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Journal of Microbiological Methods Dec 2023Bacterial-based genotoxicity test systems play a significant role in the detection and evaluation of genotoxicity in vitro and have gained importance due to attributes... (Review)
Review
Bacterial-based genotoxicity test systems play a significant role in the detection and evaluation of genotoxicity in vitro and have gained importance due to attributes like wide applicability, speed, high sensitivity, good reproducibility, and simplicity. The Salmonella microsomal mutagenicity assay was created by Ames and colleagues at the beginning of the 1970s, and it was based on the fundamental notion that in auxotrophic bacterial strains with inhibited growth, a mutant gene would revert to its original state on exposure to genotoxicants. This is the most successful and widely used in vitro genotoxicity test. Later, a number of additional test systems that incorporated DNA repair mechanisms including the bacterial SOS response were created. Genetic engineering has further provided significant advancement in these test systems with the development of highly sophisticated bacterial tester strains with significantly increased sensitivity to evaluate the chemical nature of hazardous substances and pollutants. These bacterial bioassays render an opportunity to detect the defined effects of compounds at the molecular level. In this review, all the aspects related to the bacterial system in genotoxicity assessment have been summarized and their role is elaborated concerning real-time requirements and future perspectives.
Topics: Reproducibility of Results; DNA Damage; Mutagenicity Tests; Bacteria; Mutagenesis
PubMed: 38008307
DOI: 10.1016/j.mimet.2023.106860 -
Regulatory Toxicology and Pharmacology... Aug 2023Consumer use of cannabidiol (CBD) for personal wellness purposes has garnered much public interest. However, safety-related data on CBD in the public domain are limited,...
Consumer use of cannabidiol (CBD) for personal wellness purposes has garnered much public interest. However, safety-related data on CBD in the public domain are limited, including a lack of quality studies evaluating its genotoxic potential. The quality of available studies is limited due to the test material used (e.g., low CBD purity) and/or study design, leading some global regulatory agencies to highlight genotoxicity as an important data gap for CBD. To address this gap, the genotoxic potential of a pure CBD isolate was investigated in a battery of three genotoxicity assays conducted according to OECD testing guidelines. In an in vitro microbial reverse mutation assay, CBD up to 5000 μg/plate was negative in Salmonella typhimurium strains TA98, TA100, TA1535, and TA1537, and Escherichia coli strain WP2 uvrA, with and without metabolic activation. Testing in an in vitro micronucleus assay was negative in human TK6 cells up to 10-11 μg/mL, with and without metabolic activation. Finally, an in vivo micronucleus assay conducted in male and female rats was negative for genotoxicity up to 1000 mg/kg-bw/d. Bioanalysis of CBD and its primary metabolite, 7-carboxy CBD, confirmed a dose-related increase in plasma exposure. Together, these assays indicate that CBD is unlikely to pose a genotoxic hazard.
Topics: Rats; Male; Humans; Female; Animals; Mutagenicity Tests; Cannabidiol; Micronucleus Tests; Salmonella typhimurium; DNA Damage; Escherichia coli
PubMed: 37271419
DOI: 10.1016/j.yrtph.2023.105425 -
Environmental Pollution (Barking, Essex... Jan 2024The paper provides the first assessment of the occurrence of hormetic dose responses using the Comet assay, a genotoxic assay. Using a priori evaluative criteria based... (Review)
Review
The paper provides the first assessment of the occurrence of hormetic dose responses using the Comet assay, a genotoxic assay. Using a priori evaluative criteria based on the Hormetic Database on peer-reviewed comet assay experimental findings, numerous examples of hormetic dose responses were obtained. These responses occurred in a large and diverse range of cell types and for agents from a broad range of chemical classes. Limited attempts were made to estimate the frequency of hormesis within comet assay experimental studies using a priori entry and evaluative criteria, with results suggesting a frequency in the 40% range. These findings are important as they show that a wide range of genotoxic chemicals display evidence that is strongly suggestive of hormetic dose responses. These findings have significant implications for study design issues, including the number of doses selected, dose range and spacing. Likewise, the widespread occurrence of hormetic dose responses in this genotoxic assay has important risk assessment implications.
