Strains TA98 Research Articles

Whole Genome Sequencing Analysis of Model Organisms Elucidates the Association Between Environmental Factors and Human Cancer Development

Determining a novel etiology and mechanism of human cancer requires extraction of characteristic mutational signatures derived from chemical substances. This study explored the mutational signatures of N-nitroso bile acid conjugates using Salmonella strains. Exposing S. typhimurium TA1535 to N-nitroso-glycine/taurine bile acid conjugates induced a predominance of C:G to T:A transitions. Two mutational signatures, B1 and B2, were extracted. Signature B1 is associated with N-nitroso-glycine bile acid conjugates, while Signature B2 is linked to N-nitroso-taurine bile acid conjugates. Signature B1 revealed a strong transcribed strand bias with GCC and GCT contexts, and the mutation pattern of N-nitroso-glycine bile acid conjugates in YG7108, which lacks O6-methylguanine DNA methyltransferases, matched that of the wild-type strain TA1535, suggesting that O6-methyl-deoxyguanosine contributes to mutations in the relevant regions. COSMIC database-based similarity analysis revealed that Signature B1 closely resembled SBS42, which is associated with occupational cholangiocarcinoma caused by overexposure to 1,2-dichlolopropane (1,2-DCP) and/or dichloromethane (DCM). Moreover, the inflammatory response pathway was induced by 1,2-DCP exposure in a human cholangiocyte cell line, and iNOS expression was positive in occupational cholangiocarcinomas. These results suggest that 1,2-DCP triggers an inflammatory response in biliary epithelial cells by upregulating iNOS and N-nitroso-glycine bile acid conjugate production, resulting in cholangiocarcinoma via DNA adduct formation.

Ecotoxicity and Mutagenicity Assessment of Novel Antifungal Agents VT-1161 and T-2307.

Antifungal substances are essential for managing fungal infections in humans, animals, and plants, and their usage has significantly increased due to the global rise in fungal infections. However, the extensive application of antifungal agents in pharmaceuticals, personal care products, and agriculture has led to their widespread environmental dissemination through various pathways, such as excretion, improper disposal, and agricultural runoff. Despite advances in wastewater treatment, many antifungal compounds persist in the environment, affecting non-target organisms and contributing to resistance development. This study investigates the environmental impact of two novel antifungal agents, VT-1161 and T-2307, recently introduced as alternatives for treating resistant Candida spp. We assessed their ecotoxicity and mutagenicity using multiple bioassays: immobilization of Daphnia magna, growth inhibition of Raphidocelis subcapitata, luminescence inhibition of Aliivibrio fischeri, and mutagenicity on Salmonella typhimurium strain TA100. Results indicate that both VT-1161 and T-2307 exhibit lower toxicity compared to existing antifungal compounds, with effective concentrations (EC50) causing 50% response ranging from 14.34 to 27.92 mg L-1. Furthermore, both agents were classified as less hazardous based on the Globally Harmonized System of Classification and Labeling of Chemicals. Despite these favorable results, further research is needed to understand their environmental behavior, interactions, and potential resistance development among non-target species. Our findings highlight the importance of comprehensive environmental risk assessments to ensure the sustainable use of new antifungal agents.

Heterocyclic phytometabolites formononetin and arbutin prevent in vitro oxidative and alkylation-induced mutagenicity

