Identification of 2-Amino-1,7-dimethylimidazo[4,5-g]quinoxaline: An Abundant Mutagenic Heterocyclic Aromatic Amine Formed in Cooked Beef
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- 作者：Robert J. Turesky ; Angela K. Goodenough ; Weijuan Ni ; Lynn McNaughton ; David M. LeMaster ; Ricky D. Holland ; Rebekah W. Wu ; James S. Felton
- 刊名：Chemical Research in Toxicology
- 出版年：2007
- 出版时间：March 2007
- 年：2007
- 卷：20
- 期：3
- 页码：520 - 530
- 全文大小：608K
- 年卷期：v.20,no.3(March 2007)
- ISSN：1520-5010
文摘
A previously unknown isomer of the carcinogenic heterocyclic aromatic amine (HAA) 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (8-MeIQx) was recently discovered in the urine of meat eaters andsubsequently detected in cooked ground beef (Holland, R.D., et al. (2004) Chem. Res. Toxicol. 17, 1121-1136). In this current investigation, the identity of the analyte was determined through a comparison ofits chromatographic tR by HPLC and through UV and mass spectral comparisons to the synthesizedisomers of 8-MeIQx. Angular tricyclic isomers of 8-MeIQx were excluded as potential structures of thenewly discovered HAA, on the basis of dissimilar tR and product ion mass spectral data. The lineartricyclic isomers 2-amino-1,6-dimethylimidazo[4,5-g]quinoxaline (6-MeIgQx) and 2-amino-1,7-dimethylimidazo[4,5-g]quinoxaline (7-MeIgQx) were postulated as plausible structures. Both compounds weresynthesized from 4-fluoro-5-nitro-benzene-1,2-diamine in five steps. The structure of the analyte wasproven to be 7-MeIgQx, on the basis of co-injection of the compound with the synthetic isomers, andcorroborated by comparisons of the UV and mass spectral data of the analyte and MeIgQx isomers.7-MeIgQx induced 348 revertants/
r.gif">g in the S. typhimurium tester strain YG1024, when liver S-9homogenate of rats pretreated with polychlorinated biphenyls (PCBs) was used for bioactivation. Thisnewly discovered 7-MeIgQx molecule is one of the most abundant HAAs formed in cooked ground beefpatties and pan-fried scrapings. The human health risk of 7-MeIgQx requires investigation.
r.gif">g in the S. typhimurium tester strain YG1024, when liver S-9homogenate of rats pretreated with polychlorinated biphenyls (PCBs) was used for bioactivation. Thisnewly discovered 7-MeIgQx molecule is one of the most abundant HAAs formed in cooked ground beefpatties and pan-fried scrapings. The human health risk of 7-MeIgQx requires investigation.