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 s C 18 column (150 mm 4.6 mm, 5 mm) with isocratic elution using a mobile phase consisting of watermethanol (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 (r2A sensitive, simple and rapid high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed and fully validated for the simultaneous quantification of buprenorphine (BUP) and its N-dealkylated metabolite norbuprenorphine (NBUP) in 200 mL human plasma. Human plasma samples were prepared using liquid-liquid extraction, and then separated on a Shiseido MG C18 (5 mm, 2.0 mm 50 mm) via 4.1 min gradient elution. Following electrospray ionization, the analytes were quantified on a triple-quadrupole mass spectrometer in multiple-reaction-monitoring (MRM) positive ion mode. Linearity was achieved from 25.0 to 10000 pg/mL for buprenorphine, from 20.0 to 8000 pg/mL for norbupre-norphine with r2>0.99. The method was demonstrated with acceptable accuracy, precision and specificity for the detection of buprenorphine and norbuprenorphine. Recovery was 81.8-88.8% for buprenorphine and 77.0-84.6% for norbuprenorphine, and the matrix effect was 95.6-97.4% for buprenorphine and 94.0-96.9% for norbuprenorphine; all were not concentration dependent. With validated matrix and autosampler stability data, this method was successfully applied in a bioequivalence study to support abbreviated new drug application. 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.