title: Characterisation of diarylheptanoid- and flavonoid-type phenolics in Corylus avellana L. leaves and bark by HPLC/DAD-ESI/MS.
abstract: BACKGROUND
  The leaves of Corylus avellana L. (common hazel, Betulaceae), a plant with a wide distribution in Europe, have been used in folk medicine for various diseases, but phytochemical exploration of C. avellana is still incomplete. To the best of our knowledge there is no previous report concerning diarylheptanoids in C. avellana, although these compounds show a frequent occurrence among Betulaceae plants.
  
  
  OBJECTIVE
  To improve existing online chromatographic methods for the investigation of the phenolic compounds in C. avellana leaves and bark, focusing on diarylheptanoid-type molecules.
  
  
  METHODS
  Dried and powdered leaves and bark of C. avellana were extracted with increasing polarity solvents (n-hexane, chloroform, ethyl acetate and methanol) in Soxhlet extractor apparatus. For the characterisation of the phenolic compounds in the ethyl acetate and methanolic extracts, UV spectral data, obtained by LC with a diode-array detector (DAD), accurate molecular mass and formula, acquired by LC and electrospray ionisation (ESI) with time-of-flight (TOF) MS and fragmentation pattern, given by LC-ESI/MS/MS analyses were used. Quantitation of the compounds was performed by LC-MS/MS.
  
  
  RESULTS
  In the methanolic and ethyl acetate extracts of C. avellana bark four flavonoid glycosides and a caffeoyl hexoside derivative were detected and characterised, while in C. avellana leaves, seven diarylheptanoid-type molecules were tentatively identified in addition to six flavonoid components. As far as we know this is the first study where the presence of diarylheptanoids in C. avellana is reported.
  
  
  CONCLUSIONS
  The improved HPLC/DAD-ESI/MS method was successfully utilised for the characterisation and quantitation of the phenolic compounds in C. avellana bark and leaves extracts.
authors.affiliation: Department of Pharmacognosy, Semmelweis University, H-1085, Hungary.
authors.forename: Eszter
authors.initials: E
authors.lastname: Riethmüller
authors.forename: Agnes
authors.initials: A
authors.lastname: Alberti
authors.forename: Gergő
authors.initials: G
authors.lastname: Tóth
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Béni
authors.forename: Francesco
authors.initials: F
authors.lastname: Ortolano
authors.forename: Agnes
authors.initials: A
authors.lastname: Kéry
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D036381:Diarylheptanoids / Q000032:analysis*; D005419:Flavonoids / Q000032:analysis*; D010636:Phenols / Q000032:analysis* / Q000737:chemistry; D024301:Plant Bark / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D036381:Diarylheptanoids; D005419:Flavonoids; D010636:Phenols
keywords: Corylus avellana; HPLC-MS; diarylheptanoid; flavonoid; hazel