Structural Differentiation of Diastereomeric Benzo[ghi]fluoranthene Adducts of Deoxyadenosine by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry and Postsource Decay

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• 作者：M. Paul Chiarelli ; Hui-Fang Chang ; Kenneth W. Olsen ; Damon Barbacci ; and Bongsup P. Cho
• 刊名：Chemical Research in Toxicology
• 出版年：2003
• 出版时间：October 2003
• 年：2003
• 卷：16
• 期：10
• 页码：1236 - 1241
• 全文大小：166K
• 年卷期：v.16,no.10(October 2003)
• ISSN：1520-5010

文摘

The product ion formation characteristics of four diastereomeric deoxyadenosine adductsformed by the reaction of the syn and anti diastereomers of trans-3,4-dihydroxy-5,5a-epoxy-3,4,5,5a-tetrahydrobenzo[ghi]fluoranthene are studied by matrix-assisted laser desorptionionization and postsource decay (PSD) to determine fragmentation pathways that may permitdifferentiation of their structures. The two adducts derived from each diol-epoxide with DNAdiffer in structure based on the cis/trans arrangement of the 3'-hydroxyl group on the benzo[ghi]fluoranthene (B[ghi]F) and the adenine base bound to the B[ghi]F 5a carbon. The twoadduct diastereomers with the cis adenine-3'-hydroxyl configuration produce product ions atm/z 394 and m/z 510 formed by the loss of water that are not observed in the PSD spectra ofthe two trans isomers. The data suggest a mechanism of water loss that is initiated by ahydrogen-bonding interaction between the charge-bearing proton on the N1 atom and the3'-hydroxyl oxygen on the polycyclic aromatic hydrocarbon (PAH). Fragmentation is initiatedby the transfer of the adenine N1 proton from the nitrogen to the PAH 3'-hydroxyl oxygen andinductive cleavage of the C3-O³ bond to form a benzylic carbocation on B[ghi]F. The proposedmechanism is supported by semiempirical molecular modeling calculations.