Simultaneous quantification of cryptotanshinone and its active metabolite tanshinone IIA in plasma by liquid chromatography/tandem mass spectrometry (LC–MS/MS)

A rapid and sensitive method for the simultaneous determination of cryptotanshinone and its active metabolite tanshinone IIA in rat plasma was developed and well validated, using high-performance liquid chromatographic separation with tandem mass spectrometric detection. This method entailed a single step of liquid–liquid extraction with ethyl acetate from a small volume of plasmas. The analytes and internal standard diazepam were baseline separated on a Shim-pack VP-ODS analytical column. Detection was performed on a triple quadrupole tandem mass spectrometer equipped with electrospray ionization source operated under selected reaction monitoring (SRM) mode. The method was linear in the concentration range of 1–100 ng/ml for both tanshinone IIA and cryptotanshinone. The intra- and inter-day precisions (R.S.D.%) were within 10.2% for both analytes. Deviation of the assay accuracies was within ±12.0% for both analytes. Both analytes were proved to be stable during all sample storing, preparation and analytic procedures. The method was successfully applied to a pharmacokinetic study after an oral administration of cryptotanshinone to rats with a dose of 20 mg/kg. With the lower limits of quantification at 1.0 ng/ml for tanshinone IIA and 0.2 ng/ml for cryptotanshinone, this method was proved to be sensitive enough and reproducible for the pharmacokinetics study of both tanshinones.