Identification, occurrence and fate of transformation products and metabolites of fluoxetine and metformin in the aquatic environment

In dieser Studie wurden anhand verschiedener Abbauexperimente (Elektrochemie, mikrobieller Abbau, Photoabbau, Fischembryo-Metabolismus) Transformationsprodukte (TPs) der umweltrelevanten Arzneimitteln Metformin (MF, Antidiabetikum) und Fluoxetin (FLX, Antidepressivum) generiert und anhand eines Workflows mit Flüssigchromatographie gekoppelt an hochauflösende Massenspektrometrie (LC-HRMS) identifiziert. Mittels Elektrochemie konnten vier neue umweltrelevante TPs von MF generiert und identifiziert werden, welche sich durch Zyklisierung und Demethylierung bildeten. Die neu identifizierten TPs (MBG, 2,4-AMT, 2,4-DAT) konnten im Abstrom von Kläranlagen nachgewiesen werden. Anhand von Batchexperimenten mit Belebtschlamm wurde der aerobe Abbau von MF in eine 1:1 Umwandlung in die TPs gezeigt. Der bekannte Metabolit Guanylharnstoff (GU) war dabei das Hauptprodukt und die elektrochemisch identifizierten TPs stellten 2% des abgebauten MF dar. Es konnte außerdem erstmals die Abbaubarkeit von GU in Belebtschlamm nachgewiesen werden, wobei im aeroben Milieu die Abbaubarkeit zusätzlich von der Herkunft des Belebtschlamms, und somit der mikrobiellen Gemeinschaft, abhängig war. Anhand von Photolyse und Fisch-Metabolismus konnten neue TPs von Fluoxetin identifiziert werden. Mit einer Sonnensimulationskammer konnten 27 TPs durch direkten und indirekten Photoabbau von FLX identifiziert werden, welche durch O-Dealkylierung, Hydroxylierung, CF3-Subsitution und N-Acylierung mit Aldehyden und Carboxylsäuren gebildet wurden. Der menschliche Hauptmetabolit Norfluoxetine (NFLX) spielte dabei eine untergeordnete Rolle. In Abbauexperimenten mit Oberflächenwasser anstatt Reinstwasser zeigte sich der Einfluss der indirekten Photolyse durch die größte gebildete Intensität an TPs, insbesondere der hydroxylierten TPs. Im Extrakt von Zebrafischembryonen (96 h nach Befruchtung) konnten sieben der abiotischen TPs nachgewiesen werden, sowie drei neue TPs identifiziert werden. Diese bildeten sich durch N-Hydroxylierung, N-Methylierung und N-Acylierung von FLX mit einer Aminogruppe. FLX aus dem Expositionsmedium (5 mg/L) reicherte sich 110-fach in den Embryonen an, wobei 1% in NFLX umgewandelt wurde und als Hauptmetabolit nachgewiesen werden konnte

Impact of the Antidiabetic Drug Metformin and Its Transformation Product Guanylurea on the Health of the Big Ramshorn Snail (Planorbarius corneus)

Pharmaceuticals can enter surface waters via sewage treatment plants. In the environment, the substances and their transformation products, formed by the degradation of the parent compounds, can affect aquatic wildlife, including freshwater invertebrates. However, research on pharmaceutical-induced effects in wild freshwater organisms other than fish is still scarce. In our study, we investigated the impact of the highly consumed antidiabetic drug metformin and its main transformation product, guanylurea, on the health of a freshwater gastropod—the big ramshorn snail (Planorbarius corneus) by analysing its biochemical and cellular stress responses and apical parameters. The snails were exposed to different concentrations of the drug (0, 0.01, 0.1, 1, and 10 mg/L) and its transformation product (0, 0.1, 10, and 100 mg/L). The examined parameters were mortality, weight, tissue integrity of the hepatopancreas, and the levels of stress proteins and lipid peroxides. Mortality and the levels of stress proteins and lipid peroxides were not influenced by the two substances. In response to the highest concentrations of both chemicals, the weight of the snails was slightly but not significantly reduced. The histopathological investigation of the hepatopancreas revealed a significant effect of guanylurea at a concentration of 100 mg/L with an increased number of symptoms of cellular responses in the tissue (e.g., dilated lumen, disturbed compartmentation of the digestive cells, nucleus deformation, hyperplasia, and hypertrophy of crypt cells). For the parent compound, a similar trend was also observed for the highest concentration. Overall, the observed effects did not occur at environmentally relevant concentrations, but at concentrations which were 10,000 times higher than these. Thus, the results did not give rise to a major concern that metformin and guanylurea could pose a risk to the big ramshorn snail in the environment

