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 (250×4.6 mm, 5 μm). Blood samples were measured with a Surveyor photodiode array (PDA) detector at a wavelength of 263 nm. The LCQ DECA XP(Plus) 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 μg/mL for sinomenine in plasma and over the range of 0.01-5.00 μg/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 μg/mL for plasma, and 0.01 μg/g for brain tissue. Identification of sinomenine was reproducible at 0.5, 5, and 50 μg/mL in the plasma and at 0.05, 0.50, and 2.00 μg/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.