In vivo metabolism of epothilone B in tumor-bearing nude mice: identification of three new epothilone B metabolites by capillary high-pressure liquid chromatography/mass spectrometry/tandem mass spectrometry

Abstract

Epothilone B is a 16‐membered macrolide produced by the myxobacterium Sorangium cellulosum and is currently under clinical investigation. Experimentally, epothilone B demonstrates potent antiproliferative activity at the nanomolar level in vitro, and potent regression‐producing antitumor activity in vivo, similar to paclitaxel (Taxol®). In order to foster the design of improved derivatives, the potential biotransformation products of epothilone B formed in liver of tumor‐bearing mice after intravenous administration of 10 mg/kg were characterized in an early stage of compound development. Solely on the basis of capillary high‐performance liquid chromatography, combined either with electrospray tandem mass spectrometry (in precursor and product ion scan mode) and single analyzing time‐of‐flight mass spectrometry (H/D exchange and accurate mass measurement), three main metabolites could be detected. The three metabolites, formed by the liver, have in common that the epoxide ring was hydrolyzed and that the macrocyclic lactone ring was opened to the acid. In two cases it is assumed that open‐chain intermediates re‐cycled either to a lactone or, after conjugation with taurine, to the respective lactam. The proposed structures were additionally supported by the determination of the number of the exchangeable hydrogen atoms and by confirmation of the proposed elemental composition by exact mass measurement. Copyright © 2000 John Wiley & Sons, Ltd.

Effects of Alkali Metal Ion Cationization on Fragmentation Pathways of Triazole-Epothilone

“…Four major fragment ions with m/z 417, 317, 289, and 233 were observed. The results are very similar to the ESI MS results of epothilone B reported by Blum et al [19]. The proposed fragment pathway is shown in Scheme 2.…”

“…Recently, chemical compounds with different macrocyclic rings inside themselves have attracted more interests in different research fields, including synthetic chemistry, natural products, and chemical biology [13][14][15][16][17][18][19][20][21]. For example, as one of the most attractive drugs for cancer therapy, epothilones and their relatives have evoked a vast research effort within academic and pharmaceutical research groups that include numerous total and partial syntheses and extensive structure-activity relationship studies [15][16][17][18][19][20][21].…”

“…For example, as one of the most attractive drugs for cancer therapy, epothilones and their relatives have evoked a vast research effort within academic and pharmaceutical research groups that include numerous total and partial syntheses and extensive structure-activity relationship studies [15][16][17][18][19][20][21]. Surely, it will be very important to know how the cationation by metal ions can affect structures and functions of these types of drugs.…”

Structural characterization of sulfadiazine metabolites using H/D exchange combined with various MS/MS experiments

“…Surprisingly, this method has infrequently been applied for characterization of metabolites° [25][26][27][28][29][30][31][32][33].°The°higher°cost°of°D 2 O could be considered a certain drawback, but the consumption of D 2 O can be significantly reduced by using smaller columns and smaller solvent bottles. Alternatively, fractions can be collected and redissolved in D 2 O containing solvents.…”

Oxidative Metabolism of Epothilones A and B (Patupilone) by Cytochromes P450: Involvement of CYP3A and CYP2C

“…Recent efforts to superimpose the structures of Epo and paclitaxel have been published in order to define a common pharmacophore motif able to bind tubulin [7,8,13]. However, there are also clear structural differences between epothilones and taxoids like the lactone group of Epo, which gives rise to a different mode of metabolic inactivation due to hydrolysis [14].…”