Does the antidiabetic drug metformin affect embryo development and the health of brown trout (Salmo trutta f. fario)?

Abstract Background Due to the rising number of type 2 diabetes patients, the antidiabetic drug, metformin is currently among those pharmaceuticals with the highest consumption rates worldwide. Via sewage-treatment plants, metformin enters surface waters where it is frequently detected in low concentrations (µg/L). Since possible adverse effects of this substance in aquatic organisms have been insufficiently explored to date, the aim of this study was to investigate the impact of metformin on health and development in brown trout (Salmo trutta f. fario) and its microbiome. Results Brown trout embryos were exposed to 0, 1, 10, 100 and 1000 µg/L metformin over a period from 48 days post fertilisation (dpf) until 8 weeks post-yolk sac consumption at 7 °C (156 dpf) and 11 °C (143 dpf). Chemical analyses in tissues of exposed fish showed the concentration-dependent presence of metformin in the larvae. Mortality, embryonic development, body length, liver tissue integrity, stress protein levels and swimming behaviour were not influenced. However, compared to the controls, the amount of hepatic glycogen was higher in larvae exposed to metformin, especially in fish exposed to the lowest metformin concentration of 1 µg/L, which is environmentally relevant. At higher metformin concentrations, the glycogen content in the liver showed a high variability, especially for larvae exposed to 1000 µg/L metformin. Furthermore, the body weight of fish exposed to 10 and 100 µg/L metformin at 7 °C and to 1 µg/L metformin at 11 °C was decreased compared with the respective controls. The results of the microbiome analyses indicated a shift in the bacteria distribution in fish exposed to 1 and 10 µg/L metformin at 7 °C and to 100 µg/L metformin at 11 °C, leading to an increase of Proteobacteria and a reduction of Firmicutes and Actinobacteria. Conclusions Overall, weight reduction and the increased glycogen content belong to the described pharmaceutical effects of the drug in humans, but this study showed that they also occur in brown trout larvae. The impact of a shift in the intestinal microbiome caused by metformin on the immune system and vitality of the host organism should be the subject of further research before assessing the environmental relevance of the pharmaceutical

Interacting Effects of Polystyrene Microplastics and the Antidepressant Amitriptyline on Early Life Stages of Brown Trout (Salmo trutta f. fario)

Whether microplastics themselves or their interactions with chemicals influence the health and development of aquatic organisms has become a matter of scientific discussion. In aquatic environments, several groups of chemicals are abundant in parallel to microplastics. The tricyclic antidepressant amitriptyline is frequently prescribed, and residues of it are regularly found in surface waters. In the present study, the influence of irregularly shaped polystyrene microplastics (<50 µm), amitriptyline, and their mixture on early life-stages of brown trout were investigated. In a first experiment, the impacts of 100, 104, and 105 particles/L were studied from the fertilization of eggs until one month after yolk-sac consumption. In a second experiment, eggs were exposed in eyed ova stages to 105, 106 particles/L, to amitriptyline (pulse-spiked, average 48 ± 33 µg/L) or to two mixtures for two months. Microplastics alone did neither influence the development of fish nor the oxidative stress level or the acetylcholinesterase activity. Solely, a slight effect on the resting behavior of fry exposed to 106 particles/L was observed. Amitriptyline exposure exerted a significant effect on development, caused elevated acetylcholinesterase activity and inhibition of two carboxylesterases. Most obvious was the severely altered swimming and resting behavior. However, effects of amitriptyline were not modulated by microplastics