Background: ZT55 is a novel natural product isolated from Radix isatidis. It is a highlyselective
tyrosine kinase inhibitor against myeloproliferative neoplasms. Although earlier research has
described the pharmacodynamic properties of ZT55 in vivo and in vitro, the quantitative determination
and pharmacokinetic profile in vivo have not been thoroughly studied.
Methods: A novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed
and validated for the quantification of ZT55 in rat plasma. A Waters symmetry C18 column was
used for chromatographic separation; 0.1% formic acid in acetonitrile and 0.1% formic aqueous solution
was used as the mobile phase. Detection was performed by Multiple Reaction Monitoring (MRM)
mode using electrospray ionization in the positive ion mode. UPLC-QTOF-MS was used for the identification
Results: The method was linear (R2=0.9988) over the concentration range of 1-2500 ng/mL. The lower
limit of quantification was 1 ng/mL. The intra-day and inter-day precision of ZT55 showed a relative
standard deviation within 8.47%, whereas the accuracy (RE) ranged from -4.84% to 4.45%. The recoveries
ranged from 92.89% to 97.21%. ZT55 reached the highest plasma concentration at 0.5h. The peak
concentrations with three dosages were 103.59±10.11, 185.23±29.56, and 355.98±28.86 ng/mL. The
AUC0-24 of three dosages were 874.70±72.33, 433.80±49.33, and 231.65±19.41 ng•h/ml respectively.
Five metabolites of ZT55 from plasma were confirmed. The main pathways of ZT55 in vivo were hydrolysis,
N-dealkylation, glycosylation, and sulfonation.
Conclusion: LC-MS/MS method was successfully applied to the pharmacokinetic study of ZT55 after
oral administration and intravenous. ZT55 exhibited rapid oral absorption, high elimination, and low
absolute bioavailability. This study provides important pharmacokinetic and metabolism information
for further pharmacological and toxicological research on ZT55.