title: Structure-fragmentation relationship and rapid dereplication of Buxus steroidal alkaloids by electrospray ionization-quadrupole time-of-flight mass spectrometry.
abstract: BACKGROUND
  Tandem mass spectrometric studies of natural products revealed the identification of key fragments which can be helpful for their rapid dereplication in plant extracts utilizing a liquid chromatography/tandem mass spectrometry (LC/MS/MS) approach, particularly for the thermally labile compounds. The knowledge of the collision-induced dissociation (CID) fragmentation pattern of the molecule is essentially required prior to the analysis by LC/MS/MS.
  
  
  METHODS
  The fragmentation patterns of eleven Buxus steroidal alkaloids were studied by using a positive ion electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-QqTOF-MS/MS) hybrid instrument. Chromatographic separation of a Buxus papillosa extract was achieved using a capillary HPLC system coupled with the mass instrument.
  
  
  RESULTS
  ESI-QqTOF-MS (positive ion mode) showed the presence of several characteristic fragments which can be used to rapidly identify various classes of Buxus steroidal alkaloids. The presence of a cyclopropane ring in the cycloartenol skeleton and the hydroxyl group at C-10 was found to effect on the fragmentation pattern and afford characteristic peaks. This study distinguishes between different types of Buxus steroidal alkaloids based on logical fragmentation pathways. This strategy was successfully applied in LC/ESI-QqTOF-MS/MS analysis of Buxus papillosa extract to investigate and characterize Buxus steroidal alkaloids and 14 compounds were identified as steroidal alkaloids.
  
  
  CONCLUSIONS
  The knowledge of the fragmentation pattern was used for the rapid identification of this bioactive group of biosynthetically unique steroidal alkaloids in complex plant extracts of Buxus species, especially in the absence of any reference material, by combining key fragments, exact mass measurements and relative abundances of diagnostic fragment ions.
authors.affiliation: H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan. musharraf1977@yahoo.com
authors.forename: Syed Ghulam
authors.initials: SG
authors.lastname: Musharraf
authors.forename: Madiha
authors.initials: M
authors.lastname: Goher
authors.forename: Salma
authors.initials: S
authors.lastname: Shahnaz
authors.forename: M Iqbal
authors.initials: MI
authors.lastname: Choudhary
authors.lastname: Atta-ur-Rahman
mesh_terms: D000470:Alkaloids / Q000032:analysis / Q000737:chemistry*; D031235:Buxus / Q000737:chemistry*; D008970:Molecular Weight; D010936:Plant Extracts / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013329:Structure-Activity Relationship; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D000470:Alkaloids; D010936:Plant Extracts