Phenolic phytometabolites are promising bioactive compounds for management of genomic instability related diseases. Formononetin (FMN) and arbutin (ARB) are found in several plant sources. Our goal was to investigate the safety and efficacy of FMN and ARB using in vitro both standardized and alternative toxicogenetic methods. FMN and ARB were evaluated through the OECD’S guidelines No. 471 (Bacterial Reverse Mutation Test –Salmonella/microsome) and No. 487 (In vitro Mammalian Micronucleus Test – CBMN assay), accordingly to the mentioned recommendations. Also, antimutagenicity of FMN and ARB was assessed in S. Typhimurium strains TA98, TA100 and TA1535, following pre-, co- and post- treatment protocols. Liver human lineages HepG2 and F C3H were assayed for cytotoxicity after exposure to FMN and ARB (24, 48 and 72 h) using in vitro WST-1 test. ARB showed no mutagenicity in the Salmonella/microsome test under both metabolic conditions (in presence or absence of 4 % S9 mix), but FMN was cytotoxic to the TA97 and TA100 strains after metabolic activation. Under this same condition, FMN induced an increase in the mutagenic index of strain TA1535 at two of the highest tested concentrations. Even so, ARB and FMN exhibited protection against the induced alkylation of DNA in multiple action modes. In the antimutagenicity assay, FMN reached the maximum of 80 % of oxidative-provoked mutagenicity reduction in TA98 strain in co-treatment with known mutagen, besides 69 % of reduction in TA100 in the same exposure condition. ARB showed up to reduce induced mutagenicity in strains TA100 and TA1535, reaching percentages from 55 % to 100 % of antimutagenicity in all of the tested exposure models against alkylating agent. In the CBMN assay, no increase in micronuclei formation was observed. The results suggest that FMN and ARB prevent DNA from mutation using multi-targeted antimutagenic roles. Finally, our data suggests that FMN and ARB are not genotoxic and presented encouraging antimutagenicity action in vitro, being promising compounds for use in genomic instability-related diseases therapeutics.

Optimizing the detection of N-nitrosamine mutagenicity in the Ames test

Accurately determining the mutagenicity of small-molecule N-nitrosamine drug impurities and nitrosamine drug substance-related impurities (NDSRIs) is critical to identifying mutagenic and cancer hazards. In the current study we have evaluated several approaches for enhancing assay sensitivity for evaluating the mutagenicity of N-nitrosamines in the bacterial reverse mutagenicity (Ames) test. Preincubation assays were conducted using five activation conditions: no exogenous metabolic activation and metabolic activation mixes employing both 10% and 30% liver S9 from hamsters and rats pretreated with inducers of enzymatic activity. In addition, preincubations were conducted for both 60 min and 30 min. These test variables were evaluated by testing 12 small-molecule N-nitrosamines and 17 NDSRIs for mutagenicity in Salmonella typhimurium tester strains TA98, TA100, TA1535, and TA1537, and Escherichia coli strain WP2 uvrA (pKM101). Eighteen of the 29 N-nitrosamine test substances tested positive under one or more of the testing conditions and all 18 positives could be detected by using tester strains TA1535 and WP2 uvrA (pKM101), preincubations of 30 min, and S9 mixes containing 30% hamster liver S9. In general, the conditions under which NDSRIs were mutagenic were similar to those found for small-molecule N-nitrosamines.

Toxicological assessment of reactive blue 19 dye aqueous solutions under UV-LED light

Abstract The dye-contaminated industrial effluent causes serious health issues when it gets mixed with underground water without primary treatment. The current project was designed to treat reactive blue-19 dye aqueous solutions in the presence of hydrogen peroxide (H2O2) and titanium dioxide (TiO2) under UV-LED light. The characterization of the photocatalyst was carried out via X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) for structure, purity, and surface study. The effect of various factors such as pH, TiO2 dose, UV-LED light exposure time, H2O2, and dye concentration, on the degradation rate and cytotoxicity reduction was evaluated and optimized through the Response Surface Methodology (RSM). The maximum degradation of dye solution and chemical oxygen demand (COD) reduction was achieved at 98.81 and 86.22 %, respectively for 50 ppm solution, using UV-LED/H2O2(3 %)/TiO2(6 g/L) hybrid process. The toxicity evaluation through the Allium cepa test demonstrated a 62.40, 65.2, and 56.97 % increase in root length (RL), root count (RC), and mitotic index (MI), respectively, following treatment with the UV-LED/H₂O₂/TiO₂ combined process for 150 min. The hemolytic and brine shrimp tests revealed a reduction in toxicity up to 92.18 and 84.08 %, respectively, after applying the same treatment. Additionally, the Ames test indicated up to 80.94 % reduction in mutagenicity for TA98 and an 84.04 % reduction for TA100 strain when dye samples were treated with UV-LED light in the presence of H₂O₂ and TiO₂ for 150 min. The findings suggested that UV-LED light in conjunction with H2O2 and TiO2 can be a useful tool for the degradation and detoxification of toxic pollutants found in textile wastewater.

