{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,10]],"date-time":"2026-03-10T00:30:24Z","timestamp":1773102624457,"version":"3.50.1"},"reference-count":47,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2025,10,14]],"date-time":"2025-10-14T00:00:00Z","timestamp":1760400000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Portuguese Foundation for Science and Technology","award":["UIDB\/04469"],"award-info":[{"award-number":["UIDB\/04469"]}]},{"DOI":"10.13039\/501100001871","name":"LABBELS\u2014Associate Laboratory in Biotechnology, Bioengineering and Microelectrochemical Systems","doi-asserted-by":"publisher","award":["LA\/P\/0029\/2020"],"award-info":[{"award-number":["LA\/P\/0029\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Toxics"],"abstract":"<jats:p>Pharmaceuticals can be found in the aquatic environment and cause unwanted effects on organisms. The present work aimed to characterize the toxic mode of action of the antidepressant fluoxetine (FLX) on the freshwater microalga Raphidocelis subcapitata. With this aim, the microalga was exposed to low levels (\u00b5g\/L) of FLX for 72 h. Exposure to 20\u201330 \u00b5g\/L FLX arrested algal growth, which can be explained by the blockage of algal nuclear division. In addition, FLX (15\u201330 \u00b5g\/L) deeply altered the alga\u2019s metabolism, which was reflected by an increase in esterase activity, mitochondrial dysfunction (hyperpolarization of inner mitochondrial membrane), and reduction in the content of photosynthetic pigments: chlorophyll a (chla) and carotenoids (car). A sharp decline in photosynthetic performance, revealed by the reduction in maximum photochemical quantum yield (Fv\/Fm), effective photochemical quantum yield (\u03a6PSII), and photosynthetic electron transport rate (ETR) of photosystem II (PSII), was also observed. FLX, at 30 \u00b5g\/L, induced the intracellular accumulation of reactive oxygen species (ROS) and lipid peroxidation, with a marginal loss (1%) of cell membrane integrity. The results presented here contribute to the elucidation of the toxic mode of action of FLX on the microalgae R. subcapitata and, simultaneously, warn of the negative impact of the presence of pharmaceutical compounds in freshwater aquatic environments.<\/jats:p>","DOI":"10.3390\/toxics13100876","type":"journal-article","created":{"date-parts":[[2025,10,15]],"date-time":"2025-10-15T14:04:02Z","timestamp":1760537042000},"page":"876","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["The Unhappy Effects of the Antidepressant Fluoxetine on the Freshwater Microalga Raphidocelis subcapitata"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3519-8654","authenticated-orcid":false,"given":"Manuela D.","family":"Machado","sequence":"first","affiliation":[{"name":"CIETI\u2014Bioengineering Laboratory, ISEP, Polytechnic of Porto, Rua Dr. Ant\u00f3nio Bernardino de Almeida, 4249-015 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2280-5291","authenticated-orcid":false,"given":"Eduardo V.","family":"Soares","sequence":"additional","affiliation":[{"name":"CIETI\u2014Bioengineering Laboratory, ISEP, Polytechnic of Porto, Rua Dr. Ant\u00f3nio Bernardino de Almeida, 4249-015 Porto, Portugal"},{"name":"CEB\u2014Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal"},{"name":"LABBELS\u2014Associate Laboratory, Braga\/Guimar\u00e3es, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2025,10,14]]},"reference":[{"key":"ref_1","unstructured":"Kamal, K.M., Chiumente, M., Nakagawa, S., Giannetti, V., and Marlin, T. (2022). Disposal practices for unused and expired medications: Pilot data from three cities in three countries. GMS Health Innov. Technol., 16."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"907","DOI":"10.1097\/FPC.0b013e32833132cb","article-title":"Selective serotonin reuptake inhibitors pathway","volume":"19","author":"Sangkuhl","year":"2009","journal-title":"Pharmacogenet Genom."},{"key":"ref_3","unstructured":"(2025, January 13). DrugBank Fluoxetine. Available online: https:\/\/go.drugbank.com\/drugs\/DB00472."},{"key":"ref_4","unstructured":"Clincal Fluoxetine (2025, January 13). Drug Usage statistics, United States, 2013\u20132022. Available online: https:\/\/Clincalc.Com\/DrugStats\/Drugs\/Fluoxetine."