Submitted to: Applied and Environmental Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/31/2000
Publication Date: 2/20/2001
Citation: Freeman, B., Wilson, R.E., Binder, R.G., Haddon, W.F., 2001. Halogenated 2, 5-pyrrolidinediones: synthesis, bacterial mutagenicity in ames tester strain ta-100 and semi-empirical molecular orbital calculations. Nutrition Research 490 (2001) 89-98. Interpretive Summary: The Food Safety and Health Unit was asked by the Food Safety and Inspection Service to provide information on the chemical nature of biologically active by-products formed in poultry chiller water when permitted levels of chlorine were exceeded in poultry processing operations. The research led to the identifcation of a single chemical compound, a multiply-chlorinated imide, which accounted for most of the biological activity of simulated poultry chiller water, as measured in a widely accepted test method called the Ames bacterial mutagensis bioassay. The newly identified Ames-active compound is similar in molecular structure to a previously discovered disinfection by-product of drinking water chlorination called "MX". MX is a member of the chlorofuranone class of compounds. The present work links the toxicology risk assessment of these two classes of chemicals with a computer model based on calculated electronic properties. The newly discovered chloroimide and six synthetic analogs are compared with MX and nine additional chlorofuranones. This computer model will provide FSIS and the poultry industry with an improved understanding of the chemistry and toxicology of chlorinated poultry chiller water.
Technical Abstract: The chloroimide 3,3-dichloro-4-(dichloromethylene)-2,5-pyrrolidinedione, a tetrachloroitaconimide, is the principal mutagen produced by chlorination of simulated poultry chiller water. It is the second most potent mutagenic disinfection by-product of chlorination ever reported. Six of seven new synthetic analogs of this compound are direct-acting mutagens in Ames tester strain TA-100. Computed energies of the lowest unoccupied molecular orbital (ELUMO) and of the radical anion stability ( Hf rad - Hf) from MNDO-PM3 for the chloroimides show a quantitative correlation with the Ames TA-100 bacterial mutagenicity values. The molar mutagenicities of these direct acting mutagenic imides having an exocyclic double bond fit the same linear correlation (ln Mm vs. ELUMO; ln Mm vs. Hf rad - Hf) as the chlorinated 2(5H)-furanones, including the potent mutagen MX, 3-chloro-4-(dichloro-methyl)-5-hydroxy-2(5H)-furanon nby-product of water chlorination and paper bleaching with chlorine. Mutagenicity data for related haloimides having endocyclic double bonds are also given. For the same number of chlorine atoms, the imides with endocyclic double bonds have significantly higher Ames mutagenicity compared to their structural analogs with exocyclic double bonds, but do not follow the same ELUMO or Hfrad - Hf correlation as the exocyclic chloroimides and the chlorinated 2(5H)-furanones.