Designing a biorefinery for the valorization of invasive seaweed: the case of Sargassum muticum and Asparagopsis armata

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Evaluating the in vitro potential of natural extracts to protect lipids from oxidative damage

Publication . Félix, Rafael; Valentão, Patrícia; Andrade, Paula B.; Félix, Carina; Novais, Sara C.; Lemos, Marco F.L.

Lipid peroxidation is a chemical reaction known to have negative impacts on living organisms’ health and on consumer products’ quality and safety. Therefore, it has been the subject of extensive scientific research concerning the possibilities to reduce it, both in vivo and in nonliving organic matrices. It can be started by a variety of oxidants, by both ROS-dependent and -independent pathways, all of them reviewed in this document. Another feature of this reaction is the capacity of lipid peroxyl radicals to react with the non-oxidized lipids, propagating the reaction even in the absence of an external trigger. Due to these specificities of lipid peroxidation, regular antioxidant strategies—although being helpful in controlling oxidative triggers—are not tailored to tackle this challenge. Thus, more suited antioxidant compounds or technologies are required and sought after by researchers, either in the fields of medicine and physiology, or in product development and biotechnology. Despite the existence of several laboratory procedures associated with the study of lipid peroxidation, a methodology to perform bioprospecting of natural products to prevent lipid peroxidation (a Lipid Peroxidation Inhibitory Potential assay, LPIP) is not yet well established. In this review, a critical look into the possibility of testing the capacity of natural products to inhibit lipid peroxidation is presented. In vitro systems used to peroxidize a lipid sample are also reviewed on the basis of lipid substrate origin, and, for each of them, procedural insights, oxidation initiation strategies, and lipid peroxidation extent monitoring are discussed.

2020Journal article

Open access

Stress response markers in the blood of São Tomé green sea turtles (Chelonia mydas) and their relation with accumulated metal levels

Publication . Morão, Inês F.C.; Lemos, Marco F.L.; Félix, Rafael; Vieira, Sara; Barata, Carlos; Novais, Sara C.

Metals are persistent worldwide being harmful for diverse organisms and having complex and combined effects with other contaminants in the environment. Sea turtles accumulate these contaminants being considered good bioindicator species for marine pollution. However, very little is known on how this is affecting these charismatic animals. Sâo Tomé and Príncipe archipelago harbours important green sea turtle (Chelonia mydas) nesting and feeding grounds. The main goal of this study was to determine metal and metalloid accumulation in the blood of females C. mydas nesting in São Tomé Island, and evaluate the possible impacts of this contamination by addressing molecular stress responses. Gene expression analysis was performed in blood targeting genes involved in detoxification/sequestration and metal transport (mt, mtf and fer), and in antioxidant and oxidative stress responses (cat, sod, gr, tdx, txrd, selp and gclc). Micronuclei analysis in blood was also addressed as a biomarker of genotoxicity. Present results showed significant correlations between different gene expressions with the metals evaluated. The best GLM models and significant relationships were found for mt expression, for which 78% of the variability was attributed to metal levels (Al, Cu, Fe, Hg, Pb and Zn), followed by micronuclei count (65% - Cr, Cu, Fe, Hg, Mn and Zn), tdx expression (52% - Cd, Fe, Mn, Pb and Se), and cat expression (52% - As, Fe, Se and Cd x Hg). Overall, this study demonstrates that these green sea turtles are trying to adapt to the oxidative stress and damage produced by metals through the increased expression of antioxidants and other protectors, which raises concerns about the impacts on these endangered organisms’ fitness. Furthermore, promising biomarker candidates associated to metal stress were identified in this species that may be used in future biomonitoring studies using C. mydas’ blood, allowing for a temporal follow-up of the organisms.

2022Journal article

Restricted access

Asparagopsis armata exudate cocktail: the quest for the mechanisms of toxic action of an invasive seaweed on marine invertebrates

Publication . Silva, Carla; Simões, Tiago; Félix, Rafael; A.M.V.M., Soares; Barata, Carlos; Novais, Sara C.; Lemos, Marco F.L.

