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NIAF: Sustainable antifouling agents: from grape wastes to the sea with the green chemistry leading the way

Antifouling (AF) paints used to prevent biofouling on underwater surfaces, are continuing releasing copper and other biocides to the oceans. As a result, the marine industry is facing rigid environmental regulations on the use of coatings with biocide-releasing mechanism. AF paints that are meant to end up in the oceans cannot be part of a sustainable future. The European Commission has been pushing member states to work harder on finding alternatives to copper-based coatings investing in harmless systems. Under the scope of a previous FCT-funded project, heading by the Pl, nature-inspired antifoulants (NIAFs) were synthesized and some were chemical immobilized in commercial marine coatings. It was observed that NIAFs did not lose their bioactivity after chemical immobilization and therefore they may provide new non-toxic bioactive coatings systems able to prevent hard fouling with minimal release of the bioactive compound into the aquatic environment. These results strongly motivate the PI to further explore these NIAFs as viable option to replace copper. A multidisciplinary team was gathered in this project to synergically act to consolidate, strengthen, and increase the international competitiveness of these potential environmentally benign AF products. To achieve this goal, synthetic procedures will be optimized to significantly reduce the environmental footprint and NIAFs starting materials will be extracted from grape wastes with green methodologies developed by our consultant. This will bring an opportunity to offer a sustainable alternative to the AF industry. To understand NIAFs persistence, and consequently their risk for long-term adverse effects in the ecosystem, the half-life determination will be conducted through hydrolysis, photolysis, and biodegradation by the new team of Environmental Chemists and Microbiologists, and the main transformation products (TPs) will be identified by Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS). Bioaccumulation studies are also included in this project to assess biomagnification through the food chain. An innovative method to assess lipophilicity based on a liposome model (logKlipw) designed to mimic marine environment will be developed in this project, which can be used in the future as a tool to accurately predict the bioaccumulation potential of emerging pollutants in the marine environment. Through an international collaboration with Buffalo University, USA, in-vivo bioaccumulative studies with Emerald shiner fish as model organism will be performed. Ecotoxicologists and Biologists were also joined to this team to provide safety assessment in human and environmental health. The biocide SeaNine211 awarded with the "Green Chemistry Challenge Award" for its environmental safety as a marine AF agent was later found to have endocrine-disrupting and reproductive impairing effects. To avoid history repeating itself, standardized ecotoxicological bioassays with a diverse array of aquatic animals will be combined with in silica and in vitro cell-based assays that allow testing chemical affinity to a vast collection of nuclear receptors from different metazoans. To become an approved product, the AF mechanism of action must be elucidated. Therefore, the molecular targets underlying the anti-settlement activity of NIAFs will be studied in this project through a shotgun proteomics approach, performed with an international collaboration with Linkoping University, Sweden. The presence of Organic and Pharmaceutical Chemists  will allow the synthesis of the main TPs identified in the degradation studies. The information about the effects and toxicity of TPs represents a significant knowledge gap to understand the global risk for aquatic ecosystems of booster biocides, with TPs being some times more toxic than the parent compound. The synthesis of the main TPs will allow their ecotoxicity evaluation and mitigate the risks of developing pseudo-environmental friendly compounds. Only by studying the fate and effects of both NIAFs and TPs in environment it will be possible to produce benign products that do not incur any impact on non-target species and the ecosystem as a whole. These new compounds will also be screened for the AF activity, offering an opportunity to discover new AF agents. On the other hand, if a NIAF or TP exerts some toxicity or bioaccumulative potential, the team of Pharmacists and Medical Chemists will proceed to NIAF optimization by molecular modification, accordingly to the medicinal chemistry principles applied in drug design and development; with this approach, it is highly probable that the necessary balance between sustainable synthesis, low toxicity, and bioaccumulation will be found. If this project is recommended for funding, national protection and international extension via PCT will allow the economic valorization and commercialization of these products.

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