High performance liquid chromatographic assay of saikosaponins from radix Bupleuri in China

Abstract

In this study, the quantitative analysis of saikosaponins from Radix Bupleuri in China was performed by high performance liquid chromatography. Saikosaponin-a and -d were converted completely into saikosaponin-b1 and -b2 by mild acid treatment. Distinctive measuring of these converted diene-saponins provided a rapid and selective method for the determination of saikosaponin-a and -d in commercial samples of Radix Bupleuri. The conditions of extraction and conversion of saikosaponins were optimized using orthogonal design L9(3(4)). The HPLC analysis was performed on ODS-C18 column with a flow rate of 1.0 ml/min and detection wavelength of 250 nm. Well resolved chromatograms of saikosaponin-b1 and -b2 were obtained with an isocratic elution of acetonitrile : 1% formic acid water (37.5 : 62.5). Calibration curves of saikosaponin-b1 and -b2 were linear in the range of 4.9-98.0 microg/ml and 3.5-71.0 microg/ml, respectively. The average recovery of saikosaponin-b1 and -b2 were 98.3% (RSD = 3.1%) and 96.4% (RSD = 1.8%), respectively. Seventeen samples of different species and habitats of Radix Bupleuri were analyzed by the developed HPLC method.