five solvents were applied to the extraction of pigments from nine brown algae, followed by their determination and quantification by HPLC-DAD. A total of 13 compounds were detected: Six were identified as chlorophylls, six were classified as xanthophylls, and one compound was reported as a carotene. Fucoxanthin was reported in all extracts, which is the most prominent pigment of these algae. Among them, L. saccharina and U. pinnatifida present the highest concentration of fucoxanthin (4.5–4.7 mg·g −1 dry weight). Ethanol and acetone were revealed as the most efficient solvents for the extraction of pigments, showing a maximal value of 11.9 mg of total pigments per gram of dry alga obtained from the ethanolic extracts of H. elongata, followed by the acetonic extracts of L. ochroleuca. Indeed, ethanol was also revealed as the most efficient solvent according to its high extraction yield along all species evaluated. Our results supply insights into the pigment composition of brown algae, opening new perspectives on their commercial exploitation by food, pharmaceutical, and cosmeceutical industries
- Reinforcement of starch film with Castanea sativa shells polysaccharides: Optimized formulation and characterizationPublication . Amaral, Leonardo; Rodrigues, Francisca; Silva, Aurora; Costa, Paulo; Delerue-Matos, Cristina; Vieira, Elsa F.Chestnut (Castanea sativa) shells, generated from the peeling process of the fruit, contains appreciable amounts of lignin and cellulose. In this work, a starch-based film reinforced with these polysaccharides was developed. Response Surface Methodology was employed to optimize the composition of the film with improved elongation, tensile strength, and elasticity modulus properties. The optimal film was characterized regarding structural, optical barrier and thermal properties. The optimum composition was obtained with 10% (w/w) fibers and 50% (w/w) glycerol; the elongation responses, tensile strength and modulus of elasticity reached values of 34.19%, 7.31 N and 4.15 N, respectively. The values of tension strength and modulus of elasticity were approximately 3.5 times higher than those obtained for the control film. The reinforced film was opaque and exhibited improved water solubility, UV-barrier capacity, and thermal stability compared to control. The optimized starch film based on chestnut shells fibers’ has the potential to produce biodegradable food packaging with improved properties.
- Tabela Periódica: Um Elemento em cada casa, uma casa para cada ElementoPublication . Delerue-Matos, Cristina; Morais, Simone; Freitas, Olga; Teixeira, Salomé; Soares da Silva, Maria Aurora; de Sá Barroso, Maria de FátimaUm concurso sobre a Tabela Periódica? Mas isso, é o que eu penso que é? e é motivo para um concurso? O resultado está à vista. Os cerca de 40 trabalhos apresentados a concurso, envolvendo um total de 180 participantes, utilizaram técnicas diversificadas nas área da pintura, escultura, música, literatura, fotografia, culinária, vídeo, novas tecnologias… A Tabela Periódica transformou-se, associando o carácter científico e sua semiótica a uma visão mais abrangente no campo da percepção, da estética, da imagem, das sensações, isto é da Arte. Surge assim uma abordagem inovadora e irreverente, de uma matéria classificada pelos alunos de "árida e inacessível". Um processo de levar a Química às camadas mais jovens e a todos aqueles que se interessam pela Ciência.