Differential genotoxicity of Polygoni Multiflori in rat and human: insights from Ames test and S9 metabolic activation system

The Ames test is used worldwide to initially screen the mutagenic potential of new chemicals. In the standard Ames test, S. typhimurium strains (TA100, TA98, TA1535, and TA1537) and Escherichia coli (WP2uvrA) are treated with substances with/without cytochrome P450s (CYPs)-induced rat S9 fractions for identifying mutagens and pro-mutagens. However, many substances show completely different toxicity patterns depending on whether the liver S9 fraction belongs to rats or humans. The natural product Polygoni Multiflori Radix (PMR) can also show bacterial reverse mutation, followed by the rat or human liver S9 fraction. While PMR elicits reverse mutations in the TA1537 strain in rat liver S9 but not in human liver S9, this mechanism has not been verified yet. To explain this, the differences in metabolic enzymes compositions commonly observed between rats and humans have been implicated. This study aimed to explore the key factors that cause differences in the genotoxicity of PMR between rat and human liver S9 metabolic enzymes. The results of next-generation sequencing (NGS) analysis showed that both rat and human metabolic enzymes caused similar mutations in TA1537. However, when the metabolic enzymes in each S9 fraction were analyzed using ion mobility tandem mass spectrometry (IM-MS), rat- and human-specific enzymes were identified among the cytochrome (CYP) family, especially aryl hydrocarbon receptor (AHR)-related CYPs. These findings suggest that CYP1A1 isoforms contribute to the mechanism of PMR in the Ames test. Therefore, an in vitro Ames test might be more reliable in predicting genotoxicity for both rodents and humans. This will also help overcome the limitations of laboratory animal-based toxicity evaluations, which provide unreliable results due to interspecies differences between humans and rodents.

Assessment of receptor-mediated activity (AhR and ERα), mutagenicity, and teratogenicity of metal shredder wastes in Wallonia, Belgium.

In this study, hazardous wastes including fluff, dust, and scrubbing sludge were sampled in 2019 from two metal shredding facilities located in Wallonia, Belgium. To assess the extent of the contamination, a global approach combining chemical and biological techniques was used, to better reflect the risks to health and the environment. The samples investigated induced significant in vitro aryl hydrocarbon receptor (AhR) agonistic bioactivities and estrogenic receptor (ERα) (ant)agonistic bioactivities in the respective CALUX (chemical activated luciferase gene expression) bioassays. The mutagenicity of the samples was investigated with the bacterial reverse gene mutation test using the Salmonella typhimurium TA98 and TA100 strains. Except for the sludge sample (site 3), all samples induced a mutagenic response in the TA98 strain (± S9 metabolic fraction) whereas in the TA100 strain (+ S9 metabolic fraction), only the sludge sample (site 2) showed a clear mutagenic effect. The in vivo toxicity/teratogenicity of the shredder wastes was further evaluated with zebrafish embryos. Except for the dust sample (site 2), all samples were found to be teratogenic as they returned teratogenic indexes (TIs) > 1. The high levels of contamination, the mutagenicity, and the teratogenicity of these shredder wastes raise significant concerns about their potential negative impacts on both human health and environment.

A novel procedure for selection of molecular descriptors: QSAR model for mutagenicity of nitroaromatic compounds.

Nitroaromatic compounds (NACs) stand out as pervasive organic pollutants, prompting an imperative need to investigate their hazardous effects. Computational chemistry methods play a crucial role in this exploration, offering a safer and more time-efficient approach, mandated by various legislations. In this study, our focus lay on the development of transparent, interpretable, reproducible, and publicly available methodologies aimed at deriving quantitative structure-activity relationship models and testing them by modelling the mutagenicity of NACs against the Salmonella typhimurium TA100 strain. Descriptors were selected from Mordred and RDKit molecular descriptors, along with several quantum chemistry descriptors. For that purpose, the genetic algorithm (GA), as the most widely used method in the literature, and three alternative algorithms (Boruta, Featurewiz, and ForwardSelector) combined with the forward stepwise selection technique were used. The construction of models utilized the multiple linear regression method, with subsequent scrutiny of fitting and predictive performance, reliability, and robustness through various statistical validation criteria. The models were ranked by the Multi-Criteria Decision Making procedure. Findings have revealed that the proposed methodology for descriptor selection outperforms GA, with Featurewiz showing a slight advantage over Boruta and ForwardSelector. These constructed models can serve as valuable tools for the quick and reliable prediction of NACs mutagenicity.

