Simultaneous determination of five bioactive components in radix glycyrrhizae by pressurised liquid extraction combined with UPLC-PDA and UPLC/ESI-QTOF-MS confirmation.

INTRODUCTION: Glycyrrhizae species are popular ingredients of herbal medicine in most traditional Chinese medicine prescriptions, and they mainly contain flavonoids and triterpene saponins. The contents of these bioactive compounds may vary in different batches and affect the therapeutic effects. Thus comprehensive quality control and monitoring of their herbal formulation are of paramount concern.
OBJECTIVE: To establish a rapid, effective pressurised liquid extraction (PLE) and ultra-performance liquid chromatography coupled with photodiode array (UPLC-PDA) method to evaluate the quality of Glycyrrhizae species.
METHODS: Radix Glycyrrhizae was extracted by PLE using 70% ethanol at 100°C for 15 min during three static extraction cycles. Separation was performed using an UPLC system to quantify five bioactive compounds, namely liquiritin apioside, liquiritin, liquiritigenin, glycyrrhizic acid and glycyrrhetinic acid, in 12 batches of samples of different origins in China. Furthermore, the samples were analysed using an ultra-performance liquid chromatography coupled with electrospray ionisation and time-of-flight mass spectrometry (UPLC/ESI-QTOF-MS) system to confirm the results.
RESULTS: The calibration curves of all five analytes showed good linearity (R(2)  > 0.9997). Accuracy, precision and repeatability were all within required limits. The mean recoveries measured at the three concentrations were higher than 93.7% with RSDs lower than < 3.33% for the targets.
CONCLUSION: The established PLE and UPLC-PDA method could serve as a rapid and effective method for quality evaluation of Radix Glycyrrhizae. The UPLC technique can be considered as an attractive alternative to HPLC in routine quality control of Chinese medicine, especially in situations where high sample throughput and fast analytical speed are required.