Psychoactive drugs citalopram and mirtazapine caused oxidative stress and damage of feeding behavior in Daphnia magna

Non-targeted identification of tianeptine photodegradation products in water samples by UHPLC-QTOF MS/MS

This study aims the characterization of several tianeptine transformation products in ultrapure water by simulated sunlight irradiation. Tianeptine was completely degraded after 106 h of exposition following pseudo-first-order kinetics (half-life time = 12.0 ± 2.4 h). Furthermore, an ultra-high-performance liquid chromatography coupled with a high-resolution quadrupole time-of-flight-mass spectrometry method was developed and fully validated taking into account different method performance parameters for the quantification of tianeptine in river water up to a concentration of 400 pg L-1. Following a non-targeted approach based on mass data-independent acquisition, eight different transformation products not previously reported in the literature were identified and accordingly elucidated, proposing a photodegradation mechanism based on the accurate tandem mass spectrometry information acquired. Irradiation experiments were replicated for a tianeptine solution prepared in a blank river water sample, resulting in the formation of the same transformation products and similar degradation kinetics. In addition, a toxicity assessment of the photoproducts was performed by in silico method, being generally all TPs of comparable toxicity to the precursor except for TP1, and showing a similar persistence in the environment except for TP2 and TP6, while TP4 was the only TP predicted as mutagenic. The developed method was applied for the analysis of four river water samples.

Assessing the pharmaceutical residues as hotspots of the main rivers of Catalonia, Spain

The global increase in pharmaceutical consumption, driven by factors such as aging populations and chronic diseases, has raised concerns regarding the environmental impact of pharmaceutical contaminants. Europe, and more specifically Catalonia (Spain), exhibits high pharmaceutical consumption rates, potentially exacerbating environmental contamination. Pharmaceuticals enter rivers through various pathways, persisting after wastewater treatment plants and posing risks to aquatic organisms and human health. Llobregat and Besòs Rivers in Catalonia, crucial water sources, demonstrate detectable pharmaceutical levels, necessitating comprehensive analysis. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) proves effective in detecting pharmaceutical residues, facilitating their risk assessment. This paper reviews the occurrence, fate, and risks associated with 78 pharmaceuticals and metabolite in Llobregat and Besòs Rivers, using LC-MS/MS for analysis. Understanding pharmaceutical impacts on Catalonian River ecosystems is essential for developing mitigation strategies.

Evaluation of the citalopram toxicity on early development of zebrafish: Morphological, physiological and biochemical responses

Citalopram, an antidepressant drug have been detected in different environmental matrices due to its high consumption. Previous study has proved that citalopram may alter the behaviour of aquatic organisms at environmentally relevant concentrations. However, scientific knowledge is still lacking on the ecotoxicological effects of citalopram on aquatic organisms. For this reason, the present study is aimed to investigate the potential toxicity of citalopram in terms of development, antioxidant, neurotoxicity, apoptosis, lipogenesis, and bone mineralization in embryonic and larval zebrafish (Danio rerio) at environmentally relevant concentrations. We noticed that citalopram exposure at 1 and 10 μg/L concentration delays hatching and heartbeat at 24, 48, 72 and 96 hpf. Exposure to citalopram also significantly increased mortality at 10 μg/L. Abnormal development with yolk sac edema, pericardial edema and scoliosis were also observed after citalopram treatment. In addition, citalopram significantly (P < 0.001) induced superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST) and lipid peroxidation (LPO) levels. A significant decrease in acetylcholine esterase (AChE) activity was also observed in citalopram exposed groups. We found significant dose-and time-dependent increases in apoptosis, lipogenesis, and bone mineralization. In conclusion, the findings of the present study can provide new insights on the ecotoxicity of citalopram in the aquatic environment.

Systematic analysis of circadian disrupting substances with a high-throughput zebrafish circadian behavior screening approach

Circadian rhythm aligns numerous biological functions in majority of animals. Aside from well-known external factors such as the light-dark cycle and temperature, circadian rhythm can also be regulated by rarely explored factors such as synthetic substances. Here, we established a circadian behavior screening approach utilizing zebrafish larvae model, which integrated high-throughput capabilities with automated batch processing. With this approach, we systematically analyzed the circadian disruptive effects of >60 synthetic substances commonly detected in aquatic environment by assessing both the circadian period length and amplitude of circadian behavior, with an exposure concentration set at 100 μg/L. Among tested substances, a series of circadian disrupting compounds (circadian disruptors) were identified. Several categories of the hit compounds can be recognized, such as phthalate (diisopentyl phthalate (DIPP), with 10.1 % and 49.6 % increases for circadian period length and amplitude, respectively), neuroactive substance (mirtazapine, with 10.6 % and 63.1 % increases, respectively), and biocides (thiamethoxam, with 100.3 % increase for amplitude). Among these compounds, DIPP increased circadian period length and amplitude with a high degree. Aside from DIPP, we further examined eleven other phthalates and demonstrated that benzyl butyl phthalate, diisobutyl phthalate and diisohexyl phthalate could also significantly increase the zebrafish circadian period length by 7.9 %, 3.7 % and 8.5 %, respectively. Collectively, the present findings substantiated the feasibility of this high throughput screening strategy for circadian disruptor's discovery and provided novel insights into understanding of the potential risks of synthetic substances.