Evaluation of XQ528 tartrate on embryo-fetus developmental toxicity in SD rats and genotoxicity

The effects of XQ528 tartrate on the embryonic and fetal development of fertile Sprague-Dawley (SD) rats, along with their embryos and littermates, were evaluated using an embryo-fetus developmental toxicity assay. fertile SD rats exhibited no significant general toxic effects when administered doses of 0.25, 1.25, and 5.0 mg/kg intranasally from days 6 to 15 of gestation. The genotoxicity of the compound was evaluated through an amalgam of tests that included the Ames test, the Chinese hamster ovary (CHO) cell chromosome aberration test, and the micronucleus test in ICR mice. The results from the Ames test indicated non-mutagenicity at concentrations of 5000, 500, 50.0, 5.0, and 0.5 μg/dish across strains TA97, TA98, TA100, TA102, and TA1535. Additionally, the chromosomal aberration rates in CHO cells were not significantly altered at concentrations of 50.5, 101.0, and 202.0 μg/mL. No micronuclei induction was observed in ICR mice at dosage levels of 11.25, 22.50, and 45.00 mg/kg post intranasal administration. In conclusion, the no observed adverse effect level (NOAEL) for developmental toxicity of XQ528 tartrate in fertile SD rats, embryos, and littermates under the test conditions in this study was established at 5.0 mg/kg/day. Under these test conditions, XQ528 tartrate did not exhibit any significant genotoxic or carcinogenic potential.

Assessment of Carcinogenic/Mutagenic Potential of Different Series of Synthetic Compounds

The new drug research is usually based on synthesis medicine. The use of these medications has created problems such as tolerance in humans, for a long time and due to legitimate use of anti-infection, microbial defense against branded medication is growing. A mutagensis study by Ames in the early 1970's, used worldwide by drug and chemicals companies to diagnose mutagens carcinogenes, making it possible for them to be detected, and to be added to the mutagenic synthesis portion or radiation source triggering irreversible changes, and to the genetic material transmitted from the parent. deoxyribonucleic acid (DNA). The purpose of this study was to assessment of carcinogenicity of synthetic compounds series by hemolytic, Ames and Damaged DNA protection assay. The cytotoxicity was determined with hemolytic assay and DNA Damage protection assay while mutagenicity was resolute by using S. typhimurium TA100 and TA98 strains. It is concluded that the compounds with less hemolytic compounds are good for uses in drugs. Synthetic compounds were determined to be non- mutagenic in nature. Analysis of variance (ANOVA) was applied to compare the hemolysis percent between different concentrations.

Apiole, an important constituent of parsley, is a mixed-type inhibitor of the CYP1A subfamily

Apiole (1-allyl-2,5-dimethoxy-3,4-methylenedioxybenzene) and parsley leaves ethanolic extract containing it inhibit the rat liver microsomal ethoxy- and methoxyresorufin-O-deacetylase activities associated with cytochrome P450 (CYP) 1A1 and 1A2, respectively. Cytochrome P4501A subfamily metabolizes environmental mutagens and several drugs, leading to the formation of mutagenic metabolites. Docking analysis showed that residue Phe123 within the active site of the CYP1A1 enzyme is bound to apiole through a π/π stacking of its benzene ring. In the case of 1A2, its Phe226 interacts with the dioxolane ring of apiole. Furthermore, apiole behaves as a mixed-type inhibitor of bacterial human recombinant CYP1A1. To explore one of the possible biological implications of this inhibitory effect, we tested the capacity of apiole and the parsley ethanolic extract to interfere with the mutagenicity of the promutagen 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) metabolized by CYP1A subfamily. As expected, both apiole and the plant extract reduced the number of revertant colonies of Salmonella typhimurium TA98 Ames strain after exposure to MeIQx, reaching a 78 % and 100 % reduction, respectively. Neither apiol nor parsley extract were mutagenic to the TA98 strain. We speculate that consuming apiole, a constituent of edible herbs, in conjunction with the utilization of pharmaceuticals metabolized by the CYP1A subfamily, may result in herb-drug interactions. Furthermore, the consumption of apiole by individuals who regularly ingest fresh vegetables may contribute to the low incidence of cancer observed in those who adhere to such a dietary regimen.

