Identification of 2-[2-(acetylamino)-4-amino-5-methoxyphenyl]-5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-4) as a potent mutagen in river water in Kyoto and Aichi prefectures, Japan

We have previously isolated five mutagens in blue rayon-adsorbed substances from water at a site below sewage plants in the Nishitakase River, in Kyot o, Japan, and identified two of them as 2-phenylbenzotriazole derivatives, 2-[2-(acetylamino)-4-[bis(2- methoxyethyl)amino]-5-methoxyphenyl]-5-amino-7 -bromo-3-chloro-2H-benzotriazole (PBa-1) and 2-[2-(acetylamino)-4- [(2-cyan oethyl)ethylamino]-5- methoxyphenyl]-5- amino-7-bromo-4-chloro-2H-benzotria zole (PBTA-2). In the present study, we collected adsorbed materials on blu e cotton (3 kg x 9 times) at the same location, and isolated a sufficient a mount (97 mug) of one of the remaining three mutagens other than PBTA-1 and PBTA-2, for structural analysis, by multiple column chromatography. The st ructure of mutagen, accounting for 12% of the total mutagenicity of the blu e rayon-adsorbed substances, was determined to be a PBTA-1 analogue, 2-[2-( acetylamino)-4-amino-5-methoxyphen -5-amino-7-bromo-4chloro-2H-benzotriazol e (PBTA-4). PBTA-4 is a potent mutagen, inducing 190,000 and 7,800,000 reve rtants of Salmonella typhimurium TA98 and YG1024 per microgram, respectivel y, in the presence of S9 mix. In addition to the water of the Nishitakase R iver, PBTA-4 was detected in water samples from two rivers that flow throug h other regions where textile-dyeing industries have been developed. Like o ther PBTA analogues, PBTA-4 might also be produced from azo dyes during ind ustrial processes in dyeing factories and treatment at sewage plants. (C) 2 001 Elsevier Science B.V. All rights reserved.