Influence of Acylation by Hydroxycinnamic Acids on the Reversible and Irreversible Processes of Anthocyanins in Acidic to Basic Aqueous Solution

文献类型： 外文期刊

第一作者： Yang, Peiqing

作者： Yang, Peiqing;Liao, Xiaojun;Xu, Zhenzhen;Yang, Peiqing;Basilio, Nuno;Pina, Fernando;Xu, Zhenzhen;Dangles, Olivier

作者机构：

关键词： acylated anthocyanins; stopped flow; kinetics; thermodynamics; degradation

期刊名称：JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY （ 影响因子：6.2； 五年影响因子：6.4 ）

ISSN： 0021-8561

年卷期： 2024 年 72 卷 46 期

页码：

收录情况： SCI

摘要： In this work, the thermodynamics and kinetics of the reversible and irreversible processes of cyanidin 3,5-O-diglucoside and cyanidin 3-O-(2-O-glucosyl, 6-O-sinapoyl)glucoside-2-O-glucoside, 5-O-glucoside were studied by covering all pH range (holistic approach). The acylation (i) decreases the mole fraction of the colorless hemiketal in acidic medium and increases that of the colored quinoidal base, (ii) expands the pH domain of the flavylium cation, and (iii) moderately decreases the rate of tautomerization and isomerization of the neutral and monoanionic species. Degradation of cyanidin-3,5-O-diglucoside in a basic medium occurs in two distinct stages. After the formation of the anionic quinoidal bases (double proton loss from flavylium cation), a fast kinetic step, only observed by stopped flow, gives rise to the B4 n- hydroxide adducts (n = 2,3) in equilibrium with the respective quinoidal bases A n- (n = 1,2), leading to a first transient state. The quinoidal bases and B4 n- adducts disappear completely from the first to a second transient state by means of two parallel reactions: (i) one reversible, giving the anionic cis- and trans-chalcones, (ii) the other irreversible, giving degradation products and exhibiting a pH-dependent bell-shaped mole fraction with maximum around pH = 12. From the second transient state, the anionic chalcones disappear completely in a few days. Acylation prevents formation of the first transient state. All of these effects are compatible with anthocyanidin-acyl pi-stacking interactions (intramolecular copigmentation).

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