Amantadine mitigates the cytotoxic and genotoxic effects of doxorubicin in SH-SY5Y cells and reduces its mutagenicity

Amantadine (AMA) is a useful drug in neuronal disorders, but few studies have been performed to access its toxicological profile. Conversely, doxorubicin (Dox) is a well-known antineoplastic drug that has shown neurotoxic effects leading to cognitive impairment. The aims of this study are to evaluate the cytotoxic, genotoxic, and mutagenic effects of AMA, as well as its possible protective actions against deleterious effects of Dox. The Salmonella/microsome assay was performed to assess mutagenicity while cytotoxicity and genotoxicity were evaluated in SH-SY5Y cells using MTT and comet assays. Possible modulating effects of AMA on the cytotoxicity, genotoxicity, and mutagenicity induced by Dox were evaluated through cotreatment procedures. Amantadine did not induce mutations in the Salmonella/microsome assay and decreased Dox-induced mutagenicity in the TA98 strain. AMA reduced cell viability and induced DNA damage in SH-SY5Y cells. In cotreatment with Dox, AMA attenuated the cytotoxicity of Dox and showed an antigenotoxic effect. In conclusion, AMA does not induce gene mutations, although it has shown a genotoxic effect. Furthermore, AMA decreases frameshift mutations induced by Dox as well as the cytotoxic and genotoxic effects of Dox in SH-SY5Y cells, suggesting that AMA can interfere with Dox mutagenic activity and attenuate its neurotoxic effects.

Vanilla from Brazilian Atlantic Forest: In vitro and in silico toxicity assessment and high-resolution metabolomic analysis of Vanilla spp. ethanolic extracts

The natural vanilla market, which generates millions annually, is predominantly dependent on Vanilla planifolia, a species characterized by low genetic variability and susceptibility to pathogens. There is an increasing demand for natural vanilla, prized for its complex, authentic, and superior quality compared to artificial counterparts. Therefore, there is a necessity for innovative production alternatives to ensure a consistent and stable supply of vanilla flavors. In this context, vanilla crop wild relatives (WRs) emerge as promising natural sources of the spice. However, these novel species must undergo toxicity assessments to evaluate potential risks and ensure safety for consumption. This study aimed to assess the non-mutagenic and non-carcinogenic properties of ethanolic extracts from V. bahiana, V. chamissonis, V. cribbiana, and V. planifolia through integrated metabolomic profiling, in vitro toxicity assays, and in silico analyses. The integrated approach of metabolomics, in vitro assays, and in silico analyses has highlighted the need for further safety assessments of Vanilla cribbiana ethanolic extract. While the extracts of V. bahiana, V. chamissonis, and V. planifolia generally demonstrated non-mutagenic properties in the Ames assay, V. cribbiana exhibited mutagenicity at high concentrations (5000 μg/plate) in the TA98 strain without metabolic activation. This finding, coupled with the dose-dependent cytotoxicity observed in WST-1 (Water Soluble Tetrazolium) assays, a colorimetric method that assesses the viability of cells exposed to a test substance, underscores the importance of concentration in the safety evaluation of these extracts. Kaempferol and pyrogallol, identified with higher intensity in V. cribbiana, are potential candidates for in vitro mutagenicity. Although the results are not conclusive, they suggest the safety of these extracts at low concentrations. This study emphasizes the value of an integrated approach in providing a nuanced understanding of the safety profiles of natural products, advocating for cautious use and further research into V. cribbiana mutagenicity.