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2561","DOI":"10.1897\/05-613R.1","article-title":"Laboratory persistence and fate of fluoxetine in aquatic environments","volume":"25","author":"Kwon","year":"2006","journal-title":"Environ. Toxicol. Chem."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1016\/j.jhazmat.2009.10.100","article-title":"Ecotoxicological aspects related to the presence of pharmaceuticals in the aquatic environment","volume":"175","author":"Santos","year":"2010","journal-title":"J. Hazard. Mater."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"542","DOI":"10.1021\/acsestwater.0c00081","article-title":"Occurrence and fate of psychiatric pharmaceuticals in wastewater treatment plants in Hong Kong: Enantiomeric profiling and preliminary risk assessment","volume":"1","author":"Wu","year":"2021","journal-title":"ACS EST Water"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"159486","DOI":"10.1016\/j.scitotenv.2022.159486","article-title":"Effects of fluoxetine on fish: What do we know and where should we focus our efforts in the future?","volume":"857","author":"Correia","year":"2023","journal-title":"Sci. Total Environ."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"8280","DOI":"10.1039\/C6RA28351A","article-title":"The degradation and persistence of five pharmaceuticals in an artificial climate incubator during a one year period","volume":"7","author":"Yin","year":"2017","journal-title":"RSC Adv."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Bean, T.G., Boxall, A.B.A., Lane, J., Herborn, K.A., Pietravalle, S., and Arnold, K.E. (2014). Behavioural and physiological responses of birds to environmentally relevant concentrations of an antidepressant. Philos. Trans. R. Soc. B Biol. Sci., 369.","DOI":"10.1098\/rstb.2013.0575"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"269","DOI":"10.1016\/j.aquatox.2014.08.014","article-title":"Aquatic toxicology of fluoxetine: Understanding the knowns and the unknowns","volume":"156","author":"Stewart","year":"2014","journal-title":"Aquat. Toxicol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"169","DOI":"10.1016\/S0378-4274(03)00066-3","article-title":"Aquatic ecotoxicology of fluoxetine","volume":"142","author":"Brooks","year":"2003","journal-title":"Toxicol. Lett."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1016\/S0045-6535(03)00103-6","article-title":"Waterborne and sediment toxicity of fluoxetine to select organisms","volume":"52","author":"Brooks","year":"2003","journal-title":"Chemosphere"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"300","DOI":"10.1016\/j.chemosphere.2008.06.029","article-title":"Fluoxetine effects assessment on the life cycle of aquatic invertebrates","volume":"73","author":"Gust","year":"2008","journal-title":"Chemosphere"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"4992","DOI":"10.1007\/s11356-014-3662-5","article-title":"Toxicities of 48 pharmaceuticals and their freshwater and marine environmental assessment in Northwestern France","volume":"23","author":"Minguez","year":"2016","journal-title":"Environ. Sci. Pollut. Res."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1016\/j.aquatox.2006.03.002","article-title":"Behavioural responses of Gammarus pulex (Crustacea, Amphipoda) to low concentrations of pharmaceuticals","volume":"78","author":"Noordoven","year":"2006","journal-title":"Aquat. Toxicol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"77","DOI":"10.1016\/j.aquatox.2013.10.012","article-title":"Environmental concentrations of the selective serotonin reuptake inhibitor fluoxetine impact specific behaviors involved in reproduction, feeding and predator avoidance in the fish Pimephales promelas (fathead minnow)","volume":"151","author":"Weinberger","year":"2014","journal-title":"Aquat. Toxicol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"34943","DOI":"10.1007\/s11356-019-06619-4","article-title":"Environmental concentration of fluoxetine disturbs larvae behavior and increases the defense response at molecular level in zebrafish (Danio rerio)","volume":"26","author":"Parolini","year":"2019","journal-title":"Environ. Sci. Pollut. Res."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"128","DOI":"10.1016\/j.ecoenv.2006.03.016","article-title":"Toxicity and hazard of selective serotonin reuptake inhibitor antidepressants fluoxetine, fluvoxamine, and sertraline to algae","volume":"67","author":"Johnson","year":"2007","journal-title":"Ecotoxicol. Environ. Saf."