{"title":"The Intercalator Ethidium Bromide Generates Covalent Adducts at Apurinic/Apyrimidinic Sites in DNA.","authors":"Tanhaul Islam, Saosan Binth Md Amin, Kent S Gates","doi":"10.1021/acs.chemrestox.4c00378","DOIUrl":"https://doi.org/10.1021/acs.chemrestox.4c00378","url":null,"abstract":"<p><p>Ethidium bromide was first described as a DNA intercalator 60 years ago and, over the ensuing years, may be the most widely used fluorescent DNA stain in molecular biology, biochemistry, and histology. Noncovalent DNA binding by ethidium has been well characterized, but to date, there have been no reports of covalent DNA adduct formation by ethidium bromide. This report describes the characterization of covalent adducts generated by the reaction of ethidium with apurinic/apyrimidinic (AP) sites in DNA. Adduct formation proceeds via the reaction of the amino group(s) on ethidium with the ring-opened aldehyde residue of the AP site in DNA to yield an imine. Ethidium-AP adducts may form under a variety of circumstances due to the ubiquitous occurrence of AP sites in cellular and synthetic DNA.</p>","PeriodicalId":31,"journal":{"name":"Chemical Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142566664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Practical Aspects of Flavin-Containing Monooxygenase-Mediated Metabolism.","authors":"John R Cashman","doi":"10.1021/acs.chemrestox.4c00316","DOIUrl":"https://doi.org/10.1021/acs.chemrestox.4c00316","url":null,"abstract":"<p><p>Hepatic flavin-containing monooxygenase 3 (FMO3) is arguably the most important FMO in humans from the standpoint of drug metabolism. Recently, adult hepatic FMO3 has been linked to several conditions including cardiometabolic diseases, aging, obesity, and atherosclerosis in small animals. Despite the importance of FMO3 in drug and chemical metabolism, relative to cytochrome P-450 (CYP), fewer studies have been published describing drug and chemical metabolism. This may be due to the properties of human hepatic FMO3. For example, FMO3 is thermally labile, and often methods reported in the study of human hepatic FMO3 are not optimal. Herein, I describe some practical aspects for studying human hepatic FMO3 and other FMOs.</p>","PeriodicalId":31,"journal":{"name":"Chemical Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142556539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Mitochondrial Dysfunction in Environmental Toxicology: Mechanisms, Impacts, and Health Implications.","authors":"Mingyang Zuo, Mingqi Ye, Haofeng Lin, Shicheng Liao, Xiumei Xing, Jianjun Liu, Desheng Wu, Zhenlie Huang, Xiaohu Ren","doi":"10.1021/acs.chemrestox.4c00328","DOIUrl":"https://doi.org/10.1021/acs.chemrestox.4c00328","url":null,"abstract":"<p><p>Mitochondria, pivotal to cellular metabolism, serve as the primary sources of biological energy and are key regulators of intracellular calcium ion storage, crucial for maintaining cellular calcium homeostasis. Dysfunction in these organelles impairs ATP synthesis, diminishing cellular functionality. Emerging evidence implicates mitochondrial dysfunction in the etiology and progression of diverse diseases. Environmental factors that induce mitochondrial dysregulation raise significant public health concerns, necessitating a nuanced comprehension and classification of mitochondrial-related hazards. This review systematically adopts a toxicological perspective to illuminate the biological functions of mitochondria, offering a comprehensive exploration of how toxicants instigate mitochondrial dysfunction. It delves into the disruption of energy metabolism, the initiation of mitochondrial fragility and autophagy, and the induction of mutations in mitochondrial DNA by mutagens. The overarching objective is to enhance our understanding of the repercussions of mitochondrial damage on human health.</p>","PeriodicalId":31,"journal":{"name":"Chemical Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142556538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Richard B van Breemen, Bianca Flores, Israel Rubinstein, Douglas L Feinstein
{"title":"Deploying Validated Mass Spectrometry for Frontline Detection and Treatment of Human Poisoning by Long-Acting Anticoagulant Rodenticides.","authors":"Richard B van Breemen, Bianca Flores, Israel Rubinstein, Douglas L Feinstein","doi":"10.1021/acs.chemrestox.4c00344","DOIUrl":"https://doi.org/10.1021/acs.chemrestox.4c00344","url":null,"abstract":"<p><p>Derived from the same natural anticoagulant as warfarin (dicoumarol), long-acting anticoagulant rodenticides (LAARs) or superwarfarins have much longer half-lives in human blood than warfarin (weeks instead of hours) and are more potent inhibitors of the same enzyme, vitamin K epoxide reductase component 1. While used effectively worldwide as rodenticides, LAARs can elicit severe, protracted, life-threatening coagulopathy in humans at blood concentrations >10 ng/mL leading to numerous accidental and intentional poisonings annually. To facilitate timely identification and quantitative analysis of LAARs in patients presenting unexplained severe, protracted, life-threatening coagulopathy, several analytical methods have been developed, all of which are based on electrospray liquid chromatography-mass spectrometry (LC-MS). In this perspective, we evaluated and compared these LC-MS methods in terms of validation, simultaneous detection of multiple LAARs, measurement of individual stereoisomers, and clinical applications.</p>","PeriodicalId":31,"journal":{"name":"Chemical Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142542857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Megan Ford, Paul J Thomson, Jan Snoeys, Xiaoli Meng, Dean J Naisbitt
