LC–MS/MS determination and pharmacokinetic study of bergenin, the main bioactive component of Bergenia purpurascens after oral administration in rats

Bergenin, a C-glucoside of 4-O-methyl gallic acid from Bergenia purpurascens, is a naturally antitussive and expectorant agent. A rapid and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the determination of the active component-bergenin, in rat plasma after oral administration of aqueous B. purpurascens extract. The plasma samples were pretreated by protein precipitation with acetonitrile and chromatographic separation was achieved on a Diamonsil® C18 column (150 mm×4.6 mm, 5 μm) with isocratic elution using a mobile phase consisting of water-methanol (30:70, v/v) at a flow rate of 0.6 mL/min. The detection was accomplished by a triple-quadrupole tandem mass spectrometer in multiple-reaction monitoring (MRM) scanning via an electrospray ionization (ESI) source operating in the negative mode. The optimized mass transition ion-pairs (m/z) for quantitation were 327.3/192.0 for bergenin, and 431.1/311.1 for IS. The time for each analysis run was only 3.5 min between injections. The calibration curve exhibited good linearity (r2>0.99) over a range of 1.00-2000 ng/mL for bergenin. The lower limit of quantitation (LLOQ) was 1.00 ng/mL. The intra- and inter-day precisions were no more than 11.8%, and relative errors (RE) were within the range of 0.0-4.4%. The validated method was successfully applied to investigate the pharmacokinetics of bergenin after oral administration of B. purpurascens extract in rats.