Determination of diosbulbin B in rat plasma and urine by LC–MS/MS and its application in pharmacokinetic and urinary excretion studies

A sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) was developed for determination of diosbulbin B in rat plasma and urine after oral administration. The detector was a Q-trap™ mass spectrometer with an electro-spray ionization interface operating in the multiple reaction monitoring mode. After extracted with methyl tert-butyl ether, diosbulbin B and busprione (internal standard, IS) were separated on an Agilent Zorbax C18 column (4.6 mm × 50 mm, 3.5 μm) using a gradient mobile phase consisting of water and methanol. Linearity was obtained over the concentration range of 5–5000 ng/ml for diosbulbin B in rat plasma and urine. The lower limit of quantitation was 5.0 ng/ml. The accuracy (relative error, RE) and precision (relative standard deviation, RSD) of disobulblin B in two biological matrices ranged from −8.2% to 1.4% RE and 1.9 to 10.1% RSD, respectively. The fully validated method was applied to a pharmacokinetic and urine excretion study for the first time. The main pharmacokinetic parameters Tmax, Cmax, T1/2, and Ke were 1.88 ± 0.22 h, 18.0 ± 3.1 ng/ml, 6.89 ± 1.0 h and 0.103 ± 0.01 l/h, respectively. A cumulative excretion of disobulbin B in rat urine was 2.69 ± 0.43 μg at 60 h after dosing, accounting for 0.89% of the total dose.

Graphical abstractProduct ion mass spectra of [M+Na]+ ion of (A) diosbulbin B and [M+H]+ ion of (B) buspirone (IS).Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► LC–MS method was developed for determination of diosbulbin B in rat plasma and urine. ► Pharmacokinetic parameters of diosbulbin B were firstly reported in rats. ► Urinary excretion results of diosbulbin B in rat were reported for the first time.