Structural characterization of steroidal saponins from Smilax trinervula using ultra high-performance liquid chromatography coupled with LTQ-Orbitrap mass spectrometry.

Steroid saponins are a class of naturally existing substances widely distributed in the plants of Smilacaceae. Their biological activities have been attracting the interest of scientists in the chemical field for the past few years. To our best knowledge, there has been no study on structural characterization of steroidal saponins from Smilax trinervula (S. trinervula) using LTQ-Orbitrap mass spectrometry, which could provide an excellent approach for rapid screening of steroidal saponins in other plants of Smilacaceae. An ultra high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC/HRMS) method was therefore developed to characterize steroidal saponins in S. trinervula. This method was operated in both negative and positive ion modes with HRMS, as a result, a total of twenty-two steroidal saponins with three aglycone skeletons were elucidated in the crude extract from the root of S. trinervula. The characteristic-fragment ions could well identify and differentiate the three types of aglycone skeletons (diosgenyl saponins, furostanol saponins, C27-hydroxy diosgenyl saponins).