A path from synthesis to emergency use authorization of molnupiravir as a COVID-19 therapy

Coronaviruses are a group of enveloped viruses with non-segmented, single-stranded, and positive-sense RNA genomes. It belongs to the 'Coronaviridae family', responsible for various diseases, including the common cold, SARS, and MERS. The COVID-19 pandemic, which began in March 2020, has affected 209 countries, infected over a million people, and claimed over 50,000 lives. Significant efforts have been made by repurposing several approved drugs including antiviral, to combat the COVID-19 pandemic. Molnupiravir is found to be the first orally acting efficacious drug to treat COVID-19 cases. It was approved for medical use in the UK in November 2021 and other countries, including USFDA, which granted approval an emergency use authorization (EUA) for treating adults with mild to moderate COVID-19 patients. Considering the importance of molnupiravir, the present review deals with its various synthetic strategies, pharmacokinetics, bio-efficacy, toxicity, and safety profiles. The comprehensive information along with critical analysis will be very handy for a wide range of audience including medicinal chemists in the arena of antiviral drug discovery especially anti-viral drugs against any variant of COVID-19.

Can Salvinia auriculata bioremediate the toxic effects of Fipronil 800wg on the tadpoles of Dendropsophus minutus?

Worldwide, the indiscriminate and escalating application of pesticides has led to extensive impacts on both the environment and non-target organisms. Phytoremediation, which employs plants to decontaminate environments, is a potential strategy for the mitigation of this damage. The present study assessed the phytoremedial potential of Salvinia auriculata, an aquatic macrophyte known to be effective for the removal of environmental contaminants. In the laboratory, Dendropsophus minutus tadpoles were exposed to different concentrations (0.035, 0.1, 1.0, and 1.5 mg/l) of the commercial insecticide Fipronil 800wg in two treatments - (i) simple exposure for 96 h, and (ii) exposure for 168 h in aquariums containing S. auriculata. In the first experiment, a mortality rate of 33.3 % was recorded at the highest Fipronil concentration (1.5 mg/l), and genotoxic parameters increased at all concentrations except 0.035 mg/L, in comparison with the control. In the second experiment, phytoremediation occurred at all the concentrations tested, with lower frequencies of cells with micronuclei, and binucleated, anucleated, and pyknotic nuclei being observed, in comparison with the first experiment. These findings highlight the potential effectiveness of S. auriculata for the phytoremediation of environments contaminated by pesticides and contribute to the understanding of the benefits of this approach for the protection and preservation of aquatic biodiversity.

Cytogenotoxicity and inflammatory response in liver of rats exposed to different doses of cannabis nano emulsions

Cannabis is the most used illicit substance for recreational purposes around the world. However, it has become increasingly common to witness the use of approved cannabis preparations for symptoms management in various diseases. The aim of this study was to investigate the effects of cannabis nano emulsion in the liver of Wistar rats, with different proportions of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). For this, a total of 40 male Wistar rats were distributed into 5 groups, as follows (n = 8 per group): Control: G1, Experimental group (G2): treated with cannabis nano emulsion (THC and CBD) at a dose of 2.5 mg/kg, Experimental group (G3): treated with cannabis nano emulsion (THC and CBD) at a dose of 5 mg/kg, Experimental group (G4): treated with cannabis nano emulsion (CBD) at a dose of 2.5 mg/kg; Experimental group (G5): treated with cannabis nano emulsion (CBD) at a dose of 5 mg/kg. Exposure to the nano emulsion was carried out for 21 days, once a day, orally (gavage). Our results showed that cannabis nano emulsions at higher doses (5 mg/kg), regardless of the composition, induced histopathologic changes in the liver (G3 and G5) in comparison with the control group. In line with that, placental glutathione S-transferase (GST-P) positive foci increased in both G3 and G5 (p < 0.05), as well as the immune expression of Ki-67, vascular endothelial growth factor (VEGF) and p53 (p < 0.05). Also, the nano emulsion intake induced an increase in the number of micronucleated hepatocytes in G5 (p < 0.05) whereas G3 showed an increase in binucleated cells (p < 0.05). As for metanuclear alterations, karyolysis and pyknosis had an increased frequency in G3 (p < 0.05). Taken together, the results show that intake of cannabis nano emulsion may induce degenerative changes and genotoxicity in the liver in higher doses, demonstrating a clear dose-response relationship.

Determining Recommended Acceptable Intake Limits for N-Nitrosamine Impurities in Pharmaceuticals: Development and Application of the Carcinogenic Potency Categorization Approach (CPCA)

N-Nitrosamine impurities, including nitrosamine drug substance-related impurities (NDSRIs), have challenged pharmaceutical industry and regulators alike and affected the global drug supply over the past 5 years. Nitrosamines are a class of known carcinogens, but NDSRIs have posed additional challenges as many lack empirical data to establish acceptable intake (AI) limits. Read-across analysis from surrogates has been used to identify AI limits in some cases; however, this approach is limited by the availability of robustly-tested surrogates matching the structural features of NDSRIs, which usually contain a diverse array of functional groups. Furthermore, the absence of a surrogate has resulted in conservative AI limits in some cases, posing practical challenges for impurity control. Therefore, a new framework for determining recommended AI limits was urgently needed. Here, the Carcinogenic Potency Categorization Approach (CPCA) and its supporting scientific rationale are presented. The CPCA is a rapidly-applied structure-activity relationship-based method that assigns a nitrosamine to 1 of 5 categories, each with a corresponding AI limit, reflecting predicted carcinogenic potency. The CPCA considers the number and distribution of α-hydrogens at the N-nitroso center and other activating and deactivating structural features of a nitrosamine that affect the α-hydroxylation metabolic activation pathway of carcinogenesis. The CPCA has been adopted internationally by several drug regulatory authorities as a simplified approach and a starting point to determine recommended AI limits for nitrosamines without the need for compound-specific empirical data.

AMPred-CNN: Ames mutagenicity prediction model based on convolutional neural networks

Mutagenicity assessment plays a pivotal role in the safety evaluation of chemicals, pharmaceuticals, and environmental compounds. In recent years, the development of robust computational models for predicting chemical mutagenicity has gained significant attention, driven by the need for efficient and cost-effective toxicity assessments. In this paper, we proposed AMPred-CNN, an innovative Ames mutagenicity prediction model based on Convolutional Neural Networks (CNNs), uniquely employing molecular structures as images to leverage CNNs' powerful feature extraction capabilities. The study employs the widely used benchmark mutagenicity dataset from Hansen et al. for model development and evaluation. Comparative analyses with traditional ML models on different molecular features reveal substantial performance enhancements. AMPred-CNN outshines these models, demonstrating superior accuracy, AUC, F1 score, MCC, sensitivity, and specificity on the test set. Notably, AMPred-CNN is further benchmarked against seven recent ML and DL models, consistently showcasing superior performance with an impressive AUC of 0.954. Our study highlights the effectiveness of CNNs in advancing mutagenicity prediction, paving the way for broader applications in toxicology and drug development.

Strategy proposal using QSAR models to approach mutagenicity assessment of non intentionally added substances in recycled plastic resins

CONTEXT

Transition to the use of recycled plastics raises an issue concerning safety assessment of Non Intentionally Added Substances (NIAS). To assess the mutagenic potential of the recycled polyethylene impurities and to evaluate the need to perform in vitro assays on recycled resins, this study lies in identifying existing NIAS associated with recycled Low/High Density Polyethylene and assessing the mutagenicity data-gaps by employing in silico tools.

METHODS

Quantitative Structure-Activity Relationship (QSAR) models predicting Ames mutagenicity were selected from literature, then NIAS were run to 1/evaluate performances of each model, 2/apply a QSAR strategy on the NIAS molecular space and address data-gaps.

RESULTS

Among the 165 NIAS identified, experimental Ames results were not found for 50 substances while the substances with experimental data were predominantly negatives. No individual model was able to predict all NIAS due to applicability domain limitations. Taking into account 1/calculated performances, 2/availability of applicability domain, 3/description of the Training Set, an Integrated Strategy was founded including Sarpy, Consensus and Protox to extend the applicability domain.

CONCLUSION & PERSPECTIVES

Existing data and predictions generated by this strategy suggest a low mutagenic potential of NIAS. Further investigation is needed to explore other genotoxicity mechanisms.

Ecotoxicological evaluation of surface waters in Northern Namibia

The increasing pressure on freshwater systems due to intensive anthropogenic use is a big challenge in central-northern Namibia and its catchment areas, the Kunene and the Kavango Rivers, and the Cuvelai-Etosha Basin, that provide water for more than 1 million people. So far, there is no comprehensive knowledge about the ecological status and only few knowledge about the water quality. Therefore, it is crucial to learn about the state of the ecosystem and the ecological effects of pollutants to ensure the safe use of these resources. The surface waters of the three systems were sampled, and three bioassays were applied on three trophic levels: algae, daphnia, and zebrafish embryos. Additionally, in vitro assays were performed to analyze mutagenicity (Ames fluctuation), dioxin-like potential (micro-EROD), and estrogenicity (YES) by mechanism-specific effects. The results show that acute toxicity to fish embryos and daphnia has mainly been detected at all sites in the three catchment areas. The systems differ significantly from each other, with the sites in the Iishana system showing the highest acute toxicity. At the cellular level, only weak effects were identified, although these were stronger in the Iishana system than in the two perennial systems. Algae growth was not inhibited, and no cytotoxic effects could be detected in any of the samples. Mutagenic effects and an estrogenic potential were detected at three sites in the Iishana system. These findings are critical in water resource management as the effects can adversely impact the health of aquatic ecosystems and the organisms within them.

