Determination of chikusetsusaponin V and chikusetsusaponin IV in rat plasma by liquid chromatography-mass spectrometry and its application to a preliminary pharmacokinetic study.

A sensitive liquid chromatography-electrospray ionization-mass spectrometry method has been developed and validated for determination of two major bioactive saponins in rat plasma after oral administration of saponins extracted from Rhizoma Panacis Japonici, including chikusetsusaponin V and chikusetsusaponin IV for the first time. Akebia saponin D was used as the internal standard (IS). Plasma samples were prepared by protein precipitation with methanol. A Phenomenex C18 column (150 × 4.6 mm, 4 µm) was used as the analytical column with a mobile phase of acetonitrile and 0.05% aqueous formic acid. Mass spectrometric detection was achieved by single quadrupole mass spectrometer equipped with an electrospray ionization interface operating in negative ionization mode. Calibration curves showed good linearity over the concentration range of 5-500 ng/mL for the two analytes in rat plasma. The lower limit of quantification was 5 ng/mL. The intra- and inter-batch precisions were within 10.3% and accuracy ranged from -3.9 to 5.4%. The method was validated and successfully applied to the preliminary pharmacokinetic study of chikusetsusaponin V and chikusetsusaponin IV in rat plasma after oral administration of saponins extracted from Rhizoma Panacis Japonici.