Further studies are needed to identify the molecular mechanism un

Further studies are needed to identify the molecular mechanism underlying PHT-induced genotoxic effects. We wish to thank CNPq, CAPES,

Instituto Claude Bernard, FUNCAP and FINEP for their financial support in the form of grants and fellowship awards. We are also grateful to Dr. A. Leyva for English editing of the manuscript. “
“Over 800,000 tons of dyestuffs see more are annually produced throughout the World, of which 60–70% are azo dyes (Anliker, 1977 and Combes and Haveland-Smith, 1982). At least 3000 azo dyes were in use in the 1990s (Chung and Cerneglia, 1992), produced by the diazotization of aromatic amines, and used to provide color in products manufactured by the textile, leather, printing, paper, food and cosmetic industries. It has been estimated that 10–15% of the total amount of dyes are released PD332991 into the environment

during manufacturing (Nam and Renganathan, 2000, Moutaouakkil et al., 2003 and Mansour et al., 2007), such a discharge being undesirable for esthetic reasons and also because many azo dyes and their breakdown products are toxic, mutagenic and carcinogenic to both humans and aquatic life (Spadaro et al., 1992, Van Der Zee et al., 2001, Pinheiro et al., 2004 and Seesuriyachan et al., 2007). The toxic effects of azo dyes, mainly their mutagenicity, can be caused by both the dyes themselves and by their metabolites, such as arylamines and free radicals (Collier et al., 1993 and Weisburger, 1997). One of the criteria used to classify a dye as harmful to humans is its ability to reductively cleave, and consequently to form aromatic amines when

in contact with sweat, saliva or gastric juices. Some of these aromatic amines are carcinogenic and can accumulate in food chains (Pielesz, 1999 and Pielesz et al., 2002). Examples of such aromatic amines are the biphenylamines such as benzidine and 4-biphenylamine, which are present in the environment, constituting a threat to human health and to the ecosystems in general (Choudhary, 1996 and Chung et al., 2000). After the oral ingestion of an azo dye, it can be reduced to free aromatic amines by anaerobic intestinal microflora and possibly by mammalian azo reductase Pyruvate dehydrogenase in the intestinal wall or in the liver (Umbuzeiro et al., 2005). Such a biotransformation can occur in a wide variety of mammalian species including both Rhesus monkeys ( Rinde and Troll, 1975 and Prival and Mitchell, 1982) and humans ( Watabe et al., 1980). The activation of azo dyes involves nitro reduction and azo reduction (Umbuzeiro et al., 2005), and thus it is reasonable that the intestinal microflora play an important role in this activation process (Chung, 1983, Chung et al., 1992 and Lima et al., 2007), and the CYP450 enzymes present in the intestine could also play a part in the activation of these dyes (Umbuzeiro et al., 2005 and Lima et al., 2007).

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