O-glycoside sequence of pentacyclic triterpene saponins from Phytolacca bogotensis using HPLC-ESI/multi-stage tandem mass spectrometry.
BACKGROUND
The lack of pharmacopoeial methodologies for the quality control of plants used for therapeutic purposes is a huge problem that impacts directly upon public health. In the case of saponins, their great structural complexity, weak glycoside bonds and high polarity hinder their identification by conventional techniques.


OBJECTIVE
To apply high-performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI/MS(n)) to identify the O-glycoside sequence of saponins from the roots of Phytolacca bogotensis.


METHODS
Saponins were isolated by preparative HPLC and characterised by NMR spectroscopic experiments. Collision-induced dissociation (CID) of isolated saponins was performed producing typical degradation reactions that can be associated with several glycosidic bonds as empirical criteria. A method using solid-phase extraction (SPE) and HPLC/ESI-MS(n) for the characterisation of saponins and identification of novel molecules is described.


RESULTS
Three saponins reported for the first time in P. bogotensis were isolated and characterised by NMR spectroscopy. Characteristic cross ring cleavage reactions have been used as empirical criteria for the characterisation of the glycosidic bonds most frequently reported for Phytolacca saponins. One new saponin was proposed on the basis of empirical criteria, and other five saponins were identified for the first time for P. bogotensis using HPLC-ESI/MS(n).


CONCLUSIONS
Electrospray ionisation in combination with tandem mass spectrometry has been established as a powerful tool for the profiling of saponins from roots of P. bogotensis. CID proved to be a useful tool for the characterisation and identification of known and novel saponins from the plant family Phytolaccaceae and can be used for quality control purposes of crude plant extracts.
Montoya
Guillermo
G
Grupo de Investigación en Sustancias Bioactivas, Sede de Investigación Universitaria, Universidad de Antioquia A.A 1226. Medellín-Colombia. gmontoya@farmacia.udea.edu.co
Arango
Gabriel J
GJ
Unger
Matthias
M
Holzgrabe
Ulrike
U
D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006027:Glycosides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D029603:Phytolacca / Q000737:chemistry*; D012503:Saponins / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014315:Triterpenes / Q000737:chemistry*
D006027:Glycosides; D012503:Saponins; D014315:Triterpenes