Identification of the principal circulating metabolite of a synthetic 5,4′-diaminoflavone (NSC 686288), an antitumor agent, in the rat

Autor: Lawrence R. Phillips, Tyra House, Tracy L. Wolfe, John Buckley, Chris Bramhall, Sherman F. Stinson
Rok vydání: 2000
Předmět:
Zdroj: Journal of Chromatography B: Biomedical Sciences and Applications. 741:205-211
ISSN: 0378-4347
DOI: 10.1016/s0378-4347(00)00094-3
Popis: During the course of our study to develop analytical methodology for quantitating the investigative antitumor agent 5-amino-2-(4-amino-3-fluorophenyl)-6,8-difluoro-7-methyl-4H-1-benzopyran -4-one (DAF; NSC 686288) in plasma, a significant concentration of a metabolite was observed in a post-dosed rat. The results of electron-ionization (EI) mass spectrometric analysis of the metabolite suggested that N-acetylation had occurred, but, interestingly, that only one of the compound's two primary amino groups had been transformed. Comparing the mass spectra and gas chromatographic retention times of a mono-acetylated sample of DAF and that of the metabolite showed both to be the same. A retro-Diels-Alder (RDA) fragmentation of the B ring of DAF results in formation of two abundant product ions, each retaining one of the amino groups. The EI mass spectrum of mono-N-acetamido-d3 DAF shows loss of ketene-d2, leading to formation of an -NHD group. The ensuing RDA fragmentation easily identifies which of the two product ions contains the deuterium, thereby allowing us to assign the site of N-acetylation as the amino group on ring C (the 4' position) of DAF.
Databáze: OpenAIRE