Antimutagenic activity of different forms of Bifidobacterium lactis probiotic against aflatoxin B1 by Ames method

The health risks caused by aflatoxins, as one of the most important contaminants of human food and feed and the main cause of cancer, especially hepatocellular carcinoma (HCC) were investigated. The aim of the study was to assess the antimutagenic effects of Bifidobacterium lactis (B. lactis) probiotic against aflatoxin B1 (AFB1). The study was conducted with 27 treatments and three replications. The independent variables were aflatoxin concentrations at three levels of 5, 15, and 25 ng/g and probiotic content in three forms of cellular sedimentation (CS), cell-free supernatant (CFS), and cell suspension. The antimutagenic activity of B. lactis against AFB1 was measured. The lowest score of antimutagenic activity of B. lactis was observed in bacterial cellular sediment treatment at 107 CFU/g and 25 ng/g of AFB1 (20.8 ± 3.80%) and the highest score was achieved with cell suspension at 109 CFU/g and 5 ng/g of AFB1 (74.9 ± 7.11%). In addition, the lack of mutagenicity of probiotics was confirmed. Therefore, probiotics not only alleviate aflatoxin in food matrices and benefit the consumer, but also notably decrease mutagenicity of AFB1.

Ninety-day toxicity and genotoxic effects of synthetically derived fully saturated forms of anacardic acid in mice

Organically synthesized fully saturated form of Anacardic acid (AA) has previously shown to be effective in the treatment of inflammatory autoimmune disease. In this study, organically synthesized fully saturated form of AA was orally administered to male and female Swiss albino mice for 90 consecutive days at doses of 25, 50 and 100 mg/kg BW (n = 20 per sex/group). Administration of AA was well tolerated at all dose levels. The treated animals did not show a dose-response toxicity in their hematology, liver, or metabolic profile. Minimally significant changes in serum biochemistry and hematology parameters were noted, but these were not considered to be of biological or toxicological importance and were not outside the known accepted ranges. Sporadic differences in organ weights were observed between groups, but all were minimal (<10%) and unlikely to indicate toxicity. The incidence of histopathological lesions was comparable between treated and control groups across all tested organs. Based upon these findings, the no-observed-adverse-effect level was determined to be ≥ 100 mg/kg BW, which was the highest dose tested. There were no genotoxic (mutagenic and clastogenic) effects seen in In-vivo micronucleus test, In-vitro chromosomal aberration test and Bacterial reverse mutation test. These results support, no genotoxicity and no toxicity associated with oral consumption of AA in mice as a dietary supplement for beverages and food.

Organic toxicants and emerging contaminants in hospital interiors before and during the SARS-CoV2 pandemic: alkanes and PAHs

Indoor pollution and deposition dust (DD), in particular, are acquiring concern, due to long exposure time and importance of intake by humans through contact and ingestion. Hospitals look a special category of sites, owing to peculiar contaminants affecting them and to presence of people prone to adverse effects induced by toxicants. Four in-field campaigns aimed at understanding the chemical composition of DD were performed in five Italian hospitals. Measurements were performed before (autumn 2019), during (spring 2021), and after (winter 2022) the peak of SARS-CoV2 and when restrictions caused by pandemic were revoked (winter 2023). Parallel measurements were made outdoors (2022), as well as in a university and a dwelling. Targeted contaminants were n-alkanes and polycyclic aromatic hydrocarbons (PAHs), while iso- and anteiso-alkanes were analyzed to assess the impact of tobacco smoking. Total n-alkanes ranged from 3.9 ± 2.3 to 20.5 ± 4.2 mg/g, with higher percentages of short chain homologs in 2019. PAHs ranged from 0.24 ± 0.22 to 0.83 ± 0.50 mg/g, with light congeners (≤ 228 a.m.u.) always exceeding the heavy ones (≥ 252 a.m.u.). According to carbon preference indexes, alkanes originated overall from anthropogenic sources. Microorganisms resulted to affect a hospital, and tobacco smoke accounted for ~ 4-20‰ of DD mass. As for PAH sources, the diagnostic concentration ratios suggested the concourse of biological matter burning and vehicle emission. Benzo[a]pyrene equivalent carcinogenic and mutagenic potencies of depositions at hospitals ranged ~ 9-39 μg/g and ~ 15-76 μg/g, respectively, which seems of concern for health. DD composition in hospitals was different from that outside the premises, as well as that found at university and at dwelling.

In vitro Genotoxicity and In silico Docking Analyses of the Essential Oils of Thuja orientalis

Two main objectives were pursued to assess the reliability of Thuja orientalis essential oils (TOEO). The first objective was to extract TOEO, analyze them by GC-MS, and determine their in vitro genotoxicity against selected plants using the RAPD-PCR method. The second objective was to evaluate the in-silico toxicity of TOEO. The binding sites and energies of each content was calculated against B-DNA. In-silico analyses were performed using a simulation program, AutoDock Vina, and Toxicity Estimation Software Tools. 3-carene, cedrol, and 2-pinene were identified as the predominant components. In vitro studies showed that the TOEO had a more significant impact on reducing genomic stability in wheat compared to the amaranth. The lowest stability was determined as 39.78 % in wheat and 53.58 % in amaranth. Cedrol (-5,7 kcal/mol) and selinene (-5,6 kcal/mol) exhibited the highest binding affinity. The toxicity test indicated that components other than cyclohexene may have toxic effects, none of them were predicted to be mutagenic, and LD50 (mol/kg) values could vary between 1.33 and 1.55.

Assessment of the performance of the Ames MPF™ assay: A multicenter collaborative study with six coded chemicals

The Ames MPF™ is a miniaturized, microplate fluctuation format of the Ames test. It is a standardized, commercially available product which can be used to assess mutagenicity in Salmonella and E. coli strains in 384-well plates using a color change-based readout. Several peer-reviewed comparisons of the Ames MPF™ to the Ames test in Petri dishes confirmed its suitability to evaluate the mutagenic potential of a variety of test items. An international multicenter study involving seven laboratories tested six coded chemicals with this assay using five bacterial strains, as recommended by the OECD test guideline 471. The data generated by the participating laboratories was in excellent agreement (93%), and the similarity of their dose response curves, as analyzed with sophisticated statistical approaches further confirmed the suitability of the Ames MPF™ assay as an alternative to the Ames test on agar plates, but with advantages with respect to significantly reduced amount of test substance and S9 requirements, speed, hands-on time and, potentially automation.

Assessment of the genotoxic and mutagenic effects induced by T-2 mycotoxin in HepG2 cells

The T-2 toxin is a mycotoxin produced by molds belonging to Fusarium. Among the Fusarium mycotoxins, trichothecenes are frequently reported in food and feed, being the T-2 toxin (T-2) the mycotoxin which possesses the highest toxicity. According to EFSA, T-2 is found in various cereal grains used in food and feed products, mainly in oats, and it has a high environmental impact due to its mechanisms of toxicity. However, recent information on its genotoxic and mutagenic effects is lacking. This work aimed to evaluate the genotoxic and mutagenic potential of T-2 in vitro. For this purpose, HepG2 cells were exposed to 15, 30, and 60 nM T-2 for 24 h, then the DNA damage was evaluated by the micronucleus and the comet assays. In addition, point mutation analysis was performed by the bacterial reverse mutation test using 0.15-60 nM of T-2 concentrations. The results showed chromosomal damage at 60 nM T-2 since significantly more MN appeared at this concentration than in the control samples. Regarding the comet assay, DNA double helix breaks appeared at all concentrations tested and, in a concentration-dependent manner. However, no mutagenic effects were observed at any of the concentrations tested for the Salmonella typhimurium (S. Typhimurium) strains TA98, TA100, TA1535, TA1537, or the Escherichia coli (E. Coli) WP2 strain in the absence or presence of a metabolic activation system. Therefore, these results showed that T-2 mycotoxin produced genotoxic effects by MN and comet assay, while no mutagenicity was observed. However, further research simulating different metabolic activation pathways and the combined exposure of this mycotoxin with other mutagenic chemicals that could be present in the diet is necessary to discard the mutagenic potential of T-2 fully. These results highlight the carcinogenic potential and danger associated with T-2 exposure and should be considered to prevent associated food risks for the human population.

Inoculum cell count influences separation efficiency and variance in Ames plate incorporation and Ames RAMOS test

The Ames test is one of the most applied tools in mutagenicity testing of chemicals ever since its introduction by Ames et al. in the 1970s. Its principle is based on histidine auxotrophic bacteria that regain prototrophy through reverse mutations. In the presence of a mutagen, more reverse mutations occur that become visible as increased bacterial growth on medium without histidine. Many miniaturized formats of the Ames test have emerged to enable the testing of environmental water samples, increase experimental throughput, and lower the required amounts of test substances. However, most of these formats still rely on endpoint determinations. In contrast, the recently introduced Ames RAMOS test determines mutagenicity through online monitoring of the oxygen transfer rate. In this study, the oxygen transfer rate of Salmonella typhimurium TA100 during the Ames plate incorporation test was monitored and compared to the Ames RAMOS test to prove its validity further. Furthermore, the Ames RAMOS test in 96-well scale is newly introduced. For both the Ames plate incorporation and the Ames RAMOS test, the influence of the inoculum cell count on the negative control was highlighted: A lower inoculum cell count led to a higher coefficient of variation. However, a lower inoculum cell count also led to a higher separation efficiency in the Ames RAMOS test and, thus, to better detection of a mutagenic substance at lower concentrations.

