5-Fluorouracil accumulation in green microalgae and its biogenetic transfer into ciliate protozoan

Assessing the impact of antineoplastic drugs in the aquatic environment: State of the art and future perspective for freshwater organisms

Since the late 70s, the continuous pharmaceuticals` input into the environment has raised concerns regarding the eventual risk posed by such compounds to human and environmental health. A major group of pharmaceuticals in terms of environmental impact are the antineoplastic agents (AAs). Herein, we followed a systematic review method to retrieve antineoplastic agents (AAs') ecotoxicological information regarding freshwater species. In this analysis, data from diverse taxonomic groups, from microorganisms to vertebrate species, looked at different levels of biological organization, including cell lines. Furthermore, this review gathers ecotoxicological parameters (EC₅₀ and LC₅₀) for imatinib (IM), cisplatin (CisPt), and 5-fluorouracil (5-FU) in species sensitivity distribution (SSD) curves and estimates the hazard concentration (HC₅) considering the protection of 95% of the ecological community. Lastly, we suggest how we can improve AAs' Environmental Risk Assessment (ERA), considering potential adoptable toxicity endpoints, test duration, AAs metabolites testing, and AAs mixture exposure.

Assessing the effects of the cytostatic drug 5-Fluorouracil alone and in a mixture of emerging contaminants on the mussel Mytilus galloprovincialis

The assessment of contaminants of emerging concern, alone and in mixtures, and their effects on marine biota requires attention. 5-Fluorouracil is a cytostatic category 3 anti-cancer medication (IARC) that is used to treat a variety of cancers, including colon, pancreatic, and breast cancer. In the presence of other pollutants, this pharmaceutical can interact and form mixtures of contaminants, such as adhering to plastics and interaction with metal nanoparticles. This study aimed to comprehend the effects of 5-Fluorouracil (5FU; 10 ng/L) and a mixture of emerging contaminants (Mix): silver nanoparticles (nAg; 20 nm; 10 μg/L), polystyrene nanoparticles (nPS; 50 nm; 10 μg/L) and 5FU (10 ng/L), in an in vivo (21 days) exposure of the mussel Mytilus galloprovincialis. A multibiomarker approach namely genotoxicity, the antioxidant defence system (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidases (GPx), glutathione - S - transferases (GST) activities), and oxidative damage (LPO) was used to assess the effects in gills and digestive gland of mussels. Both treatments cause genotoxicity in mussel's haemolymph, and antagonism between contaminants was observed in the Mix. Genotoxicity observed confirms 5FU's mode of action (MoA) by DNA damage. The antioxidant defence system of mussels exposed to 5FU kicked in and counter balanced ROS generated during the exposure, though the same was not seen in Mix-exposed mussels. Mussels were able to withstand the effects of the single compound but not the effects of the Mix. For oxidative stress and damage, the interactions of the components of the mixture have a synergistic effect.

Aquatic ecotoxicology of anticancer drugs: A systematic review

Anticancer drugs in the aquatic environment have drawn a lot of attention in the last decade. Since wastewater treatment plants are inefficient at fully eliminating trace concentrations of anticancer drugs, these compounds are continuously discharged into the aquatic environment. Subsequently, non-target organisms such as the aquatic biota are directly exposed to a variety of anticancer drugs. To understand the potential impact on the aquatic organisms, a systematic review was conducted in compliance with the PRISMA guidelines. The results acquired from the 152 included studies were analysed and sorted into four categories: the impact of each included anticancer drug, the effect of metabolites, the effect of a mixture of drugs, and risk assessment. Findings showed that risk to the aquatic biota was unlikely to occur as the concentrations needed to induce effects were much higher than those detected in the environment. However, these data were based on acute toxicity and included only basic toxicity endpoints. The concentrations that produced significant effects were much lower when tested in the long-term or in multi-generational studies. Heterogeneity in results was also observed; this depended on the organism tested, the assessment adopted, and the endpoints selected. In this systematic review, an overall view of the research studies was generated by which all the variability factors to be considered were reported and recommendations to guide future studies were proposed.

