Original Article

Identification of guanfu base A hydrochloride phase I and phase II metabolites in rat bile by liquid chromatography mass spectrometry.

Ji-Ye A, Guang-Ji WANG, Min-Shu WU, Jing-Han LIU


AIM: To study metabolites of guanfu base A hydrochloride (GFA) in rat bile.
METHODS: An analytical method was developed to identify guanfu base A and its
metabolites by liquid chromatography mass spectrometry (LC-MS) and electrospray
ionization tandem mass spectrum (MS-MS). Rat bile was collected after iv
injection of GFA. Phase I metabolite was identified by comparison with authentic
standard for their retention time, molecular ion peaks, fragment ions, and UV
spectrums. In order to identified Phase II conjugates, the aglycones were
identified after rat bile was treated with either glucuronidase or sulfatase
firstly. Phase II conjugates were also separated and determined for their
molecular ions by LC-MS, at last they were verified by identifying characteristic
product ions or precursor ions by MS-MS.
RESULTS: Phase I metabolite, guanfu base I (GFI), was identified in rat bile.
After phase II conjugates were treated with glucuronidase or sulfatase, GFA and
GFI occurred in chromatograms. Quasi molecular ions m/z 606 and 510 were
separated and detected in rat bile. They were indicated to be GFA glucuronide and
GFA sulfate, respectively. Furthermore, GFA glucuronide was confirmed to exist in
rat bile by identifying two characteristic ions, m/z 177, [M+H]+ of glucuronic
acid, and m/z 430, [M+H]+ of GFA, as product ions of m/z 606.
CONCLUSION: Phase I metabolite GFI and phase II conjugates, GFA glucuronide and
sulfate, GFI glucuronide and sulfate, were identified in rat bile.

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