Development of a read-across-derived classification model for the predictions of mutagenicity data and its comparison with traditional QSAR models and expert systems

Mutagenicity is considered an important endpoint from the regulatory, environmental and medical points of view. Due to the wide number of compounds that may be of concern and the enormous expenses (in terms of time, money, and animals) associated with rodent mutagenicity bioassays, this endpoint is a major target for the development of alternative approaches for screening and prediction. The majority of old-aged expert systems and quantitative structure-activity relationship (QSAR) models may show reduced performance over time for their application on newer chemical candidates; thus, researchers constantly try to improve the modeling strategies. In our report, we initially performed traditional classification-based linear discriminant analysis (LDA) QSAR modeling using the benchmark Ames dataset of diverse chemicals (6512 compounds) to recognize the relationship between the molecules and their potential mutagenic behavior. The classical LDA QSAR model is developed from a selected set of 2D descriptors. The LDA QSAR model was developed by using a total of 31 descriptors identified from the analysis of the most discriminating features. Additionally, we have used similarity-derived features obtained from the read-across (RA) to develop an RA-based QSAR model. The developed RA-based LDA QSAR model has better predictivity, transferability, and interpretability compared to the LDA QSAR model, and it uses a very small number of descriptors compared to the classical QSAR model. Different machine learning (ML) models were also developed using the descriptors appearing in the read-across-based LDA QSAR model for comparative studies. We have checked the prediction quality of 216 true external set compounds using the novel similarity-derived RA model. The performance of the OECD toolbox is also compared with the RA-derived LDA QSAR model for a true external set. The current study aimed to explore the significance of the read-across-based algorithm and its application to the most current experimental mutagenicity data to complement already available expert systems.

Toxicological assessment of minoxidil: A drug with therapeutic potential besides alopecia

Minoxidil is regularly prescribed for alopecia, and its therapeutic potential has expanded in recent times. However, few studies have been conducted to evaluate its toxicity, and controversial findings regarding its mutagenic activities remain unsolved. This study aimed to access cytotoxic, genotoxic, and mutagenic properties of minoxidil using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay, comet assay, and micronucleus test in mouse fibroblast (L929) cells and its point mutation induction potential in the Salmonella/microsome assay. Furthermore, an in vivo toxicity assessment was conducted in Caenorhabditis elegans. Minoxidil showed cytotoxicity at 2.0 mg/mL in MTT assay. Genotoxicity was observed after 3 h treatment in L929 cells using comet assay. No mutagenic effect was observed in both the micronucleus test and the Salmonella/microsome assay. The lethal dose 50 in C. elegans was determined to be 1.75 mg/mL, and a delay in body development was detected at all concentrations. In conclusion, minoxidil induces DNA damage only in early treatment, implying that this DNA damage may be repairable. This observation corroborates the absence of mutagenic activities observed in L929 cells and Salmonella typhimurium strains. However, the toxicity of minoxidil was evident in both C. elegans and L929 cells, underscoring the need for caution in its use.

Evaluation of the probable synergistic toxicity of selected potentiated antiretroviral and antibiotics on some aquatic biomarker organisms

Environmental effects of active pharmaceutical compounds (APCs) in the environment are not well characterized, hence the need for comprehensive evaluation. This study employed three bioassays using three organisms, namely, Allium cepa, Daphnia magna, and Salmonella typhimurium, in the ecotoxicity study of lone and a mixture of selected APCs, namely, lamivudine (L), an antiretroviral, and ciprofloxacin (C) and sulfamethoxazole (S), antibiotics, at a concentration range between 10 and 100 ppb, in order to evaluate the potential of the lone and ternary mixture to exert synergistic toxicity. Study results from exposure to lone APCs showed that the L, C, and S trio individually had fatal impacts on daphnids, with mortality rates of 100, 75, and 95%, respectively, after 48 h. Sulfamethoxazole showed a mutagenic tendency, with a mutation ratio (background/sample ratio) of 2.0. Lamivudine showed a lethal impact on the root length of A. cepa (p > 0.05, p = 3.60E-3). Further microscopic examination of the A. cepa root tip revealed chromosomal aberrations on exposure to each compound. The LCS-mix ecotoxicology bioassays indicated a synergistic effect on the daphnids, probably due to potentiation. Although the LCS mix had a cytotoxic effect (evidenced by the absence of bacteria colonies) on exposed TA 98 P450 Salmonella typhimurium strain, this effect was not observed in other bacterial strains. Microscopic examination of A. cepa exposed to the LCS-mix revealed an aberration in the mitotic stage of the cell. The impact of combination of the pharmaceuticals in aqueous ecosystems was greater than when exposed to the tested individual pharmaceutical compounds. Study result showed that these compounds have tendencies to pose a higher risk to exposed living entities when in combined/potentiated forms, and this could lead to distortion of the regular functioning of the ecosystem, particularly bacterial and other microbial populations that are listed among primary producers of the aquatic food web.

Toxicity prediction and analysis of flavonoid apigenin as a histone deacetylase inhibitor: an in-silico approach

Occurrence of cancer is driving up on a global scale that exerts greater implications on the physical, psychological and economic stability of the human population. In the present context, numerous research studies are being conducted to explore and discover the drug molecule as an anticancer agent. Diverse scales of flavonoids entail the human diet, and they displayed prospective curative effects against an array of ailments. Among different categories of flavonoids, apigenin a trihydroxy flavone has been proven to have various pharmacological effects. Molecular docking is a key tool in structural molecular biology and computer assisted drug design. In this study, HDAC inhibitory action of apigenin and its probable toxicity was assessed by docking study using Auto dock platform. Molecular dynamics simulation was done by using iMODS server for elucidating the stability of the receptor-ligand complex. Toxicity predictions were evaluated by using tools such as CarcinoPred for carcinogenicity study, pkCSM for ADMET analysis, ProTox-II for rodent oral toxicity, lazar for estimating mutagenicity, BOILED Egg plot analysis for examining the gastrointestinal absorption and blood brain permeability, PASS prediction to identify the various biological functions and DruLiTo program to compute the drug likeness property.

Graphical abstract

Mutagenicity and genotoxicity assessment of the emerging mycotoxin Versicolorin A, an Aflatoxin B1 precursor

Aflatoxin B1 (AFB1) is the most potent natural carcinogen among mycotoxins. Versicolorin A (VerA) is a precursor of AFB1 biosynthesis and is structurally related to the latter. Although VerA has already been identified as a genotoxin, data on the toxicity of VerA are still scarce, especially at low concentrations. The SOS/umu and miniaturised version of the Ames test in Salmonella Typhimurium strains used in the present study shows that VerA induces point mutations. This effect, like AFB1, depends primarily on metabolic activation of VerA. VerA also induced chromosomal damage in metabolically competent intestinal cells (IPEC-1) detected by the micronucleus assay. Furthermore, results from the standard and enzyme-modified comet assay confirmed the VerA-mediated DNA damage, and we observed that DNA repair pathways were activated upon exposure to VerA, as indicated by the phosphorylation and/or relocation of relevant DNA-repair biomarkers (γH2AX and 53BP1/FANCD2, respectively). In conclusion, VerA induces DNA damage without affecting cell viability at concentrations as low as 0.03 μM, highlighting the danger associated with VerA exposure and calling for more research on the carcinogenicity of this emerging food contaminant.

Comparison of the transgenic rodent mutation assay, error corrected next generation duplex sequencing, and the alkaline comet assay to detect dose-related mutations following exposure to N-nitrosodiethylamine

N-Nitrosodiethylamine (NDEA), a well-studied N-nitrosamine, was tested in rats to compare the dose-response relationship of three genotoxicity endpoints. Mutant / mutation frequencies were determined using the transgenic rodent (TGR) gene mutation assay and error corrected next generation sequencing (ecNGS) (i.e., duplex sequencing (DS)), and genetic damage was detected by the alkaline comet assay. Big Blue® (cII Locus) animals (n = 6 per dose group) were administered doses of 0.001, 0.01, 0.1, 1, 3 mg/kg/day NDEA by oral gavage. Samples were collected for cII mutation and DS analyses following 28-days of exposure and 3 days recovery. In a separate study, male Sprague-Dawley (SD) rats (n = 6 per dose group) were administered the same doses by oral gavage for two consecutive days and then samples collected for the alkaline comet assay. A dose-related increase in mutant / mutation frequencies of the liver but not duodenum was observed using the TGR assay and DS with DS resulting in a slightly more sensitive response, with a lower benchmark dose (BMD). In addition, a dose-related increase in percent tail DNA was observed in the liver using the alkaline comet assay. Therefore, DS and comet assays showed good utility for hazard identification and dose-response analysis of a representative N-nitrosamine comparable to the TGR gene mutation assay.

