Analysis and pharmacokinetic study of curdione in Rhizoma Curcumae by UPLC/QTOF/MS

An ultra-performance liquid chromatography-quadrupole time-of-flight/mass spectrometry (UPLC/QTOF/MS) method was established to determine the chemical components of curcuma rhizomes (Ezhu) and their pharmacokinetics. Chromatographic separation was performed by UPLC using a 1.8 µm column in order to obtain good resolution and increase the sensitivity of analysis. Accurate mass measurement within 5 ppm error for each ion produced in positive mode electrospray ionization and the subsequent QTOF product ions enabled 12 compounds to be identified. Several of the identified components, including β-elemene, curcumol, germacrone and curdione, are thought to be the biologically active ingredients. Quantitative pharmacokinetic analysis was also carried out by UPLC/QTOF/MS. Using 20(S)-protopanoxadiol as an internal standard, samples were prepared by protein precipitation with methanol. Chromatographic separation was performed on an Agilent Extend-C18 column (2.1 × 50 mm, 1.8 µm) with acetonitrile (0.1% formic acid)-water (0.1% formic acid) for gradient elution. Curdione calibration plots were linear over the range of 0.1-12.2 µg/mL for curdione in plasma with the lower quantification limit being 6.5 ng/mL, and the recovery from plasma was about 105.2%. The RSD for both intra- and inter-day precision was <9.9%.