title: Identification of glucosinolates in capers by LC-ESI-hybrid linear ion trap with Fourier transform ion cyclotron resonance mass spectrometry (LC-ESI-LTQ-FTICR MS) and infrared multiphoton dissociation.
abstract: An liquid chromatography-mass spectrometry method using electrospray ionization in negative ion mode coupled with a hybrid quadrupole linear ion trap and Fourier transform ion cyclotron resonance (FTICR) mass spectrometer was applied to characterize of intact glucosinolates (GLSs) in crude sample extracts of wild bud flowers of Capparis spinosa (Capparis species, family Capparaceae). Structural information of GLSs was obtained upon precursor ions' isolation within the FTICR trapping cell and subsequent fragmentation induced by infrared multiphoton dissociation (IRMPD). Such a fragmentation was found very useful in terms of chemical identification of all precursor ions [M-H](-) including sulfur-rich GLSs reported here for the first time. Along with most common GLSs already found in capers such as glucocapparin, isopropyl/n-propyl-GLS, mercapto-glucocapparin, and two indolic GLS, i.e., 4-hydroxyglucobrassicin and glucobrassicin, the occurrence of the uncommon glycinyl-glucocapparin as well as two sulfur-rich GLSs is reported. IRMPD showed an increased selectivity towards disulfide bond cleavages with thiol migration, suggesting the side chain structure of non-targeted compounds, i.e., disulfanyl-glucocapparin and trisulfanyl-glucocapparin. Glucocapparin [2.05 ± 0.25 mg/g, dry weight (dw)] was the most abundant GLS, followed by glucobrassicin (232 ± 18 µg/g, dw) and 4-hydroxyglucobrassicin (89 ± 12 µg/g, dw). All other compounds were present at very low content ranging from 0.5 to 1.5 µg/g dw.
authors.affiliation: Dipartimento di Chimica, Università degli Studi della Basilicata, Via dell'Ateneo Lucano, n° 10-85100, Potenza, Italy.
authors.forename: Giuliana
authors.initials: G
authors.lastname: Bianco
authors.forename: Filomena
authors.initials: F
authors.lastname: Lelario
authors.forename: Fabio Giuseppe
authors.initials: FG
authors.lastname: Battista
authors.forename: Sabino A
authors.initials: SA
authors.lastname: Bufo
authors.forename: Tommaso R I
authors.initials: TR
authors.lastname: Cataldi
mesh_terms: D031484:Capparis / Q000737:chemistry*; D002853:Chromatography, Liquid / Q000379:methods*; D005961:Glucosinolates / Q000032:analysis*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013055:Spectrophotometry, Infrared; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D005961:Glucosinolates