HPLC and LC-MS analysis of sinomenine and its application in pharmacokinetic studies in rats

Aim: To improve and validate analytical methods based on HPLC and liquid chromatography coupled to electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) for the quantitative measurement of sinomenine in rat plasma and brain tissue. Methods: The separation of analytes and the internal standard (IS), chloramphenicol, was performed on an Agilent TC-C18 column (250x4.6 mm, 5 mu m). Blood samples were measured with a Surveyor photodiode array (PDA) detector at a wavelength of 263 nm. The LCQ DECA XPPlus mass spectrometer was operated in the multiple reactions monitoring mode using positive electrospray ionization, and the transition from the precursor ion (m/z 279) to the product ion (m/z 224) for sinomenine was measured in brain tissue. Results: Measurements were linear over the concentration range of 0.1-100 mu g/mL for sinomenine in plasma and over the range of 0.01-5.00 mu g/g for sinomenine in brain tissue. The intra-and inter-day variabilities were less than 10% of the relative standard deviation (RSD), and the extraction and recovery of sinomenine was 72.48%-80.26% from plasma and 73.75%-80.26% from brain tissue. The limit of quantification (LOQ) was 0.1 mu g/mL for plasma, and 0.01 mu g/g for brain tissue. Identification of sinomenine was reproducible at 0.5, 5, and 50 mu g/mL in the plasma and at 0.05, 0.50, and 2.00 mu g/g in brain tissue. The concentration of sinomenine measured in brain tissue after a single ip dose had a neuroprotective effect on H2O2-induced injury in PC12 cells in vitro. Conclusion: Our methods offered a sensitivity within a wide linear concentration range for sinomenine. These methods were successfully applied to evaluate sinomenine pharmacokinetics over time in rat brain tissue after a single ip dose of 30 mg/kg.