Development of a framework for risk assessment of dietary carcinogens

Although there are a number of guidance documents and frameworks for evaluation of carcinogenicity, none of the current methods fully reflects the state of the science. Common limitations include the absence of dose-response assessment and not considering the impact of differing exposure patterns (e.g., intermittent, high peaks vs. lower, continuous exposures). To address these issues, we have developed a framework for risk assessment of dietary carcinogens. This framework includes an enhanced approach for weight of evidence (WOE) evaluation for genetic toxicology data, with a focus on evaluating studies based on the most recent testing guidance to determine whether a chemical is a mutagen. Included alongside our framework is a discussion of resources for evaluating tissue dose and the temporal pattern of internal dose, taking into account the chemical's toxicokinetics. The framework then integrates the mode of action (MOA) and associated dose metric category with the exposure data to identify the appropriate approach(es) to low-dose extrapolation and level of concern associated with the exposure scenario. This framework provides risk managers with additional flexibility in risk management and risk communication options, beyond the binary choice of linear low-dose extrapolation vs. application of uncertainty factors.

DeepAmes: A deep learning-powered Ames test predictive model with potential for regulatory application

The Ames assay is required by the regulatory agencies worldwide to assess the mutagenic potential risk of consumer products. As well as this in vitro assay, in silico approaches have been widely used to predict Ames test results as outlined in the International Council for Harmonization (ICH) guidelines. Building on this in silico approach, here we describe DeepAmes, a high performance and robust model developed with a novel deep learning (DL) approach for potential utility in regulatory science. DeepAmes was developed with a large and consistent Ames dataset (>10,000 compounds) and was compared with other five standard Machine Learning (ML) methods. Using a test set of 1,543 compounds, DeepAmes was the best performer in predicting the outcome of Ames assay. In addition, DeepAmes yielded the best and most stable performance up to when compounds were >30% outside of the applicability domain (AD). Regarding the potential for regulatory application, a revised version of DeepAmes with a much-improved sensitivity of 0.87 from 0.47. In conclusion, DeepAmes provides a DL-powered Ames test predictive model for predicting the results of Ames tests; with its defined AD and clear context of use, DeepAmes has potential for utility in regulatory application.

Synergistic effects on mutagenicity of tandem lesions containing 8-oxo-7,8-dihydro-2'-deoxyguanosine or Fapy•dG flanked by a 3' 5-formyl-2'-deoxyuridine in human cells

Modified nucleotides often hinder and/or decrease the fidelity of DNA polymerases. Tandem lesions, which are comprised of DNA modifications at two contiguous nucleotide positions, can be even more detrimental to genome stability. Recently, tandem lesions containing 5-formyl-2'-deoxyuridine (5fdU) flanked at the 5'-position by 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-OxodGuo) or N-(2-deoxy-α,β-D-erythropentofuranosyl)-N-(2,6-diamino-4-hydroxy-5-formamidopyrimidine (Fapy•dG) were discovered. We examined the replication of 5'- 8-OxodGuo-5fdU and 5'-Fapy•dG-5fdU tandem lesions in HEK 293T cells and several polymerase deficient variants by transfecting single-stranded vectors containing them. The local sequence of the tandem lesions encompasses the 273 codon of the p53 gene, a mutational hot-spot. The bypass efficiency and mutation spectra of the tandem lesions were compared to those of the isolated lesions. Replication of weakly mutagenic 5-fdU is little changed when part of the 5'- 8-OxodGuo-5fdU tandem lesion. G → T transversions attributable to 8-OxodGuo increase > 10-fold when the tandem lesion is bypassed. 5'-Fapy•dG-5fdU has a synergistic effect on the error-prone bypass of both lesions. The mutation frequency (MF) of 5'-Fapy•dG-5fdU increases 3-fold compared to isolated Fapy•dG. In addition, a 5'-adjacent Fapy•dG significantly increases the MF of 5fdU. The major mutation, G → T transversions, decrease by almost a third in hPol κ- cells, which is the opposite effect when isolated Fapy•dG in the same sequence context is replicated in HEK 293T cells in the same sequence. Steady-state kinetics indicate that hPol κ contributes to greater G → T transversions by decreasing the specificity constant for dCTP compared to an isolated Fapy•dG. The greater conformational freedom of Fapy•dG compared to 8-OxodGuo and its unusual ability to epimerize at the anomeric center is believed to be the source of the complex effects of 5'-Fapy•dG-5fdU on replication.

A deep dive into historical Ames study data for N-nitrosamine compounds

Mutagenicity data is a core component of the safety assessment data required by regulatory agencies for acceptance of new drug compounds, with the OECD-471 bacterial reverse mutation (Ames) assay most widely used as a primary screen to assess drug impurities for potential mutagenic risk. N-Nitrosamines are highly potent mutagenic carcinogens in rodent bioassays and their recent detection as impurities in pharmaceutical products has sparked increased interest in their safety assessment. Previous literature reports indicated that the Ames test might not be sensitive enough to detect the mutagenic potential of N-nitrosamines in order to accurately predict a risk of carcinogenicity. To explore this hypothesis, public Ames and rodent carcinogenicity data pertaining to the N-nitrosamine class of compounds was collated for analysis. Here we present how variations to the OECD 471-compliant Ames test, including strain, metabolic activation, solvent type and pre-incubation/plate incorporation methods, may impact the predictive performance for carcinogenicity. An understanding of optimal conditions for testing of N-nitrosamines may improve both the accuracy and confidence in the ability of the Ames test to identify potential carcinogens.

Morphine decreases cytotoxicity and mutagenicity of doxorubicin in vitro: Implications for cancer chemotherapy

Morphine is the most common opioid analgesic administered to treat pain in patients undergoing cancer chemotherapy. This study aimed to evaluate the cytotoxic and mutagenic effects of morphine alone and in combination with doxorubicin (Dox), an antineoplastic agent largely used in patients with solid cancers. Cytotoxicity was evaluated in neuroblastoma (SH-SY5Y) and fibroblast (V79) cells using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) colorimetric assay while mutagenicity was assessed using the Salmonella/microsome assay in the absence and in the presence of S9 mix. Morphine showed a cytotoxic effect mainly on SH-SY5Y cells and reduced the cytotoxic effects of Dox when evaluated in a co-treatment procedure. In the Salmonella/microsome assay, it was observed that morphine did not induce mutations and, in fact, decreased the mutagenic effects induced by Dox in TA98 and TA102 strains in the absence of metabolic activation. Furthermore, in the presence of metabolic activation, no induction of mutations was observed with morphine. In conclusion, morphine decreased Dox cytotoxicity in both neuronal and non-neuronal cells and showed antimutagenic effects in the TA102 strain which detects mutagens inducing DNA oxidative damages. However, morphine decreased frameshift mutations induced by Dox in non-cytotoxic concentrations, an effect suggesting interference of Dox intercalation activity that could decrease its chemotherapeutic efficacy. These compelling findings highlight the importance of conducting further studies to explore the potential implications of co-administering morphine and Dox during cancer chemotherapy.

Analysis of chemical structures and mutations detected by Salmonella TA98 and TA100

As part of an analysis performed under the auspices of the International Workshop on Genotoxicity Testing (IWGT) in 2017, we and others showed that Salmonella frameshift strain TA98 and base-substitution strain TA100 together + /- S9 detected 93% of the mutagens detected by all the bacterial strains recommended by OECD TG471 (Williams et al., Mutation Res. 848:503081, 2019). We have extended this analysis by identifying the numbers and chemical classes of chemicals detected by these two strains either alone or in combination, including the role of S9. Using the Leadscope 2021 SAR Genetox database containing > 21,900 compounds, our dataset containing 7170 compounds tested in both TA98 and TA100. Together, TA98 and TA100 detected 94% (3733/3981) of the mutagens detected using all the TG471-recommended bacterial strains; 39% were mutagenic in one or both strains. TA100 detected 77% of all of these mutagens and TA98 70%. Considering the overlap of detection by both strains, 12% of these mutagens were detected only by TA98 and 19% only by TA100. In the absence of S9, sensitivity dropped by 31% for TA98 and 29% for TA100. Overall, 32% of the mutagens required S9 for detection by either strain; 9% were detected only without S9. Using the 2021 Leadscope Genetox Expert Alerts, TA100 detected 18 mutagenic alerting chemical classes with better sensitivity than TA98, whereas TA98 detected 10 classes better than TA100. TA100 detected more chemical classes than did TA98, especially hydrazines, azides, various di- and tri-halides, various nitrosamines, epoxides, aziridines, difurans, and half-mustards; TA98 especially detected polycyclic primary amines, various aromatic amines, polycyclic aromatic hydrocarbons, triazines, and dibenzo-furans. Model compounds with these structures induce primarily G to T mutations in TA100 and/or a hotspot GC deletion in TA98. Both TA98 and TA100 + /- S9 are needed for adequate mutagenicity screening with the Salmonella (Ames) assay.

Toxicity of fresh and aged anthropogenic smoke particles emitted from different burning conditions

There is substantial evidence that photochemical reactions in the atmosphere cause physico-chemical transformation of combustion smoke, but how this processing modifies potential health effects in exposed populations is not well understood. Here we utilized a new approach to simulate photochemical aging of anthropogenic smoke emissions (a mixture of plastic, plywood, and cardboard smoke) from two different burning conditions (smoldering vs. flaming) and investigated their adverse outcomes associated with mutagenic activity and the relative potencies of different polycyclic aromatic hydrocarbons (PAHs). Aging resulted in increased oxygenated volatile organic compound (VOC) emissions but largely degraded particle-bound PAH components in the smoke. Chemical transformation during aging was more dramatic for flaming versus smoldering smoke. Due to the PAH degradation, mutagenicity of the aged smoke from flaming combustion was much lower (up to 4 times) than that of the fresh smoke on per-particle mass basis. However, on the basis of particle emitted per fuel mass burned, the aged and fresh smoke particles exhibited similar mutagenic activities, which were up to 3 times higher for smoldering versus flaming smoke emissions. Similarly, the PAH toxicity equivalent (PAH-TEQ) of the aged smoldering smoke was 3 times higher than that of the aged flaming smoke particles, suggesting that some PAHs (e.g., indeno[c,d]pyrene and benzo[b]fluoranthene) in the smoldering smoke were more photochemically stable during aging. These findings increase understanding of the evolution of smoke emitted at different burning conditions and the role of photochemical transformations on mutagenicity and PAH-induced toxicity.

