direct-black-3 and 4-biphenylamine

Direct black 38 (DB38) dye is a well-established toxic and carcinogenic compound. Present investigation reports isolation of an Enterococcus gallinarum strain capable of decolorizing and degrading it. Changes in toxicity and mutagenicity of DB38 and its metabolites were also determined using a battery of carefully selected tests (cytotoxicity, respiration inhibition test and Ames test). Toxicity assays were carried out on E. gallinarum itself as this also gave information about suitability of this strain for the dye decolorization operation. The strain was found to reduce both toxicity and mutagenicity of DB38 metabolites. Benzidine and 4-aminobiphenyl (4-ABP) were identified as the DB38 metabolites, responsible for its toxic and mutagenic properties, by HPLC-MS analysis. Further degradation of benzidine and 4-ABP was found to result in the decrease in toxicity and mutagenicity.

Topics: Aminobiphenyl Compounds; Azo Compounds; Benzidines; Biodegradation, Environmental; Chromatography, High Pressure Liquid; Coloring Agents; Enterococcus; Inactivation, Metabolic; Mass Spectrometry; Mutagenicity Tests; Salmonella typhimurium

The activity of benzidine and three structurally related carcinogens in an in vivo/in vitro rat liver assay for unscheduled DNA synthesis is described. The first three of these chemicals, benzidine, 4-aminobiphenyl (4AB) and Direct Black 38 have been reported as positive in this assay by other investigators, albeit the data reported for 4AB were limited. The fourth compound, 3,3'-dichlorobenzidine has not been studied in this assay before. Each compound gave a clear positive response under conditions of routine testing.

Topics: 3,3'-Dichlorobenzidine; Aminobiphenyl Compounds; Animals; Azo Compounds; Benzidines; Carcinogens; DNA Replication; Liver; Mutagens; Rats

Benzidine-based azo dyes are proven mutagens and have been linked to bladder cancer. Previous studies have indicated that their initial reduction is the result of the azo reductase activity of the intestinal microbiota. Metabolism of the benzidine-based dye Direct Black 38 was examined by using a semicontinuous culture system that simulates the lumen of the human large intestine. The system was inoculated with freshly voided feces, and an active flora was maintained as evidenced by volatile fatty acid and gas production. Within 7 days after exposure to the dye, the following metabolites were isolated and identified by gas chromatography-mass spectrometry:benzidine, 4-aminobiphenyl, monoacetylbenzidine, and acetylaminobiphenyl. Benzidine reached its peak level after 24 h, accounting for 39.1% of the added dye. Its level began to decline, and by day 7 the predominant metabolite was acetylaminobiphenyl, which accounted for 51.1% of the parent compound. Formation of the deaminated and N-acetylated analogs of benzidine, which have enhanced mutagenicity and lipophilicity, previously has not been attributed to the intestinal microbiota.

Topics: Aminobiphenyl Compounds; Azo Compounds; Bacteria, Anaerobic; Benzidines; Biotransformation; Chromatography, Gas; Chromatography, Ion Exchange; Feces; Fermentation; Humans; Mutagens; Oxidation-Reduction; Time Factors