REQUIMTE/LAQV, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal.
REQUIMTE/LAQV, Department of Chemistry, Faculty of Sciences and Technology, New University of Lisbon, 2829-516 Caparica, Portugal.
Food Chem. 2019 Aug 1;288:386-394. doi: 10.1016/j.foodchem.2019.02.132. Epub 2019 Mar 10.
Two anthocyanins from purple-fleshed sweet potato were isolated and characterized by LC-MS and NMR analysis. They were identified as peonidin-3-(6'-hydroxybenzoyl)-sophoroside-5-glucoside and peonidin-3-(6'-hydroxybenzoyl-6″-caffeoyl)-sophoroside-5-glucoside. The acid-base dynamics of these acylated anthocyanins was evaluated by means of pH jump techniques. Equilibrium and kinetic constants were determined and, in general, these anthocyanins demonstrated a higher capacity in retaining the red and blue colors at acidic and basic pH values, suggesting a higher resistance to pH variations compared to the parent anthocyanin, peonidin-3-O-glucoside. The presence of acyl groups and additional glucoside moieties seems to determine this particular characteristic. The fluorescence properties of these anthocyanins were evaluated. Overall, the species present at higher pH values (7-9) showed higher fluorescence intensity for both anthocyanins, with an optimum λ/λ pair at λ 610 nm/λ 640 nm. The fluorescence characteristics of these anthocyanins were used to evaluate their location in gastric and intestinal cells by fluorescence microscopy.
两种从紫色甘薯中分离得到的花色苷通过 LC-MS 和 NMR 分析进行了鉴定和表征。它们被鉴定为矢车菊素-3-(6'-羟基苯甲酰基)-槐糖苷-5-葡萄糖苷和矢车菊素-3-(6'-羟基苯甲酰基-6″-咖啡酰基)-槐糖苷-5-葡萄糖苷。通过 pH 跃变技术评估了这些酰化花色苷的酸碱动力学。测定了平衡和动力学常数，一般来说，这些花色苷在酸性和碱性 pH 值下保持红色和蓝色的能力更高，表明与母体花色苷矢车菊素-3-O-葡萄糖苷相比，它们对 pH 变化的抵抗力更高。酰基和额外的葡萄糖苷部分的存在似乎决定了这一特殊特性。评估了这些花色苷的荧光性质。总的来说，在较高 pH 值（7-9）下存在的两种花色苷的荧光强度都更高，在 λ 610nm/λ 640nm 处有最佳 λ/λ 对。利用这些花色苷的荧光特性通过荧光显微镜评估了它们在胃和肠细胞中的位置。
