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Detection and Identification of Catalpol Metabolites in the Rat Plasma, Urine and Faeces Using Ultra-high Performance Liquid Chromatography-Q Exactive Hybrid Quadrupole-orbitrap High-resolution Accurate Mass Spectrometry

[ Vol. 22 , Issue. 3 ]

Author(s):

Zedong Xiang, Shaoping Wang, Haoran Li, Pingping Dong, Fan Dong, Zhen Li, Long Dai* and Jiayu Zhang*   Pages 173 - 184 ( 12 )

Abstract:


Background: Catalpol, an iridoid glycoside, is one of the richest bioactive components present in Rehmannia glutinosa. More and more metabolites of drugs have exhibited various pharmacological effects, thus providing guidance for clinical application. However, few researches have paid attention to 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 the 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 is still needed to further find the polar metabolites of catalpol.

Keywords:

Catalpol, metabolite, ultra-high performance liquid chromatography, high-resolution mass, bioactive components, parallel reaction monitoring mode, spectrometry.

Affiliation:

College of Pharmaceutical Science, Shandong University of Traditional Chinese Medicine, Jinan, School of Pharmacy, Binzhou Medical University, Yantai, College of Pharmaceutical Science, Shandong University of Traditional Chinese Medicine, Jinan, College of Pharmaceutical Science, Shandong University of Traditional Chinese Medicine, Jinan, School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, College of Pharmaceutical Science, Shandong University of Traditional Chinese Medicine, Jinan, College of Pharmaceutical Science, Shandong University of Traditional Chinese Medicine, Jinan, School of Pharmacy, Binzhou Medical University, Yantai



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