Browsing by Author "Freitas, Marta V."
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- Antioxidant and antimicrobial properties of selected red seaweeds from Central PortugalPublication . Freitas, Marta V.; Inácio, Leonardo G.; Ruas, Ana; Silva, Isabela A.; Mouga, Teresa; Pereira, Leonel; Afonso, CléliaThroughout the ages, macroalgae have provided humankind with elements beneficial to human health, and often with bioactive abilities. Yet, while today we fully acknowledge such potential, especially that of the most widely known species, an even greater number of species remain unaknowledged. This holds particularly true for the highly diverse phylum Rhodophyta (red seaweeds) and, therefore, the present study aims to unveil the antioxidant and the antimicrobial potential of twelve red seaweed species collected in central Portugal. Results obtained from the antioxidant assays ABTS and TPC highlighted the high scavenging capacity of the coralline algae Corallina officinalis, Ellisolandia elongata and Amphiroa rigida, and the high phenolic content of Porphyra umbilicalis, whereas the antimicrobial analyses through MIC determination emphasized the activities of Sphaerococcus coronopifolius and Mesophyllum lichenoides against, respectively, Bacillus subtilis and Saccharomyces cerevisiae. This study raised awareness of the bioactive potential waiting to be discovered regarding less known Rhodophyta species, such as Amphiroa rigida and Mesophyllum lichenoides. Therefore, we believe this study provides extra steps in pinpointing Rhodophyta species with bioactive potential, encouraging further studies tailored toward a biotechnological perspective, and, ultimately, influencing current perspectives regarding the exploration of seaweeds.
- Assessing High-Value Bioproducts from Seaweed Biomass: A Comparative Study of Wild, Cultivated and Residual Pulp SourcesPublication . Ferreira, Henrique S.; Mouga, Teresa; Lourenço, Sílvia; Matias, Margarida H.; Freitas, Marta V.; Clélia Neves-AfonsoThis study aimed to evaluate the biochemical composition and bioactivities of biomass derived from wild (Laminaria ochroleuca and Saccorhiza polyschides) and cultivated (Macrocystis pyrifera) kelps, as well as industrially extracted residual pulp from M. pyrifera, to assess the potential production of high value bioproducts. All samples had a low lipid content, with M. pyrifera having the lowest (1.3% dw) and S. polyschides showing the highest value (3.3%). Fatty acids such as palmitic acid (C16:0), oleic acid (C18:1n-9 cis), alpha-linolenic acid (ALA, C18:3n-3), and eicosapentaenoic acid (EPA, C20:5n-3) were present, with the residual pulp having a distinctive n-6/n-3 ratio of less than one. The protein content was around 9% dry weight (dw) in all samples. The residual pulp and S. polyschides had the highest polyphenol content, with 4.86 and 4.94 mg GAE·g−1 extract, respectively. Hydroethanolic extracts (30–70%) confirmed Fe3+ reducing activity (FRAP) in all samples. These findings offer valuable insights on the biochemical composition and bioactivity of the kelp species under study and the residual kelp biomass (pulp), underlining their significant potential for applications in the field of Blue Biotechnology.
- Identification of Gracilariaceae (Rhodophyta) of central Portugal by histological and genetic methodsPublication . Freitas, Marta V.; Simões, Marco; Valdez, Christian; Afonso, Clélia; Trindade, Beatriz G.; Correia, Ana; Baptista, Teresa; Mouga, TeresaThis study aims to identify different populations of Gracilariaceae collected from the central coast of Portugal through light microscopy, anatomical observations and genetic tools, essential approaches to correctly assign species identity. Samples were obtained from Ria de Aveiro (AV), Figueira da Foz (FFBC, FFMD), and Lagoa de Óbidos (LOBR, LOEV, LOBS). Although histological observations offered a visual representation of the characteristic pseudoparenchymatous organization, they did not allow a clear distinction among the species. The amplification of a ∼700 bp fragment of the mitochondrial cytochrome oxidase I gene, and its sequencing enabled us to assign the populations FFBC and LOBS to Gracilaria gracilis, and the populations AV, FFMD, LOBR, and LOEV to Agarophyton vermiculophyllum. This contribution will help phycologists to correctly identify the Portuguese populations of Gracilaria sensu lato at the species level, which will be crucial in ensuring that future studies and industrial exploration accurately target the correct species.
- New applications for Gelidium corneum: Antimicrobial and antioxidant activity within a biorefinery conceptPublication . Mouga, Teresa; Cavaco, Mário; Duarte, Adriana; Correia, Ana Patrícia; Freitas, Marta V.; Bernardino, Susana; Afonso, CléliaThere are more than four hundred endogenous seaweeds that occur in Portugal, and red seaweeds (Rhodophyta) are the most abundant. Among these, Gelidium corneum, common in the Atlantic coast of Portugal, is currently being collected in the wild, in S. Martinho do Porto, exclusively for the extraction of agar. During the summer season this species is harvested from the bottom of the ocean, dried and sold, representing an important economic local activity. Yet, besides agar, this species is important for its bioactivities, namely for its antioxidant and antimicrobial capacities, thus most of the biomass is currently being disregarded as an important marine resource. Therefore, to further research the potential of G. corneum as a source of bioactive compounds, the biomass was seasonally harvested and characterized (protein, ash, moisture), and different extract were made (aqueous and ethanolic). These extracts were analyzed for the antioxidant potential (DDPH, ABTS, TPC and FRAP), and for antimicrobial capacity (against Escherichia coli, Bacillus subtilis, Candida albicans, Saccharomyces cerevisiae and Staphylococcus epidermidis). Preliminary results show that there are seasonal variations in the chemical composition of the biomass. Extracts tested also show interesting free radical scavenging capacity and antimicrobial activity against some of the strains tested. The attained results demonstrate that the biorefinery concept should be implemented to the agar industry, valuing the seaweeds’ biomass so to allow its use in other industries, such as textiles or cosmetics.
