Plant saponins are important natural product with biologically active. However, the metabolism of these compounds has rarely been studied due to their low bioavailability and the complexity of their metabolite structures. In this study, ultra-performance liquid chromatography/Fusion Lumos Orbitrap mass spectrometry was used to analyze the metabolites of hederasaponin B in vivo, and its possible metabolic pathways were proposed. After oral administration of the parent drug, a total of 47 metabolites are identified in rat feces (42), urine (11), and plasma (9) samples. These metabolites resulted from the metabolic processes in phases I and II reactions involved in deglycosylation, hydroxylation, acetylation, oxidation, gluconalciation and glycosylations. Deglycosylation is the main metabolic pathway (accounts for 52.46 % of all metabolites in feces samples). Among the identified metabolites, four were glycosylated (deprotonated precursors at m/z = 1335.7, 1365.7, 1467.9, and 1379.6) with higher molecular weight than the parent drug . These glycosylated compounds account for 11.55 % of the metabolites in rat feces according to the semi-quantitative chromatographic peak areas. To sum up, the results of this study provide a basis for further understanding the metabolism of plant saponins in vivo.
Keywords: Hederasaponin B; Structural identification of metabolites; UHPLC-Fusion Lumos Orbitrap mass spectrometry.
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