REQUIMTE/LAQV, Departamento de Química e, Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, s/n, 4169-007, Porto, Portugal.
LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade, Nova de Lisboa, 2829-516, Caparica, Portugal.
Chemistry. 2019 Sep 6;25(50):11696-11706. doi: 10.1002/chem.201901912. Epub 2019 Aug 13.
The interaction of two anthocyanins with a water-soluble polyanionic dendrimer was studied through UV/Vis, stopped-flow, and NMR spectroscopy. Cyanidin-3-glucoside (cy3glc) revealed a stronger interaction than malvidin-3-glucoside (mv3glc) at pH 1 according to their apparent association constants. A higher color increased was also obtained for cy3glc at pH 3.5 as a result of this stronger interaction. A high-frequency chemical shift of the cy3glc aromatic protons suggest the formation of ionic pairs. The interaction parameters (K≈700 m , n≈295) indicated the binding of approximately two anthocyanin molecules by each sulfate group. The equilibrium and rate constants of cy3glc in the presence of dendrimer showed an increased stability of the flavylium cation and a higher protection of this species from hydration (pK' and pK increased almost one pH unit). The tuning and color stabilization of anthocyanins by using this dendrimer allow novel applications as colorimetric sensors for food packaging.
通过紫外/可见分光光度法、停流法和 NMR 光谱法研究了两种花色苷与一种水溶性聚阴离子树状大分子的相互作用。根据它们的表观结合常数，矢车菊素-3-葡萄糖苷（cy3glc）在 pH 1 时与花葵素-3-葡萄糖苷（mv3glc）相比表现出更强的相互作用。由于这种更强的相互作用，在 pH 3.5 时，cy3glc 的颜色也增加了。cy3glc 芳环质子的高频化学位移表明形成了离子对。相互作用参数（K≈700 m ，n≈295）表明每个硫酸根基团结合大约两个花色苷分子。在树状大分子存在的情况下，cy3glc 的平衡和速率常数表明花青苷阳离子的稳定性增加，并且该物质对水合的保护作用更高（pK' 和 pK 增加了近一个 pH 单位）。通过使用这种树状大分子对花色苷进行调谐和颜色稳定化，可以将其作为食品包装的比色传感器进行新的应用。