In vitro and in silico evaluation of the design of nano-phyto-drug candidate for oral use against Staphylococcus aureus

Onopordum acanthium is a medicinal plant with many important properties, such as antibacterial, anticancer, and anti-hypotensive properties. Although various studies reported the biological activities of O. acanthium, there is no study on its nano-phyto-drug formulation. The aim of this study is to develop a candidate nano-drug based on phytotherapeutic constituents and evaluate its efficiency in vitro and in silico. In this context, poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) of O. acanthium extract (OAE) were synthesized and characterized. It was determined that the average particle size of OAE-PLGA-NPs was 214.9 ± 6.77 nm, and the zeta potential was -8.03 ± 0.85 mV, and PdI value was 0.064 ± 0.013. The encapsulation efficiency of OAE-PLGA-NPs was calculated as 91%, and the loading capacity as 75.83%. The in vitro drug release study showed that OAE was released from the PLGA NPs with 99.39% over the 6 days. Furthermore, the mutagenic and cytotoxic activity of free OAE and OAE-PLGA-NPs were evaluated by the Ames test and MTT test, respectively. Although 0.75 and 0.37 mg/mL free OAE concentrations caused both frameshift mutation and base pair substitution (p < 0.05), the administered OAE-PLGA NP concentrations were not mutagenic. It was determined with the MTT analysis that the doses of 0.75 and 1.5 mg/mL of free OAE had a cytotoxic effect on the L929 fibroblast cell line (p < 0.05), and OAE-PLGA-NPs had no cytotoxic effect. Moreover, the interaction between the OAE and S. aureus was also investigated using the molecular docking analysis method. The molecular docking and molecular dynamics (MD) results were implemented to elucidate the S. aureus MurE inhibition potential of OAE. It was shown that quercetin in the OAE content interacted significantly with the substantial residues in the catalytic pocket of the S. aureus MurE enzyme, and quercetin performed four hydrogen bond interactions corresponding to a low binding energy of -6.77 kcal/mol with catalytic pocket binding residues, which are crucial for the inhibition mechanism of S. aureus MurE. Finally, the bacterial inhibition values of free OAE and OAE-PLGA NPs were determined against S. aureus using a microdilution method. The antibacterial results showed that the inhibition value of the OAE-PLGA NPs was 69%. In conclusion, from the in vitro and in silico results of the nano-sized OAE-PLGA NP formulation produced in this study, it was evaluated that the formulation may be recommended as a safe and effective nano-phyto-drug candidate against S. aureus.

Fate, detection technologies and toxicity of heterocyclic PAHs in the aquatic and soil environments

Heterocyclic polynuclear aromatic hydrocarbons (PAH) are characterized by higher aqueous solubility and enhanced bioavailability due to presence of nitrogen, sulfur or oxygen heteroatoms in their chemical structure and are referred to as nitrogen (PANH), sulfur (PASH) and oxygen (PAOH) heterocyclic PAHs, respectively. Inspite of their significant ecotoxicity and human health impacts, these compounds have not yet been included in the U.S. EPA's list of "priority PAH". The current paper presents a comprehensive review of the environmental fate, various detection techniques and toxicity of heterocyclic PAH compounds, highlighting their significant environmental impacts. Heterocyclic PAHs have been detected at 0.03 to 11,000 ng/L in various aquatic bodies and at 0.1 to 3210 ng/g in contaminated land. PANHs are the most polar heterocyclic PAHs, having aqueous solubility at least 10 to 10,000 times higher than PAH, PASH, and PAOH compounds, which make them more bioavailable. Aquatic fate of heterocyclic PAHs is dominated by volatilization and biodegradation processes for low molecular weight (MW) compounds and photochemical oxidation for high MW compounds. Sorption of heterocyclic PAHs on soil is governed by partitioning to soil organic carbon, cation exchange, and surface complexation mechanisms for PANHs and non-specific interactions, such as van der Waals forces with soil organic carbon for PASHs and PAOHs. Various chromatographic and spectroscopic techniques, such as HPLC and GC, NMR, and TLC have been employed to elucidate their distribution and fate in the environment. PANHs are also the most acutely toxic heterocyclic PAHs with EC₅₀ values ranging from 0.001 to 1100 mg/L in various species of bacteria, algae, yeast, invertebrate, and fish. Heterocyclic PAHs also induce mutagenicity, genotoxicity, carcinogenicity, teratogenicity, and phototoxicity in various aquatic and benthic organisms and terrestrial animals. Compounds, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and some acridine derivatives are proven human carcinogens and several other heterocyclic PAHs are suspected human carcinogens.

Biological effects of particulate matter samples during the COVID-19 pandemic: a comparison with the pre-lockdown period in Northwest Italy

In 2020, during the COVID-19 pandemic, containment measures were applied inducing potential changes in air pollutant concentrations and thus in air toxicity. This study evaluates the role of restrictions on biological effects of particulate matter (PM) in different Northwest Italy sites: urban background, urban traffic, rural, and incinerator. Daily PM samples collected in 2020 were pooled according to restrictions: January/February (no restrictions), March and April (first lockdown), May/June and July/August/September (low restrictions), October/November/December (second lockdown). The 2019 samples (pre-pandemic period) were pooled as 2020 for comparison. Pools were extracted with organic solvents and extracts were tested to assess cytotoxicity (WST-1 assay) and genotoxicity (comet assay) on BEAS-2B cells, mutagenicity (Ames test) on TA98 and TA100 Salmonella typhimurium strains, and estrogenic activity (gene reporter assay) on MELN cells. Pollutant concentrations were also analyzed (PM10, PM2.5, polycyclic aromatic hydrocarbons). No difference was observed for PM and polycyclic aromatic hydrocarbon concentrations between 2020 and 2019. During lockdown months (2020), PM cytotoxicity/genotoxicity was significantly lower in some sites than during 2019, while considering PM mutagenicity/estrogenic activity some differences were detected but without statistical significance. PM extract effects decreased in some sites during 2020; this may be due to lockdowns that reduced/modified pollutant emissions and may be related also to complex PM origin/formation and to meteorological conditions. In conclusion, the study confirms that PM biological effects cannot be assessed considering only the PM concentration and suggests to include a battery of bioassay for air quality monitoring in order to protect human health from air pollution effects.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s11869-023-01381-6.

Genotoxicity evaluation of cannabidiol

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.

Toxicological safety assessment of HempChoice® hemp oil extract; a proprietary extract consisting of a high concentration of cannabidiol (CBD) in addition to other phytocannabinoids and terpenes derived from CannabissativaL

HempChoice® Hemp Oil Extract (Geocann, LLC) is an extract of the aerial parts of hemp (Cannabis sativa L.) primarily comprised of 55-75% cannabidiol (CBD), 1-15% other phytocannabinoids and 1-15% terpenes. The results of multiple safety studies demonstrated that it was non-mutagenic in an Ames and mammalian cell micronucleus. test and was well tolerated in a 14-day range-finding study at dose levels up to 96.03. mg/kg BW/day. In the 90-day study, no HempChoice® Hemp Oil Extract-related significant changes were noted in weekly BW, daily BW gain, food consumption, functional observational battery or motor activity assessment. In addition, no HempChoice® Hemp Oil Extract related mortalities, abnormal clinical observations and ophthalmological changes were reported. Some HempChoice® Hemp Oil Extract-related changes were reported in the hematology and clinical chemistry parameters evaluated. These changes were not outside the normal range and were considered reversible during the 28-day recovery period. No macroscopic findings were reported, and histopathological changes related to HempChoice® Hemp Oil Extract exposure were limited to adaptive changes in the liver which were not observed in the recovery group animals. The no observed adverse effect level (NOAEL) for HempChoice® Hemp Oil Extract was determined to be 185.90 mg/kg BW/day in male and female Sprague-Dawley rats.

Impact of DNA repair polymorphisms on DNA instability biomarkers induced by lead (Pb) in workers exposed to the metal

Although the mechanisms of Pb-induced genotoxicity are well established, a wide individual's variation response is seen in biomarkers related to Pb toxicity, despite similar levels of metal exposure. This may be related to intrinsic variations, such as genetic polymorphisms; moreover, very little is known about the impact of genetic variations related to DNA repair system on DNA instability induced by Pb. In this context, the present study aimed to assess the impact of SNPs in enzymes related to DNA repair system on biomarkers related to acute toxicity and DNA damage induced by Pb exposure, in individuals occupationally exposed to the metal. A cross-sectional study was run with 154 adults (males, >18 years) from an automotive batteries' factory, in Brazil. Blood lead levels (BLL) were determined by ICP-MS; biomarkers related to acute toxicity and DNA instability were monitored by the buccal micronucleus cytome (BMNCyt) assay and genotyping of polymorphisms of MLH1 (rs1799977), OGG1 (rs1052133), PARP1 (rs1136410), XPA (rs1800975), XPC (rs2228000) and XRCC1 (rs25487) were performed by TaqMan assays. BLL ranged from 2.0 to 51 μg dL^-1 (mean 20 ± 12 μg dL^-1) and significant associations between BLL and BMNCyt biomarkers related to cellular proliferation and cytokinetic, cell death and DNA damage were observed. Furthermore, SNPs from the OGG1, XPA and XPC genes were able to modulate interactions in nuclear bud formation (NBUDs) and micronucleus (MNi) events. Taken together, our data provide further evidence that polymorphisms related to DNA repair pathways may modulate Pb-induced DNA damage; studies that investigate the association between injuries to genetic material and susceptibilities in the workplace can provide additional information on the etiology of diseases and the determination of environmentally responsive genes.