{"title":"Selective HLA Class II Allele-Restricted Activation of Atabecestat Metabolite-Specific Human T-Cells.","authors":"Megan Ford, Paul J Thomson, Jan Snoeys, Xiaoli Meng, Dean J Naisbitt","doi":"10.1021/acs.chemrestox.4c00262","DOIUrl":"10.1021/acs.chemrestox.4c00262","url":null,"abstract":"<p><p>Elevations in hepatic enzymes were detected in several trial patients exposed to the Alzheimer's drug atabecestat, which resulted in termination of the drug development program. Characterization of hepatic T-lymphocyte infiltrates and diaminothiazine (DIAT) metabolite-responsive, human leukocyte antigen (HLA)-DR-restricted, CD4+ T-lymphocytes in the blood of patients confirmed an immune pathogenesis. Patients with immune-mediated liver injury expressed a restricted panel of HLA-DRB1 alleles including HLA-DRB1*12:01, HLA-DRB1*13:02, and HLA-DRB1*15:01. Thus, the objectives of this study were to (i) generate DIAT-responsive T-cell clones from HLA-genotyped drug-naive donors, (ii) characterize pathways of DIAT-specific T-cell activation, and (iii) assess HLA allele restriction of the DIAT-specific T-cell response. Sixteen drug-naive donors expressing the HLA-DR molecules outlined above were recruited, and T-cell clones were generated. Cellular phenotype, function, and HLA-allele restriction were assessed using culture assays. Peptides displayed by HLA class II molecules in the presence and absence of atabecestat were analyzed by mass spectrometry. Several DIAT-responsive CD4+ clones, displaying no reactivity toward the parent drug, were successfully generated from donors expressing HLA-DRB1*12:01, HLA-DRB1*13:02, and HLA-DRB1*15:01 but not from other donors expressing other HLA-DRB1 alleles. T-cell clones were activated following direct binding of DIAT to HLA-DR proteins expressed on the surface of antigen presenting cells. DIAT binding did not alter the HLA-DRB1 peptide binding repertoire, indicative of a binding interaction with the HLA-associated peptide rather than with the HLA protein itself. DIAT-specific T-cell responses displayed HLA-DRB1*12:01, HLA-DRB1*13:02, and HLA-DRB1*15:01 restriction. These data demonstrate that DIAT displays a degree of selectivity toward HLA protein and associated peptides, with expression of certain alleles increasing and that of others decreasing, the likelihood that a drug-specific T-cell response develops.</p>","PeriodicalId":31,"journal":{"name":"Chemical Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11497358/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142337331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Interview with Professor Amanda Bryant-Friedrich, 2024 Founders Award Winner, American Chemical Society Division of Chemical Toxicology.","authors":"Andrea Andress Huacachino","doi":"10.1021/acs.chemrestox.4c00360","DOIUrl":"10.1021/acs.chemrestox.4c00360","url":null,"abstract":"","PeriodicalId":31,"journal":{"name":"Chemical Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142386384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Martin Adamczewski, Britta Nisius, Nina Kausch-Busies
{"title":"Derisking Future Agrochemicals before They Are Made: Large-Scale In Vitro Screening for In Silico Modeling of Thyroid Peroxidase Inhibition.","authors":"Martin Adamczewski, Britta Nisius, Nina Kausch-Busies","doi":"10.1021/acs.chemrestox.4c00248","DOIUrl":"10.1021/acs.chemrestox.4c00248","url":null,"abstract":"<p><p>Inhibition of thyroid peroxidase (TPO) is a known molecular initiating event for thyroid hormone dysregulation and thyroid toxicity. Consequently, TPO is a critical off-target for the design of safer agrochemicals. To date, fewer than 500 structurally characterized TPO inhibitors are known, and the most comprehensive result set generated under identical conditions encompasses approximately 1000 compounds from a subset of the ToxCast compound collection. Here we describe a collaboration between wet lab and data scientists combining a large in vitro screen and the subsequent development of an in silico model for predicting TPO inhibition. The screen encompassed more than 100,000 diverse drug-like agrochemical compounds and yielded more than 6000 structurally novel TPO inhibitors. On this foundation, we applied different machine learning techniques and compared their performance. We discuss use cases for in silico TPO models in agrochemical research and explain that model recall is of particular importance when selecting compounds from large virtual compound collections. Furthermore, we show that due to the higher structural diversity of our training data, our final model allowed better generalization than models trained on the ToxCast data set. We now have a tool to predict TPO inhibition even for molecules that are only available virtually, such as hits from virtual screenings, or compounds under consideration for inclusion in our screening collection. Structures and activity data for 34,524 compounds are provided. This data set includes almost all inhibitors, including more than 3000 proprietary structures, and a large proportion of the inactives.</p>","PeriodicalId":31,"journal":{"name":"Chemical Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142277306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Isidora Loncarevic, Seyran Mutlu, Martina Dzepic, Sandeep Keshavan, Alke Petri-Fink, Fabian Blank, Barbara Rothen-Rutishauser
