Quantitation of ursolic acid in human plasma by ultra performance liquid chromatography tandem mass spectrometry and its pharmacokinetic study.

Abstract Ursolic acid is a hydroxy pentacyclic triterpene, which proved to have sedation, anti-inflammatory, antibacterial, antiulcer and anti-cancer activities. An ultra-performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS) method with high selectivity, sensitivity and throughput has been established and validated for quantitation of total ursolic acid in human plasma. Plasma samples were pretreated by liquid–liquid extraction with ethyl acetate and were chromatographed by an ACQUITY UPLC BEH C 8 column (100 mm × 2.1 mm, I.D., 1.7 μm) using mobile phase consisting of acetonitrile and 10 mM ammonium formate (90:10, v/v) at 0.2 mL/min. The duration of chromatography analysis was 3 min. The multiple reaction monitoring (MRM) was performed at m / z 455.1 → 455.0 for ursolic acid and m / z 469.3 → 425.2 for glycyrrhetinic acid (internal standard, IS) in the negative ion mode with electrospray ionization (ESI) source. The assay showed good linearity over the range of 10–5000 ng/mL for ursolic acid in human plasma with a lower limit of quantitation of 10 ng/mL. The mean extraction recovery was 73.2 ± 4.5% and the matrix ion suppression ranged from −11.4% to −5.6%. The intra- and inter-day precisions were less than 7.0% and 7.2%, respectively, and the accuracy was within ±2.0%. Ursolic acid was stable during the analysis and the storage period. The validated method has been successfully applied to a pharmacokinetic study after intravenous infusion of Ursolic Acid Nano-liposomes to healthy volunteers.