Metabolic Analysis of Triptolide Microspheres in Human, Dog, Rabbit and Rat Liver Microsomes with UPLC-MS/MS Method

Objectives: Riptolide (TPL) has been shown to have a good clinical effect on rheumatoid arthritis (RA). We designed TPL microspheres (TPL-MS) and investigated its metabolic behavior in human, dog, rabbit and rat liver microsomes (HLM, DLM, RLM and SDRLM) with UPLC-MS/MS method. Methods: First, a UPLC-MS/MS method was established to measure the concentration of TPL in samples. The sample was separated on a C18 column (2.1x100 mm, 1.8 mu m) and eluted with a gradient elution. The precursor ions/product ions were m/z 378.1/361.0 for TPL and 260.0/116.2 for the internal standard. Then T-1/2, V-max and CLint were calculated from the above data. Finally, the metabolites of TPL-MS were identified by high-resolution UPLC-MS/MS. The sample was separated on a C18 column (2.1x100 mm, 2.2 mu m) and eluted with isocratic elution. Mass spectrometric detection was carried out on a thermo Q-exactive mass spectrometer with HESI. The scanning range of precursor ions was from m/z 50 to m/z 750. Results: Through several indicators including standard curve, precision, accuracy, stability, matrix effect and recovery rate, the enzymatic kinetics parameters including T-1/2, V-max and CLint were evaluated. Several metabolites of TPL-MS were identified. Discussion: UPLC-MS/MS method is an accurate and sensitive method for the determination of TPL in liver microsome samples with good precision, accuracy and stability. The variation of parameters indicated that the microspheres can delay the elimination of TPL in liver microsomes. Conclusion: The metabolism of TPL-MS varied among species, but no new metabolites appeared.