- Red seaweed pigments from a biotechnological perspectivePublication . Freitas, Marta V.; Pacheco, Diana; Cotas, João; Mouga, Teresa; Afonso, Clélia; Pereira, LeonelAlgae taxa are notably diverse regarding pigment diversity and composition, red seaweeds (Rhodophyta) being a valuable source of phycobiliproteins (phycoerythrins, phycocyanin, and allophycocyanin), carotenes (carotenoids and xanthophylls), and chlorophyll a. These pigments have a considerable biotechnological potential, which has been translated into several registered patents and commercial applications. However, challenges remain regarding the optimization and subsequent scale-up of extraction and purification methodologies, especially when considering the quality and quantity needs, from an industrial and commercial point of view. This review aims to provide the state-of-the-art information on each of the aforementioned groups of pigments that can be found within Rhodophyta. An outline of the chemical biodiversity within pigment groups, current extraction and purification methodologies and challenges, and an overview of commercially available products and registered patents, will be provided. Thus, the current biotechnological applications of red seaweeds pigments will be highlighted, from a sustainable and economical perspective, as well as their integration in the Blue Economy.
- Valorization of the red seaweed Gracilaria gracilis through a biorefinery approachPublication . Martins, Alice; Pinto, Filipa R.; Barroso, Sónia; Pereira, Tatiana; Mouga, Teresa; Afonso, Clélia; Freitas, Marta V.; Pinteus, Susete; Pedrosa, Rui; Gil, Maria MThe interest in seaweeds as an abundant feedstock to obtain valuable and multitarget bioactive ingredients is continuously growing. In this work, we explore the potential of Gracilaria gracilis, an edible red seaweed cultivated worldwide for its commercial interest as a source of agar and other ingredients for cosmetic, pharmacological, food, and feed applications. G. gracilis growth conditions were optimized through vegetative propagation and sporulation while manipulating the physicochemical conditions to achieve a large biomass stock. Green extraction methodologies with ethanol and water were performed over the seaweed biomass. The bioactive potential of extracts was assessed through a set of in vitro assays concerning their cytotoxicity, antioxidant, and antimicrobial properties. Additionally, dried seaweed biomass was incorporated into pasta formulations to increase food's nutritional value. Pigments extracted from G. gracilis have also been incorporated into yogurt as a natural colorant, and their stability was evaluated. Both products were submitted to the appreciation of a semitrained sensorial panel aiming to achieve the best final formulation before reaching the market. Results support the versatility of G. gracilis whether it is applied as a whole biomass, extracts and/or pigments. Through implementing several optimized protocols, this work allows the development of products with the potential to profit the food, cosmetic, and aquaculture markets, promoting environmental sustainability and a blue circular economy. Moreover, and in line with a biorefinery approach, the residual seaweed biomass will be used as biostimulant for plant growth or converted to carbon materials to be used in water purification of the in-house aquaculture systems of MARE-Polytechnic of Leiria, Portugal.
- The Vibrant Spectra of the Oceans: Unravelling the Diversity, Functions, and Applications of Seaweed PigmentsPublication . Freitas, Marta V.; Afonso, Clélia; Pereira, Leonel; Mouga, Teresa; Trivedi, , Nitin; Reddy,, C. R. K.; Critchley,, Alan T.Seaweeds are photosynthetic organisms that harvest sunlight and convert it into essential energy through a highly effective biochemical process powered by light, which in turn is captured and directed to the reactive centers by pigments. Seaweed pigments are fundamental to the seaweed photosynthetic process and are also responsible for their current taxonomic classification into three distinct divisions. The Chlorophyta comprises the green seaweeds, which hold high levels of both chlorophyll a and b, along with lesser amounts of β-carotene and xanthophylls. The Ochrophyta integrates the brown seaweeds (class Phaeophyceae), which are particularly rich in the xanthophyll fucoxanthin, while also showing lower levels of other xanthophylls, chlorophyll a and c, and β-carotene. The Rhodophyta houses the red seaweeds, which are characterized by holding high levels of phycoerythrin, as well as lower quantities of phycocyanin, chlorophyll a, β-carotene, and xanthophylls. However, regardless of their designation, seaweed species exhibit a significant range of colors and hues that go beyond “green,” “brown,” and “red,” rendering them visually unique, due to the relative composition and abundance of each pigment within their living cells. Nowadays, science has unveiled not only the diversity of these pigments, but also their biological function. Targeted extraction methods and potential end-use applications for these pigments have been researched and developed, with the resulting product often designed to protect and promote human health. Today, humankind acknowledges the benefits of natural products obtained from the oceans, including those obtained from seaweed pigments. This chapter aims to supply insight on the diversity, functions, and applications of the pigments found in all the three divisions, thus contributing to a greater understanding of the benefits these functional molecules can provide to humanity.