Food Supplements of Tribulus terrestris L.:An HPLC-ESI-MS Method for an Estimationof the Saponin Content

An HPLC-ESI-MS method in a positive mode is proposed to qualitatively analyse the saponin fractions from dietary supplements of Tribulus terrestris L. This method allows for the separation of structural isomers, as highlighted for some terrestrosines. The MS fragmentation pattern resulted diagnostic to collect structural information and the characteristic loss of water from some furostanolic saponins was highlighted for the first time. Due to the wide number of glycosidic furostanolic and spirostanolic saponins extracted from tribulus, a complete reference "molecular weight map" was created. Finally, a semi-quantitative evaluation of the total saponin content was carried out by HPLC-MS using protodioscin as external standard.