Genotoxic and antiproliferative properties of Endopleura uchi bark aqueous extract

ABSTRACT The bark extract from Endopleura uchi has been widely used in traditional medicine to treat gynecological-related disorders, diabetes, and dyslipidemias albeit without scientific proof. In addition, E. uchi bark extract safety, especially regarding mutagenic activities, is not known. The aim of this study was to determine the chemical composition, antitumor, and toxicological parameters attributed to an E. uchi bark aqueous extract. The phytochemical constitution was assessed by colorimetric and chromatographic analyzes. The antiproliferative effect was determined using sulforhodamine B (SRB) assay using 4 cancer cell lines. Cytotoxic and genotoxic activities were assessed utilizing MTT and comet assays, respectively, while mutagenicity was determined through micronucleus and Salmonella/microsome assays. The chromatographic analysis detected predominantly the presence of gallic acid and isoquercitrin. The antiproliferative effect was more pronounced in human colon adenocarcinoma (HT-29) and human breast cancer (MCF-7) cell lines. In the MTT assay, the extract presented an IC50 = 39.1 µg/ml and exhibited genotoxic (comet assay) and mutagenic (micronucleus test) activities at 20 and 40 µg/ml in mouse fibroblast cell line (L929) and mutagenicity in the TA102 and TA97a strains in the absence of S9 mix. Data demonstrated that E. uchi bark possesses bioactive compounds which exert cytotoxic and genotoxic effects that might be associated with its antitumor potential. Therefore, E. uchi bark aqueous extract consumption needs to be approached with caution in therapeutic applications.

Investigation of the mutagenic, cytotoxic and antimicrobial effect of bikaverin mycotoxin

Bikaverin is a reddish pigment produced by different fungi species (Mycogone jaapii, Verticillium agaricinum, Beauveria bassiana, Paecilomyces fumosoroseus, Polyporus sulphureus), mainly of the Fusarium genus. Due to its pigment feature, bikaverin can be used as a dye in various fields in the industry. However, it is extremely important to study the mutagenic/genotoxic effects, cytotoxic effects and antimicrobial properties of bikaverin for application of industrial areas. In the study, the mutagenic, cytotoxic and antimicrobial effects of bikaverin were investigated. The mutagenic effect of bikaverin was studied with the Ames test. Salmonella typhimurium TA97a, TA98, TA100, TA102 and TA1535 strains were used in the test. Five different doses of bikaverin (0.075, 0.1, 0.2, 0.3 and 0.5 μg/plate) were tested against strains. It was determined that there was no mutagenic effect of bikaverin. The cytotoxicity of bikaverin was evaluated by MTT test on L929 fibroblast cell line. Bikaverin demonstrated no cytotoxic effect on L929 fibroblast cell line, according to cell viability calculations that showed >73% for all concentrations (1, 0.5, 0.4, 0.3, 0.2, 0.1, 0.075, 0.05, 0.025, 0.01, 0.005 and 0.001 μg/mL) examined. Bikaverin's IC50 value was determined to be 1.79±0.51 g/mL. The antimicrobial activity of the bikaverin was evaluated by using the microdilution method. Bikaverin was found to have antimicrobial effects on Methicillin resistant Staphylococcus aureus, Vancomycin resistant Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Candida albicans and Candida krusei, as MIC values ranged from 1.25 -5 µg/ mL.

Newly discovered clouting interplay between matrix metalloproteinases structures and novel quaternary Ammonium K21: computational and in-vivo testing

