Determination of scutellarein in human plasma by enzymatic hydrolysis and liquid chromatograph-triple quadrupole tandem mass spectrometer analysis: Its use in determining the bioequivalence of scutellarin in Chinese volunteers

IntroductionScutellarin (SG) is widely used for the treatment of occlusive cerebral vascular diseases in China. The purpose of this study was to establish a liquid chromatograph-triple quadrupole tandem mass spectrometer (LC-MS/MS) method combined with sample hydrolysis by β-glucuronidase for the determination of scutellarein (S), the aglycone form of SG, in human plasma to evaluate the relative bioequivalence of two SG oral formulations in healthy Chinese volunteers.MethodsPlasma samples were prepared by β-glucuronidase hydrolysis and protein precipitation with methanol in succession. The chromatographic separation was performed on a C18 column with the mobile phase of acetonitrile, methanol and water (containing 0.1% formic acid and 1% isopropanol) (40/10/50, v/v/v). The quantitation was performed on a triple quadrupole mass spectrometer operating through a multiple reaction monitoring (MRM) and negative ion mode. The precursor to product ion transitions monitored for S and quercetin (internal standard, IS) were m/z 285 → 137 and 301 → 121, respectively.ResultsThe calibration curve was linear (r = 0.999) over the concentration range of 4.0-513 ng/mL with a lower limit of quantitation of 4.0 ng/mL. The intra- and inter-day precision expressed by coefficient of variation (CV, %) was below 7.2%. The recovery was greater than 80%. The relative bioavailability of the test formulation to the reference was (108.4 ± 32.5)%.ConclusionsThe method developed in the present study was successfully validated and applied in a bioequivalence study of SG preparations in twenty-four healthy Chinese male volunteers.