Natural Coumarin Shows Toxicity to Spodoptera litura by Inhibiting Detoxification Enzymes and Glycometabolism

Coumarin and its derivatives are plant-derived compounds that exhibit potent insecticidal properties. In this study, we found that natural coumarin significantly inhibited the growth and development of Spodoptera litura larvae through toxicological assay. By transcriptomic sequencing, 80 and 45 differentially expressed genes (DEGs) related to detoxification were identified from 0 to 24 h and 24 to 48 h in S. litura after coumarin treatment, respectively. Enzyme activity analysis showed that CYP450 and acetylcholinesterase (AChE) activities significantly decreased at 48 h after coumarin treatment, while glutathione S-transferases (GST) activity increased at 24 h. Silencing of SlCYP324A16 gene by RNA interference significantly increased S. litura larval mortality and decreased individual weight after treatment with coumarin. Additionally, the expression levels of DEGs involved in glycolysis and tricarboxylic acid (TCA) cycle were inhibited at 24 h after coumarin treatment, while their expression levels were upregulated at 48 h. Furthermore, metabonomics analysis identified 391 differential metabolites involved in purine metabolism, amino acid metabolism, and TCA cycle from 0 to 24 h after treated with coumarin and 352 differential metabolites associated with ATP-binding cassette (ABC) transporters and amino acid metabolism. These results provide an in-depth understanding of the toxicological mechanism of coumarin on S. litura.

Environmentally relevant concentrations of antidepressant mirtazapine impair the neurodevelopment of zebrafish (Danio rerio)

Mirtazapine is a commonly prescribed antidepressant and has been found widespread in aquatic environments. However, its toxicities to aquatic organisms has rarely been explored. Herein, we conducted a comprehensive study on the developmental effects of mirtazapine on early life stages of zebrafish at environmentally relevant concentrations (3.9 ng/L and 43.5 ng/L). Out of the endpoints measured, spontaneous contraction of embryos at 24 h post fertilization (hpf) and hatching rate and heart rate of embryos at 50 hpf and 56 hpf, respectively, were significantly affected. In light-dark transition behavior test, mirtazapine significantly reduced the swimming frequency and swimming speed of embryos at both concentrations of 3.9 ng/L and 43.5 ng/L. Furthermore, the total swimming distances in dark conditions were also significantly reduced. Transcriptomic analysis was further conducted. It demonstrated that the decreased neural activities in embryos may be associated with altered epinephrine and neuregulin signaling. The present results fill a data gap regarding the exposure of fish to mirtazapine at environmentally relevant concentrations and provide new insights into the neurotoxic mechanisms of mirtazapine exposure.

Toxic Effects of Methylene Blue on the Growth, Reproduction and Physiology of Daphnia magna

Methylene blue (MB) is a disinfectant used in aquaculture to prevent and treat fish diseases. However, the release of MB can pose a risk to the receiving water bodies. Zooplankton are the most sensitive organisms among aquatic life. Hence, this study examined the acute and chronic toxic effects of MB on zooplankton using Daphnia magna (D. magna) as a test organism to provide basic data for risk assessment. The results show that 48 h-EC₅₀ and 24 h-LC₅₀ were 61.5 ± 2.3 and 149.0 ± 2.2 μg/L, respectively. Chronic exposure to MB affected the heart rate, beat frequency of the thoracic limbs, and reproductive ability of D. magna at environmental concentrations higher than 4.7 μg/L. The cumulative molts, time to production of the first brood, and total number of living offspring were affected at different MB concentrations, while "abortions" were observed in high-exposure groups. The activity of superoxide dismutase was increased, while glutathione S-transferase activity was stimulated at low concentrations and inhibited at high concentrations. In addition, the malondialdehyde content increased with increasing concentrations of MB. Our findings demonstrate the impact of MB on the reproduction and growth of freshwater species, as well as their physiological responses. These results have implications for establishing guidelines on the use of MB in aquaculture and setting discharge standards.

