Hydrogen peroxide (H2O2) is an oxidative and genotoxic chemical that has widespread use as marine antifoulant treatment, anti-parasitic treatment in finfish farming, and chemical waste discharged from municipal sources. Marine species can experience short-term exposure to high concentrations before dilution and degradation of H2O2. Benthic adult sea urchins spawn gametes directly into the water column, making them a valuable sentinel model for assessing impacts of pelagic exposure. Sea urchin gametes were exposed to H₂O₂ (1 mM, 10 min) and evaluated for DNA damage (strand breaks, oxidised nucleotides, and total cytosine methylation) by the modified fast micromethod and cross-fertilized to produce sea urchin embryos to assess DNA damage and developmental anomalies. A significant increase of DNA damage with strand scission factor of up to 0.11 ± 0.01 (mean ± SD) was detected in blastula embryos (age 24 h) and up to 0.10 ± 0.01 (mean ± SD) in re-exposed blastula embryos fertilised from unexposed eggs and exposed (1 mM H2O2) sperm. No significant differences in total methylation were detected in any cross-fertilisation treatments after gamete exposure, but there was a non-significant trend in hypermethylation in embryos fertilised from unexposed eggs and exposed sperm, suggesting that paternal exposure to H₂O₂ poses a grater genotoxic risk to developing embryos than maternal exposure. The consequences of hypermethylation for larval development and survival remain unresolved. Integrating measures of DNA damage with epigenetic methylation changes across the gamete-embryo transition and early embryonic development provides critical insight into cross-generational mechanistic impacts of genotoxicants on ecologically critical broadcast spawning species in marine ecosystems.
Aryl guanylhydrazones are a class of compounds with diverse biological activities, including antibacterial, antimalarial, and antiparasitic effects. Despite their therapeutic potential, some derivatives may present toxicological concerns, particularly regarding genotoxicity and mutagenicity. This study aimed to evaluate the genotoxic and mutagenic potential of two aryl guanylhydrazone derivatives: 2,6-dichlorobenzylidene guanylhydrazone (Guanabenz-1), used as a structural reference compound, and 2-bromo-4,5-methylenedioxybenzylidene guanylhydrazone (GHBrPip-2), a candidate compound. In vivo assays included the Comet assay and the Micronucleus (MN) test in Mus musculus under repeated-dose conditions. Guanabenz-1 was administered at 125, 250, and 500 mg/kg, and GHBrPip-2 at 375, 750, and 1500 mg/kg, via oral gavage in three consecutive doses at 24-hour intervals. For the Comet assay, peripheral blood was collected at 4 and 8 h after the first administration and at 72 h (corresponding to 24 h after the final dose), while liver and bone marrow samples were collected at 72 h. The MN test was performed in bone marrow and peripheral blood at 72 h. Both compounds induced increases in DNA damage at specific time points. GHBrPip-2 showed earlier and more pronounced effects in the Comet assay, whereas Guanabenz-1 exhibited limited and less consistent responses. However, no clear dose–response relationship was observed for either compound. Notably, increased variability, including elevated mean DNA damage at lower doses without statistical significance, suggests that some findings may reflect inter-individual variation rather than consistent biological effects. In the MN assay, minimal effects were observed in bone marrow, while increases in micronucleus frequency were detected in peripheral blood, particularly for GHBrPip-2. These differences should be interpreted with caution, as peripheral blood analysis was included as a complementary endpoint under repeated-dose conditions. All effects were observed at or near maximum tolerated doses. Overall, Guanabenz-1 demonstrated low and inconsistent genotoxic effects, whereas GHBrPip-2 showed a higher propensity to induce DNA damage under the experimental conditions. These findings should be considered as part of an initial hazard identification approach, and further studies using optimized experimental designs and pharmacologically relevant dose ranges are required to clarify the genotoxic profile of GHBrPip-2.
