Effects of emerging contaminants on neurotransmission and biotransformation in marine organisms — An in vitro approach Luis G. Luis a , Ângela Barreto a , Tito Trindade b , Amadeu M.V.M. Soares a , Miguel Oliveira a, ⁎ a Department of Biology & CESAM, University of Aveiro, 3810-193 Aveiro, Portugal b Department of Chemistry & CICECO, University of Aveiro, 3810-193 Aveiro, Portugal abstract article info Article history: Received 9 June 2015 Received in revised form 20 February 2016 Accepted 26 February 2016 Available online xxxx The effects of gold (ionic form and nanoparticles — AuNPs) and pharmaceuticals (carbamazepine and fluoxetine) on enzymes involved in neurotransmission (acetylcholinesterase — AChE) and biotransformation (glutathione S- transferases — GST) were assessed by their incubation with Mytilus galloprovincialis' hemolymph and subcellular fraction of gills, respectively. AuNPs did not alter enzymatic activities unlike ionic gold that inhibited AChE and GST activities at 2.5 and 0.42 mg·L -1 , respectively. Carbamazepine inhibited AChE activity at 500 mg·L -1 and fluoxetine at 1000 mg·L -1 . GST was inhibited by carbamazepine at 250 mg·L -1 and by fluoxetine at 125 mg·L -1 . Increased AChE activity was found in simultaneous exposures to fluoxetine and bovine serum albu- min coated AuNPs (BSA-AuNPs). Concerning GST, in the simultaneous exposures, AuNPs revealed protective ef- fects against carbamazepine (citrate and polyvinylpyrrolidone coated) and fluoxetine (citrate and BSA coated) induced inhibition. However, BSA-AuNPs increased the inhibition caused by carbamazepine. AuNPs demonstrat- ed ability to interfere with other chemicals toxicity justifying further studies. © 2016 Elsevier Ltd. All rights reserved. Keywords: Gold nanoparticles Human pharmaceuticals Mixtures Phase II biotransformation Neurotransmission Mytilus galloprovincialis 1. Introduction Estuarine and coastal areas are under strong anthropogenic pressure in several regions around the world, being contaminated by complex mixtures of contaminants that include, among other classes of contam- inants, persistent organic pollutants (Doong et al., 2008), metals (Doong et al., 2008; Oliveira et al., 2010) and pharmaceuticals (Buchberger, 2007). Nanoparticles (NPs) are among the classes of environmental contaminants currently considered as contaminants of emerging con- cern (Sauve and Desrosiers, 2014), due to their increased use in several areas of human activity (e.g. electronics, cosmetics and biomedicine), their size dependent characteristic and the poor knowledge on their im- pact into the environment. It is expected that NPs will eventually end up in waterways, where they may exert pernicious effects to aquatic biota (Moore, 2006; Baun et al., 2008; Canesi et al., 2010). Despite the in- creased production of NPs-containing materials and the constant dis- covery of new applications, the knowledge on the biological effects of NPs exposure is still limited, particularly in terms of effects to saltwater organisms, likely due to their reported instability in high ionic strength media (such as saltwater). However, the use of stabilizing coatings and the presence, in natural waters, of a variety of substances that may act as dispersants and NPs stabilizers (Klaine et al., 2008) may increase the stability of these particles in high ionic strength environments such as estuaries. Gold nanoparticles (AuNPs) are among the most widely used NPs in several fields of research from energy to biomedical applications (Lapresta-Fernández et al., 2012). Citrate layer, which is able to stabilize NPs by electrostatic repulsion (Manson et al., 2011), may easily be re- placed by ligands binding stronger to the particle surface. In biomedical applications, AuNPs have been used coated with a variety of biomole- cules such as proteins, DNA and carbohydrate moieties to increase their stability and applications (Housni et al., 2008). In the presence of proteins, AuNPs tend to form a protein corona (Pino et al., 2014). Bovine serum albumin (BSA) is a commonly studied protein that has a great im- portance in nanomedicine (Thi Ha Lien et al., 2010), presenting a high amino acid sequence similarity with human serum. It is biocompatible, water soluble and has the potential to increase the stability of AuNPs. Polyvinylpyrrolidone (PVP) is another capping/reducing/nucleating agent increasingly used in the coating of AuNPs due to its non-toxic, high stabilizing ability and outstanding solubility in various polar sol- vents (Behera and Ram, 2014). With the increased use of AuNPs, it is expected that their levels in the environment increase, having potential to become a significant persis- tent nanomaterial input to environmental systems (Hull et al., 2011). However, the available information on the levels of AuNPs in the aquatic environment is very limited (García-Negrete et al., 2013). Predictions originating from their use in consumer products estimate levels be- tween 0.1 and 1.43 μg·L -1 in water (Boxall et al., 2007). However, the properties (e.g. size and surface characteristics) of these particles after environmental release are hard to predict due to several environmental factors and, for example, passage through wastewater treatment plants, Marine Pollution Bulletin xxx (2016) xxx–xxx ⁎ Corresponding author. E-mail address: migueloliveira@ua.pt (M. Oliveira). MPB-07523; No of Pages 9 http://dx.doi.org/10.1016/j.marpolbul.2016.02.064 0025-326X/© 2016 Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul Please cite this article as: Luis, L.G., et al., Effects of emerging contaminants on neurotransmission and biotransformation in marine organisms — An in vitro approach, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.02.064