Aims and objectivesTo analyze anti-MMP mode of action of Quaternary Ammonium Silane (QAS, codenamed as k21) by binding onto specific MMP site using computational molecular simulation and Anti-Sortase A (SrtA) mode of action by binding onto specific site using computational molecular simulation.Materials and methodsIn silico Molecular Dynamics (MD) was used to determine the interactions of K21 inside the pocket of the targeted protein (crystal structure of fibroblast collagenase-1 complexed to a diphenyl-ether sulphone based hydroxamic acid; PDB ID: 966C; Crystal structure of MMP-2 active site mutant in complex with APP-derived decapeptide inhibitor. MD simulations were accomplished with the Desmond package in Schrödinger Drug Discovery Suite. Blood samples (~ 0.5 mL) collected into K2EDTA were immediately transferred for further processing using the Litron MicroFlow® PLUS micronucleus analysis kit for mouse blood according to the manufacturer’s instructions. Bacterial Reverse Mutation Test of K21 Molecule was performed to evaluate K21 and any possible metabolites for their potential to induce point mutations in amino acid-requiring strains of Escherichia coli (E. coli) (WP2 uvrA (tryptophan-deficient)).ResultsMolecular Simulation depicted that K21 has a specific pocket binding on various MMPs and SrtA surfaces producing a classical clouting effect. K21 did not induce micronuclei, which are the result of chromosomal damage or damage to the mitotic apparatus, in the peripheral blood reticulocytes of male and female CD-1 mice when administered by oral gavage up to the maximum recommended dose of 2000 mg/kg. The test item, K21, was not mutagenic to Salmonella typhimurium (S. typhimurium) strains TA98, TA100, TA1535 and TA1537 and E. coli strain WP2 uvrA in the absence and presence of metabolic activation when tested up to the limit of cytotoxicity or solubility under the conditions of the test.ConclusionK21 could serve as a potent protease inhibitor maintaining the physical and biochemical properties of dental structures.

Unveiling the potential toxicity and mutagenicity of traditional remedies used for gynaecological and obstetric ailments in Maputaland, South Africa

Medicinal plants play an important role in the primary healthcare of lay people around the world, including the rural community of Maputaland, South Africa. According to an ethnobotanical survey conducted in 2014, the lay people in northern Maputaland use plant species independently and in combination to treat gynaecology and obstetric ailments. These plant species were generally regarded as safe by the lay people except for one plant species, Trichilia dregeana Harv. & Sond. The aim of this study was to investigate the safety of 16 plant combinations using the brine shrimp lethality assay (BSLA) for toxicity and Ames test using S. typhimurium TA98 and TA100 strains for mutagenicity. Toxicity studies on 33 medicinal plant species independently needed to be analysed first in order to make a comparison of combined with single use. The aqueous and organic (1:1 methanol-dichloromethane) extracts were prepared from 51 plant samples (including leaf samples collected as a substitution for the roots). There were three plant species (Acalypha villicaulis Horchst. Ex A.Rich. root, Grewia occidentalis L. root and Gymnosporia senegalensis Loes. leaves) indicated neither toxicity nor mutagenicity when tested at 1 and 5 mg/ml using the BSLA and Ames test, respectively. Hermannia boraginiflora Hook., Sapium integerrimum (Hochst. ex Krauss), Scadoxus puniceus (L.) Friis Nordal and Tabernaemontana elegans Stapf demonstrated toxicity even after dilution to the lowest concentration of 0.031 mg/ml. The three plant combinations which were found to be non-toxic in the BSLA (both aqueous and organic extracts) were Euphobia tirucalli L. (root) with Ozoroa engleri R.Fern & A.Fern. (bark), S. puniceus (bulb) and Senecio serratuloides DC. (whole plant); Bridelia cathartica G.Bertol. (root) with Opuntia stricta Haw. (stem) with Searsia nebulosa (Schoenland) Moffett (bark); and B. cathartica (root) with Erythrina humeana Spreng (root). In the Ames test, the plant samples which appeared to be non-mutagenic against both S. typhimurium TA98 and TA100 strains were A. villicaulis root, Cyperus natalensis Hochst. ex Krauss root, Euclea natalensis A.DC. leaves, G. occidentalis root, Ochna natalitia Walp. leaves, S. integerrimum leaves and S. puniceus bulb. This study indicated that medicinal plant species (independently and in combination) may have toxic and/ or mutagenic effects, even without any obvious signs after consumption. More importantly, it was determined that toxicity can be reduced by carefully managing the dose.

Preliminary study on the enhanced bioremediation of PAH-contaminated soil in Beijing and assessment of remediation effects based on toxicity tests.

