Determination of Astragaloside IV in Rat Plasma by UPLC-MS/MS and Application to a Pharmacokinetic Study

Astragaloside IV is a monomeric compound isolated from total saponins of Radix astragali (Astragalus sp. root) and the pharmacological studies showed that it owns many effects, such as immune regulation, anti-inflammation, anti-virus, antioxidant, hypoglycemic, improving insulin resistance. In this work, a sensitive and selective ultra-performance liquid-chromatography tandem mass spectrometry (UPLC-MS/MS) method for determination of astragaloside IV in rat plasma is developed. The UPLC-MS/MS method was validated for selectivity, linearity, accuracy, precision, recovery and stability with a total run time of 4 min. After addition of hirsuterine as an internal standard (IS), protein precipitation by acetonitrile was used to prepare samples. Chromatographic separation was achieved on a UPLC BEH C18 column (2.1 x 50 mm, 1.7 mu m) with 0.1% formic acid and acetonitrile as the mobile phase with gradient elution. An electrospray ionization source was applied and operated in positive ion mode; multiple reactions monitoring (MRM) mode was used for quantification using target fragment ions m/z 785.5 -> 143.0 for astragaloside IV, and m/z 367.2 -> 170.0 for IS. Calibration plots were linear throughout the range 1-200 ng/mL for astragaloside IV in rat plasma. Mean recoveries of astragaloside IV in rat plasma were better than 80.3%. RSD of intra-day and inter-day precision were both less than 10%. The accuracy of the method was between 98.3% and 109.0%. The method was successfully applied to pharmacokinetic study of astragaloside IV after oral administration in rats.