Simultaneous quantification of nine components in the plasma of depressed rats after oral administration of Chaihu-Shugan-San by ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry and its application to pharmacokinetic studies

Chaihu-Shugan-San (CSS), a classic Chinese formula, has long been used to treat depression. For a better and rational use of this formula, here, we investigated the comprehensive pharmacokinetic features of multiple ingredients from CSS using ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC-QTOF-MS) in depressed rats. Force swimming experiments were conducted to establish a rat model of depression. Prolonged immobility time, increased plasma adrenocorticotropic hormone, and decreased plasma 5-hydroxytryptamine (5-HT) and dopamine (DA) were confirmed in this model. Nine compounds from CSS, including ferulic acid, naringin, hesperidin, meranzin hydrate, glycyrrhizic acid, saikosaponin A, nobiletin, and hesperetin, were simultaneously determined in plasma samples. Sulfamethoxazole and schisandrin were used as internal standards. The separation was performed on a C18 column with gradient elution over 10 min, and detection was executed using multiple reaction monitoring (MRM) in the positive ionization mode. The optimized MRM transitions showed no interference in rat plasma. Validation parameters were all in accordance with the current criterion. The established method was successfully applied to the pharmacokinetic study of these nine components after the oral administration of CSS to depressed rats. This study provides a chemical basis for the clinical application of this formula.