Erika Salas

Screening of Anthocyanins and Anthocyanin-Derived Pigments in Red Wine Grape Pomace Using LC-DAD/MS and MALDI-TOF Techniques.

Two phenolic extracts were made from a red wine grape pomace (GP) and fractionated first by sequential liquid-liquid extraction with organic solvents. The aqueous fraction was fractionated by low-pressure chromatography on Toyopearl HW-40 gel and on C18. Different fractions were obtained by sequential elution with aqueous/organic solvents, and then analyzed by liquid chromatography and mass spectrometry (LC-DAD/MS and MALDI-TOF). Over 50 anthocyanin-based pigments were detected by LC-DAD/MS in GP, mainly pyranoanthocyanins including A- and B-type vitisins and methylpyranoanthocyanins. The presence of oligomeric malvidin-3-O-coumaroylglucoside-based anthocyanins was also detected in GP using both LC-DAD/MS and MALDI-TOF.

Theoretical Characterization by Density Functional Theory (DFT) of Delphinidin 3-O-Sambubioside and Its Esters Obtained by Chemical Lipophilization

Anthocyanins are water-soluble phenolic pigments. However, their poor solubility in lipidic media limits their use. This hurdle can be overcome with the lipophilization of anthocyanins, which consists of adding an aliphatic chain to a hydrophilic compound, in order to increase its solubility in lipids. Still, the unspecific chemical lipophilization of anthocyanin-esters produces molecules with different properties from their precursors. In this work, experimental changes of anthocyanin-esters obtained by chemical lipophilization are investigated in silico aiming specifically at observing their molecular behavior and comparing it with their anthocyanin precursor. Thus, the analysis of delphinidin 3-O-sambubioside and its esters employing Density Functional Theory (DFT) methods, such as the hybrid functional B3LYP in combination with the 6-31++G(d,p) Pople basis set, provides the ground state properties, the local reactivity and the molecular orbitals (MOs) of these compounds. Excited states properties were analyzed by TD-DFT with the B3LYP functional, and the M06 and M06-2X meta-GGA functionals. Local reactivity calculations showed that the electrophilic site for all the anthocyanin-esters was the same as the one for the anthocyanin precursor, however the nucleophilic site changed depending localization of the esterification. TD-DFT results indicate that the place of esterification could change the electronic transitions and the MOs spatial distribution.