Genotoxicity of the herbicide imazethapyr in mammalian cells by oxidative DNA damage evaluation using the Endo III and FPG alkaline comet assays

Abstract

We evaluated the role of oxidative stress in the genotoxic damage induced by imazethapyr (IMZT) and its formulation Pivot® in mammalian CHO-K1 cell line. Using the alkaline comet assay, we observed that a concentration of 0.1 μg/mL of IMZT or Pivot® was able to induce DNA damage by increasing the frequency of damaged nucleoids. To test whether the DNA lesions were caused by oxidative stress, the DNA repair enzymes endonuclease III (Endo III) and formamidopyrimidine-DNA glycosylase (Fpg), which convert base damage to strand breaks, were used. Our results demonstrate that after treatment of CHO-K1 cells with the pure active ingredient as well as the commercial formulation Pivot®, an increase in DNA strand breaks was observed after incubation of both Endo III and Fpg enzymes, indicating that both compounds induce DNA damage involving both pyrimidine and purine-based oxidations, at least in CHO-K1 cells. Our findings confirm the genotoxic potential of IMZT and suggest that this herbicide formulation must be employed with great caution, especially not only for exposed occupational workers but also for other living species.

Ecotoxicological assessment of Uruguay River and affluents pre- and post-pesticides’ application using Caenorhabditis elegans for biomonitoring

“…For instance, it has been found to cause oxidative stress and endocrine disruption in rats (Yang et al 2018) and developmental toxicity associated to thyroid dysfunction in zebrafish (Li et al 2020). Finally, imazethapyr has also been reported by causing metabolic alterations in Cyprinus carpio (Moraes et al 2011), genotoxicity in tadpoles of Rhinella arenarum and Hypsiboas pulchellus species (Carvalho et al 2019;Perez-Iglesias et al 2017;Perez-Iglesias et al 2015), and also in mammalian cells (Soloneski et al 2017); however, the toxicity of herbicide is poorly characterized and needs to be further investigated.…”

Evaluation of imazethapyr-induced DNA oxidative damage by alkaline Endo III- and Fpg-modified single-cell gel electrophoresis assay in Hypsiboas pulchellus tadpoles (Anura, Hylidae)

“…We could emphasize the importance of using the modified SCGE technique to assess oxidative damage introduced into the DNA of amphibians as a consequence of pesticide exposure. Our observations reveal that treatment with both Endo III and Fpg buffers induce an enhancement in the frequency of DNA damage duce lesions into cellular DNA, and thus increasing the length of the nucleoids (Collins and Azqueta, 2012;Demir et al, 2014;Soloneski et al, 2016Soloneski et al, , 2017. Furthermore, our results demonstrate that the modified SCGE assay using Fpg, but not Endo III, turned out to be highly sensitive and effective in detecting genetic oxidative damage introduced into the DNA of circulating blood cells of H. pulchellus tadpoles by the herbicide IMZT-based commercial formulation Pivot H ® at purine bases, but not pyrimidines.…”

“…Whereas IMZT did not induce chromosomal aberrations in rat bone marrow cells, both negative and positive results have been reported for CHO cells with and without metabolic activation, respectively (USEPA, j). Furthermore, several studies employing the conventional alkaline version of the comet assay have shown that IMZT is genotoxic to some nontarget organisms, i.e., bacteria Salmonella typhimurium and Escherichia coli (USEPA, 1989) and plants such as Allium cepa (Liman et al, 2015) as well as mammalian exposed in vitro cells (Soloneski et al, 2017). Recently, we demonstrated for the first time that the herbicide jeopardizes anuran amphibian Hypsiboas pulchellus tadpoles by inducing micronuclei induction and DNA primary damage evaluated the SCGE assay (Pérez-Iglesias et al, 2015).…”

Occupational Exposure to Pesticides in Tobacco Fields: The Integrated Evaluation of Nutritional Intake and Susceptibility on Genomic and Epigenetic Instability

“…Based on scientific evidence, it is fully justified to investigate the real, predicted, and perceived risks of pesticides endured by humans. Pesticides used at tobacco fields have been shown to increase DNA damage, as observed in cell lines [ 4 – 6 ], animal models [ 7 , 8 ], and human studies [ 9 – 11 ]. They were also already evaluated either as single chemicals [ 6 , 7 , 12 ] or as mixtures (reviewed by [ 13 ]).…”

“…Pesticides used at tobacco fields have been shown to increase DNA damage, as observed in cell lines [ 4 – 6 ], animal models [ 7 , 8 ], and human studies [ 9 – 11 ]. They were also already evaluated either as single chemicals [ 6 , 7 , 12 ] or as mixtures (reviewed by [ 13 ]). The latter is the standard method of pesticide application in crop farming worldwide [ 13 ], including for Brazilian tobacco farmers [ 14 – 17 ].…”