{"title":"Current Challenges to Align Inflammatory Key Events in Animals and Lung Cell Models <i>In Vitro</i>.","authors":"Isidora Loncarevic, Seyran Mutlu, Martina Dzepic, Sandeep Keshavan, Alke Petri-Fink, Fabian Blank, Barbara Rothen-Rutishauser","doi":"10.1021/acs.chemrestox.4c00113","DOIUrl":"10.1021/acs.chemrestox.4c00113","url":null,"abstract":"<p><p>With numerous novel and innovative <i>in vitro</i> models emerging every year to reduce or replace animal testing, there is an urgent need to align the design, harmonization, and validation of such systems using <i>in vitro-in vivo</i> extrapolation (IVIVE) approaches. In particular, in inhalation toxicology, there is a lack of predictive and prevalidated <i>in vitro</i> lung models that can be considered a valid alternative for animal testing. The predictive power of such models can be enhanced by applying the Adverse Outcome Pathways (AOP) framework, which casually links key events (KE) relevant to IVIVE. However, one of the difficulties identified is that the endpoint analysis and readouts of specific assays in <i>in vitro</i> and animal models for specific toxicants are currently not harmonized, making the alignment challenging. We summarize the current state of the art in endpoint analysis in the two systems, focusing on inflammatory-induced effects and providing guidance for future research directions to improve the alignment.</p>","PeriodicalId":31,"journal":{"name":"Chemical Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11497357/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141904971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Using 2-(2-Chlorophenyl)thiazolidine-4-carboxylic Acid as a Novel Biomarker for 2-Chlorobenzalmalononitrile Exposure.","authors":"Guanrui Pan, Hei-Tak Tse, Ho-Wai Chan, Wan Chan","doi":"10.1021/acs.chemrestox.4c00304","DOIUrl":"10.1021/acs.chemrestox.4c00304","url":null,"abstract":"<p><p>This study addressed the development of a novel biomarker for 2-chlorobenzalmalononitrile (CS) gas exposure. Using liquid chromatographic and mass spectrometric techniques, we found that CS underwent rapid hydrolysis into 2-chlorobenzaldehyde (2-CBA), a highly reactive intermediate that reacted swiftly with endogenous cysteine (Cys) and Cys residues in proteins, producing a stable 2-(2-chlorophenyl)thiazolidine-4-carboxylic acid adduct (ClPh-SPro) in high yield, which may be used as a CS exposure dosimeter. In particular, it was found that most CS was rapidly hydrolyzed under physiologically relevant conditions, with over 90% of CS being converted into 2-CBA in as short as 20 min. The resultant 2-CBA then reacted swiftly with Cys (<i>k</i> = 0.086 M<sup>-1</sup> s<sup>-1</sup>), forming the stable thiazolidine-4-carboxylic acid adduct, which was detected both in the intracellular fluid and in the cell-isolated proteins of CS-exposed lung cells, as well as in purified human serum albumin. It is expected that the results of this study will facilitate exposure assessment for bystanders who may have been exposed to high levels of CS gas unwillingly.</p>","PeriodicalId":31,"journal":{"name":"Chemical Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142378779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Mechanistic Insights into Toxicity of Titanium Dioxide Nanoparticles at the Micro- and Macro-levels.","authors":"Sharmistha Chatterjee, Parames C Sil","doi":"10.1021/acs.chemrestox.4c00235","DOIUrl":"10.1021/acs.chemrestox.4c00235","url":null,"abstract":"<p><p>Titanium oxide nanoparticles (TiO<sub>2</sub> NPs) have been regarded as a legacy nanomaterial due to their widespread usage across multiple fields. The TiO<sub>2</sub> NPs have been and are still extensively used as a food and cosmetic additive and in wastewater and sewage treatment, paints, and industrial catalysis as ultrafine TiO<sub>2</sub>. Recent developments in nanotechnology have catapulted it into a potent antibacterial and anticancer agent due to its excellent photocatalytic potential that generates substantial amounts of highly reactive oxygen radicals. The method of production, surface modifications, and especially size impact its toxicity in biological systems. The anatase form of TiO<sub>2</sub> (<30 nm) has been found to exert better and more potent cytotoxicity in bacteria as well as cancer cells than other forms. However, owing to the very small size, anatase particles are able to penetrate deep tissue easily; hence, they have also been implicated in inflammatory reactions and even as a potent oncogenic substance. Additionally, TiO<sub>2</sub> NPs have been investigated to assess their toxicity to large-scale ecosystems owing to their excellent reactive oxygen species (ROS)-generating potential compounded with widespread usage over decades. This review discusses in detail the mechanisms by which TiO<sub>2</sub> NPs induce toxic effects on microorganisms, including bacteria and fungi, as well as in cancer cells. It also attempts to shed light on how and why it is so prevalent in our lives and by what mechanisms it could potentially affect the environment on a larger scale.</p>","PeriodicalId":31,"journal":{"name":"Chemical Research in Toxicology","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142337328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}