, 2009). This dye also exhibited mutagenic activity in the Salmonella/microsome assay with the strains TA98, TA100, YG1041 and YG1042 in the absence of metabolic activation, but after adding the S9 mix, its mutagenicity was decreased (or eliminated). It has been proposed that the P450-dependent metabolism probably generated more stable products, with a Gemcitabine reduced probability of interacting with DNA ( Ferraz et al., 2010). It is therefore important to know the toxicity of both the original dye and its metabolic products, since the effluent

treatment applied by industries does not completely remove the mutagenic compounds, and consequently they can be found in treated water ( Oliveira et al., 2007). Thus the aim of the present study was to investigate the oxidation and reduction products obtained from the azo dye DR1 using the methodologies of HPLC–DAD and GC–MS. It also proposed to evaluate the mutagenic potential of these products using two different methods: the Salmonella/microsome Quizartinib ic50 assay with the strains TA98 and YG1041 in the absence of exogenous metabolic

activation (S9), and the mouse lymphoma assay (MLA). The Salmonella/microsome mutagenicity assay (Salmonella test; Ames test) is a short-term bacterial reverse mutation assay specifically designed to detect a wide range of chemical substances that can produce genetic damage leading to gene mutation ( Mortelmans and Zeiger, 2000). The MLA, using the thymidine kinase (Tk) gene as the target, is the most widely used of the in vitro assays for gene mutation in mammalian cells ( Moore et al., 2003), Casein kinase 1 detecting a broad spectrum of genetic damage, such as gene and chromosomal mutations ( Clements, 2000 and Soriano et al., 2007). The dye DR1 (CAS No. 2872–52-8) was purchased from Sigma (St. Louis, MO, purity > 95%)

(Fig. 1). The metabolic pathways of the dye were investigated using the mimetic system based on oxidation and reduction processes. The oxidation reactions were evaluated using three different techniques, one enzymatic (using an exogenous metabolic system – S9 mixture) and two chemical techniques (spectroelectrochemistry and controlled potential electrolysis). The reduction reactions were carried out by the two techniques used in chemical oxidation. The S9 metabolizing system is widely used in mutagenicity assays (mainly the Salmonella/microsome mutagenicity assay) in order to mimic the oxidation reactions that take place via cytochrome P450. These reactions are extremely important in toxicology, because they may generate more or less toxic products, i.e. bioactivation and detoxification, respectively. Considering this, the role of the cytochrome P450 isoenzymes in the chromophore group of this dye was monitored spectrophotometrically in the present study, promoting the reaction between DR1 and S9, as described below.