Synthesis of 2-phenylbenzotriazole-type mutagens, PBTA-5 and PBTA-6, and their detection in river water from Japan
T Watanabe1, H Nukaya, Y Terao
1Department of Public Health, Kyoto Pharmaceutical University, 5 Nakauchicho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan. watanabe@mb.kyoto-phu.ac.jp
Abstract:
We previously determined the chemical structures of four 2-phenylbenzotriazole mutagens (PBTA-1, -2, -3 and -4) in blue rayon-adsorbed material from the Nishitakase River in Kyoto prefecture and the Nikko River in Aichi prefecture in Japan. On the basis of a synthesis study, these four PBTA derivatives were deduced to have originated from corresponding dinitrophenylazo dyes by reduction and chlorination. 2-[(2-Bromo-4,6-dinitrophenyl)azo]-5-[bis(2-acetoxyethyl) amino]-4-methoxyacetanilide (Color Index Name, Disperse Blue 79:1; CAS Registry Number, 75497-74-4) is a very common dinitrophenylazo dye used in textile dyeing factories. In the present study, we synthesized 2-[4-[bis(2-acetoxyethyl)amino]-2-(acetylamino)-5-methoxyphenyl]-5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-5) from Disperse Blue 79:1 by reduction with sodium hydrosulfite and subsequent chlorination with sodium hypochlorite. On hydrolysis of PBTA-5 with alkali, 2-[2-(acetylamino)-4-[bis(2-hydroxyethyl)amino]-5-methoxyphenyl]-5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-6) was obtained. Both PBTA-5 and -6 were potent mutagens, inducing 723,000 revertants and 485,000 revertants per microgram of Salmonella typhimurium YG1024, respectively, in the presence of S9 mix. To clarify whether PBTA-5 and -6 exist in the environment, water samples were collected from five rivers flowing through regions where textile dyeing industries are developed. PBTA-6 was detected at levels of 3-134 ng/g blue rayon in all water samples that were examined. On the other hand, the amount of PBTA-5 in the samples was less than the detection limit.
Insights
Researchers synthesized two new 2-phenylbenzotriazole mutagens (PBTA-5 and PBTA-6) from a common textile dye. PBTA-6 was detected in river water, indicating environmental contamination from textile dyeing industries.
Area of Science:
- Environmental Chemistry
- Organic Synthesis
- Mutagenesis Studies
Background:
- 2-phenylbenzotriazole mutagens (PBTA) are environmental contaminants.
- PBTA-1 to -4 were previously identified in Japanese rivers.
- These mutagens are likely derived from dinitrophenylazo dyes used in textile dyeing.
Purpose of the Study:
- To synthesize new PBTA derivatives from a common textile dye, Disperse Blue 79:1.
- To assess the mutagenicity of the synthesized compounds.
- To determine the environmental occurrence of PBTA-5 and PBTA-6 in rivers near textile industries.
Main Methods:
- Chemical synthesis of PBTA-5 from Disperse Blue 79:1 via reduction and chlorination.
- Hydrolysis of PBTA-5 to yield PBTA-6.
- Mutagenicity testing using Salmonella typhimurium YG1024 with S9 mix.
- Environmental water sample analysis using blue rayon adsorption.
Main Results:
- PBTA-5 and PBTA-6 were successfully synthesized.
- Both PBTA-5 and PBTA-6 exhibited potent mutagenic activity.
- PBTA-6 was detected in all examined river water samples at levels of 3-134 ng/g blue rayon.
- PBTA-5 was found below the detection limit in environmental samples.
Conclusions:
- Disperse Blue 79:1 is a precursor to potent mutagens PBTA-5 and PBTA-6.
- PBTA-6 is an environmental contaminant found in rivers associated with textile dyeing.
- The study highlights the need to monitor and control dye-derived mutagens in aquatic environments.
