Production of 3,4-cis- and 3,4-trans-Leucocyanidin and Their Distinct MS/MS Fragmentation Patterns
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Journal of Agricultural and Food Chemistry. 2018, vol. 66, n° 1, p. 351-358
Resumen en inglés
(+)-2,3-trans-3,4-cis-Leucocyanidin was produced by acidic epimerization of (+)-2,3-trans-3,4-trans-leucocyanidin synthesized by reduction of (+)-dihydroquercetin with NaBH4, and structures of the two stereoisomers purified ...Leer más >
(+)-2,3-trans-3,4-cis-Leucocyanidin was produced by acidic epimerization of (+)-2,3-trans-3,4-trans-leucocyanidin synthesized by reduction of (+)-dihydroquercetin with NaBH4, and structures of the two stereoisomers purified by C18- and phenyl-reverse-phase high-performance liquid chromatography (HPLC) were confirmed by NMR spectroscopy. We confirm that only 3,4-cis-leucocyanidin is used by leucoanthocyanidin reductase as substrate. The two stereoisomers are quite stable in aqueous solution at -20 degrees C. Characterization of the two stereoisomers was also performed using electrospray ionization tandem mass spectrometry (ESI-MS/MS), and we discuss here for the first time the corresponding MS/MS fragmentation pathways, which are clearly distinct. The main difference is that of the mode of dehydration of the 3,4-diol in positive ionization mode, which involves a loss of hydroxyl group at either C-3 or C-4 for the 3,4-cis isomer but only at C-3 for the 3,4-trans isomer. Tandem mass spectrometry therefore proves useful as a complementary methodology to NMR to identify each of the two stereoisomers.< Leer menos
Palabras clave en inglés
Leucocyanidin
NMR
leucoanthocyanidin reductase
reverse-phase HPLC
tandem mass spectrometry
fragmentation pathways
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