Detection of a Novel Mutagen, 3,6-Dinitrobenzo[e]pyrene, as a Major Contaminant in Surface Soil in Osaka and Aichi Prefectures, Japan
文摘
We previously identified 1,3-, 1,6-, and 1,8-dinitropyrene (DNP) isomers as major mutagensin surface soil in three metropolitan areas of Japan. In the present study, an organic extractfrom surface soil collected at a park in Takatsuki in Osaka Prefecture, which showed extremelyhigh mutagenicity in Salmonella typhimurium TA98 in the absence of mammalian metabolicsystem (S9 mix), was investigated to identify major mutagens. A new powerful bacterialmutagen, as well as 1,6- and 1,8-DNP isomers, was isolated from the organic extract (1.8 g) ofthe soil sample (2.2 kg) by column chromatography. On the basis of mass spectra, the newmutagen, which accounted for 15% of the total mutagenicity of the soil extract, was thoughtto be a dinitrated polycyclic aromatic hydrocarbon with a molecular weight of m/z 342. Themutagen was synthesized from benzo[e]pyrene by nitration and was determined to be 3,6-dinitrobenzo[e]pyrene (DNBeP) based on its 1H NMR spectrum. The mutagenic potency of 3,6-DNBeP in the Ames/Salmonella assay was extremely high, in that it induced 285 000revertants/nmol in TA98 and 955 000 revertants/nmol in YG1024 without S9 mix and wascomparable to those of DNP isomers, which are some the most potent bacterial mutagensreported so far. In addition to the soil sample from Takatsuki, 3,6-DNBeP was also detectedin surface soil samples collected at parks in four different cities, i.e., Izumiotsu and Takaishiin Osaka Prefecture and Nagoya and Hekinan in Aichi Prefecture, and accounted for 22-29%of the total mutagenicity of these soil extracts in TA98 without S9 mix. These results suggestthat 3,6-DNBeP is a major mutagen in surface soil and may largely contaminate the surfacesoil in these two regions in Japan.