Fabiola De Marchi1, Mirko De Rosso1, Riccardo Flamini2. 1. Council for Agricultural Research and Economics - Viticulture & Oenology (CREA-VE), Viale XXVIII Aprile 26, 31015, Conegliano (TV), Italy. 2. Council for Agricultural Research and Economics - Viticulture & Oenology (CREA-VE), Viale XXVIII Aprile 26, 31015, Conegliano (TV), Italy. riccardo.flamini@crea.gov.it.
Abstract
INTRODUCTION: The biochemical diversity of flavonoids is based on glycosylation, methylation, acylation, and many other modifications of the flavonoid backbone. Liquid chromatography coupled to high-resolution mass spectrometry demonstrated to be a powerful approach to gain new insights into the flavonoid composition of many plant species, including grapes. OBJECTIVES: Among different metabolomic approaches, suspect screening analysis relies on the construction of a specific database and on ultra-high performance liquid chromatography/quadrupole time-of-flight (UHPLC/QTOF) analysis to find new compounds of oenological interest. METHODS: A homemade database containing mass data information retrieved from the literature specific for plant flavonoid derivatives (GrapeFlavMet) was constructed. Tandem mass spectrometry analysis of V. vinifera and hybrid grape extracts was performed, and MS/MS fragmentation allowed to assign the putative flavonoid chemical structure to various identification levels, as established by the Metabolomics Standard Initiative. RESULTS: By this approach, putative flavonoid derivatives with different glycosylation and acylation patterns were identified. They include three pentoside derivatives of tetrahydroxy-flavone, tetrahydroxy-flavanone and myricetin isomers, a putative dihydrorhamnetin hexoside derivative, three cinchonain isomers (phenylpropanoid-substituted flavan-3-ols with antidiabetic properties), and two syringetin isomer derivatives (acetyl- and p-coumaroyl-hexoside). Two acetyl-hexoside derivatives of dihydrorhamnetin and pentahydroxy-methoxy-flavanone, and three derivatives of tetrahydroxy-dimethoxy-flavanone (acetyl, p-coumaroyl, and caffeoyl-hexoside) were tentatively annotated. CONCLUSIONS: Most of the compounds were identified in grape for the first time, while two putative syringetin derivatives previously proposed in the literature were confirmed. These findings deepen the current knowledge on grape flavonoids, suggesting more connections at the biochemical level.
INTRODUCTION: The biochemical diversity of flavonoids is based on glycosylation, methylation, acylation, and many other modifications of the flavonoid backbone. Liquid chromatography coupled to high-resolution mass spectrometry demonstrated to be a powerful approach to gain new insights into the flavonoid composition of many plant species, including grapes. OBJECTIVES: Among different metabolomic approaches, suspect screening analysis relies on the construction of a specific database and on ultra-high performance liquid chromatography/quadrupole time-of-flight (UHPLC/QTOF) analysis to find new compounds of oenological interest. METHODS: A homemade database containing mass data information retrieved from the literature specific for plant flavonoid derivatives (GrapeFlavMet) was constructed. Tandem mass spectrometry analysis of V. vinifera and hybrid grape extracts was performed, and MS/MS fragmentation allowed to assign the putative flavonoid chemical structure to various identification levels, as established by the Metabolomics Standard Initiative. RESULTS: By this approach, putative flavonoid derivatives with different glycosylation and acylation patterns were identified. They include three pentoside derivatives of tetrahydroxy-flavone, tetrahydroxy-flavanone and myricetin isomers, a putative dihydrorhamnetin hexoside derivative, three cinchonain isomers (phenylpropanoid-substituted flavan-3-ols with antidiabetic properties), and two syringetin isomer derivatives (acetyl- and p-coumaroyl-hexoside). Two acetyl-hexoside derivatives of dihydrorhamnetin and pentahydroxy-methoxy-flavanone, and three derivatives of tetrahydroxy-dimethoxy-flavanone (acetyl, p-coumaroyl, and caffeoyl-hexoside) were tentatively annotated. CONCLUSIONS: Most of the compounds were identified in grape for the first time, while two putative syringetin derivatives previously proposed in the literature were confirmed. These findings deepen the current knowledge on grape flavonoids, suggesting more connections at the biochemical level.
Authors: Chiara Barnaba; Eduardo Dellacassa; Giorgio Nicolini; Mattia Giacomelli; Tomas Roman Villegas; Tiziana Nardin; Roberto Larcher Journal: Food Res Int Date: 2017-01-13 Impact factor: 6.475