title: Characterisation of homoflavonoids from three Ophioglossum species using liquid chromatography with diode array detection and electrospray ionisation tandem mass spectrometry.
abstract: BACKGROUND
  Homoflavonoids, characterised by one more carbon atom directly added to C6 -C3 -C6 backbone of flavonoids, are rich in the species of genus Ophioglossum. Up to now we have little knowledge about their MS fragmentation patterns. It is therefore necessary to investigate their MS fragmentation pathways so as to distinguish them from other types of flavonoids.
  
  
  OBJECTIVE
  To develop a rapid method for identifying homoflavonoids from Ophioglossum based on their characteristic MS fragmentation.
  
  
  METHODS
  Mass spectrometry fragmentation pathways and qualitative analysis of homoflavonoids in three ferns of Ophioglosssum were investigated by using high-performance liquid chromatography coupled with diode-array detection and electrospray ionisation tandem mass spectrometry (HPLC-DAD-ESI/MS(n) ).
  
  
  RESULTS
  The analyses of the MS(n) spectra of the homoflavonoids allowed us to classify them into two types according to their fragmentation characteristics. The type I homoflavonoids, with an attached additional carbon atom to the C-3 position of the C-ring, presented the initial competing loss of H2 O and CH2 O from their aglycone ions, compared to the initial removal of H2 O or CO in the case of the type II homoflavonoids, which bear the additional carbon atom at the C-2' site of the B-ring and forming ring D. The above characteristic fragmentations of homoflavonoids were quite different from those of other flavonoids, and were successfully applied to identify homoflavonoids in the crude extracts of three Ophioglossum species.
  
  
  CONCLUSIONS
  The HPLC-DAD-ESI/MS(n) method obtained in the present study provided a powerful tool for identifying homoflavonoids from ferns in the genus Ophioglossum.
authors.affiliation: State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing, 210009, China; Key Laboratory of Protection and Utilization of Biological Resources in Tarim Basin of Xinjiang Production & Construction Group, Tarim University, Alar, 843300, China.
authors.forename: Chuan-Xing
authors.initials: CX
authors.lastname: Wan
authors.forename: Jian-Guang
authors.initials: JG
authors.lastname: Luo
authors.forename: Yu-Cheng
authors.initials: YC
authors.lastname: Gu
authors.forename: De-Ran
authors.initials: DR
authors.lastname: Xu
authors.forename: Ling-Yi
authors.initials: LY
authors.lastname: Kong
mesh_terms: D004365:Drugs, Chinese Herbal / Q000737:chemistry*; D005419:Flavonoids / Q000032:analysis* / Q000737:chemistry / Q000145:classification; D019906:Nuclear Magnetic Resonance, Biomolecular; D010946:Plants, Medicinal / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D004365:Drugs, Chinese Herbal; D005419:Flavonoids
keywords: HPLC-DAD-ESI/MSn; Ophioglossum; fragmentation pathway; homoflavonoids