Biosystems & Integrative Sciences Institute

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Publications

Antioxidant and neuroprotective potential of the brown seaweed Bifurcaria bifurcata in an in vitro Parkinson’s Disease Model

Publication . Silva, Joana; Alves, Celso; Freitas, Rafaela; Martins, Alice; Pinteus, Susete; Ribeiro, Joana; Gaspar, Helena; Alfonso, Amparo; Pedrosa, Rui

Bifurcaria bifurcata is a marine brown seaweed mainly found on the Atlantic coast. Herein, we report the antioxidant and neuroprotective activities of seven fractions (F1–F7) obtained by normal phase chromatography from the B. bifurcata dichloromethane extract, as well as of its two major isolated diterpenes. Total phenolic content of fractions was determined by the Folin–Ciocalteu method, while antioxidant activity was evaluated by the DPPH, ORAC, and FRAP assays. Neuroprotective effects were evaluated in a neurotoxic model induced by 6-hydroxydopamine (6-OHDA) in a human neuroblastoma cell line (SH-SY5Y), while the mechanisms associated to neuroprotection were investigated by the determination of mitochondrial membrane potential, H2O2 production, Caspase-3 activity, and by observation of DNA fragmentation. Fractions F4 and F5 exhibited the best neuroprotective and antioxidant activities, respectively. F4 fraction prevented changes in mitochondrial potential, and induced a reduction of H2O2 levels production and an increase in cell viability, suggesting that it may contain multi-target compounds acting on different pathways. Hence, this fraction was subjected to purification steps, affording the known diterpenes eleganolone and eleganonal. Both compounds exhibited antioxidant potential, being interesting candidates for further neuroprotective studies.

2019Journal article

Open access

Effect biomarkers of the widespread antimicrobial triclosan in a marine model diatom

Publication . Duarte, Bernardo; Feijão, Eduardo; Carvalho, Ricardo Cruz de; Matos, Ana Rita; Cabrita, Maria Teresa; Novais, Sara C.; Moutinho, Ariana; Lemos, Marco F.L.; Marques, João Carlos; Caçador, Isabel; Reis-Santos, Patrick; Fonseca, Vanessa

The present-day COVID-19 pandemic has led to the increasing daily use of antimicrobials worldwide. Triclosan is a manmade disinfectant chemical used in several consumer healthcare products, and thus frequently detected in surface waters. In the present work, we aimed to evaluate the effect of triclosan on diatom cell photophysiology, fatty acid profiles, and oxidative stress biomarkers, using the diatom Phaeodactylum tricornutum as a model organism. Several photochemical effects were observed, such as the lower ability of the photosystems to efficiently trap light energy. A severe depletion of fucoxanthin under triclosan application was also evident, pointing to potential use of carotenoid as reactive oxygen species scavengers. It was also observed an evident favouring of the peroxidase activity to detriment of the SOD activity, indicating that superoxide anion is not efficiently metabolized. High triclosan exposure induced high cellular energy allocation, directly linked with an increase in the energy assigned to vital functions, enabling cells to maintain the growth rates upon triclosan exposure. Oxidative stress traits were found to be the most efficient biomarkers as promising tools for triclosan ecotoxicological assessments. Overall, the increasing use of triclosan will lead to significant effects on the diatom photochemical and oxidative stress levels, compromising key roles of diatoms in the marine system.

2022Journal article

Open access

Fluoxetine induces photochemistry-derived oxidative stress on Ulva lactuca

Publication . Feijão, Eduardo; Carvalho, Ricardo Cruz de; Duarte, Irina A.; Matos, Ana Rita; Cabrita, Maria Teresa; Utkin, Andrei B.; Caçador, Isabel; Marques, João Carlos; Novais, Sara C.; Lemos, Marco F.L.; Reis-Santos, Patrick; Fonseca, Vanessa; Duarte, Bernardo

