An LC-MS/MS method for determination of 3,6'-disinapoylsucrose in rat plasma and its application to a pharmacokinetic study.

3,6'-Disinapoylsucrose (DSS), a major active component of traditional Chinese medicine Yuan-Zhi (the roots of Polygala tenuifolia), has significant effects for neuroprotection and improving learning memory. In order to explore the pharmacokinetic properties of DSS so as to further understand its in vivo activities, a sensitive LC-MS/MS method was developed for determination of DSS in rat plasma and applied to a pharmacokinetic study in the present study. After treatment by protein precipitation, the plasma sample was separated on a C(18) HPLC column and analyzed by a mass spectrometry under positive electrospray ionization. Multiple-reaction monitoring was employed to measure the ion transition at m/z 777.4 --> 409.2 for DSS and m/z 557.2 --> 309.1 for forsythin as internal standard. The method was linear over the studied concentration range of 0.5-1000.0 ng/mL. The precision and accuracy ranged from 1.4 to 18.4%, and from -3.7 to -9.5%, respectively, for within-day and between-day assay. Extraction recovery was higher than 86.6%. The limits of detection and quantification were 0.3 and 0.5 ng/mL, respectively. The present method was successfully applied to a pharmacokinetic study. DSS was found to have poor oral absorption with only about 0.5% bioavailability.