The in vivo genotoxicity studies on nivalenol and deoxynivalenol

Abstract

Nivalenol (NIV) and deoxynivalenol (DON) are structurally related mycotoxins produced by Fusarium fungi. These fungi typically infest cereal crops such as wheat, maize, barley, oats and rye, and NIV and DON are regularly found in cereal grains, food and feed. Recent risk assessments identified possible data gaps for both DON and NIV in particular with respect to genotoxicity and carcinogenicity. The overall objective of the project was to assess the genotoxicity of DON and NIV, including the identification of potential modes of action. A battery of in vivo genotoxicity tests was performed in mice: Comet assay with and without fpg in seven organs (duodenum, colon, blood, liver, spleen, kidney, bone marrow), micronucleus assay in bone marrow and colon, and Pig-a assay in peripheral blood. In addition, to clarify the genotoxic mode of action of both mycotoxins, we performed in vitro Comet assay studies in TK6 cells to investigate potential genotoxic oxidative stress induced by mycotoxins. The response in all the genotoxicity assays with NIV after three oral doses at 5, 10 and 20 mg/kg, were uniformly negative. In the case of DON, we found that DON failed to induce micronuclei formation in bone marrow and colon and failed to induce DNA damage in all organs observed by the Comet assay with and without fpg at 4, 8 and 16 mg/kg. The Pig-a assay with DON after three oral gavage doses at 2, 4 and 8 mg/kg, did not show any mutagenic effect at day 28 and 45 after the last dose. In vitro studies indicated that both mycotoxins did not induce DNA damage in the Comet assay with or without fpg in TK6 cells even after GSH depletion. It was concluded that NIV and DON could be considered as devoid of genotoxic potential and pose no genotoxic or mutagenic risk.

Effects of chronic deoxynivalenol exposure on p53 heterozygous and p53 homozygous mice

“…In contrast, Comet assays did not detect genotoxicity due to DON in human lymphoblastoid TK6 cells and metabolically competent human hepatoma HepaRG cells . In vivo studies in mice found DON to be nongenotoxic in multiple organs and tissues using a battery of assays, including the Comet assay, Pig-a assay and micronucleus assay (Le H egarat et al, 2014). The lack of tumours and pre-neoplastic lesions in p53þ/À mice supports the conclusion that the potential for direct DNA damage due to DON exposure is low.…”

Risks to human and animal health related to the presence of deoxynivalenol and its acetylated and modified forms in food and feed

“…Additionally, in vitro and in vivo genotoxicity studies of DON have been carried out by Le Hégarat et al. (). These were conducted according to the EFSA Scientific opinion on genotoxicity testing strategies applicable to food and feed safety assessment (EFSA Scientific Committee, ) in the context of a grant agreement between EFSA and the authors.…”

Comet assay: an essential tool in toxicological research

“…Till now the etiology of hedgehogs is rather uncertain (OECD 2014), but comet data using rat liver samples suggest that they can be the result of mechanical-induced damage during sample preparation or substance-related cytotoxicity (Guerard et al 2014). Furthermore, they were detected using a formamidopyrimidine DNA glycosylase (FPG)-modified comet assay in different tissues of methyl methanesulfonate (MMS)-treated mice, indicating a high level of oxidized and/or alkylated bases and/or FPG lesions (Le Hégarat et al 2014). In addition, previous studies suggest that they are not diagnostic of apoptosis and should not be taken as an indication of cytotoxicity.…”

“…The external scientific report about the genotoxicity of nivalenol (NIV) and deoxynivalenol (DON) is an excellent example of how the comet assay can be used in vivo and in vitro (Le Hégarat et al 2014). The authors performed the comet assay with and without FPG in seven organs of mice.…”