title: Saponin inventory from Argania spinosa kernel cakes by liquid chromatography and mass spectrometry.
abstract: BACKGROUND
  Argania spinosa kernel cakes, obtained from argan oil extraction process, are known to contain large amounts of saponins. Only a few have been characterised previously, due to the use of pure ethanol as extracting solvent. The use of aqueous 50% ethanol improved the extraction of more polar saponins.
  
  
  OBJECTIVE
  Identification of polar saponins in kernel cakes of Argania spinosa by liquid chromatography-mass spectrometry and NMR techniques.
  
  
  METHODS
  Defatted kernel cakes were first extracted with ethanol and then twice with 50% aqueous ethanol. Individual crude extracts were analysed with an ion-trap mass spectrometer in negative mode electrospray MS and MS/MS modes. NMR experiments were run under standard conditions at 300 K on a Bruker DRX-600 spectrometer.
  
  
  RESULTS
  The LC-MS base peak chromatogram of saponins from pure ethanol extract was dominated by 11 large and several small peaks but the UV chromatogram showed only two peaks, corresponding to the main neutral saponins found previously in Argania: arganine A and B. In 50% aqueous ethanol extracts, numerous other saponins were detected. Many of them were glucuronide oleanane-type triterpene carboxylic acid 3,28-O-bidesmosides (GOTCAB saponins). The assignments of (1) H- and (13) C-NMR spectra of the four most abundant GOTCAB saponins confirmed the MS results.
  
  
  CONCLUSIONS
  Four GOTCAB saponins were structurally identified by NMR analysis in the 50% aqueous ethanol extract. Furthermore, LC-MS analyses showed the presence of at least 19 additional polar saponins in these kernel cakes.
authors.affiliation: Groupe S.U.C.R.E.S., UMR 7565 CNRS-Nancy-Université, BP 239, 54506, Nancy-Vandœuvre, France.
authors.forename: Max
authors.initials: M
authors.lastname: Henry
authors.forename: Mariusz
authors.initials: M
authors.lastname: Kowalczyk
authors.forename: Mariateresa
authors.initials: M
authors.lastname: Maldini
authors.forename: Sonia
authors.initials: S
authors.lastname: Piacente
authors.forename: Anna
authors.initials: A
authors.lastname: Stochmal
authors.forename: Wiesław
authors.initials: W
authors.lastname: Oleszek
mesh_terms: D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D019906:Nuclear Magnetic Resonance, Biomolecular; D010936:Plant Extracts / Q000737:chemistry*; D012503:Saponins / Q000032:analysis* / Q000737:chemistry; D029632:Sapotaceae / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D010936:Plant Extracts; D012503:Saponins
keywords: Argania spinosa; MS/MS and NMR analysis; Mass spectrometry; negative ion electrospray ionisation; saponins