Masaharu Asanoma

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 Kyoto, Japan, and identified two of them as 2-phenylbenzotriazole derivatives, 2-[2-(acetylamino)-4-[bis(2-methoxyethyl)amino]-5-methoxyphenyl]-5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-1) and 2-[2-(acetylamino)-4-[(2-cyanoethyl)ethylamino]-5-methoxyphenyl]-5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-2). In the present study, we collected adsorbed materials on blue cotton (3 kg x 9 times) at the same location, and isolated a sufficient amount (97 microg) of one of the remaining three mutagens other than PBTA-1 and PBTA-2, for structural analysis, by multiple column chromatography. The structure of mutagen, accounting for 12% of the total mutagenicity of the blue rayon-adsorbed substances, was determined to be a PBTA-1 analogue, 2-[2-(acetylamino)-4-amino-5-methoxyphenyl]-5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-4). PBTA-4 is a potent mutagen, inducing 190,000 and 7,800,000 revertants of Salmonella typhimurium TA98 and YG1024 per microgram, respectively, in the presence of S9 mix. In addition to the water of the Nishitakase River, PBTA-4 was detected in water samples from two rivers that flow through other regions where textile-dyeing industries have been developed. Like other PBTA analogues, PBTA-4 might also be produced from azo dyes during industrial processes in dyeing factories and treatment at sewage plants.

Identification of methylglyoxal as a major mutagen in wood and bamboo pyroligneous acids

To identify the major mutagen in pyroligneous acid (PA), 10 wood and 10 bamboo pyroligneous acids were examined using the Ames test in Salmonella typhimurium strains TA100 and TA98. Subsequently, the mutagenic dicarbonyl compounds (DCs), glyoxal, methylglyoxal (MG), and diacetyl in PA were quantified using high-performance liquid chromatography, and the mutagenic contribution ratios for each DC were calculated relative to the mutagenicity of PA. Eighteen samples were positive for mutagens and showed the strongest mutagenicity in TA100 in the absence of S9 mix. MG had the highest mutagenic contribution ratio, and its presence was strongly correlated with the specific mutagenicity of PA. These data indicate that MG is the major mutagen in PA. Graphical abstract Pyroligneous acids showed the mutagenicity by the Ames test, and methylglyoxal was identified as a major mutagen.