Browsing by Author "Thomas, Olivier P."
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- Antioxidant and Cytoprotective Activities of Fucus spiralis Seaweed on a Human Cell in Vitro ModelPublication . Pinteus, Susete; Silva, Joana; Alves, Celso; Horta, André Gustavo Cavadas da; Thomas, Olivier P.; Pedrosa, RuiAntioxidants play an important role as Reactive Oxygen Species (ROS) chelating agents and, therefore, the screening for potent antioxidants from natural sources as potential protective agents is of great relevance. The main aim of this study was to obtain antioxidant-enriched fractions from the common seaweed Fucus spiralis and evaluate their activity and efficiency in protecting human cells (MCF-7 cells) on an oxidative stress condition induced by H₂O₂. Five fractions, F1-F5, were obtained by reversed-phase vacuum liquid chromatography. F3, F4 and F5 revealed the highest phlorotannin content, also showing the strongest antioxidant effects. The cell death induced by H₂O₂ was reduced by all fractions following the potency order F4 > F2 > F3 > F5 > F1. Only fraction F4 completely inhibited the H₂O₂ effect. To understand the possible mechanisms of action of these fractions, the cellular production of H₂O₂, the mitochondrial membrane potential and the caspase 9 activity were studied. Fractions F3 and F4 presented the highest reduction on H₂O₂ cell production. All fractions decreased both caspase-9 activity and cell membrane depolarization (except F1). Taken all together, the edible F. spiralis reveal that they provide protection against oxidative stress induced by H₂O₂ on the human MCF-7 cellular model, probably acting as upstream blockers of apoptosis.
- Antitumor and antimicrobial potential of bromoditerpenes isolated from the red alga, Sphaerococcus coronopifoliusPublication . Rodrigues, Daniel; Alves, Celso; Horta, André; Pinteus, Susete; Silva, Joana; Culioli, Gérald; Thomas, Olivier P.; Pedrosa, RuiCancer and infectious diseases continue to be a major public health problem, and new drugs are necessary. As marine organisms are well known to provide a wide range of original compounds, the aim of this study was to investigate the bioactivity of the main constituents of the cosmopolitan red alga, Sphaerococcus coronopifolius. The structure of several bromoditerpenes was determined by extensive spectroscopic analysis and comparison with literature data. Five molecules were isolated and characterized which include a new brominated diterpene belonging to the rare dactylomelane family and named sphaerodactylomelol (1), along with four already known sphaerane bromoditerpenes (2–5). Antitumor activity was assessed by cytotoxicity and anti-proliferative assays on an in vitro model of human hepatocellular carcinoma (HepG-2 cells). Antimicrobial activity was evaluated against four pathogenic microorganisms: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans. Compound 4 exhibited the highest antimicrobial activity against S. aureus (IC50 6.35 μM) and compound 5 the highest anti-proliferative activity on HepG-2 cells (IC50 42.9 μM). The new diterpene, sphaerodactylomelol (1), induced inhibition of cell proliferation (IC50 280 μM) and cytotoxicity (IC50 720 μM) on HepG-2 cells and showed antimicrobial activity against S. aureus (IC50 96.3 μM).
- Marine invasive macroalgae: Turning a real threat into a major opportunity - the biotechnological potential of Sargassum muticum and Asparagopsis armataPublication . Pinteus, Susete; Lemos, Marco F.L.; Alves, Celso; Neugebauer, Agnieszka; Silva, Joana; Thomas, Olivier P.; Botana, Luis M.; Gaspar, Helena; Pedrosa, RuiMarine invasive species are widely recognized as one of the worst threats to marine ecosystems integrity, un-balancing native communities, which may lead to paramount ecological and economic impacts. Within invasiveseaweeds, Sargassum muticum and Asparagopsis armata are recognized as successful invaders in Europe andAmerica. Despite several attempts to control the spread of marine invaders, until now, all have proven to beelusive, and therefore, alternative strategies should be embraced.Worldwide, seaweeds have been increasingly explored due to their ability to produce bioactive compounds.However, one of the main problems associated with the production/extraction of these bioactive compounds fornew products development, is the source availability and the potential negative environmental consequences ofthis exploitation.Within this framework, the use of invasive species to obtain natural bioactive compounds presents us with atwo-folded opportunity - high availability of the biological material for the extraction of unique bioactivecompounds for new products development, and through specimen collection, mitigating negative effects causedby alien species, contributing for ecosystem integrity and sustainability.Over the last decades, the brown seaweed S. muticum and the red A. armata have been studied all over theworld for their capacity to produce bioactive compounds, with main results pointing towards their high potentialas producers of antioxidant, antifouling, antimicrobial, and antitumor compounds.The present review summarizes the biotechnological potential of S. muticum and A. armata as producers ofbioactive compounds, while addressing the potential use of global threats as important blue growth pawns.