The identification of in vitro metabolites of CKD‐732 by liquid chromatography/tandem mass spectrometry

The structural elucidation of fourteen metabolites of CKD‐732, formed in vitro with rat liver microsomes, was performed using high‐performance liquid chromatography/electrospray ionization‐tandem mass spectrometry (HPLC/ESI‐MS/MS). To identify proposed structures of the metabolites, the product ion mass spectra of the protonated molecules ([M + H] + ), the retention times on reversed‐phase HPLC, and UV‐Vis spectra were utilized. Characteristic product ions for the identification of CKD‐732 metabolites were observed at m/z 231, 236, and 252. The fragment ions at m/z 236 and 252 indicated the unchanged form and the N‐oxide of the dimethylaminoethoxycinnamoyl group, respectively. The ion at m/z 231 indicated the presence of the hydroxylated form of the fumagillol group. The N‐oxide of CKD‐732, which was detected at m/z 515 and eluted later than CKD‐732 in the reversed‐phase HPLC system, was measured as a major metabolite. Three cis‐trans isomers were also found. Copyright © 2002 John Wiley & Sons, Ltd.