Journal of Applied Toxicology publishes peer-reviewed original reviews and hypothesis-driven research articles on mechanistic, fundamental and applied research relating to the toxicity of drugs and chemicals at the molecular, cellular, tissue, target organ and whole body level in vivo (by all relevant routes of exposure) and in vitro / ex vivo. All aspects of toxicology are covered (including but not limited to nanotoxicology, genomics and proteomics, teratogenesis, carcinogenesis, mutagenesis, reproductive and endocrine toxicology, toxicopathology, target organ toxicity, systems toxicity (eg immunotoxicity), neurobehavioral toxicology, mechanistic studies, biochemical and molecular toxicology, novel biomarkers, pharmacokinetics/PBPK, risk assessment and environmental health studies) and emphasis is given to papers of clear application to human health, and/or advance mechanistic understanding and/or provide significant contributions and impact to their field.
AbstractPsychoactive compounds, N‐methyl‐5‐(2‐aminopropyl)benzofuran (5‐MAPB) and 3,4‐methylenedioxy‐N‐methamphetamine (MDMA), are known to be hepatotoxic in humans and/or experimental animals. As previous studies suggested that these compounds elicited cytotoxicity via mitochondrial dysfunction and/or oxidative stress in rat hepatocytes, the protective effects of fructose and N‐acetyl‐l‐cysteine (NAC) on 5‐MAPB‐ and MDMA‐induced toxicity were studied in rat hepatocytes. These drugs caused not only concentration‐dependent (0–4 mm) and time‐dependent (0–3 hours) cell death accompanied by the depletion of cellular levels of adenosine triphosphate (ATP) and glutathione (reduced form; GSH) but also an increase in the oxidized form of GSH. The toxic effects of 5‐MAPB were greater than those of MDMA. Pretreatment of hepatocytes with either fructose at a concentration of 10 mm or NAC at a concentration of 2.5 mm prevented 5‐MAPB−/MDMA‐induced cytotoxicity. In addition, the exposure of hepatocytes to 5‐MAPB/MDMA caused the loss of mitochondrial membrane potential, although the preventive effect of fructose was weaker than that of NAC. These results suggest that: (1) 5‐MAPB−/MDMA‐induced cytotoxicity is linked to mitochondrial failure and depletion of cellular GSH; (2) insufficient cellular ATP levels derived from mitochondrial dysfunction were ameliorated, at least in part, by the addition of fructose; and (3) GSH loss via oxidative stress was prevented by NAC. Taken collectively, these results indicate that the onset of toxic effects caused by 5‐MAPB/MDMA may be partially attributable to cellular energy stress as well as oxidative stress.
Rita Roque Bravo, Helena Carmo, Félix Carvalho, Maria de Lourdes Bastos, Diana Dias da Silva
AbstractBenzofurans, also known by users as benzo fury or benzofury, are synthetic phenethylamines and constitute the third most prominent group of new psychoactive substances (NPS). As the use of these substances has been spread as an alternative to the classic illicit psychostimulants, such as amphetamines, their legal status was reviewed, resulting in an utter prohibition of these NPS in many countries worldwide. Herein, the prevalence of abuse, chemistry, biological effects, metabolism, and the potential harms and risky behaviors associated with the abuse of benzofurans are reviewed. The congeners of this group are mainly consumed recreationally at electronic dance music parties, in polydrug abuse settings. Benzofurans preferentially act by disturbing the functioning of serotonergic circuits, which induces their entactogenic and stimulant effects and is the reason behind the considerable number of recent benzo fury‐related deaths. The slight interaction of these drugs with the dopaminergic system justifies the rewarding effects of these drugs. To date, published evidence on the mechanisms of toxicity of benzo fury is very limited but a body of research is now beginning to emerge revealing an alarming public health threat regarding the abuse of these NPS.
AbstractAnthraquinones exhibit various pharmacological activities (e.g., antioxidant and laxative) and are commonly found in consumer products including foods, dietary supplements, drugs, and traditional medicines. Despite their widespread use, there are limited data available on their toxicokinetic properties. Cytochrome P450 enzymes (CYPs) in the liver play major roles in metabolizing exogenous chemicals (e.g., pharmaceuticals, food ingredients, and environmental pollutants) and endogenous biomolecules (e.g., steroid hormones and cholesterol). Inhibition of CYP activities may lead to serious interactions among these compounds. Here, in silico (quantitative structure‐activity relationship modeling) and in vitro (human recombinant enzymes and liver microsomes) methods were used to identify inhibitors of five major CYP isoforms (CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4) among 22 anthraquinones. First, in silico prediction and in vitro human recombinant enzyme assays were conducted for all compounds, and results showed that most of the anthraquinones were potent CYP1A2 inhibitors. Second, five selected anthraquinones (emodin, aloe‐emodin, rhein, purpurin, and rubiadin) were further evaluated in human liver microsomes. Finally, plasma concentrations of the five anthraquinones in animal and humans were identified in the literature and compared to their in vitro inhibition potency (IC50 values) towards CYP activities. Emodin, rhein, and aloe‐emodin inhibited activities of multiple CYPs in human liver microsomes and potential in vivo inhibition may occur due to their high plasma concentrations. These in silico and in vitro results enabled rapid identification of potential CYP inhibitors and prioritized future in‐depth studies.
