Background::
Catalpol, an iridoid glycoside, is one of the richest bioactive components present in Rehmannia
glutinosa. More and more metabolites of drugs have exhibit various pharmacological effects, thus providing guidance for
clinical application. However, few researches have paid attention on the metabolism of catalpol.
Objective::
This study aimed to establish a rapid and effective method to identify catalpol metabolites and evaluate the biotransformation
pathways of catalpol in rats.
Methods::
In this study, catalpol metabolites in rat urine, plasma and faeces were analyzed by UHPLC-Q-Exactive MS for
the characterization of metabolism of catalpol. Based on high-resolution extracted ion chromatograms (HREICs) and parallel
reaction monitoring mode (PRM), metabolites of catalpol were identified by comparing the diagnostic product ions
(DPIs), chromatographic retention times, neutral loss fragments (NLFs) and accurate mass measurement with those of catalpol
reference standard. Results: A total of 29 catalpol metabolites were detected and identified in both negative and positive
ion modes. Nine metabolic reactions including deglycosylation, hydroxylation, dihydroxylation, hydrogenation, dehydrogenation,
oxidation of methylene to ketone, glucuronidation, glycine conjugation and cysteine conjugation were proposed.
Conclusion::
A rapid and effective method based on UHPLC-Q-Exactive MS was developed to mine the metabolism information
of catalpol. Results of metabolites and biotransformation pathways of catalpol suggested that when orally administrated,
catalpol was firstly metabolized into catalpol aglycone, after which phase Ⅰ and phase Ⅱ reactions occurred. However,
hydrophilic chromatography-mass spectrometry still needed to further find the polar metabolites of catalpol.
Development of a UHPLC-MS/MS-based data-mining method for rapid profiling and characterization of magnolol metabolites in rat urine and plasma
