LC–MS/MS determination and pharmacokinetic study of five flavone components after solvent extraction/acid hydrolysis in rat plasma after oral administration of Verbena officinalis L. extract

ETHNOPHARMACOLOGICAL RELEVANCE: Traditional Chinese medicine (TCM) has been used in clinical practice for several thousand years. TCM has played an indispensable role in the prevention and treatment of diseases, especially the complicated and chronic ones. Pharmacokinetic study on active constituents in herbal preparations is a good way for us to explain and predict a variety of events related to the efficacy and toxicity of TCM. AIM OF THE STUDY: A selective and sensitive HPLC–MS/MS method was first developed and validated for the determination of luteolin, kaempferol, apigenin, quercetol, and isorhamnetin in rat plasma. MATERIALS AND METHODS: The LC system consisted of an Agilent Technologies Series 1200 system (Agilent, USA) equipped with an automatic degasser, a quaternary pump, and an autosampler. Chromatographic separations were performed on a Waters SunFire™ C₁₈ column (150mm×4.6mm, 5μm), and the column temperature was maintained at 25°C and the sample injection volume was 20μL. The current LC–MS/MS assay was validated for linearity, intra-day and inter-day precisions, accuracy, extraction recovery and stability. RESULTS: The validated method was successfully applied to monitoring the concentrations and pharmacokinetic studies of five flavone compounds in rat plasma after a single oral administration of Verbena officinalis L. extract with a dosage of 8.0mL/kg. The time to reach the maximum plasma concentration (Tₘₐₓ₁) was 0.48±2.14h for luteolin, 0.25±0.13h for kaempferol, 0.97±1.08h for apigenin, 1.04±4.25h for quercetol and 0.25±0.16h for isorhamnetin, and the maximum plasma concentration (Tₘₐₓ₂) was 3.97±1.48h, 4.05±0.46h, 4.33±0.58h, 2.99±0.48h and 4.02±0.34h. The elimination half-time (t₁/₂) of luteolin, kaempferol, apigenin, quercetol and isorhamnetin was 4.02±0.81, 7.65±0.71, 3.30±0.83, 4.55±0.49 and 5.56±1.32h, respectively. CONCLUSIONS: This paper described a simple, sensitive and validated LC–MS/MS method for simultaneous determination of luteolin, kaempferol, apigenin, quercetol and isorhamnetin in rat plasma after oral administration of V. officinalis L. extract, and investigated on their pharmacokinetic studies as well, with a short run time of 5min.