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Conformational interpretation of vescalagin and castalagin physicochemical properties

Vivas, N., Laguerre, M., Pianet de Boissel, I., Vivas de Gaulejac, N., Nonier, M.F.
Journal of agricultural and food chemistry 2004 v.52 no.7 pp. 2073-2078
tannins, molecular conformation, hydrophilic interactions, physicochemical properties, electrostatic interactions, hydrophobicity, oxidation, heat treatment, food chemistry, alcoholic beverages, oak barrels, wine aging, distilled spirits
Vescalagin and castalagin are two diastereoisomers. The variability of their principal physicochemical properties, compared with their small structural differences, suggests important conformational variations. This study shows, experimentally, that vescalagin has a greater effect on polarity, oxidizability in solution, and thermodegradability than castalagin. Conformational analysis by molecular mechanics demonstrated that vescalagin was more hydrophilic and was more reactive to electrophilic reagents than castalagin. Experimental results were thus explained and demonstrated the distinct behaviors of vescalagin and castalagin. These results were attributed to the C1 position of the two compounds because vescalin and castalin have comparable characteristics. Experimental data were confirmed and interpreted by molecular mechanics. This work represents one of the first attempts to correlate conformation and the properties of phenolic compounds. This step constitutes a predictive method for the pharmacology or chemistry of new compounds.