Development and validation of an LC-MS/MS method for the determination of hinokiflavone in rat plasma and its application to a pharmacokinetic study.

Hinokiflavone has drawn a lot of attention for its multiple biological activities. In this study, a sensitive and selective method for determination of hinokiflavone in rat plasma was developed for the first time, using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Amentoflavone was used as an internal standard. Separation was achieved on a Hypersil Gold C18 column with isocratic elution using methanol-water (65:35, v/v) as mobile phase at a flow rate of 0.3 mL/min. A triple quadrupole mass spectrometer operating in the negative electrospray mode with selected reaction monitoring was used to detect the transitions of m/z 537 → 284 for hinokiflavone and m/z 537 → 375 for IS. The LOQ was 0.9 ng/mL with a linear range of 0.9-1000 ng/mL. The intra- and inter-day accuracy (RE%) ranged from -3.75 to 6.91% and from -9.20 to 2.51% and the intra- and inter-day precision (RSD) was between 0.32-14.11 and 2.85-10.04%. The validated assay was successfully applied to a pharmacokinetic study of hinokiflavone in rats. The half-life of drug elimination at the terminal phase was 6.10 ± 1.86 h, and the area under the plasma concentration-time curve from time zero to the time of last measurable concentration and to infinity values obtained were 2394.42 ± 466.86 and 2541.93 ± 529.85 h ng/mL, respectively.