Quality evaluation of Polygala japonica through simultaneous determination of six bioactive triterpenoid saponins by HPLC-ELSD

Polygala japonica Houtt (Polygalaceae), a traditional Chinese herb, has been used as expectorant, anti-inflammatory, antibacterial and antidepressant agent. To evaluate the quality of P. japonica, a high performance liquid chromatography (HPLC) with evaporative light scattering detector (ELSD) method was developed for the simultaneous determination of six active triterpenoid saponins. With a Discovery C18 analytical column, the analytes were separated efficiently using acetonitrile–methanol–0.05% trifluoroacetic acid (TFA) as mobile phase in a gradient program. The evaporator tube temperature of ELSD was set at 105 °C, and with the nebulizing gas flow-rate of 2.6 l/min. All calibration curves showed good linear regression (γ > 0.9991) within the tested range. Additionally, reproducibility for the quantification of six saponins in P. japonica with intra- and inter-day variations of less than 5.0% was observed. Quantification of the six active saponins in P. japonica from different locations was performed by this newly developed method, which provides a new tool for the assessment of quality of P. japonica.