Quantitative determination of zebularine (NSC 309132), a DNA methyltransferase inhibitor, and three metabolites in murine plasma by high-performance liquid chromatography coupled with on-line radioactivity detection

The metabolism of zebularine (NSC 309132), a novel agent that inhibits DNA methyltransferases, is still uncharacterized. To examine the in vivo metabolism of zebularine, an analytical method was developed and validated (based on FDA guidelines) to quantitate 2-[14C]-zebularine and its major metabolites in murine plasma. Zebularine and its metabolites uridine, uracil and dihydrouracil were baseline-separated based on hydrophilic interaction chromatography by using an amino column. The assay was accurate and precise in the concentration ranges of 5.0–100 μg/mL for zebularine, 2.5–50 μg/mL for uridine, 1.0–10 μg/mL for uracil and 0.5–5.0 μg/mL for dihydrouracil. This assay is being used to quantitate zebularine and its metabolites in ongoing pharmacokinetic studies of zebularine.