Abstract
Introduction Tribulus is a well-known pharmaceutical herb that has been used for a long time in the traditional Chinese and Indian systems of medicine for the treatment of various diseases. It has been found that the genus Tribulus is rich in biologically active furostane-, cholestane- and spirostane-type steroidal saponins. Objective To develop a rapid, sensitive and accurate method based on liquid-phase extraction followed by high-performance liquid chromatography and electrospray ionisation mass spectrometry (HPLC-ESI-MS) to identify different saponins in three species of the genus Tribulus, and to quantify the compounds that are already known. Methodology After extraction from the species studied, the extracts were subjected to HPLC analyses with an XTerra (R) MS C-18-column and a binary mobile phase consisting of 0.05% formic acid in water and acetonitrile, and with an ESI-MS detection in the negative ion mode. Data were acquired and processed using the Xcalibur 1.3 software. Results The results exhibited that the profiles of native steroidal glycosides of both T. pentandrus and T. megistopterus subsp. pterocarpus were very similar to each other, but that of T. parvispinus was remarkably different. The fragmentation patterns provided evidence that the saponins possess spirostane-, cholestane- and furostane-type aglycones. Quantitative analyses suggested that these species are a rich source of steroidal saponins. Conclusion HPLCESI-MS/MS allowed identification of the key compounds without preparative isolation of the components from the crude extract of Tribulus species. Copyright (c) 2012 John Wiley & Sons, Ltd.