Genotoxicity of surface waters in Brazil

Brazil has abundant surface water resources, huge aquatic biodiversity and is home to 213 million people. Genotoxicity assays are sensitive tools to detect the effects of contaminants in surface waters and wastewaters, as well as to determine potential risks of contaminated waters to aquatic organisms and human health. This work aimed to survey the articles published in 2000-2021 that evaluated the genotoxicity of surface waters within Brazilian territory to unveil the profile and trends of this topic over time. In our searches, we considered articles focused on assessing aquatic biota, articles that conducted experiments with caged organisms or standardized tests in the aquatic sites, as well as articles that transported water or sediment samples from aquatic sites to the laboratory, where exposures were performed with organisms or standardized tests. We retrieved geographical information on the aquatic sites evaluated, the genotoxicity assays used, the percentage of genotoxicity detected, and, when possible, the causative agent of aquatic pollution. A total of 248 articles were identified. There was a trend of increase in the number of publications and annual diversity of hydrographic regions evaluated over time. Most articles focused on rivers from large metropolises. A very low number of articles were conducted on coastal and marine ecosystems. Water genotoxicity was detected in most articles, regardless of methodological approach, even in little-studied hydrographic regions. The micronucleus test and the alkaline comet assay were widely applied with blood samples, mainly derived from fish. Allium and Salmonella tests were the most frequently used standard protocols. Despite most articles did not confirm polluting sources and genotoxic agents, the detection of genotoxicity provides useful information for the management of water pollution. We discuss key points to be assessed to reach a more complete picture of the genotoxicity of surface waters in Brazil.

Ratio-dependent effects of photoactivated hypericin and manumycin A on their genotoxic and mutagenic potential

Natural compounds originated from plants and microorganisms and their combinations are currently being investigated as a possible treatment for several diseases including cancer. Hypericin (photodynamically-active pigment from Hypericum perforatum L.) and manumycin A (inhibitor of farnesyltransferase from Streptomyces parvulus) belong to the chemicals potentially applicable in clinical practice. In this study we evaluated potential cytotoxic (via trypan blue exclusion test), genotoxic (via DNA-topology and comet assays), and mutagenic effects (via bacterial reverse mutation test) of these compounds and their combinations considering the molecular mechanism of their action in cell-free and cellular systems. Our results did not reveal neither cytotoxic nor mutagenic activities of tested compounds and their combinations. Regarding the genotoxic potential, no damage of plasmid DNA in cell-free system was detected. On the other hand, photoactivated hypericin and manumycin A were able to induce primary DNA damage in human lymphocytes analyzed by comet assay. The possible antagonistic interactions between these two metabolites were estimated using SynergyFinder software analysis and experimental data obtained from comet assay. Our findings indicate that not only the presence of substances, but also their ratio plays an important role in resulting effects of the combined treatment in cellular system.

Impact of Shodhana an Ayurvedic purification process on cytotoxicity and mutagenicity of Croton tiglium Linn

BACKGROUND

Croton tiglium Linn. (CT) which is commonly called Jaypal is used in Ayurvedic preparations like Ichhabhedi Ras, Asvakancuki Rasa. Due to its toxic contents, seeds of Croton tiglium are purified before use, by the process mentioned in classical Ayurvedic texts called Shodhana meaning purification.

OBJECTIVES

The objective of the present study is to study the impact of Ayurvedic Purification process on cytotoxicity and genotoxicity of Croton tiglium Linn.

MATERIALS AND METHODS

Croton tiglium Linn. Seeds were processed for Shodhana by soaking in water, heating with milk (Snehan) and later grinding in Lemon Juice (Bhavana). Aqueous and Hydroalcoholic extracts were prepared before and after purification i.e. Shodhana. Cytotoxicity of the Croton tiglium was studied against Chinese Hamster Ovary cell line by MTT assay. Ames test was performed to study the mutagenicity of the extracts in Salmonella typhi TA 98, 100 and 102 strains. Phytoconstituents were studied by using LCMS analysis.

RESULTS

The results indicated decrease in cytotoxic concentration (IC50) of Croton tiglium seeds after purificationa from 3.03 mg/mL to 0.99 mg/mL in aqueous extract and 18.56 mg/mL to 5.45 mg/mL. Genotoxicity study by Ames test indicated Croton tiglium Linn. Croton tiglium Linn. Seeds are non-genotoxic in strains like S. typhi, TA 98, 100 and 102. There was change in Phytochemical profile before and after shodhana.

CONCLUSION

Although both the concentrations are practically non-toxic, the decrease in cytotoxic concentration indicates Purification process as described in classical ayurvedic texts i.e. Shodhana has definitely increased the potency of the seeds of Croton tiglium Linn.

Genotoxicity evaluation of graphene derivatives by a battery of in vitro assays

The interest of graphene materials has increased markedly in the recent years for their promising applications in many fields as food packing. These new applications have caused some concern regarding their safety for consumers since the intake of these materials may increase. In this sense, a battery of in vitro test is required before its use as a food contact material. Then, the aim of this study was to assess the potential mutagenicity and genotoxicity of graphene oxide (GO) and reduced-graphene oxide (rGO) following the recommendations of the European Food Safety Authority (EFSA). Thus, the mouse lymphoma assay (MLA) and the micronucleus test (MN) were performed in L5178YTk ± cells, and the Caco-2 cells were used for the standard and modified comet assays. The results indicated that GO (0-250 μg/mL) was not mutagenic in the MLA. However, rGO revealed mutagenic activity from 250 μg/mL and 125 μg/mL after 4h and 24h of exposure, respectively. In the MN test, negative results were obtained for both compounds at the concentrations assayed (0-250 μg/mL) for GO/rGO. Moreover, no DNA strand breaks, or oxidative DNA damage were detected in Caco-2 cells exposed to GO (0-250 μg/mL) and rGO (0-176.3 μg/mL for 24h and 0-166.5 μg/mL for 48h). Considering the mutagenic potential of rGO observed further investigation is needed to describe its toxic profile.

Olive juice dry extract containing hydroxytyrosol, as a nontoxic and safe substance: Results from pre-clinical studies and review of toxicological studies

Products derived from olives, such as the raw fruit and oils, are widely consumed due to their taste, and purported nutritional/health benefits. Phenolic compounds, especially hydroxytyrosol (HT), have been proposed as one of the key substances involved in these effects. An olive juice extract, standardized to contain 20% HT ("OE20HT"), was produced to investigate its health benefits. The aim of this study was to demonstrate the genotoxic safety of this ingredient based on in vitro Ames assay and in vitro micronucleus assay. Results indicated that OE20HT was not mutagenic at concentrations of up to 5000 µg/plate, with or without metabolic activation, and was neither aneugenic nor clastogenic after 3-hour exposure at concentrations of up to 60 µg/mL with or without metabolic activation, or after 24-hour exposure at concentrations of up to 40 µg/mL. To further substantiate the safety of OE20HT following ingestion without conducting additional animal studies, a comprehensive literature review was conducted. No safety concerns were identified based on acute or sub-chronic studies in animals, including reproductive and developmental studies. These results were supported by clinical studies demonstrating the absence of adverse effects after oral supplementation with olive extracts or HT. Based on in vitro data and the literature review, the OE20HT extract is therefore considered as safe for human consumption at doses up to 2.5 mg/kg body weight/day.

CDK8/19 inhibition plays an important role in pancreatic β-cell induction from human iPSCs

BACKGROUND

Transplantation of differentiated cells from human-induced pluripotent stem cells (hiPSCs) holds great promise for clinical treatments. Eliminating the risk factor of malignant cell transformation is essential for ensuring the safety of such cells. This study was aimed at assessing and mitigating mutagenicity that may arise during the cell culture process in the protocol of pancreatic islet cell (iPIC) differentiation from hiPSCs.

METHODS

We evaluated the mutagenicity of differentiation factors used for hiPSC-derived pancreatic islet-like cells (iPICs). We employed Ames mutagenicity assay, flow cytometry analysis, immunostaining, time-resolved fluorescence resonance energy transfer-based (TR-FRET) cell-free dose-response assays, single-cell RNA-sequencing and in vivo efficacy study.

RESULTS

We observed a mutagenic effect of activin receptor-like kinase 5 inhibitor II (ALK5iII). ALK5iII is a widely used β-cell inducer but no other tested ALK5 inhibitors induced β-cells. We obtained kinase inhibition profiles and found that only ALK5iII inhibited cyclin-dependent kinases 8 and 19 (CDK8/19) among all ALK5 inhibitors tested. Consistently, CDK8/19 inhibitors efficiently induced β-cells in the absence of ALK5iII. A combination treatment with non-mutagenic ALK5 inhibitor SB431542 and CDK8/19 inhibitor senexin B afforded generation of iPICs with in vitro cellular composition and in vivo efficacy comparable to those observed with ALK5iII.

