Identification of metabolites of rupestonic acid in rat urine by liquid chromatography combined with electrospray ionization quadrupole time-of-flight tandem mass spectrometry

Rupestonic acid, a potential anti-influenza agent, is an important and characteristic compound in Artemisia rupestris L., a well-known traditional Uighur medicine for the treatment of colds. In the present study, high-performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight tandem mass spectrometry was used to detect and identify the metabolites in rat urine after oral administration of rupestonic acid. A total of 10 metabolites were identified or partially characterized. The structure elucidations of the metabolites were performed by comparing the changes in accurate molecular masses and fragment ions with those of the parent compound. The results showed that the main metabolites of rupestonic acid in rat urine were formed by oxidation, hydrogenation and glucuronidation. A metabolism pathway was proposed for the first time based on the characterized structures. This metabolism study can provide essential information for drug discovery, design and clinical application of rupestonic acid. Copyright (c) 2014 John Wiley & Sons, Ltd.