Facultad de Matemática, Astronomía y Física, IFEG-CONICET, Universidad Nacional de Córdoba, Córdoba, X5000, Argentina.
CONICET, Instituto de Ciencias Químicas, FAyA, UNSE, Av. Belgrano Sur 1912, Santiago del Estero (4200), Argentina.
Phys Chem Chem Phys. 2022 Aug 17;24(32):19269-19278. doi: 10.1039/d2cp02053j.
Betalains can be used in the food, drug, and cosmetic industries and have shown their bioactive potential. For these reasons, unraveling their oxidation mechanism is of high importance and demands a systematic and multidisciplinary study. Moreover, the properties mentioned above are drastically influenced by pH and other physicochemical conditions. Betanidin (1) is a relevant molecule of this family and is crucial to elucidating the oxidation mechanism in which its pigment is involved. In the present study, the ps and oxidation potential values for all protic groups of 1 were analyzed using B3LYP/6-31+G(d,p)/SMD as the computational methodology. Moreover, six explicit water molecules were added to improve the solvation-free energy values. The oxidation mechanism at each pH was constructed and analyzed in depth. On the other hand, cyclic voltammetry simulations allowed obtaining electrochemical data from experiments and support the proposed mechanism. In the present work, the main oxidation path of 1 is described and consists of a concerted electron-proton transfer followed by a sequential electron and proton transfer to obtain the -quinone product or a quinone methide molecule.
甜菜碱可用于食品、药物和化妆品行业，并已显示出其生物活性潜力。出于这些原因，揭示其氧化机制具有重要意义，需要进行系统的多学科研究。此外，上述性质受到 pH 值和其他物理化学条件的极大影响。甜菜因（1）是该家族的一个相关分子，对于阐明其色素参与的氧化机制至关重要。在本研究中，使用 B3LYP/6-31+G(d,p)/SMD 作为计算方法，分析了 1 中所有质子基团的 ps 和氧化电位值。此外，添加了六个显式水分子以提高溶剂化自由能值。在每个 pH 值下构建并深入分析了氧化机制。另一方面，循环伏安法模拟允许从实验中获得电化学数据，并支持所提出的机制。在本工作中，描述了 1 的主要氧化途径，该途径由协同的电子-质子转移组成，随后是顺序的电子和质子转移，以获得 -醌产物或醌甲醚分子。