CONCLUSION

Our findings suggest a new risk mitigation approach for cell therapy and advance our understanding of the β-cell differentiation mechanism.

A novel combination of immobilized Enterococcus casseliflavus sp. nov. with silver nanoparticles into a reusable matrix of Ca-Alg beads as a new strategy for biotreatment of Disperse Blue 183: Insights into metabolic characterization, biotoxicity, and mutagenic properties

Recent advances in immobilized biologic systems for decolorizing azo dyes are gaining great attention due to microorganisms like bacteria and nanoparticles that could stimulate decolorization. Enhanced decolorization performance was observed in this study, indicating the great potential of the immobilized complex of bacterial cells and AgNPs as an alternative to the traditional biological processes to improve the performance of biological systems. The biodegradation and decolorization of Disperse Blue183 (DB 183) were investigated utilizing a novel combination of Enterococcus casseliflavus strain A₂ mediated by silver nanoparticles synthesized by Marinospirillum alkaliphilum strain N in three different conditions. Ⅰ: free bacterial strain A₂ (100% dye removal in 72 h), Ⅱ: immobilized bacterial strain A₂ in Ca-Alg beads (100% dye removal in 15 h), and Ⅲ: immobilized bacterial strain A₂ with silver nanoparticles (AgNPs) as support in Ca-Alg beads (100% dye removal in 9 h). The presence of bacterial cells and nanoparticles in Ca-Alg beads was assessed and proved by scanning electron microscope (SEM) and X-ray energy diffraction (EDX) analysis. Moreover, DB 183 and its decolorization metabolites were evaluated by applying UV-Vis, infrared spectroscopy (FTIR), and GC/MS, and the results showed that the dye was degraded. The antimicrobial effect, brine shrimp toxicity (BST) test, and mutagenicity assay in the presence and absence of metabolic activation (+S9/-S9) were run to assess DB 183 and metabolite obtained from biodegradation. The antimicrobial activity of DB 183 disappeared after treatment. Further, the results of the BST test determined that the dye has moderate biotoxicity (LC₅₀:0.064 mg/mL), and the after-treatment product was not toxic. According to the Ames test, DB 183 had mutagenicity effect (69-84%), and the metabolic activation increased the mutagenicity of the dye) 12-25%). However, the percentage mutagenicity of decolorization products decreased, ranging from 50 to 80% without activation (-S9) and 83-96% in present activation (+S9). This work used the immobilized bacterial cells and AgNPs Ca-Alg gel beads for the first time to introduce this kind of system as a suitable technique for rapid decolorization. Using this application enables a remarkable reduction in the time dedicated to the bioremediation of dyeing wastewater.

Comparative chemical analysis, mutagenicity, and genotoxicity of Petroleum refinery wastewater and its contaminated river using prokaryotic and eukaryotic assays

Concern on the toxicity of final wastewater generated by the petroleum refining industry has increased in recent years due to the potential health threats associated with their release into the waterways. This study determined the mutagenic and genotoxic potential of petroleum refinery wastewater and a receiving river using the Ames fluctuation test on Salmonella typhimurium strains TA100 and TA98, SOS chromotest on Escherichia coli PQ37, and piscine peripheral micronucleus (MN) assay. Analyses of the physicochemical parameters, heavy metal, and organic contents of the samples were also performed. Ames test result showed that the two tested samples were mutagenic with TA100 strain as the more responsive strain for both the refinery wastewater and the river sample in terms of the calculated mutagenic index. A similar result was obtained in the SOS chromotest; however, the E. coli PQ37 system recorded a slightly higher sensitivity for detecting genotoxins than the Salmonella assay in the two samples. MN data showed induction of a concentration-dependent significant (p < 0.05) increase in the frequency of MN by both samples when compared with the negative control. Generally, the refinery wastewater induced the highest mutagenicity and genotoxicity compared to the river sample in the three assays used. Haemoglobin, platelets, red blood cells, mean corpuscular volume, total white blood cells, heterophils, haematocrit, and eosinophils reduced significantly with increased lymphocytes, basophils, mean corpuscular haemoglobin, and mean corpuscular haemoglobin concentration in fishes exposed to both samples. Total petroleum hydrocarbon, benzene, toluene, phenol index, polycyclic aromatic hydrocarbons, cadmium, mercury, nickel, lead, and vanadium contents analysed in the samples were believed to be responsible for the observed genotoxicity and mutagenicity. The findings of this study revealed that petroleum refinery wastewater is a potential mutagenic and genotoxic risk to the environment.

In vitro genotoxicity assessment of graphene quantum dots nanoparticles: A metabolism-dependent response

Nanomaterials are progressively being applied in different areas, including biomedical uses. Carbon nanomaterials are relevant for biomedical sciences because of their biocompatibility properties. Graphene quantum dots (GQD) have a substantial potential in drug-delivery nanostructured biosystems, but there is still a lack of toxicological information regarding their effects on human health and the environment. We thus evaluated the mutagenicity, cytotoxicity and genotoxicity of this nanomaterial using alternative methods applied in regulatory toxicology guidelines. The Ames test was carried out in the presence and absence of exogenous metabolization. Salmonella enterica serovar Typhimurium strains TA97a, TA98, TA100, TA102, TA104, and TA1535 were exposed to GQD with concentrations ranging from 1 to 1000 μg/plate. The mammal cell viability assays were carried out with HepG2 and 3T3BalbC cell lineages and the in vitro Cytokinesis-Block Micronucleus assay (CBMN) was applied for 24 h of exposure in non-cytotoxic concentrations. Mutagenicity was induced in the TA97a strain in the absence of exogenous metabolization, but not in its presence. Mutagenicity was also detected in the TA102 strain in the assay with exogenous metabolization, suggesting redox misbalance mutagenicity. The WST-1 and LDH assays demonstrated that GQD decreased cell viability, especially in 3T3BalbC cells, which showed more sensitivity to the nanomaterial. GQD also increased micronuclei formation in 3T3BalbC and caused a cytostatic effect. No significant impact on HepG2 micronuclei formation was observed. Different metabolic systems interfered with the mutagenic, cytotoxic, and genotoxic effects of GQD, indicating that liver metabolism has a central role in the detoxification of this nanomaterial.

Evaluation of mutagenic, cytotoxic, mitochondrial dysfunction, apoptotic activity, and acute toxicity of ethanolic extract of Cissus quadrangularis

Recent studies have focused on exploring the efficacy of Cissus quadrangularis extract (EECQ) against various metabolic disorders involving the liver as the prime target organ, suggesting a considerable threat of hepatotoxicity in the person encountering it. Consequently, the current study was aimed to unravel the mutagenic, cytotoxic, mitochondrial dysfunction, apoptotic activity in HepG2 cells, and acute toxicity of EECQ. MTT, SRB, trypan blue dye exclusion, and lactate dehydrogenase (LDH) assay were performed in HepG2 cell lines to determine the cytotoxicity of the extract. The mutagenic potential was determined by the Ames test using various strains of Salmonella typhimurium. Acute toxicity was done at a dose of 2000 mg/kg in Sprague Dawley rats. MTT and SRB cytotoxicity assays demonstrated dose-dependent cytotoxicity of extract. The three highest noncytotoxic doses from the above assay, investigated by trypan blue dye exclusion and LDH assay, did not reveal cytotoxicity. Besides, mitochondrial dysfunction was determined by measuring cellular and mitochondrial ROS, ATP, NAD, mitochondrial membrane potential, Bax/Bcl2 ratio, mitochondrial and cytoplasmic cytochrome c, and apoptosis-inducing factor, were found to be equivalent in both extract exposed and unexposed cells. Moreover, the apoptotic cell morphology and the expression of pro-apoptotic mRNAs and proteins were equivalent in both the group. In acute toxicity, EECQ in rats did not cause any significant change in body weight, liver index, and liver function test. All-encompassing, the present study unraveled that EECQ is not mutagenic, cytotoxic, nor apoptotic in human hepatic cells, as well as neither acute toxicity.

Is Poland at risk of urban road dust? Comparison studies on mutagenicity of dust

Depopulation concerns many polish cities, with the exception of a few metropolises such as Wrocław (Lower Silesia) and Katowice (Upper Silesia) where investments are growing and therefore more humans are exposed to urban environmental pollution. Accumulation of toxic substances on road surfaces is a major global challenge requiring methods of assessing risk that initiate the proper management strategies. In this study urban road dust (URD) has been collected at seventeen sites in Lower and Upper Silesia regions in Poland renowned for their elevated level of pollution. The aim of the study was: (i) to determine PAH concentration in URD in both regions with the identification of their possible sources based on diagnostic ratio; (ii) to assess possible mutagenic effects of URD with the application of Ames test (Salmonella assay); (iii) to define a possible carcinogenic risk related to URD in both studied regions. We found that the total PAH content of collected URD samples ranged from 142.4 to 1349.4 ng g^-1. The diagnostic ratio of PAHs in URD for all studied sites showed that pyrogenic combustion predominated indicating traffic-related and biomass sources of pollution. The Ames assay, which has never been used in studies of URD in Poland, demonstrated that in both regions, URD samples (from eight sites), were characterised by the highest mutagenicity values. Additionally, Incremental Lifetime Cancer Risk (ILCR) values, based on PAH content only, were between 10 and 6 to 10-4 indicating potential risk of cancer. Reassuming, humans in both agglomerations are exposed to factors or compounds with carcinogenic properties which may have an adverse health effect through the urban road dust mainly due to vehicular traffic, heating systems and industrial activities.

