Synthesis, Identification, and Structure Elucidation of Adducts Formed by Reactions of Hydroxycinnamic Acids with Glutathione or Cysteinylglycine.
Grape polyphenols, especially hydroxycinnamic acids such as caftaric and caffeic acid, are prone to enzymatic oxidation reactions during the winemaking process, forming o-quinones and leading to color darkening. Glutathione is capable of trapping these o-quinones and thus limiting juice browning. In this study, the addition of glutathione or cysteinylglycine onto caftaric or caffeic acid o-quinones formed by polyphenoloxidase-catalyzed reactions was investigated by UPLC-DAD-ESIMS and NMR data analyses. Complete identification of adducts has been achieved via NMR data. The results confirmed that the favored reaction is the substitution of the sulfanyl group of cysteine at C-2 of the aromatic ring. Several minor isomers, namely, the cis-isomer of the 2-S adduct and trans-isomers of the 5-S and 6-S adducts, and the 2,5-di-S-glutathionyl adducts were also identified and quantified by qNMR. With the exception of 2-(S-glutathionyl)- and 2,5-di(S-glutathionyl)-trans-caftaric acid, these products had never been formally identified. In particular, the 5-S and 6-S derivatives are reported here for the first time. The first formal identification of 2-S cis-derivatives is also provided. Moreover, NMR and UPLC-DAD-ESIMS analysis showed that signature UV and MS spectra can serve as markers of the conformation and substitution position in the aromatic ring for each of the isomers.
INRA, UMR1083 Sciences Pour l'œnologie , Plateforme Polyphénols, 2, Place Viala, Montpellier Cedex, 34060, France.|Departamento de Ciência e Tecnologia de Alimentos CAL/CCA, Universidade Federal de Santa Catarina , Rod. Admar Gonzaga, 1346, Itacorubi, Florianópolis, SC, Brazil.
Nayla
N
Ferreira-Lima
INRA, UMR1083 Sciences Pour l'œnologie , Plateforme Polyphénols, 2, Place Viala, Montpellier Cedex, 34060, France.|Centro de Investigación Biomédica en Red de la Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III , Madrid 28029, Spain.
Anna
A
Vallverdú-Queralt
INRA, UMR1083 Sciences Pour l'œnologie , Plateforme Polyphénols, 2, Place Viala, Montpellier Cedex, 34060, France.
Emmanuelle
E
Meudec
INRA, UMR1083 Sciences Pour l'œnologie , Plateforme Polyphénols, 2, Place Viala, Montpellier Cedex, 34060, France.
Jean-Paul
JP
Mazauric
INRA, UMR1083 Sciences Pour l'œnologie , Plateforme Polyphénols, 2, Place Viala, Montpellier Cedex, 34060, France.
Nicolas
N
Sommerer
Departamento de Ciência e Tecnologia de Alimentos CAL/CCA, Universidade Federal de Santa Catarina , Rod. Admar Gonzaga, 1346, Itacorubi, Florianópolis, SC, Brazil.
Marilde T
MT
Bordignon-Luiz
INRA, UMR1083 Sciences Pour l'œnologie , Plateforme Polyphénols, 2, Place Viala, Montpellier Cedex, 34060, France.
Véronique
V
Cheynier
INRA, UMR1083 Sciences Pour l'œnologie , Plateforme Polyphénols, 2, Place Viala, Montpellier Cedex, 34060, France.
Christine
C
Le Guernevé
D002109:Caffeic Acids / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D003373:Coumaric Acids / Q000138:chemical synthesis* / Q000737:chemistry*; D004151:Dipeptides / Q000737:chemistry*; D005978:Glutathione / Q000737:chemistry*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction; D011809:Quinones / Q000737:chemistry; D013237:Stereoisomerism; D027843:Vitis / Q000737:chemistry*
D002109:Caffeic Acids; D003373:Coumaric Acids; D004151:Dipeptides; D011809:Quinones; C028505:cysteinylglycine; D005978:Glutathione; C040048:caffeic acid