The stereoselective toxicity of dinotefuran to Daphnia magna: A systematic assessment from reproduction, behavior, oxidative stress and digestive function

Dinotefuran is a promising neonicotinoid insecticide with chiral structure. In the present study, the stereoselective toxicity of dinotefuran to Daphnia magna (D. magna) was studied. The present result showed that S-dinotefuran inhibited the reproduction of D. magna at 5.0 mg/L. However, both R-dinotefuran and S-dinotefuran had no genotoxicity to D. magna. Additionally, neither R-dinotefuran nor S-dinotefuran had negative influences on the motor behavior of D. magna. However, S-dinotefuran inhibited the feeding behavior of D. magna at 5.0 mg/L. Both R-dinotefuran and S-dinotefuran induced oxidative stress effect in D. magna after exposure. R-dinotefuran significantly activated the activities of superoxide dismutase (SOD) and glutathione S-transferase (GST), while S-dinotefuran showed the opposite effect. S-dinotefuran had more obvious activation effect on the acetylcholinesterase (AchE) activity and trypsin activity compared to R-dinotefuran. The transcriptome sequencing results showed that S-dinotefuran induced more DEGs in D. magna, and affected the normal function of ribosome. The DEGs were mainly related to the synthesis and metabolism of biomacromolecules, indicating the binding mode between dinotefuran enantiomer and biomacromolecules were different. Additionally, the present result indicated that the digestive enzyme activity and digestive gene expression levels in D. magna were greatly enhanced to cope with the inhibition of S-dinotefuran on the feeding.

Evaluation of Complex Mixture Toxicity in the Milwaukee Estuary (WI, USA) Using Whole-Mixture and Component-Based Evaluation Methods

Anthropogenic activities introduce complex mixtures into aquatic environments, necessitating mixture toxicity evaluation during risk assessment. There are many alternative approaches that can be used to complement traditional techniques for mixture assessment. Our study aimed to demonstrate how these approaches could be employed for mixture evaluation in a target watershed. Evaluations were carried out over 2 years (2017-2018) across 8-11 study sites in the Milwaukee Estuary (WI, USA). Whole mixtures were evaluated on a site-specific basis by deploying caged fathead minnows (Pimephales promelas) alongside composite samplers for 96 h and characterizing chemical composition, in vitro bioactivity of collected water samples, and in vivo effects in whole organisms. Chemicals were grouped based on structure/mode of action, bioactivity, and pharmacological activity. Priority chemicals and mixtures were identified based on their relative contributions to estimated mixture pressure (based on cumulative toxic units) and via predictive assessments (random forest regression). Whole mixture assessments identified target sites for further evaluation including two sites targeted for industrial/urban chemical mixture effects assessment; three target sites for pharmaceutical mixture effects assessment; three target sites for further mixture characterization; and three low-priority sites. Analyses identified 14 mixtures and 16 chemicals that significantly contributed to cumulative effects, representing high or medium priority targets for further ecotoxicological evaluation, monitoring, or regulatory assessment. Overall, our study represents an important complement to single-chemical prioritizations, providing a comprehensive evaluation of the cumulative effects of mixtures detected in a target watershed. Furthermore, it demonstrates how different tools and techniques can be used to identify diverse facets of mixture risk and highlights strategies that can be considered in future complex mixture assessments. Environ Toxicol Chem 2023;42:1229-1256. © 2023 SETAC.

Integrated Approach for Synthetic Cathinone Drug Prioritization and Risk Assessment: In Silico Approach and Sub-Chronic Studies in Daphnia magna and Tetrahymena thermophila

Synthetic cathinones (SC) are drugs of abuse that have been reported in wastewaters and rivers raising concern about potential hazards to non-target organisms. In this work, 44 SC were selected for in silico studies, and a group of five emerging SC was prioritized for further in vivo ecotoxicity studies: buphedrone (BPD), 3,4-dimethylmethcathinone (3,4-DMMC), butylone (BTL), 3-methylmethcathinone (3-MMC), and 3,4-methylenedioxypyrovalerone (MDPV). In vivo short-term exposures were performed with the protozoan Tetrahymena thermophila (28 h growth inhibition assay) and the microcrustacean Daphnia magna by checking different indicators of toxicity across life stage (8 days sublethal assay at 10.00 µg L^-1). The in silico approaches predicted a higher toxic potential of MDPV and lower toxicity of BTL to the model organisms (green algae, protozoan, daphnia, and fish), regarding the selected SC for the in vivo experiments. The in vivo assays showed protozoan growth inhibition with MDPV > BPD > 3,4-DMMC, whereas no effects were observed for BTL and stimulation of growth was observed for 3-MMC. For daphnia, the responses were dependent on the substance and life stage. Briefly, all five SC interfered with the morphophysiological parameters of juveniles and/or adults. Changes in swimming behavior were observed for BPD and 3,4-DMMC, and reproductive parameters were affected by MDPV. Oxidative stress and changes in enzymatic activities were noted except for 3-MMC. Overall, the in silico data agreed with the in vivo protozoan experiments except for 3-MMC, whereas daphnia in vivo experiments showed that at sublethal concentrations, all selected SC interfered with different endpoints. This study shows the importance to assess SC ecotoxicity as it can distress aquatic species and interfere with food web ecology and ecosystem balance.