Physicochemical characterization and oxidative potential of size fractionated Particulate Matter: Uptake, genotoxicity and mutagenicity in V-79 cells

For many years, the impact of Particulate Matter (PM) in the ambient air has been one of the major concerns for the environment and human health. The consideration of the heterogeneity and complexity of different size fractions is notably important for the assessment of PM toxicological effects. The aim of the study was to present a comprehensive size-composition-morphology characterization and to assess the oxidative potential, genotoxicity, and mutagenicity of the atmospheric PM fractions, collected by using MOUDI near a busy roadside in Lucknow, India. Physicochemical characterization of ambient coarse particles (1.8-10 µm), fine particles (0.32-1.8 µm), quasi-ultrafine (0.1-0.32 µm) and ultrafine particles (≤0.1 µm) along with SRM 1649b was done using TEM, SEM, DLS, NTA, ICP-MS, and IC in parallel with the estimation of exogenous Reactive Oxygen Species (ROS) by acellular assays. In this study, two different acellular assays, dithiothreitol (DTT) and the CM-H₂DCFDA assay, indicated stronger mass-normalized bioactivity for different size ranges. Enrichment factor analysis indicated that the different size fractions were highly enriched with elements of anthropogenic origin as compared to elements of crustal origin. The endotoxin concentration in different size fractions was also estimated. Cellular studies demonstrated significant uptake, cytotoxicity, ultrastructural changes, cellular ROS generation, and changes in the different phases of the cell cycle (Sub G1, G1, S, G2/M) exposed to different size fractions. The Comet assay and the Micronucleus assay were used to estimate genotoxicity. Mutagenic potential was revealed by the HGPRT gene forward mutation assay in V-97 cells. Conclusively, our results clearly indicate that the genotoxic and mutagenic potential of the coarse PM was greater than the other fractions, and interestingly, the ultrafine PM has higher bioactivity as compared to quasi-ultrafine PM.

Screening of natural surface waters of the Almaty region of the Republic of Kazakhstan for toxic and mutagenic activity

Natural aquatic ecosystems are a habitat for many organisms, a source of drinking water, and a resource for human economic activity. However, natural surface waters have been subjected to intense anthropogenic pressure in recent decades. The current study was dedicated to investigating genotoxic potential in 15 rivers and 2 lakes of Almaty agglomeration (Kazakhstan) using a battery of bioassays. Non-diluted surface water samples were tested for mutagenic potential using Lux-based bacterial biosensors and a chromosome aberration test on Hordeum vulgare and Mus musculus. The studies involved lux-biosensors pRecA-lux, pColD-lux, pSoxS-lux, pKatG-lux did not find any genotoxic and oxidative effects. However, the mutagenicity of the studied water samples was detected by using plant and animal tests (Hordeum vulgare and Mus musculus). Mutagenic (increase in the frequency of chromosomal aberrations) activity of the water samples was observed. Among 17 sample collection points, surface waters of 12 were considered to possess mutagenic activity when tested on Hordeum vulgare. The results of the cytogenetic assay on mice bone marrow are alarming, as the survey proposed the strong genotoxic potential of water for mammals. Among 17 sample collection points, surface waters of 7 were considered to possess mutagenic activity when tested on Mus musculus. This comprehensive study indicates that the contamination of the surface natural waters poses a threat to river dwellers and the human population in the rivers and lakes areas.

Microcystin-LR-induced nuclear translocation of cGAS promotes mutagenesis in human hepatocytes by impeding homologous recombination repair

Microcystin-LR (MC-LR) has been recognized as a typical hepatotoxic cyclic peptides produced by cyanobacteria. Nowadays, due to the frequent occurrence of cyanobacterial blooms, the underlying hepatotoxic mechanism of MC-LR has become the focus of attention. In our present work, the mutagenic effect of MC-LR on human normal hepatic (HL-7702) cells regulated by cGAS was mainly studied. Here, we showed that exposure to MC-LR for 1-4 days could activate the cGAS-STING signaling pathway and then trigger immune response in HL-7702 cells. Notably, relative to the treatment with 1 μM MC-LR for 1-3 days, it was observed that when HL-7702 cells were exposed to 1 μM MC-LR for 4 days, the mutation frequency at the Hprt locus was remarkably increased. In addition, cGAS in HL-7702 cells was also found to complete the nuclear translocation after 4-day exposure. Moreover, co-immunoprecipitation and homologous recombination (HR)-directed DSB repair assay were applied to show that homologous recombination repair was inhibited after 4-day exposure. However, the intervention of the nuclear translocation of cGAS by transfecting BLK overexpression plasmid restored homologous recombination repair and reduced the mutation frequency at the Hprt locus in HL-7702 cells exposed to MC-LR. Our study unveiled the distinct roles of cGAS in the cytoplasm and nucleus of human hepatocytes as well as potential mutagenic mechanism under the early and late stage of exposure to MC-LR, and provided a novel insight into the prevention and control measures about the hazards of cGAS-targeted MC-LR.

Environmentally realistic concentrations of eprinomectin induce phytotoxic and genotoxic effects in Allium cepa

Eprinomectin, a veterinary drug within the family of avermectins, is widely used in the agricultural sector to combat a variety of parasites, mainly nematodes. However, only 10% of the drug is metabolized in the organism, so large quantities of the drug are released into the environment through urine and/or feces. Soil is the first and main environmental compartment to be contaminated by it, and nontargeted organisms can be affected. Thus, the present study aims to evaluate the phytotoxicity (through the evaluation of germination, root development, and germination speed) and genotoxicity (through an assessment of the induction of micronuclei and chromosomal aberrations) of eprinomectin. For the analyses, Allium cepa seeds were germinated in soil contaminated with a range of concentrations of eprinomectin: from 0.5 to 62.5 μg/g for the genotoxicity test and from 0.5 to 128.0 μg/g for the phytotoxicity test. The results showed that seed germination was not affected, but root development was affected at concentrations of 0.5 μg/g, 1.0 μg/g, 4.0 μg/g, 8.0 μg/g, 64.0 μg/g, and 128.0 μg/g, and germination speed was significantly changed at concentrations of 1.0 μg/g, 4.0 μg/g, 16.0 μg/g, 32.0 μg/g, and 64.0 μg/g. Significant differences in the mitotic index and genotoxicity index were observed only at concentrations of 2.5 μg/g and 12.5 μg/g, respectively. Only the 0.5 μg/g concentration did not show significant induction of micronuclei in the meristematic cells, but the damage observed at other concentrations did not persist in F₁ cells. According to the results, eprinomectin is both phytotoxic and genotoxic, so the release of eprinomectin into the environment should be minimized.

Safety assessment of marigold flavonoids from marigold inflorescence residue

ETHNOPHARMACOLOGICAL RELEVANCE

Marigold flavonoids, extracted from marigold (Tagetes erecta L.) inflorescence residues, have attracted significant attention with respect to antioxidant, anti-inflammatory and chelating properties. However, the toxicity of marigold flavonoids have not yet been fully investigated.

AIM OF THE STUDY

The main purpose of this study was to assess the safety of marigold flavonoids extracted from Marigold (Tagetes erecta L.) in order to provide information on its nonclinical safety. Thus, the acute oral toxicity, in vitro Ames test, sperm aberration study, bone marrow micronucleus test, subchronic oral toxicity test, and teratogenic potential were carried out in rats or mice.

MATERIALS AND METHODS

For an acute oral toxicity test, SD rats and ICR mice (male and female, n = 5) orally received a single dose of 5000 mg/kg marigold flavonoids. Evaluation of marigold flavonoids genotoxic potential with a battery of tests, including an in vitro bacterial reverse mutation test using four mutant strains of Salmonella typhimurium (TA₉₇、TA₉₈、TA₁₀₀、TA₁₀₂), an sperm aberration test and an in vivo micronucleus test using bone marrow cells ICR mice that were orally administered marigold flavonoids, an subchronic oral toxicity study and teratogenic test employing male and female SD rats that were orally administered marigold flavonoids. All animals tests were completed in accordance with GB 15193 for toxicity tests.

RESULTS

In the acute oral toxicity test, marigold flavonoids given at the dose of 5000 mg/kg body weight for 14 days didn't produce any abnormal clinical symptoms or mortality in SD rats and ICR mice (both sex, n = 5). There was no evidence of genotoxicity of marigold flavonoids based on the results of the in vitro bacterial reverse mutation test (up to 1250 μg/plate), the sperm aberration test (up to 5000 mg/kg body weight), the in vivo micronucleus test (up to 5000 mg/kg body weight), the subchronic oral toxicity study (up to 10 g/kg feed dose) and the teratogenic test (up to 1250 mg/kg body weight).

CONCLUSIONS

We found that marigold flavonoids are safe with regard to acute toxicity in rats or mice as well as genotoxicity such as mutagenesis or clastogenesis under the present experimental conditions. These results might support the safety of marigold flavonoids as a potential therapeutic material for the traditional use of herbal medicines and for the further development of novel antioxidant.