Imazethapyr induces oxidative damage in DNA purines bases in Hypsiboas pulchellus tadpoles (Anura, hylidae) evaluated by the comet assay

PÉREZ IGLESIAS J.M.; RUIZ ARCAUTE C.; NATALE, G.S.; SOLONESKI S.; LARRAMENDY M.L.

Buenos Aires

Congreso; SETAC Latin America 11th Biennial Meeting; 2015

Society of Environmental Toxicology and Chemistry (SETAC)

Imazethapyr (IMZT) [5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-4,5-dihydroimidazol-1H-2-yl)nicotinicacid] is a member of the imidazolinone herbicides used to controlgrasses, broadleaved weeds, and others in a variety of crops and non cropsituations. IMZT has been classified as a slightly toxic compound (Class III)by the USEPA. The European Union has classified the herbicide as a dangerouscompound for the environment and has reported IMZT as a harmful irritant forthe respiratory track, skin, and eyes,as well as classified by the European Union.IMZT is a selective post-emergent herbicide with residual action. Availabledata analyzing its effects in aquatic vertebrates are scarce. In previousstudies we demonstrated that IMZT induces lesions into the DNA of Hypsiboas pulchellus tadpoles using thesingle-cell gel electrophoresis (SCGE) assay as a biomarker for genotoxicity.Currently, this assay can be modified including incubation with lesion-specificendonucleases, e.g., endonuclease III (EndoIII) and formamidopyrimidine DNAglycosylase (Fpg) which detect oxidized purine and pyrimidine bases,respectively. The aim of this study was to evaluate oxidative DNA damage incirculating blood cells of H. pulchellus tadpolesexposed ex vivo to Pivot H®(10.59% IMZT) at a concentration equivalent to 25% LC5096h (0.39 mgIMZT/L) by a pulse treatment of 1 h. H2O2 (50 µM) andphosphate-buffered saline  were employedas positive and negative controls, respectively. The results revealed  that a treatment with Fpg but EndoIII producesa significant increase in the genetic damage index of those peripheral bloodcells of H. pulchellus tadpolesexposed ex vivo to IMZT-basedherbicide commercial formulation compared with control values (enzyme buffertreated cells) (P < 0.001). Ourresults demonstrate that the herbicide induces oxidative DNA damage on H. pulchellus tadpoles at purine basesbut not at pyrimidines. Furthermore, they represent the first evidence ofoxidative damage caused not only by IMZT, in particular, but also by herbicides,in general, on anuran DNA using the alkaline EndoIII- and Fpg-modified SCGE assay.