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"203","DOI":"10.1007\/s00244-007-9032-2","article-title":"Individual and mixture effects of selected pharmaceuticals and personal care products on the marine phytoplankton species Dunaliella tertiolecta","volume":"54","author":"DeLorenzo","year":"2008","journal-title":"Arch. Environ. Contam. Toxicol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"266","DOI":"10.1016\/j.aquatox.2010.10.008","article-title":"The pH-dependent toxicity of basic pharmaceuticals in the green algae Scenedesmus vacuolatus can be explained with a toxicokinetic ion-trapping model","volume":"101","author":"Neuwoehner","year":"2011","journal-title":"Aquat. Toxicol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"114045","DOI":"10.1016\/j.ecoenv.2022.114045","article-title":"Ecotoxicological effects of the antidepressant fluoxetine and its removal by the typical freshwater microalgae Chlorella pyrenoidosa","volume":"244","author":"Xie","year":"2022","journal-title":"Ecotoxicol. Environ. Saf."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Feij\u00e3o, E., Cruz de Carvalho, R., Duarte, I.A., Matos, A.R., Cabrita, M.T., Novais, S.C., Lemos, M.F.L., Ca\u00e7ador, I., Marques, J.C., and Reis-Santos, P. (2020). Fluoxetine arrests growth of the model diatom Phaeodactylum tricornutum by increasing oxidative stress and altering energetic and lipid metabolism. Front. Microbiol., 11.","DOI":"10.3389\/fmicb.2020.01803"},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Machado, M.D., and Soares, E.V. (2024). Features of the microalga Raphidocelis subcapitata: Physiology and applications. Appl. Microbiol. Biotechnol., 108.","DOI":"10.1007\/s00253-024-13038-0"},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Suzuki, S., Yamaguchi, H., Nakajima, N., and Kawachi, M. (2018). Raphidocelis subcapitata (=Pseudokirchneriella subcapitata) provides an insight into genome evolution and environmental adaptations in the Sphaeropleales. Sci. Rep., 8.","DOI":"10.1038\/s41598-018-26331-6"},{"key":"ref_26","unstructured":"OECD (2011). Test No. 201: Freshwater Alga and Cyanobacteria, Growth Inhibition Test, Organization for Economic Cooperation and Development."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1035","DOI":"10.1007\/s00253-012-4185-y","article-title":"Development of a short-term assay based on the evaluation of the plasma membrane integrity of the alga Pseudokirchneriella subcapitata","volume":"95","author":"Machado","year":"2012","journal-title":"Appl. Microbiol. Biotechnol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"8245","DOI":"10.1007\/s00253-022-12267-5","article-title":"Life and death of Pseudokirchneriella subcapitata: Physiological changes during chronological aging","volume":"106","author":"Machado","year":"2022","journal-title":"Appl. Microbiol. Biotechnol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1358","DOI":"10.1007\/s11270-012-1358-3","article-title":"Optimization of a microplate-based assay to assess esterase activity in the alga Pseudokirchneriella subcapitata","volume":"224","author":"Machado","year":"2013","journal-title":"Water. Air. Soil Pollut."},{"key":"ref_30","unstructured":"APHA (1989). Standard Methods for the Examination of Water and Wastewater, American Public Health Association (APHA). [17th ed.]."},{"key":"ref_31","unstructured":"Strickland, J., and Parsons, T.R. (1972). A Practical Handbook of Seawater Analysis, Fisheries Research Board of Canada. [2nd ed.]."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1286","DOI":"10.1093\/plcell\/koab008","article-title":"Light-adapted charge-separated state of Photosystem II: Structural and functional dynamics of the closed reaction center","volume":"33","author":"Sipka","year":"2021","journal-title":"Plant Cell"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"179","DOI":"10.1016\/j.aquatox.2019.01.014","article-title":"Impact of erythromycin on a non-target organism: Cellular effects on the freshwater microalga Pseudokirchneriella subcapitata","volume":"208","author":"Machado","year":"2019","journal-title":"Aquat. Toxicol."