Topics: Hormesis; Dose-Response Relationship, Drug; Comet Assay; DNA Damage; Research Design
PubMed: 37979647
DOI: 10.1016/j.envpol.2023.122929 -
Scientific Reports Oct 2023Lilial (also called lysmeral) is a fragrance ingredient presented in many everyday cosmetics and household products. The concentrations of lilial in the final products...
Lilial (also called lysmeral) is a fragrance ingredient presented in many everyday cosmetics and household products. The concentrations of lilial in the final products is rather low. Its maximum concentration in cosmetics was limited and recently, its use in cosmetics products was prohibited in the EU due to the classification as reproductive toxicant. Additionally, according to the European Chemicals Agency, it was under assessment as one of the potential endocrine disruptors, i.e. a substance that may alter the function of the endocrine system and, as a result, cause health problems. Its ability to act as an androgen receptor agonist and the estrogenic and androgenic activity of its metabolites, to the best of our knowledge, have not yet been tested. The aim of this work was to determine the intestinal absorption, cytotoxicity, nephrotoxicity, mutagenicity, activation of cellular stress-related signal pathways and, most importantly, to test the ability to disrupt the endocrine system of lilial and its Phase I metabolites. This was tested using set of in vitro assays including resazurin assay, the CHO/HPRT mutation assay, γH2AX biomarker-based genotoxicity assay, qPCR and in vitro reporter assays based on luminescence of luciferase for estrogen, androgen, NF-κB and NRF2 signalling pathway. It was determined that neither lilial nor its metabolites have a negative effect on cell viability in the concentration range from 1 nM to 100 µM. Using human cell lines HeLa9903 and MDA-kb2, it was verified that this substance did not have agonistic activity towards estrogen or androgen receptor, respectively. Lilial metabolites, generated by incubation with the rat liver S9 fraction, did not show the ability to bind to estrogen or androgen receptors. Neither lilial nor its metabolites showed a nephrotoxic effect on human renal tubular cells (RPTEC/TERT1 line) and at the same time they were unable to activate the NF-κB and NRF2 signalling pathway at a concentration of 50 µM (HEK 293/pGL4.32 or pGL4.37). Neither lilial nor its metabolites showed mutagenic activity in the HPRT gene mutation test in CHO-K1 cells, nor were they able to cause double-strand breaks in DNA (γH2AX biomarker) in CHO-K1 and HeLa cells. In our study, no negative effects of lilial or its in vitro metabolites were observed up to 100 µM using different in vitro tests.
Topics: Humans; Rats; Animals; Hypoxanthine Phosphoribosyltransferase; HeLa Cells; NF-kappa B; HEK293 Cells; NF-E2-Related Factor 2; Estrogens; Androgens; Biomarkers
PubMed: 37898679
DOI: 10.1038/s41598-023-45598-y -
Scientific Reports Oct 2023Concerns have recently increased that the integrity of some scientific research is questionable due to the inability to reproduce the claimed results of some experiments...
Concerns have recently increased that the integrity of some scientific research is questionable due to the inability to reproduce the claimed results of some experiments and thereby confirm that the original researcher's conclusions were justified. This phenomenon has been described as 'reproducibility crisis' and affects various fields from medicine to basic applied sciences. In this context, the REPLICA project aims to replicate previously conducted in vitro studies on the toxicity of cigarette smoke and e-cigarette aerosol, sometimes adding experiments or conditions where necessary, in order to verify the robustness and replicability of the data. In this work the REPLICA Team replicated biological and toxicological assessment published by Rudd and colleagues in 2020. As in the original paper, we performed Neutral Red Uptake (NRU) assay for the evaluation of cytotoxicity, Ames test for the evaluation of mutagenesis and In Vitro Micronuclei (IVMN) assay for the evaluation of genotoxicity on cells treated with cigarette smoke or e-cigarette aerosol. The results showed high cytotoxicity, mutagenicity and genotoxicity induced by cigarette smoke, but slight or no cytotoxic, mutagenic and genotoxic effects induced by the e-cigarette aerosol. Although the two studies presented some methodological differences, the findings supported those previously presented by Rudd and colleagues.
Topics: Mutagens; Electronic Nicotine Delivery Systems; Cigarette Smoking; Reproducibility of Results; Nicotiana; Mutagenesis; DNA Damage; Aerosols; Mutagenicity Tests
PubMed: 37903810
DOI: 10.1038/s41598-023-44626-1 -
Toxicology Letters Oct 2023Anthraquinone is a recently identified contaminant present in teas globally, and its potential teratogenic and genotoxic impacts have yet to be fully comprehended....