The seaweed Asparagopsis armata exhibits a strong invasive behavior, producing halogenated compounds with effective biological effects. This study addresses the biochemical responses to sublethal concentrations of A. armata exudate on the marine snail Gibbula umbilicalis whole body and the shrimp Palaemon elegans eyes and hepatopancreas. Antioxidant defenses superoxide dismutase (SOD) and glutathione-S-transferase (GST), oxidative damage endpoints lipid peroxidation (LPO) and DNA damage, the neuronal parameter acetylcholinesterase (AChE), and the fatty acid profile were evaluated. Results revealed different metabolic responses in both species. Despite previous studies indicating that the exudate affected G. umbilicalis’ survival and behavior, this does not seem to result from oxidative stress or neurotoxicity. For P. elegans, the inhibition of AChE and the decrease of antioxidant capacity is concomitant with the increase of LPO, suggesting neurotoxicity and oxidative stress as contributor mechanisms of toxicity for this species. Fatty acid profile changes were more pronounced for P. elegans with a general increase in polyunsaturated fatty acids (PUFAs) with the exudate exposure, which commonly means a defense mechanism protecting from membrane disruption. Nonetheless, the omega-3 PUFAs arachidonic acid (ARA) and docosapentaenoic acid (DPA) increased in both invertebrates, indicating a common regulation mechanism of inflammation and immunity responses

2021Journal article

Open access

Argan oil as a rich source of linoleic fatty acid for dietetic structured lipids production

Publication . Simões, Tiago; Ferreira, Jessica; Lemos, Marco F.L.; Augusto, Ana; Félix, Rafael; Silva, Susana F.J.; Ferreira-Dias, Suzana; Tecelão, Carla

Argan oil is rich in long-chain unsaturated fatty acids (FA), mostly oleic and linoleic, and natural antioxidants. This study addresses the production of low-calorie structured lipids by acidolysis reaction, in a solvent-free system, between caprylic (C8:0; system I) or capric (C10:0; system II) acids and argan oil, used as triacylglycerol (TAG) source. Three commercial immobilized lipases were tested: Novozym® 435, Lipozyme® TL IM, and Lipozyme® RM IM. Higher incorporation degree (ID) was achieved when C10:0 was used as acyl donor, for all the lipases tested. Lipozyme® RM IM yielded the highest ID for both systems (28.9 +- 0.05 mol.% C10:0, and 11.4 +- 2.2 mol.% C8:0), being the only catalyst able to incorporate C8:0 under the reaction conditions for biocatalyst screening (molar ratio 2:1 FA/TAG and 55ºC). The optimal conditions for Lipozyme® RM IM in system II were found by response surface methodology (66ºC; molar ratio FA/TAG of 4:1), enabling to reach an ID of 40.9 mol.% of C10:0. Operational stability of Lipozyme® RM IM in system II was also evaluated under optimal conditions, after eight consecutive 24 h-batches, with biocatalyst rehydration between cycles. The biocatalyst presented a half-life time of 103 h.

2021Journal article

Open access

Tailoring shrimp aquafeed to tackle Acute Hepatopancreatic Necrosis Disease by inclusion of industry-friendly seaweed extracts

Publication . Félix, Rafael; Félix, Carina; Januário, Adriana P.; Carmona, Ana M.; Baptista, Teresa; Gonçalves, Rui A.; Sendão, João; Novais, Sara C.; Lemos, Marco F.L.

Shrimp farming has been severely affected by Vibrio infections in southeastern Asia, with severe economic impacts. Invasive seaweeds are an increasing threat that can be strategically valorized by biotechnology, promoting economic development while contributing to ecologic remediation. Asparagopsis armata and Sargassum muticum are two such species that have been frequently reported as excellent bioactive compounds producers, namely anti-bacterial and antioxidant. Thus, A. armata and S. muticum were extracted in an industry-focused approach, using low amounts of ethanol and short extraction times at room temperature. Yield, in vitro antioxidant capacity by the 2,2-diphenyl−1-picrylhydrazyl radical scavenging assay, and in vitro antibacterial activity against Vibrio parahaemolyticus (microdilution) were optimized using Response Surface Methodology (RSM). Optimal extracts (one from each seaweed species) were incorporated in feed, and an in vivo trial using the whiteleg shrimp Penaeus vannamei was performed in industrial facilities using the supplemented feed (1.5, 3.5 and 7.5 g extract per kg feed). Feed quality (along an 8-week period under regular storage conditions) and shrimp performance (40-day trial) were studied, as well as post-challenge (infection by virulent Vibrio parahaemolyticus) mortality rate and hepatopancreas condition. The results from the RSM showed that lower extraction times and ethanol volumes maximized extracts' bioactive properties (A. armata – 20 min, 10 mL solvent per gram seaweed; S. muticum – 100 min, 10 mL.g−1). The seaweed extracts did not impact shrimp performance (no statistically significant differences in weight gain, feed conversion rate or survival). Asparagopsis armata selected extract at 7.5 g per kg feed was able to decrease feed contamination by fungi along time and reduce shrimp mortality by up to 50% upon challenge with V. parahaemolyticus. Despite lacking statistical significance, a difference in hepatopancreas condition after challenge could be identified in shrimp fed the supplemented feed.

2020Journal article

Restricted access