The effect of alkoxy substituents on the mutagenicity of some phenylenediamine-based disazo dyes

In Vitro Cytotoxicity of Textile Dyes and Extracts of Dyed/Finished Fabrics

The aim of this study was to investigate whether an in vitro test can give an indication of the overall toxicity of fabric extracts, and whether this toxicity correlates with the toxicity of the dyes and finishes used. Thirteen textile dyes and dyed/finished cotton fabrics were tested by using the Hepa-1 cytotoxicity test. Black sulphur and two blue reactive dyes were the most toxic, with IC50 (the concentration at which the total protein content was 50% of the protein content of non-exposed cells) values of 40–65μg/ml. The least toxic dyes, the black and yellow mix reactive dyes, had IC50 values of 825μg/ml and 703μg/ml, respectively. There was no correlation between the toxicities of the dyes and the fabric extracts; the extract from naphtholdyed fabric was the most cytotoxic. These results strongly support the hypothesis that the toxicity of a fabric extract cannot be predicted directly from the toxicity of the dye itself. The results also showed that flame-retardant and water/soil-repellent finishes can alter the cytotoxicity. In vitro tests, as exemplified by the Hepa-1 cytotoxicity test, could provide useful information for developing new ecotextiles.

Evaluation of new 2,2′-dimethyl-5,5′-dipropoxybenzidine- and 3,3′-dipropoxybenzidine-based direct dye analogs for mutagenic activity by use of the Salmonella/mammalian mutagenicity assay

As part of a continuing study aimed at establishing structure-activity relationships and heuristic principles useful for the design of non-genotoxic azo dyes, a series of new direct dyes based on two non-mutagenic benzidine analogs, 2,2'-dimethyl-5,5'-dipropoxybenzidine and 3,3'-dipropoxybenzidine, were evaluated for mutagenic activity in Salmonella typhimurium strains TA98 and TA100. These strains are widely used for mutagenicity screening and have been shown to detect the mutagenic activity of benzidine analogs. While some toxicity was seen with some dyes at high doses, all of the dyes examined were judged non-mutagenic with and without metabolic activation in the standard Salmonella plate-incorporation assay. The results in the standard test are consistent with the properties of the diamines themselves. However, only one of the dyes was non-mutagenic when a reductive-metabolism pre-incubation assay was used. The results of this study suggest that although benzidine analogs are potential replacements for benzidine, there is a need to understand which mutagenic products are produced when reductive metabolism is present. There is also a need to know whether or not metal complexes of these dyes are mutagenic. Such information will allow the development of new non-mutagenic azo dyes.

4-Hydroxynonenal formation during ischemia and reperfusion of rat small intestine

The metabolism and the washout of 4-hydroxynonenal (HNE), a major lipid peroxidation product, was determined in jejunal intestine of rats under normoxic, ischemic and postischemic conditions. The HNE utilization was by several orders higher than the HNE washout. Under ischemic conditions a drastic decrease of HNE utilization was found, compared with normoxic and postischemic utilization rates. The real flux rate of intracellular HNE formation during ischemia and reperfusion of small intestine was for the first time estimated on the basis of tissue HNE concentration, HNE utilization rate at defined HNE tissue concentration and HNE washout by perfusate circulation. Such estimation led to intestinal HNE formation rates of about 20 nmoles/g/min at normoxia, 20 to 40 nmoles/g/min at ischemia, 100 nmoles/g/min at 10 min of reperfusion and 20 nmoles/g/min at 60 min of reperfusion. Therefore, one can conclude that the tissue concentration of HNE only partly represents the real HNE formation rate and that the formation rate is of particular pathophysiological importance.

Postischemic accumulation of the lipid peroxidation product 4-hydroxynonenal in rat small intestine

4-Hydroxynonenal (HNE) as an indicator of lipid peroxidation was determined in rat jejunal mucosa. HNE was extracted as the dinitrophenylhydrazone derivative from the tissue, partially separated from other carbonyl compounds by thin-layer chromatography and measured by HPLC. During reperfusion of the small intestine following an ischemic period of 60 minutes a marked increase of the tissue concentration of HNE was observed. The mucosal HNE level passed a maximum value of 3.0 +/- 0.5 microM 10 min after the onset of reperfusion in comparison with 0.7 +/- 0.2 microM as initial value. The increased tissue level of the highly cytotoxic 4-hydroxyalkenal is suggested to be involved in the reperfusion induced morphological and biochemical changes of the small intestine.