Anthraquinone is a recently identified contaminant present in teas globally, and its potential teratogenic and genotoxic impacts have yet to be fully comprehended. Hence, this study's objective was to determine anthraquinone's genotoxicity using various studies such as the Ames test, Mammalian erythrocyte micronucleus test, and in-vitro mammalian chromosome aberration study. Additionally, the study assessed its effects on maternal gestational toxicity and the fetus's teratogenicity through prenatal developmental toxicity research in rats. Results indicated that anthraquinone did not manifest mutagenic effects on Salmonella typhimurium histidine-deficient, did not cause chromosomal aberrations in Chinese hamster ovary cell subclone CHO-K1, and did not exhibit a genotoxic effect on mouse bone marrow erythrocytes. However, in the prenatal developmental toxicity study, administering anthraquinone orally to pregnant rats from day 5 to day 19 of gestation resulted in decreased body weight and food consumption of pregnant rats, along with a higher number of visceral malformations in the fetuses in the highest dose group (217.6 mg/kg BW). Additionally, two pregnant rats died in this group. The study has established the no observed adverse effect level (NOAEL) as 21.76 mg/kg BW, while the lowest observed adverse effect level (LOAEL) was 217.6 mg/kg BW.
Topics: Mice; Cricetinae; Pregnancy; Female; Rats; Animals; CHO Cells; Cricetulus; Micronucleus Tests; Mutagens; Chromosome Aberrations; Anthraquinones
PubMed: 37802232
DOI: 10.1016/j.toxlet.2023.10.002 -
Journal of Xenobiotics Dec 2023Triclosan and Triclocarban, preservatives widely used in cosmetics and other consumer products, underwent evaluation using a battery of new-approach methodologies in...
Triclosan and Triclocarban, preservatives widely used in cosmetics and other consumer products, underwent evaluation using a battery of new-approach methodologies in vitro (NAMs). Specifically, the Microplate Ames Test (MPF™ Test, Xenometrix, Allschwil, Switzerland) was employed to assess mutagenicity, the Comet assay in vitro on the HaCat cell line and the Mammalian Chromosome Aberration Test were utilized to evaluate genotoxicity, and the XenoScreen YES/YAS assay was applied to investigate endocrine disruption. The chemicals did not exhibit any positive responses for mutagenicity. However, the mammalian chromosome aberration test identified both chemicals as being positive for genotoxicity at 10 µg/mL. In the Comet assay, the percentage of DNA in the tail significantly increased in a concentration-dependent manner (at 5 and 10 µg/mL for Triclosan, at 2.5, 5, and 10 µg/mL for Triclocarban). The positive response depended on the increasing concentration and the duration of exposure. Triclosan, but not Triclocarban in any of the endocrine assays performed, indicated a potential for endocrine activity in the anti-estrogenic and anti-androgenic assays. The positive in vitro results detected were obtained for concentrations relevant to final products. The alarming findings obtained with the use of new-approach methodologies (NAMs) justify the current precautionary regulatory approach, limiting the use of these preservatives.
PubMed: 38535491
DOI: 10.3390/jox14010002 -
Mutagenesis Mar 2024The robust control of genotoxic N-nitrosamine (NA) impurities is an important safety consideration for the pharmaceutical industry, especially considering recent drug...
The robust control of genotoxic N-nitrosamine (NA) impurities is an important safety consideration for the pharmaceutical industry, especially considering recent drug product withdrawals. NAs belong to the 'cohort of concern' list of genotoxic impurities (ICH M7) because of the mutagenic and carcinogenic potency of this chemical class. In addition, regulatory concerns exist regarding the capacity of the Ames test to predict the carcinogenic potential of NAs because of historically discordant results. The reasons postulated to explain these discordant data generally point to aspects of Ames test study design. These include vehicle solvent choice, liver S9 species, bacterial strain, compound concentration, and use of pre-incubation versus plate incorporation methods. Many of these concerns have their roots in historical data generated prior to the harmonization of Ames test guidelines. Therefore, we investigated various Ames test assay parameters and used qualitative analysis and quantitative benchmark dose modelling to identify which combinations provided the most sensitive conditions in terms of mutagenic potency. Two alkyl-nitrosamines, N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) were studied. NDMA and NDEA mutagenicity was readily detected in the Ames test and key assay parameters were identified that contributed to assay sensitivity rankings. The pre-incubation method (30-min incubation), appropriate vehicle (water or methanol), and hamster-induced liver S9, alongside Salmonella typhimurium strains TA100 and TA1535 and Escherichia coli strain WP2uvrA(pKM101) provide the most sensitive combination of assay parameters in terms of NDMA and NDEA mutagenic potency in the Ames test. Using these parameters and further quantitative benchmark dose modelling, we show that N-nitrosomethylethylamine (NMEA) is positive in Ames test and therefore should no longer be considered a historically discordant NA. The results presented herein define a sensitive Ames test design that can be deployed for the assessment of NAs to support robust impurity qualifications.
