Determination of steroidal saponins in Tribulus terrestris by reversed-phase high-performance liquid chromatography and evaporative light scattering detection

This paper describes the first analytical method suitable for the determination of steroidal saponins in Tribulus terrestris. A separation by high performance liquid chromatography (HPLC) was achieved by using a reversed-phase (RP-18) column, evaporative light scattering (ELS) detection, and a water/acetonitrile gradient as the mobile phase. The marker compound, protodioscin, was detected at a concentration as low as 10.0 mug/mL. Several different samples of plant material were successfully analyzed, and depending on origin and plant part used for extraction, significant differences in the composition of the saponins were observed. The analysis of market products showed considerable variations of 0.17 to 6.49% in the protodioscin content. (C) 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association.