title: Electrospray tandem mass spectrometry analysis of methylenedioxy chalcones, flavanones and flavones.
abstract: BACKGROUND
  Several methylenedioxy chalcones, flavanones and flavones substituted with mono-, di- and trimethoxy groups have been used in the treatment of proliferative conditions like cancer and inflammatory diseases. The application of these flavonoids in biology requires an analytical method to ensure a detailed knowledge of their structures after drug metabolism.
  
  
  METHODS
  Electrospray ionization mass (ESI-MS) and tandem mass (ESI-MS/MS) spectra were acquired using a Q-TOF 2 instrument. Fragmentation patterns and their pathways were analyzed by CID-MS(2-3) spectra acquired in a LXQ linear ion trap mass spectrometer using standard isolation and excitation procedures (activation q value of 0.25, activation time of 30 ms). ESI-MS and ESI-MS(n) conditions: spray voltage 5 kV, nitrogen 8.00 sheath gas flow rate (arb), heated capillary temperature 275°C, capillary voltage 10.99 V; tube lens voltage 75.01 V.
  
  
  RESULTS
  The ESI-MS/MS spectra of chalcones were nearly identical to their corresponding isomeric flavanones with (0,α)A(+)/(1,3)A(+) and (0,1')B(+)/(1,4)B(+) cleavages. Other common losses are of (•)CH3, H2O, HCHO and C2H2O. The characteristic loss of C2H2O and absence of a (0,α)B(+)/(1,3)B(+) product ion allows to distinguish between the 2- or 4-methoxy-substituted chalcones and flavanones. Common losses of (•)CH3, (•)CH3 and (•)H, and C2H2O2 characteristic for the presence of methylenedioxy groups were observed in flavones.
  
  
  CONCLUSIONS
  The substitution pattern on the B-ring leads to distinct base peak formation in the flavones. In addition, differentiation of isomers with methoxy substituents in ortho and para positions of the B-ring was achieved using MS/MS in chalcones and flavanones. This method will be helpful for identification of these compounds in biological mixtures.
authors.affiliation: Department of Chemistry & QOPNA, University of Aveiro, 3810-193 Aveiro, Portugal. josemenezes@ua.pt
authors.forename: José C J M D S
authors.initials: JC
authors.lastname: Menezes
authors.forename: José A S
authors.initials: JA
authors.lastname: Cavaleiro
authors.forename: Shrivallabh P
authors.initials: SP
authors.lastname: Kamat
authors.forename: Cristina M R F
authors.initials: CM
authors.lastname: Barros
authors.forename: M Rosário M
authors.initials: MR
authors.lastname: Domingues
mesh_terms: D047188:Chalcones / Q000032:analysis*; D044950:Flavanones / Q000032:analysis*; D047309:Flavones / Q000032:analysis*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D047188:Chalcones; D044950:Flavanones; D047309:Flavones