DETERMINATION OF ISOSTEVIOL BY LC-MS/MS AND ITS APPLICATION FOR EVALUATION OF PHARMACOKINETICS OF ISOSTEVIOL IN RAT

Isosteviol has been found to have potential preventive or therapeutic effects against hypertension, ischemia reperfusion injury, diabetes and cancer, but little is known about the pharmacokinetics (PK) of the compound. The aim of this study was to develop a liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method for determination of isosteviol in rat plasma and to assess in a preliminary manner the PK of isosteviol after intravenous bolus injection. Ions of analytes were generated using electro-spray ionization and detected in the positive-ion mode in LC-MS/MS. Multiple reaction monitoring was performed, using the precursor product ion combination for isosteviol m/z 319.4→273.4. Progesterone was used as an internal standard. Nitrogen was used as the nebulising gas and unit resolution was set for Q1 and Q3. Isosteviol solution was injected through the penile vein of rats at a dose of 8 mg/kg. Blood samples were collected from a jugular vein cannula. The PK parameters were calculated using a two - compartment PK model. The LC-MS/MS assay for isosteviol in rat plasma was linear over the range of 0.5-80 μg/ml. The terminal half life of isosteviol (t 1/2 ) was 406 ± 31.7 min and clearance (CL) was 2.9 ± 0.3 ml/min/kg. A sensitive LC-MS/MS assay for isosteviol in plasma has been successfully established and used in a preliminary PK evaluation of isosteviol in rats.