Dereplication of glycosides from Sapindus saponaria using liquid chromatography-mass spectrometry

Fruits of Sapindus saponaria (Sapindaceae), a widespread tree throughout the tropics, were collected each 30 days during six months. Liquid-chromatography with UV and MS detection (LC/UV/ESI-MS) and MS/MS fragmentation studies showed that the main glycosides present in these fruits are saponins (SAP) derived from the triterpenes hederagenin and oleanolic acid, and acyclic sesquiterpene oligoglycosides (ASOGs). Using these methods of analysis, we detected up to thirty SAPs and sixty-three ASOGs. The plant produces these compounds as a complex mixture of naturally non-regiosselective acetylated glycosides. Alkaline hydrolysis of the natural glycosides produced simplified mixtures of compounds formed of only four SAPs and five ASOGs. Quantitative analysis of the saponificated glycosides showed that the amount of SAPs accumulated during fruit maturation was almost constant at ca. 110 mg g(-1) while the quantity of ASOGs are considerably higher and hits a maximum accumulation of ca. 540 mg g(-1) at an age of ca. 3 months.