ADD VALUE TO THE MARINE INVADERS ASPARAGOPSIS ARMATA AND SARGASSUM MUTICUM

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The marine invasive seaweeds Asparagopsis armata and Sargassum muticum as targets for greener antifouling solutions

Publication . Pinteus, Susete; Lemos, Marco F.L.; Alves, Celso; Silva, Joana; Pedrosa, Rui

Biofouling is a complex phenomenon that affects all maritime dependent industries. The accumulation of both micro and macro-organisms in immerged structures increases significantly the maintenance expenses, and thus the use of antifouling substances is inevitable. Although with recognized antifouling properties, the available antifouling coatings are known to induce negative impacts in aquatic ecosystems. Therefore, greener alternatives are urgently required. Living underwater, marine organisms are prone to biofouling and some have developed strategies to defend themselves against undesirable organisms, which include the production of bioactive substances. As a result, marine organisms are promising sources of natural antifouling substances. Within this framework, the marine invasive seaweeds Sargassummuticumand Asparagopsis armatawere addressed for antifouling compounds biodiscovery. Both seaweeds revealed antifouling properties against microfoulers, namely algicidal and anti-biofilm activities; however Asparagopsis armata stand out for its capacity to inhibit marine bacteria and microalgae growth, to decrease biofilm formation, and for acting as a neurotransmitter disruptor through the inhibition of acetylcholinesterase activity. By addressing invasive species, the problematic of the biological material supply for industrial purposes is surpassed while mitigating the negative impacts of invasive species through specimen's collection.

2021Journal article

Restricted 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

Marine invasive species for high-value products' exploration: Unveiling the antimicrobial potential of Asparagopsis armata against human pathogens

Publication . Pinteus, Susete; Lemos, Marco F.L.; Simões, Marco; Alves, Celso; Silva, Joana; Gaspar, Helena; Martins, Alice; Rodrigues, Américo; Pedrosa, Rui

Infectious diseases remain one of the leading global causes of death, mainly due to the increasing number of multi-resistant microorganisms. Therefore, novel antimicrobials are continuously needed. Marine organisms have already proven to be a rich source of bioactive compounds which can be used for the development of novel pharmacological drugs. Within these, seaweeds are an important resource still underexplored. Asparagopsis armata is a marine invasive seaweed that has spread along several coastlines of the world, inducing negative pressures in marine ecosystems. Therefore, it is crucial to develop strategies to counteract their impacts. In this work, A. armata was extracted with methanol and dichloromethane (1:1) and fractionated by column chromatography with different polarity solvents, providing 8 fractions (F1-F8). All the fractions were evaluated for their antimicrobial potential against important human pathogens, namely Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis, and Candida albicans. Additionally, their capacity to inhibit biofilms formation and the effects on cytoplasmatic membrane and DNA integrity were also assessed. The most active fractions were further purified and submitted to GC–MS analysis. The results showed that A. armata produces compounds with a high inhibitory activity against S. aureus, P. aeruginosa, and C. albicans growth, possibly mediated by cytoplasmatic membrane disruption and DNA damage. GC–MS analysis suggested that the most active fractions were mainly composed of bromoditerpenes and fatty acids. The attained results point to the relevance of the invasive A. armata as a source of antimicrobial substances with broad-spectrum activity. The use of invasive species to obtain natural bioactive compounds presents a two-folded opportunity - high availability of the biological material for the extraction of bioactive compounds and, through specimen collection, the mitigation of the negative effects caused by invasive species, contributing to ecosystem integrity and sustainability.

2020Journal article

Restricted access

Natural approaches for neurological disorders: The neuroprotective potential of Codium tomentosum

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

Parkinson’s disease (PD) is the second most common neurodegenerative disorder, and is characterized by a progressive degeneration of the dopaminergic neurons in the substantia nigra. Although not completely understood, several abnormal cellular events are known to be related with PD progression, such as oxidative stress, mitochondrial dysfunction and apoptosis. Accordingly, the aim of this study was to evaluate the neuroprotective e ects of Codium tomentosum enriched fractions in a neurotoxicity model mediated by 6-hydroxydopamine (6-OHDA) on SH-SY5Y human cells, and the disclosure of their mechanisms of action. Additionally, a preliminary chemical screening of the most promising bioactive fractions of C. tomentosum was carried out by GC-MS analysis. Among the tested fractions, four samples exhibited the capacity to revert the neurotoxicity induced by 6-OHDA to values higher or similar to the vitamin E (90.11 +- 3.74% of viable cells). The neuroprotective e ects were mediated by the mitigation of reactive oxygen species (ROS) generation, mitochondrial dysfunctions and DNA damage, together with the reduction of Caspase-3 activity. Compounds belonging to different chemical classes, such as terpenes, alcohols, carboxylic acids, aldehydes, esters, ketones, saturated and unsaturated hydrocarbons were tentatively identified by GC-MS. The results show that C. tomentosum is a relevant source of neuroprotective agents, with particular interest for preventive therapeutics.

2020Journal article

Open access

Identification of Asparagopsis armata‐associated bacteria and characterization of their bioactive potential

Publication . Horta, A. C.; Alves, Celso; Pinteus, Susete; Lopes, Cláudia; Fino, Nádia; Silva, Joana; Ribeiro, Joana; Rodrigues, Daniel; Francisco, João; Rodrigues, Américo; Pedrosa, Rui

Macroalgae‐associated bacteria have already proved to be an interesting source of compounds with therapeutic potential. Accordingly, the main aim of this study was to characterize Asparagopsis armata‐associated bacteria community and evaluate their capacity to produce substances with antitumor and antimicrobial potential. Bacteria were selected according to their phenotype and isolated by the streak plate technique. The identification was carried out by the RNA ribosomal 16s gene amplification through PCR techniques. The antimicrobial activities were evaluated against seven microorganisms (Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Salmonella enteritidis, Staphylococcus aureus, Saccharomyces cerevisiae, Candida albicans) by following their growth through spectrophotometric readings. Antitumor activities were evaluated in vitro on human cell lines derived from hepatocellular (HepG‐2) and breast carcinoma (MCF‐7) using the MTT method. The present work identified a total of 21 bacteria belonging to the genus Vibrio, Staphylococcus, Shewanella, Alteromonadaceae, Bacillus, Cobetia, and Photobacterium, with Vibrio being the most abundant (42.86%). The extract of Shewanella sp. ASP 26 bacterial strain induced the highest antimicrobial activity, namely against Bacillus subtilis and Staphylococcus aureus with an IC50 of 151.1 and 346.8 μg/mL, respectively. These bacteria (Shewanella sp.) were also the ones with highest antitumor potential, demonstrating antiproliferative activity on HepG‐2 cells. Asparagopsis armata‐associated bacteria revealed to be a potential source of compounds with antitumor and antibacterial activity.

2019Journal article

Open access