Browsing by Author "Duarte, Adriana"
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- An Insight into Sargassum muticum Cytoprotective Mechanisms against Oxidative Stress on a Human Cell In Vitro ModelPublication . Pinteus, Susete; Lemos, Marco; Silva, Joana; Alves, Celso; Neugebauer, Agnieszka; Freitas, Rafaela; Duarte, Adriana; Pedrosa, RuiSargassum muticum is a brown seaweed with strong potential to be used as a functional food ingredient, mainly due to its antioxidant properties. It is widely used in traditional oriental medicine for the treatment of numerous diseases. Nevertheless, few studies have been conducted to add scientific evidence on its effects as well as on the mechanisms of action involved. In this work, the human cell line MCF-7 was used as an in vitro cellular model to evaluate the capability of Sargassum muticum enriched fractions to protect cells on an oxidative stress condition. The concentration of the bioactive compounds was obtained by vacuum liquid chromatography applied on methanol (M) and 1:1 methanol:dichloromethane (MD) crude extracts, resulting in seven enriched fractions from the M extraction (MF2-MF8), and eight fractions from the MD extraction (MDF1-MDF8). All fractions were tested for cytotoxic properties on MCF-7 cells and the nontoxic ones were tested for their capacity to blunt the damaging effects of hydrogen peroxide-induced oxidative stress. The nontoxic effects were also confirmed in 3T3 fibroblast cells as a nontumor cell line. The antioxidant potential of each fraction, as well as changes in the cell's real-time hydrogen peroxide production, in the mitochondrial membrane potential, and in Caspase-9 activity were evaluated. The results suggest that the protective effects evidenced by S. muticum can be related with the inhibition of hydrogen peroxide production and the inhibition of Caspase-9 activity.
- Cytotoxic mechanism of sphaerodactylomelol, an uncommon bromoditerpene isolated from sphaerococcus coronopifoliusPublication . Alves, Celso; Silva, Joana; Pinteus, Susete; Alonso, Eva; Alvarino, Rebeca; Duarte, Adriana; Marmitt, Diorge; Geottert, Márcia Inês; Gaspar, Helena; Alfonso, Amparo; Alpoim, Maria C.; Botana, Luis M; Pedrosa, RuiMarine natural products have exhibited uncommon chemical structures with relevant antitumor properties highlighting their potential to inspire the development of new anticancer agents. The goal of this work was to study the antitumor activities of the brominated diterpene sphaerodactylomelol, a rare example of the dactylomelane family. Cytotoxicity (10–100 M; 24 h) was evaluated on tumor cells (A549, CACO-2, HCT-15, MCF-7, NCI-H226, PC-3, SH-SY5Y, SK-ML-28) and the effects estimated by MTT assay. Hydrogen peroxide (H2O2) levels and apoptosis biomarkers (membrane translocation of phosphatidylserine, depolarization of mitochondrial membrane potential, Caspase-9 activity, and DNA condensation and/or fragmentation) were studied in the breast adenocarcinoma cellular model (MCF-7) and its genotoxicity on mouse fibroblasts (L929). Sphaerodactylomelol displayed an IC50 range between 33.04 and 89.41 M without selective activity for a specific tumor tissue. The cells’ viability decrease was accompanied by an increase on H2O2 production, a depolarization of mitochondrial membrane potential and an increase of Caspase-9 activity and DNA fragmentation. However, the DNA damage studies in L929 non-malignant cell line suggested that this compound is not genotoxic for normal fibroblasts. Overall, the results suggest that the cytotoxicity of sphaerodactylomelol seems to be mediated by an increase of H2O2 levels and downstream apoptosis.
- 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.
- Seasonal nutritional profile of Gelidium corneum (Rhodophyta, Gelidiaceae) from the center of PortugalPublication . Cavaco, Mário; Duarte, Adriana; Freitas, Marta; Afonso, Clélia; Bernardino, Susana M.; Pereira, Leonel; Martins, Mendelson; Mouga, TeresaGelidium corneum is a well-known agarophyte, harvested worldwide for its high agar quality. However, the species also exhibits an interesting nutritional profile, but with seasonal variations. Therefore, to evaluate the nutritional value of G. corneum, ash, crude protein, total lipids, and carbohydrates were analyzed at different times of the year. The heavy metals mercury, arsenic, lead, cadmium, and tin, as well as iodine were also measured. Finally, the seasonal antioxidant capacity of G. corneum extracts was evaluated. Our results indicate that the biomass is rich in protein (up to 16.25 ± 0.33%) and carbohydrates (up to 39.5 ± 3.29%), and low in lipids (up to 2.75 ± 0.28%), and especially in the summer, the AI, TI indexes, n-6/n-3 and h/H ratios (0.93, 0.6, 0.88 and 1.08, respectively) are very interesting. None of the contaminants exceeded the legally established limits, and the iodine values were adequate for a healthy diet. Finally, the antioxidant capacity is fair, with the DPPH ≤ 10.89 ± 1.46%, and ABTS ≤ 13.90 ± 1.54% inhibition, FRAP ≤ 0.91 ± 0.22 AAE.g−1, and TPC ≤ 6.82 ± 0.26 GAE.g−1. The results show that G. corneum is an attractive resource, with potential use as food or as a food supplement.
- Sustainable use of seaweeds from S. Martinho do Porto, Portugal - past, present and future perspectivePublication . Cavaco, Mário; Duarte, Adriana; Bernardino, Susana; Afonso, Clélia; Mouga, Teresa; J. R. da Costa Sanches GalvãoSeaweeds have long been used by populations on the coast of Portugal as fertilizers or food during periods of scarcity. Both uses have decreased dramatically since the introduction of chemical fertilizers and horticulture food. Even so, in the past decades, globalization has brought new interest to the consumption of these organisms, raising interest on algae as a healthy and tasty food. Much scientific research is underway on the properties of seaweeds, and it is proven that past uses are well-founded. S. Martinho do Porto, in the Centre of Portugal is the only location where the commercial harvesting of seaweeds still takes place. Gelidium corneum is harvested because this species produces high-quality agar, a much sought-after phycocolloid, which is used in the food industry as gelling or thickening agent. However, the species shows other properties that have been disregarded by the seaweeds’ industry. There are also some invasive species, namely Asparagopsis armata, which is causing considerable ecological problems to local ecosystems. Thus, the Mar2020 project Limo do Cais was approved to study the sustainable use the algal biomass from S. Martinho do Porto taking into account its industrial potential. In this way, the properties of G. corneum are being studied, to increase its commercial value. As to A. armata, it shows important antimicrobial properties that are being studied aiming the use of the algal biomass in the pharmaceutical industry. Thus, past uses of seaweeds will be discussed, as well as new potential uses that scientific research has uncovered.