In this study, we focused on soil contaminated by polycyclic aromatic hydrocarbons (PAHs) at typical coking-polluted sites in Beijing, conducted research on enhanced PAH bioremediation and methods to evaluate remediation effects based on toxicity testing, and examined changes in pollutant concentrations during ozone preoxidation coupled with biodegradation in test soil samples. The toxicity of mixed PAHs in soil was directly evaluated using the Ames test, and the correlation between mixed PAH mutagenicity and benzo(a)pyrene (BaP) toxicity was investigated in an effort to establish a carcinogenic risk assessment model based on biological toxicity tests to evaluate remediation effects on PAH-contaminated soil. This study provides a theoretical and methodological foundation for evaluating the effect of bioremediation on PAH-contaminated soil at industrially contaminated sites. The results revealed that the removal rate of PAHs after 5min of O3 preoxidation and 4weeks of soil reaction with saponin surfactants and medium was 83.22%. The soil PAH extract obtained after remediation had a positive effect on the TA98 strain at a dose of 2000μg·dish-1, and the carcinogenic risk based on the Ames toxicity test was 8.98 times greater than that calculated by conventional carcinogenic PAH toxicity parameters. The total carcinogenic risk of the remediated soil samples was approximately one order of magnitude less than that of the original soil samples.

Within-laboratory reproducibility of Ames test results: Are repeat tests necessary?

The Ames test is required by regulatory agencies worldwide for assessing the mutagenic and carcinogenic potential of chemical compounds. This test uses several strains of bacteria to evaluate mutation induction: positive results in the assay are predictive of rodent carcinogenicity. As an initial step to understanding how well the assay may detect mutagens present as constituents of complex mixtures such as botanical extracts, a cross-sector working group examined the within-laboratory reproducibility of the Ames test using the extensive, publicly available National Toxicology Program (NTP) Ames test database comprising more than 3000 distinct test articles, most of which are individual chemicals. This study focused primarily on NTP tests conducted using the standard Organization for Economic Co-operation and Development Test Guideline 471 preincubation test protocol with 10% rat liver S9 for metabolic activation, although 30% rat S9 and 10 and 30% hamster liver S9 were also evaluated. The reproducibility of initial negative responses in all strains with and without 10% S9, was quite high, ranging from 95% to 99% with few exceptions. The within-laboratory reproducibility of initial positive responses for strains TA98 and TA100 with and without 10% rat liver S9 was ≥90%. Similar results were seen with hamster S9. As expected, the reproducibility of initial equivocal responses was lower, <50%. These results will provide context for determining the optimal design of recommended test protocols for use in screening both individual chemicals and complex mixtures, including botanicals.

Draft Genome Sequence of Bacillus thuringiensis INTA 103-23 Reveals Its Insecticidal Properties: Insights from the Genomic Sequence

The genome of Bacillus thuringiensis strain INTA 103-23 was sequenced, revealing a high-quality draft assembly comprising 243 contigs with a total size of 6.30 Mb and a completeness of 99%. Phylogenetic analysis classified INTA 103-23 within the Bacillus cereus sensu stricto cluster. Genome annotation identified 6993 genes, including 2476 hypothetical proteins. Screening for pesticidal proteins unveiled 10 coding sequences with significant similarity to known pesticidal proteins, showcasing a potential efficacy against various insect orders. AntiSMASH analysis predicted 13 biosynthetic gene clusters (BGCs), including clusters with 100% similarity to petrobactin and anabaenopeptin NZ857/nostamide A. Notably, fengycin exhibited a 40% similarity within the identified clusters. Further exploration involved a comparative genomic analysis with ten phylogenetically closest genomes. The ANI values, calculated using fastANI, confirmed the closest relationships with strains classified under Bacillus cereus sensu stricto. This comprehensive genomic analysis of B. thuringiensis INTA 103-23 provides valuable insights into its genetic makeup, potential pesticidal activity, and biosynthetic capabilities. The identified BGCs and pesticidal proteins contribute to our understanding of the strain’s biocontrol potential against diverse agricultural pests.