Derivatization of isothiocyanates and their reactive adducts for chromatographic analysis.
Isothiocyanates form adducts with a multitude of biomolecules, and these adducts need analytical methods. Likewise, analytical methods for hydrophilic isothiocyanates are needed. We considered reaction with ammonia to form thiourea derivatives. The hydrophilic, glycosylated isothiocyanate moringin, 4-(α-L-rhamnopyranosyloxy)benzyl isothiocyanate, was efficiently derivatized to the thiourea derivative by incubation with ammonia. The hydrophobic benzyl isothiocyanate was also efficiently derivatized to the thiourea derivative. The thiourea group provided a UV absorbing chromophore, and the derivatives showed expectable sodium and hydrogen adducts in ion trap mass spectrometry and were suitable for liquid chromatography analysis. Reactive dithiocarbamate adducts constitute the major type of reactive ITC adduct expected in biological matrices. Incubation of a model dithiocarbamate with ammonia likewise resulted in conversion to the corresponding thiourea derivative, suggesting that a variety of matrix-bound reactive isothiocyanate adducts can be determined using this strategy. As an example of the application of the method, recovery of moringin and benzyl isothiocyanate applied to cabbage leaf discs was studied in simulated insect feeding assays. The majority of moringin was recovered as native isothiocyanate, but a major part of benzyl isothiocyanate was converted to reactive adducts.
Copenhagen Plant Science Center and Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark. Electronic address: nia@plen.ku.dk.
Niels
N
Agerbirk
Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria, Centro di ricerca per le colture industriali (CRA-CIN), Via di Corticella 133, 40128 Bologna, Italy.
Gina Rosalinda
GR
De Nicola
Copenhagen Plant Science Center and Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark.
Carl Erik
CE
Olsen
Chemical Ecology, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld, Germany.
Caroline
C
Müller
Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria, Centro di ricerca per le colture industriali (CRA-CIN), Via di Corticella 133, 40128 Bologna, Italy.
Renato
R
Iori
D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D008401:Gas Chromatography-Mass Spectrometry; D006031:Glycosylation; D017879:Isothiocyanates / Q000737:chemistry*; D015394:Molecular Structure; D053719:Tandem Mass Spectrometry; D013859:Thiocarbamates / Q000737:chemistry; D013890:Thiourea / Q000737:chemistry
D017879:Isothiocyanates; D013859:Thiocarbamates; C037152:isothiocyanic acid; C031403:benzyl isothiocyanate; D013890:Thiourea
Dithiocarbamate; Isothiocyanate; Liquid chromatography; MS; NMR; Recovery; Tandem mass spectrometry; Thiourea; UV-detection