Simultaneous determination of 6-gingerol, 8-gingerol, 10-gingerol and 6-shogaol in rat plasma by liquid chromatography-mass spectrometry: Application to pharmacokinetics.

A rapid high-performance liquid chromatography-mass spectrometry (HPLC-MS) method was developed and validated for simultaneous quantification of 6-gingerol, 8-gingerol, 10-gingerol and 6-shogaol in rat plasma after oral administration of ginger oleoresin. Plasma samples extracted with a liquid-liquid extraction procedure were separated on an Agilent Zorbax StableBond-C(18) column (4.6 mm x 50 mm, 1.8 microm) and detected by MS with electrospray ionization interface in positive selective ion monitoring (SIM) mode. Calibration curves (1/x(2) weighted) offered satisfactory linearity (r(2)>0.995) in a wide linear range (0.0104-13.0 microg/mL for 6-gingerol, 0.00357-4.46 microg/mL for 8-gingerol, 0.00920-11.5 microg/mL for 10-gingerol and 0.00738-9.22 microg/mL for 6-shogaol). The lower limit of quantification (LLOQ) was in a range of 3.57-10.4 ng/mL. The analytes and internal standard can be baseline separated within 6 min. Inter- and intra-day assay variation was less than 15%. This developed method was successfully applied to pharmacokinetic studies of ginger oleoresin after oral administration to rats. Glucuronide of 6-gingerol was determined after beta-glucuronidase hydrolysis for more information, and the intestinal glucuronidation was further confirmed by comparison of plasma samples of hepatic portal vein and femoral vein.