Emerging pollutants impose a high degree of stress on marine ecosystems, compromising valuable resources, the planet and human health. Pharmaceutical residues often reachmarine ecosystems, and their input is directly related to human activities. Fluoxetine is an antidepressant, and one of the most prescribed selective serotonin reuptake inhibitors globally and has been detected in aquatic ecosystems in concentrations up to 40 μg L−1. The present study aims to evaluate the impact of fluoxetine ecotoxicity on the photochemistry, energy metabolism and enzyme activity of Ulva lactuca exposed to environmentally relevant concentrations (0.3, 0.6, 20, 40, and 80 μg L−1). Exogenous fluoxetine exposure induced negative impacts on U. lactuca photochemistry, namely on photosystem II antennae grouping and energy fluxes. These impacts included increased oxidative stress and elevated enzymatic activity of ascorbate peroxidase and glutathione reductase. Lipid content increased and the altered levels of key fatty acids such as hexadecadienoic (C16:2) and linoleic (C18:2) acids revealed strong correlations with fluoxetine concentrations tested. Multivariate analyses reinforced the oxidative stress and chlorophyll a fluorescence-derived traits as efficient biomarkers for future toxicology studies.

2022Journal article

Open access

Medusa polyps adherence inhibition: A novel experimental model for antifouling assays

Publication . Pinteus, Susete; Lemos, Marco F.L.; Freitas, Rafaela; Duarte, Inês M.; Alves, Celso; Silva, Joana; Marques, Sónia C.; Pedrosa, Rui

Although in the last decades significant advances have been made to improve antifouling formulations, the main current options continue to be highly toxic tomarine environment, leading to an urgent need for new safer alternatives. For anti-adherence studies, barnacles and mussels are commonly the first choice for experimental purposes. However, the use of these organisms involves a series of laborious and time-consuming stages. In the present work, a new approach for testing antifouling formulations was developed under known formulations and novel proposed options. Due to their high resilience, ability of surviving in hostile environments and high abundance in different ecosystems, medusa polyps present themselves as prospect candidates for antifouling protocols. Thus, a complete protocol to test antifouling formulations using polyps is presented, while the antifouling properties of two invasive seaweeds, Asparagopsis armata and Sargassum muticum, were evaluated within this new test model framework. The use of medusa polyps as model to test antifouling substances revealed to be a reliable alternative to the conventional organisms, presenting several advantages since the protocol is less laborious, less time-consuming and reproductive. The results also show that the seaweeds A. armata and S. muticum produce compounds with anti-adherence properties being therefore potential candidates for the development of new greener antifouling formulations.

2020Journal article

Restricted access

Effects of glyphosate-based herbicide on primary production and physiological fitness of the macroalgae Ulva lactuca

Publication . Carvalho, Ricardo Cruz de; Feijão, Eduardo; Matos, Ana Rita; Cabrita, Maria Teresa; Utkin, Andrei B.; Novais, Sara C.; Lemos, Marco F.L.; Caçador, Isabel; Marques, João Carlos; Reis-Santos, Patrick; Fonseca, Vanessa F.; Duarte, Bernardo

The use of glyphosate-based herbicides (GBHs) worldwide has increased exponentially over the last two decades increasing the environmental risk to marine and coastal habitats. The present study investigated the effects of GBHs at environmentally relevant concentrations (0, 10, 50, 100, 250, and 500 ug.L-1) on the physiology and biochemistry (photosynthesis, pigment, and lipid composition, antioxidative systems and energy balance) of Ulva lactuca, a cosmopolitan marine macroalgae species. Although GBHs cause deleterious effects such as the inhibition of photosynthetic activity, particularly at 250 ug.L-1, due to the impairment of the electron transport in the chloroplasts, these changes are almost completely reverted at the highest concentration (500 ug.L-1). This could be related to the induction of tolerance mechanisms at a certain threshold or tipping point. While no changes occurred in the energy balance, an increase in the pigment antheraxanthin is observed jointly with an increase in ascorbate peroxidase activity. These mechanisms might have contributed to protecting thylakoids against excess radiation and the increase in reactive oxygen species, associated with stress conditions, as no increase in lipid peroxidation products was observed. Furthermore, changes in the fatty acids profile, usually attributed to the induction of plant stress response mechanisms, demonstrated the high resilience of this macroalgae. Notably, the application of bio-optical tools in ecotoxicology, such as pulse amplitude modulated (PAM) fluorometry and laser-induced fluorescence (LIF), allowed separation of the control samples and those treated by GBHs in different concentrations with a high degree of accuracy, with PAM more accurate in identifying the different treatments.

2022Journal article

Open access