Thermodynamics and Kinetics of 3-Deoxyanthocyanidins Versus Anthocyanins: What is Common and Different

Anthocyanins, anthocyanidins, 3-deoxyanthocyanins, and 3-deoxyanthocyanidins share five common chemical species in acidic media: flavylium cation, quinoidal base, hemiketal, and <i>cis</i> and <i>trans</i> chalcones. These species are reversibly interconnected by four chemical reactions: proton transfer, hydration, tautomerization, and isomerization. The absence of a hydroxyl group or glycoside at position 3 of the flavylium cation in 3-deoxy species substantially alters their thermodynamic and kinetic properties compared to those of anthocyanins. This study compared these properties between anthocyanins and 3-deoxy species and investigated the chemistry and photochemistry of luteolinidin using an updated mathematical model. The extension of the study to basic media (holistic approach) revealed slower OH^- nucleophilic addition in luteolinidin, consequently prolonging its color retention in comparison to anthocyanins. Furthermore, luteolinidin exhibit significantly slower degradation rates. While anthocyanins generally lack significant photochemistry, 3-deoxy species display efficient photochromism, presenting promising possibilities for diverse applications.