Using zebrafish to assess the effect of chronic, early developmental exposure to environmentally relevant concentrations of 5-fluorouracil and leucovorin

Environmental contaminants can deleteriously affect aquatic animals. One such contaminant is 5-fluorouracil (5-FU), a long-prescribed chemotherapeutic drug. Leucovorin (LV) is co-administered with 5-FU, potentiating its effects. Zebrafish (Danio rerio) larvae were reared in ng/L treatments of either 5-FU, LV, or a combined 5-FU/LV mixture for 8 dy. Survival was measured daily and swimming behavior assessed every other day. After 8 dy, larval length was measured, and densitometry of p53-labeled cryostat sections determined the extent of apoptosis. No significant differences in survival or apoptosis were found; larvae in the highest concentrations were largest. Changes in behavior of 5-FU-treated larvae were based on exposure duration; changes in LV-treated larvae were affected by drug concentration and duration. Larvae co-exposed to 5-FU/LV had responses like 5-FU-treated larvae. Overall, early developmental exposure of zebrafish larvae to environmentally-relevant concentrations of 5-FU and LV did not adversely affect survival, growth, and behavior suggesting realistic concentrations are sublethal and non-toxic.

Assessment of toxicity and genotoxicity of low doses of 5-fluorouracil in zebrafish (Danio rerio) two-generation study

Residues of anti-neoplastic drugs represent new and emerging pollutants in aquatic environments. Many of these drugs are genotoxic, and it has been postulated that they can cause adverse effects in aquatic ecosystems. 5-Fluorouracil (5-FU) is one of the most extensively used anti-neoplastic drugs in cancer therapy, and this article describes the results of the first investigation using a two-generation toxicity study design with zebrafish (Danio rerio). Exposure of zebrafish to 5-FU (0.01, 1.0 and 100 μg/L) was initiated with adult zebrafish (F0 generation) and continued through the hatchings and adults of the F1 generation, and the hatchings of the F2 generation, to day 33 post-fertilisation. The exposure did not affect survival, growth and reproduction of the zebrafish; however, histopathological changes were observed in the liver and kidney, along with genotoxic effects, at all 5-FU concentrations. Increases in DNA damage determined using the comet assay were significant in the liver and blood cells, but not in the gills and gonads. In erythrocytes, a significant, dose-dependent increase in frequency of micronuclei was observed at all 5-FU concentrations. Whole genome transcriptomic analysis of liver samples of F1 generation zebrafish exposed to 0.01 μg/L and 1 μg/L 5-FU revealed dose-dependent increases in the number of differentially expressed genes, including up-regulation of several DNA-damage-responsive genes and oncogenes (i.e., jun, myca). Although this chronic exposure to environmentally relevant concentrations of 5-FU did not affect the reproduction of the exposed zebrafish, it cannot be excluded that 5-FU can lead to degenerative changes, including cancers, which over long-term exposure of several generations might affect fish populations. The data from this study contribute to a better understanding of the potential consequences of chronic exposure of fish to low concentrations of anti-neoplastic drugs, and they demonstrate that further studies into multi-generation toxicity are needed.

Oxidative stress, uptake and bioconversion of 5-fluorouracil in algae

Impact of cytostatic drug 5-fluorouracil (FU) and its metabolite 2-fluoro-3-alanine (FA) on green alga Scenedesmus quadricauda was studied. FA elevated fluorescence signal of reactive oxygen species (ROS) more pronouncedly than FU at 1 and 10 μM doses while both ROS and reactive nitrogen species (RNS/NO) increased more expressively in 100 μM FU treatment. Cellular damage staining (Acridine Orange and Calcofluor White) did no reveal substantial difference between FU and FA. Majority of free amino acids including proline was unaffected after 24h of exposure. FA depleted ascorbate peroxidase activity more than FU therefore ascorbate content (AsA) was less affected while FU stimulated glutathione reductase activity less than FA and therefore glutathione (GSH) was more depleted. Both compounds accumulated concentration-dependently with higher absolute FA amounts but FU conversion to FA was also detected. We subsequently influenced 100 μM FU- and FA-induced changes using known ROS (DTT - dithiothreitol) and RNS/NO (SNP - sodium nitroprusside and PTIO - 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) modulators and results showed that PTIO depleted NO and elevated ROS while the opposite was found after SNP and DTT addition. Changes of lipid peroxidation (using BODIPY staining) confirmed that FU and FA toxicity is related to alteration of ROS/RNS balance.