title: Phenolic profiling of Portuguese propolis by LC-MS spectrometry: uncommon propolis rich in flavonoid glycosides.
abstract: BACKGROUND
  Propolis is a chemically complex resinous substance collected by honeybees (Apis mellifera) from tree buds, comprising plant exudates, secreted substances from bee metabolism, pollen and waxes. Its chemical composition depends strongly on the plant sources available around the beehive, which have a direct impact in the quality and bioactivity of the propolis. Being as Portugal is a country of botanical diversity, the phenolic characterisation of propolis from the different regions is a priority.
  
  
  OBJECTIVE
  Extensive characterisation of the phenolic composition of Portuguese propolis from different continental regions and islands.
  
  
  METHODS
  Forty propolis ethanolic extracts were analysed extensively by liquid chromatography with diode-array detection coupled to electrospray ionisation tandem mass spectrometry (LC-DAD-ESI-MS(n) ).
  
  
  RESULTS
  Seventy-six polyphenols were detected in the samples and two groups of propolis were established: the common temperate propolis, which contained the typical poplar phenolic compounds such as flavonoids and their methylated/esterified forms, phenylpropanoid acids and their esters, and an uncommon propolis type with an unusual composition in quercetin and kaempferol glycosides - some of them never described in propolis.
  
  
  CONCLUSIONS
  The method allowed the establishment of the phenolic profile of Portuguese propolis from different geographical locations, and the possibility to use some phenolic compounds, such as kaempferol-dimethylether, as geographical markers. Data suggest that other botanical species in addition to poplar trees can be important sources of resins for Portuguese propolis.
authors.affiliation: CIMO/Escola Superior Agrária, Instituto Politécnico de Bragança, Campus de Sta. Apolónia, Apartado 1172, 5301-855 Bragança, Portugal.
authors.forename: Soraia I
authors.initials: SI
authors.lastname: Falcão
authors.forename: Nuno
authors.initials: N
authors.lastname: Vale
authors.forename: Paula
authors.initials: P
authors.lastname: Gomes
authors.forename: Maria R M
authors.initials: MR
authors.lastname: Domingues
authors.forename: Cristina
authors.initials: C
authors.lastname: Freire
authors.forename: Susana M
authors.initials: SM
authors.lastname: Cardoso
authors.forename: Miguel
authors.initials: M
authors.lastname: Vilas-Boas
mesh_terms: D015415:Biomarkers / Q000032:analysis; D002853:Chromatography, Liquid / Q000295:instrumentation / Q000379:methods*; D005419:Flavonoids / Q000032:analysis* / Q000737:chemistry; D044949:Kaempferols / Q000032:analysis; D015394:Molecular Structure; D011174:Portugal; D011429:Propolis / Q000032:analysis* / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: C464827:3,4'-dimethylkaempferol; D015415:Biomarkers; D005419:Flavonoids; D044949:Kaempferols; D011429:Propolis