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1578","DOI":"10.1002\/clen.201600020","article-title":"Short- and long-term exposure to heavy metals induced oxidative stress response in Pseudokirchneriella subcapitata","volume":"44","author":"Machado","year":"2016","journal-title":"Clean\u2013Soil Air Water"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"129","DOI":"10.1016\/0968-0004(90)90206-Q","article-title":"The measurement and mechanism of lipid peroxidation in biological systems","volume":"15","author":"Gutteridge","year":"1990","journal-title":"Trends Biochem. Sci."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"302","DOI":"10.1016\/S0076-6879(78)52032-6","article-title":"Microsomal lipid peroxidation","volume":"Volume 52","author":"Fleischer","year":"1978","journal-title":"Biomembranes\u2014Part C: Biological Oxidations"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1016\/S0166-445X(01)00254-5","article-title":"Algal esterase activity as a biomeasure of environmental degradation in a freshwater creek","volume":"59","author":"Regel","year":"2002","journal-title":"Aquat. Toxicol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"659","DOI":"10.1093\/jexbot\/51.345.659","article-title":"Chlorophyll fluorescence\u2014A practical guide","volume":"51","author":"Maxwell","year":"2000","journal-title":"J. Exp. Bot."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.chemosphere.2010.04.011","article-title":"Comparing the sensitivity of algal, cyanobacterial and bacterial bioassays to different groups of antibiotics","volume":"80","author":"Pikkemaat","year":"2010","journal-title":"Chemosphere"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"5944","DOI":"10.1021\/cr200084z","article-title":"Free radical lipid peroxidation: Mechanisms and analysis","volume":"111","author":"Yin","year":"2011","journal-title":"Chem. Rev."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.aquatox.2013.11.017","article-title":"Modification of cell volume and proliferative capacity of Pseudokirchneriella subcapitata cells exposed to metal stress","volume":"147","author":"Machado","year":"2014","journal-title":"Aquat. Toxicol."},{"key":"ref_42","unstructured":"Larkum, A.W.D., Grossman, A.R., and Raven, J.A. (2020). Chlorophyll-xanthophyll antenna complexes: In between light harvesting and energy dissipation. Photosynthesis in Algae: Biochemical and Physiological Mechanisms, Advances in Photosynthesis and Respiration, Springer."},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Stange, C. (2016). Carotenoids and photosynthesis. Carotenoids in Nature: Biosynthesis, Regulation and Function, Springer.","DOI":"10.1007\/978-3-319-39126-7"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"213419","DOI":"10.1016\/j.ccr.2020.213419","article-title":"Organic fluorescent probes for detecting mitochondrial membrane potential","volume":"420","author":"Li","year":"2020","journal-title":"Coord. Chem. Rev."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"103","DOI":"10.1023\/A:1006912010550","article-title":"Fluoxetine interacts with the lipid bilayer of the inner membrane in isolated rat brain mitochondria, inhibiting electron transport and F1F0-ATPase activity","volume":"199","author":"Curti","year":"1999","journal-title":"Mol. Cell. Biochem."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"185","DOI":"10.1016\/j.toxlet.2016.07.001","article-title":"Fluoxetine and the mitochondria: A review of the toxicological aspects","volume":"258","year":"2016","journal-title":"Toxicol. Lett."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"3181","DOI":"10.18632\/oncotarget.13689","article-title":"The antidepressant fluoxetine induces necrosis by energy depletion and mitochondrial calcium overload","volume":"8","author":"Charles","year":"2017","journal-title":"Oncotarget"}],"container-title":["Toxics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2305-6304\/13\/10\/876\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,15]],"date-time":"2025-10-15T14:27:34Z","timestamp":1760538454000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2305-6304\/13\/10\/876"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,10,14]]},"references-count":47,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2025,10]]}},"alternative-id":["toxics13100876"],"URL":"https:\/\/doi.org\/10.3390\/toxics13100876","relation":{},"ISSN":["2305-6304"],"issn-type":[{"value":"2305-6304","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,10,14]]}}}