Abstract
Purpose: To develop a highly sensitive and specific ultra-performance liquid chromatography with linear ion trap Orbitrap mass spectrometer (UPLC-LTQ-Orbitrap) method to profile and identify the metabolites of evodiamine in rats. Methods: First, blood samples were collected after oral administration of evodiamine to rats (50 mg/kg). Next, the plasma samples were pretreated using a solid-phase extraction (SPE) method. Finally, all the samples were analyzed by ultra-performance liquid chromatography LTQ-Orbitrap mass spectrometry (UPLC-LTQ-Orbitrap) coupled with electrospray ionization source (ESI) in negative mode. Results: A total of 7 metabolites (2 phase I and 4 phase II metabolites, including 4 new metabolites, viz, 10-hydroxyevodiamine sulfate, 10-hydroxyevodiamine sulfate, 10-hydroxyevodiamine glucuronide and 3-hydroxyevodiamine glucuronide) as well as the parent drug itself , were detected and identified based on accurate mass measurements, fragmentation patterns, and chromatographic retention times. The in vivo metabolic reactions of evodiamine in rats were hydroxylation, hydroxylation + sulfate conjugation, and hydroxylation + glucuronidation. Conclusion: These results provide better understanding of the metabolism of evodiamine as well as strong indications of the effective forms of the drug in vivo.
Highlights
Evodiamine belonging to indoloquinazoline alkaloids, is a major constituent isolated from the herbal medicine Evodia rutaecarpa (Wu-zhu-yu), which has been officially listed in Chinese Pharmacopoeia [1] and widely used in China for more than 2000 years
In order to facilitate the structural identification of the metabolite, the MSn fragmentation pattern of evodiamine was investigated [17]
Fragmentation of the parent ion provided characteristic fragment ions at m/z 169.0765 (2.5 ppm, C11H9N2) and m/z 142.0658 (4.7 ppm, C10H9N) by the loss of the moieties C8H7ON and Metabolites M1 and M2 were eluted at 17.42 and 19.29 min with the quasi-molecular ions of m/z 318.1248 (3.6 ppm, C19H16O2N3) and m/z 318.1245 (2.6 ppm, C19H16O2N3), 16 Da more than that of evodiamine, indicating that it might be the product of mono-hydroxylated of the prototype drug
Summary
Evodiamine belonging to indoloquinazoline alkaloids, is a major constituent isolated from the herbal medicine Evodia rutaecarpa (Wu-zhu-yu), which has been officially listed in Chinese Pharmacopoeia [1] and widely used in China for more than 2000 years. The chemical formulas for all parent ions of the selected peaks were calculated from the accurate mass using a formula predictor by setting the parameters as follows: C [0 – 30], H [0 – 50], O [0 – 20], S [0 – 4], N [0 – 4], Cl [0 – 4], and ring double bond (RDB) equivalent value [0 – 15]. Other elements such as P and Br were not considered because they are rarely present in the complex matrix
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