Abstract:

Silybin and isosilybin are mainly effective elements of silymarin. To improve the performance of treatment and decrease the side effects from the unknown components, purified silybin and isosilybin are in request. The main purpose of this research was to develop a solid phase extraction (SPE) method for the purification of silybin and isosilybin from silymarin extract. For the analysis of the samples, a liquid chromatography method with ultraviolet detector (LC-UV) was developed to separate the silybin and isosilybin from their impurities. The separation was achieved in 8 min and a total analytical time of 11 min with column washing and equilibration. In the SPE, three different SPE packings were tested, including hydrophilic-lipophilic balance (HLB), hydrophilic interaction chromatography (HILIC) and reverse phase C18 silica microspheres. Based on the selectivity against silybin and isosilybin, the C18 packings were chosen. After the optimization of the elution of SPE, the purity over 94% could be achieved for the silybin and isosilybin mixture with the recoveries of 70.5%-81.7% and 66.7%-81.8%, and the relative standard deviations (RSDs) of 2.7%-9.4% and 1.5%-6.1%, respectively. Though silybin and isosilybin could not be separated from each other by using SPE, this is a useful method for the purification of silybin and isosilybin mixture from the crude extract of their plant seeds due to its simplicity and efficiency.

Key words: isosilybin, liquid chromatography (LC), separation and purification, silybin, solid phase extraction (SPE)