Topics: Humans; Animals; Cricetinae; Nitrosamines; Mutagens; Diethylnitrosamine; Mutagenesis; Mutagenicity Tests; Carcinogens
PubMed: 38112628
DOI: 10.1093/mutage/gead033 -
Life Sciences Jan 2024Since DNA damage can occur spontaneously or be produced by the environmental genotoxins in living cells, it is important to investigate compounds that can reverse or... (Review)
Review
Since DNA damage can occur spontaneously or be produced by the environmental genotoxins in living cells, it is important to investigate compounds that can reverse or protect DNA damage. An appropriate methodology is essential for the responsive identification of protection offered against DNA damage. This review includes information on the current state of knowledge on prokaryotic cell-based assays (SOS chromotest, umu test, vitotox assay) and cytogenetic techniques (micronucleus assay, chromosome aberration test and sister chromatid exchange assay) with an emphasis on the possibility to explore genoprotective compounds. Throughout the last decade, studies have extrapolated the scientific methodologies utilized for genotoxicity to assess genoprotective compounds. Therefore, shortcomings of genotoxicity studies are also mirrored in antigenotoxicity studies. While regulatory authorities around the world (OECD, US-EPA and ICH) continue to update diverse genotoxic assay strategies, there are still no clear guidelines/approaches for efficient experimental design to screen genoprotective compounds. As a consequence, non-synergetic and inconsistent implementation of the test method by the researchers to execute such simulations has been adopted, which inevitably results in unreliable findings. The review has made the first attempt to collect various facets of experimentally verified approaches for evaluating genoprotective compounds, as well as to acknowledge potential significance and constraints, and further focus on the assessment of end points which are required to validate such action. Henceforth, the review makes an incredible commitment by permitting readers to equate several components of their test arrangement with the provided simplified information, allowing the selection of convenient technique for the predefined compound from a central repository.
Topics: Humans; Mutagenicity Tests; DNA Damage; Mutagens; Micronucleus Tests; Chromosome Aberrations
PubMed: 38101613
DOI: 10.1016/j.lfs.2023.122341 -
Archives of Toxicology Oct 2023After the detection of high environmental and occupational exposure to polychlorinated biphenyls (PCBs) in a German recycling company for transformers and capacitors in... (Review)
Review
After the detection of high environmental and occupational exposure to polychlorinated biphenyls (PCBs) in a German recycling company for transformers and capacitors in 2010, the multidisciplinary medical surveillance program "HELPcB" (Health Effects in High-Level Exposure to PCB) was established for former PCB-exposed workers of the company, their family members, employees of surrounding companies, and area residents to investigate potential adverse health effects by PCB exposure in a longitudinal study approach with up to seven examination time points between 2010 and 2019. More than 300 individuals were enrolled into the program. Assessments particularly included plasma and urine concentrations of PCB congeners and their metabolites, clinical laboratory parameters, Comet assay, analysis of telomere length, neuropsychological examinations, psychological screening, abdominal and thyroid ultrasound examination. This review summarizes the main results of the studies conducted in the HELPcB program yielding relevant new data on potential adverse effects of PCB exposure in humans and potential mechanisms that underlie these effects. Even larger studies in PCB-exposed individuals are warranted to confirm the results of this program and to further establish causality between PCB exposure and clinical effects in humans.
Topics: Humans; Polychlorinated Biphenyls; Longitudinal Studies; Comet Assay; Drug-Related Side Effects and Adverse Reactions; Electric Power Supplies
PubMed: 37594590
DOI: 10.1007/s00204-023-03578-1