A model for the estimation of oxidation potentials of polyphenols

This study developed linear models for the estimation of the first and the second oxidation potentials, Ep1 and Ep2, for seven polyphenolic compounds (myricetin (Myr), dihydromyricetin (DhMyr), epigallocatechin-3-gallate (EGCG), epigallocatechin (EGC), gallic acid (GA), epicatechin-3-gallate (ECG) and epicatechin (EC)) at different pH values. As descriptors, we used the number of vicinal (Nv) and non-vicinal (Nnv) OH groups, the number of OH neighbouring pairs (Nch), and the total number of OH groups (NOH). The separate models for the different pH's yielded an S.E. ranging from 0.001 to 0.013, and the common models for pH = 2, 3, 5, 6, and 7 (by inclusion of pH as a variable) gave S.E. = 0.016 and 0.013 for Ep1 and Ep2, respectively. An overall model for Ep1 and Ep2 was also developed, by the inclusion of an indicator variable (In = 0 and 1 for Ep1 and Ep2, respectively) along with the pH variable. The model yielded S.E. = 0.036.