AbstractThe tannin concentration of hard‐ and soft‐wood dust was determined in dust powder and in samples on filters. It varied from 1.6 ± 0.3 mg g−1(± SD) for fir, which is a soft wood, to 80 ± 30 mg g−1(± SD) for oak, which is a hard wood. The low detection limit of the spectrophotometric method (1.5 μg per sample) made the analysis possible with no interference from cellulose ester filters. In five woodworking shops the concentrations of the total dust varied from 0.2 to 20 mg m−3, while those of tannins varied from 2 to 341 μg m−3. As hard woods like oak or mahogany have a higher tannin concentration than soft woods, tannin concentration analysis in wood dust can be used as an indicator of exposure to hard‐wood dust.
Katarzyna Dziendzikowska, Joanna Gromadzka-Ostrowska, Anna Lankoff, Michał Oczkowski, Agata Krawczyńska, J. Chwastowska, M. Sadowska‐Bratek, Ewelina Chajduk, Maria Wojewódzka, Mária Dušinská, Marcin Kruszewski
Sónia Fraga, Helena Faria, Maria Elisa Soares, José Alberto Duarte, Leonor Soares, Eulália Pereira, Cristiana Pereira, João Paulo Teixeira, Maria de Lourdes Bastos, Helena Carmo
Hui Gao, Jing Chen, Fan Ding, Xin Chou, Xiaoyan Zhang, Yi Wan, Jianying Hu, Qing Wu
AbstractGlyphosate‐based herbicides have been used worldwide for decades and have been suggested to induce nephrotoxicity, but the underlying mechanism is not yet clear. In this study, we treated a human renal proximal tubule cell line (HK‐2) with glyphosate for 24 hours at concentrations of 0, 20, 40 and 60 μm. Glyphosate was found to reduce cell viability and induce apoptosis and oxidative stress in a dose‐dependent manner. Because the chemical structures of glyphosate and those of its metabolite AMPA are similar to glycine and glutamate, which are agonists of the N‐methyl‐d‐aspartate receptor (NMDAR), we investigated the potential role of the NMDAR pathway in mediating the proapoptotic effect of glyphosate on proximal tubule cells. We found that NMDAR1 expression, as well as intracellular Ca2+ ([Ca2+]i) and reactive oxygen species (ROS) levels, increased after glyphosate treatment. Blocking NMDAR attenuated glyphosate‐induced upregulation of [Ca2+]i and ROS levels as well as apoptosis. Meanwhile, inhibition of [Ca2+]i reduced glyphosate‐induced ROS and apoptosis, and inhibition of ROS alleviated glyphosate‐induced apoptosis. In mice exposed to 400 mg/kg glyphosate, the urine low molecular weight protein levels started to increase from day 7. Upregulation of apoptosis and NMDAR1 expression in renal proximal tubule epithelium and an imbalance of oxidant and antioxidative products were observed. These results strongly suggest that activation of the NMDAR1 pathway, together with its downstream [Ca2+]i and oxidative stress, is involved in glyphosate‐induced renal proximal tubule epithelium apoptosis.
Reem Rida, Rawad Hodeify, Sawsan Ibrahim Kreydiyyeh
AbstractFTY720P, an analogue of sphingosine 1‐phosphate, has emerged lately as a potential causative agent of inflammatory bowel disease, in which electrolytes movements driven by the sodium gradient established by the Na+/K+ ATPase are altered. We showed previously in Caco‐2 cells, a 50% FTY720P‐induced decrease in the ATPase activity, mediated via S1PR2 and PGE2. This work aims at delineating the mechanism underlying PGE2 release and at investigating if the ATPase inhibition is due to changes in its abundance. The activity of the ATPase and the localization of a GFP‐tagged Na+/K+‐ATPase α1‐subunit were assessed in cells treated with 7.5 nM FTY720P. The involvement of ERK, p38 MAPK, PKC, and PI3K was studied in cells treated with 7.5 nM FTY720P or 1 nM PGE2 in presence of their inhibitors, or by determining changes in the protein expression of their activated phosphorylated forms. Imaging data showed ∼30% reduction in the GFP‐tagged Na+/K+ ATPase at the plasma membrane. Both FTY720P and PGE2 showed, respectively, 50% and 60% reduction in ATPase activity that disappeared when p38 MAPK, PKC, and PI3K were inhibited individually but not with ERK inhibition. The effect of FTY720P was imitated by PMA, an activator of PKC. Western blotting revealed inhibition of ERK by FTY720P. It was concluded that FTY720P, through activation of S1PR2, downregulates the Na+/K+ ATPase by inhibiting ERK, which in turn activates p38 MAPK leading to the sequential activation of PKC and PI3K, PGE2 release, and a decrease in the Na+/K+ ATPase activity and membrane abundance.
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