Modification of the umu-assay (ISO 13829) accounting for cytotoxicity in genotoxicity assessment: a preliminary study.
In this study, the umu-assay (ISO 13829) was modified by addition of the resazurin-reduction assay to assess the cytotoxic potential of toxins. The aim was to develop a test system that was capable of examining both genotoxicity and cytotoxicity on the basis of the metabolic health of the cells so as to provide a better assessment of the negative influence of toxic effects on the evaluation of genotoxicity. The test was established and validated with mitomycin C (MMC), 1,3-dinitropyrene (1,3-DNP), 4-nitroquinoline-1-oxide (4-NQO) and chloramphenicol (CHL) as toxins with known responses in the umu-assay. The results indicate that the modified umu-assay was able to reveal genotoxic responses towards MMC, 1,3-DNP and 4-NQO up to 1μg/ml. Further, the assay was able to determine the cytotoxicity of CHL, MMC and 4-NQO. Hence, the modified umu-assay was proven to be a sensitive test for determining the cytotoxicity and genotoxicity of toxins, with results that were comparable with literature data. Moreover, the modified umu-assay showed that cytotoxic concentrations that cause >50% inhibition of dehydrogenase activity (DHA) can result in unreliable computation of genotoxicity.
Environmental Technology and Energy Economy, Hamburg University of Technology, Hamburg, Germany. toolaram@leuphana.de
Anju Priya
AP
Toolaram
Iris Raquel
IR
Gutiérrez
Wolfgang
W
Ahlf
D016923:Cell Death; D009152:Mutagenicity Tests / Q000379:methods*; D009153:Mutagens / Q000633:toxicity*; D010078:Oxazines / Q000378:metabolism; D012486:Salmonella typhimurium / Q000187:drug effects; D014966:Xanthenes / Q000378:metabolism
D009153:Mutagens; D010078:Oxazines; D014966:Xanthenes; C005843:resazurin; C014180:resorufin