DNA oxidation damage contributes to carcinogenesis and limits the efficacy of many chemotherapeutics. Although platinum-based drugs remain crucial in cancer therapy, their clinical use is restricted by toxicity and acquired resistance. However, quinazolinone derivatives have recently attracted attention as scaffolds with promising biological activities. Among these, Schiff bases are of particular interest because they can provide suitable ligands for the complexation with metals, making them a potential substitute for cisplatin. Therefore, in the search for new anticancer agents, Cu(II) complexes based on 2,3-substituted quinazolinones have been studied in detail. The radical scavenging/reducing efficiency and DNA-protective effects were monitored using DPPH, FRAP and DNA topology assays. Ligands and Cu(II) complexes, were screened for their in vitro cytotoxic, genotoxic, and protective activity in human hepatocarcinoma (HepG2) cells using the MTT and Comet assays. The results showed that compounds studied are redox-active agents. Cu(II) complexes exhibited higher DPPH radical-scavenging activity in comparison with their corresponding free ligands; they manifested comparable effects in ferric reducing power as well as in DNA topology assays. The cellular assays revealed markedly higher cytotoxicity of Cu(II) complexes compared with the corresponding free ligands. In the presence of H2O2, C1 significantly enhanced DNA damage, whereas C2 did not alter the level of DNA damage induced by H2O2 alone. On the contrary, ligands exhibited much lower toxicity and significant protection of HepG2 cells against H2O2. The incorporation of Cu(II) ions into quinazolinone Schiff base ligands substantially alters their biological activity, shifting their profile from DNA-protective to cytotoxic/pro-oxidant. DFT calculations were performed for both Cu(II) complexes to investigate molecular features that may contribute to their different biological activity. These results highlight the potential of quinazolinone-Cu(II) complexes as anticancer candidates and support further studies into their mechanisms of action.
Plastic pollution is a growing public health concern. Nanoplastics (NPs) are defined as plastic particles < 1000 nm diameter. Microplastics and NPs have been detected in foods, water, and air. In this mini-review, we assess the genotoxic effects of primary (polystyrene) and secondary (‘true-to-life’) NPs in cultured mammalian cells. Studies were identified in the PubMed, Scopus, and Web of Science databases. Narrative review of the literature was supported by statistical analysis of associations between reported genotoxic effects (positive or null effects, or semi-quantitative indicators of effect size) and cell type (immune vs. non-immune cells), genotoxicity endpoint (repairable vs. permanent DNA lesions), maximal exposure concentration, particle size (> the defined size of nanoparticles, 100 nm) and surface modification in polystyrene NP studies. Results from 36 studies show that, as determinants of the effects of polystyrene NPs, biological differences (cell type and genotoxicity endpoint) are more important than the exposure concentration or the particle characteristics (particle size and surface modification). There is higher consistency or stronger effect in studies on immune cells vs. non-immune cells, and some evidence of stronger effect on permanent DNA lesions (mainly micronuclei, MN) vs. repairable damages (mainly, comet assay endpoints). Results from nine studies on true-to-life NPs from polyethylene terephthalate (PET) plastics suggest genotoxic potential, although differences in plastic degradation methods may affect the level of genotoxicity. Overall, the analysis shows that primary (polystyrene) and true-to-life (PET) NPs can generate DNA damage in cultured mammalian cells.
Chronic hyperglycemia in diabetes mellitus (DM) may promote oxidative stress, cytotoxicity, and chromosomal instability. However, evidence regarding exfoliated urothelial cells remains limited. This study evaluated micronucleus (MN) frequency and other nuclear anomalies in urothelial cells from women with type 1 DM (T1DM) and type 2 DM (T2DM) and investigated predictors of MN formation. Twenty women with T1DM, 25 with T2DM, and 22 controls were included. Second-void urine samples were collected, and urothelial cells were Feulgen-stained. MN and other nuclear anomalies were assessed in 1000 cells per participant. Clinical and metabolic characteristics were compared, and multivariable binary logistic regression identified predictors of MN formation. Age and BMI differed significantly among T1DM, T2DM, and control groups. T2DM participants had significantly longer diabetes duration than T1DM participants. HbA1c was significantly higher in both DM groups than in controls. Total cholesterol, HDL, and triglycerides also differed significantly among groups, whereas LDL did not. MN frequency was higher in diabetic participants overall but this increase was not statistically significant. Nuclear buds and degenerative changes were significantly more frequent in both DM groups. In direct comparisons of the DM patient groups, NB, KR, KL, and CC frequencies were significantly higher in T2DM than in T1DM participants. In multivariable analysis, longer DM duration and higher HbA1c levels independently predicted MN formation. DM was associated with increased nuclear anomalies in urothelial cells, although MN frequency was not significantly elevated. Longer disease duration and higher HbA1c independently predicted MN formation, suggesting that chronic metabolic exposure may contribute to urothelial cellular damage.