Correlation between BOD/COD Ratio and Octanol/Water Partition Coefficient for Mixture Organic Compounds

Correlation between the BOD/COD ratio and Partition coefficient of octanol/ water (Pow) on a single organic substance shows that the Pow value is directly proportional to the toxicity level and inversely proportional to BOD/COD ratio. This research examined the correlation to a mixture of organic substances. The objective is to obtain a varied range of substances, as well as determining the quality of wastewater discharging to fresh waters. Need for analysis of organic substances used as antiseptics during the Covid-19 pandemic. In addition, organic substances from the organophosphate pesticide class, diazinon, were used. BOD5, COD, Pow, and LC50-96h toxicity tests using Daphnia magna were used. Six types of the mixture of organic substances included diazinon-formaldehyde-isopropyl alcohol, ethanol-oxalic acid-formaldehyde, isopropyl alcohol-glycerol-lactose, acetic acid-isopropyl alcohol-formaldehyde, sucrose-glycerol-acetic acid, and oxalic acid-formaldehyde-diazinon, with 3 different concentrations of 10, 100, and 1000 mg/L, three repetitions. The lowest BOD/COD ratio (<0.2) and the highest Pow value (>4) are found in diazinon-formaldehyde-IPA. Its toxicity in D. magna also showed the lowest LC-50 (11.82 mg/L). Whereas, sucrose-glycerol-acetic acid had the highest BOD/COD ratio (>0.7) and lowest Pow (<0.7) with the highest LC- 50 (567.88 mg/L). Other organic substances mixtures have characteristics in the range of these mixtures. Pow variability and the BOD/COD ratio have a negative correlation. A mixture of organic matter is more biodegradable making it has a higher tendency to dissolve in water.

Identification of Photodegradation Products of Escitalopram in Surface Water by HPLC-MS/MS and Preliminary Characterization of Their Potential Impact on the Environment

The study concerns the photodegradation of the antidepressant escitalopram (ESC), the S-enantiomer of the citalopram raceme, both in ultrapure and surface water, considering the contribution of indirect photolysis through the presence of nitrate and bicarbonate. The effect of nitrate and bicarbonate concentrations was investigated by full factorial design, and only the nitrate concentration resulted in having a significant effect on the degradation. The kinetics of ESC photodegradation is the pseudo-first-order (half-life = 62.4 h in ultrapure water and 48.4 h in lake water). The generation of transformation products (TPs) was monitored through a developed and validated HPLC-MS/MS method. Fourteen TPs were identified in ultrapure water (one of them, at m/z 261, for the first time) and other two TPs at m/z 327 (found for the first time in this study) were identified only in presence of a nitrate. Several TPs were the same as those formed during the photodegradation of citalopram. The photodegradation pathway of ESC and its mechanism of degradation in water is proposed. The method was applied successfully to the analyses of surface water samples, in which a few dozen of ng L−1 of ESC was determined together with the presence of TP2, TP5 and TP12. Finally, a preliminary in silico evaluation of the toxicological profile and environmental behavior of TPs by computational models was carried out; two TPs (TP4 and TP10) were identified as of potential concern, as they were predicted mutagenic by Ames test model.

Endocrine-disrupting potential and toxicological effect of para-phenylphenol on Daphnia magna

Several phenol derivatives are suspected endocrine disruptors and have received attention in risk assessment studies for several decades owing to the structural similarity between estrogens and phenolic compounds. We assessed the endocrine disrupting effect of the phenolic compound para-phenylphenol (PPP) through acute tests and evaluating chronic endpoints in an invertebrate model, Daphnia magna. Exposure of D. magna to PPP induced substantial adverse effects, namely, reduced fecundity, slowed growth rate, delayed first brood, and a reduction in neonate size. Furthermore, we investigated the mRNA expression of relevant genes to elucidate the mechanism of endocrine disruption by PPP. Exposure of D. magna to PPP induced the substantial downregulation of genes and markers related to reproduction and development, such as EcR-A, EcR-B, Jhe, and Vtg. Consequently, we demonstrated that PPP has an endocrine disrupting effect on reproduction and development in D. magna.