Centro de Investigação em Química, Departamento de Química, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal.
J Agric Food Chem. 2010 Aug 11;58(15):8814-9. doi: 10.1021/jf101408q.
A new class of stable yellowish pigments with similar unique spectral features, displaying only a pronounced broad band around 370 nm in the UV-vis spectrum, was detected in an aged Port wine fraction obtained by a combination of chromatography on TSK Toyopearl HW-40(s) and Polyamide resins. These compounds were identified by liquid chromatography-diode array detector/electrospray ionization mass spectrometry (LC-DAD/ESI/MS) and shown to be direct oxidative derivatives of carboxy-pyranoanthocyanins (vitisins A) by synthesis experiments performed in a wine model solution. Their structures were fully characterized by MS and NMR spectroscopy ((1)H, gCOSY, gHSQC, and gHMBC) and found to correspond to alpha-pyranone-anthocyanins (lactone or pyran-2-one-anthocyanins). Their formation involves first the nucleophilic attack of water into the positively charged C-10 position of vitisins, followed by decarboxylation, oxidation, and dehydration steps, yielding a new and neutral pyranone structure. The occurrence of these novel pigments in aged wines points to a new pathway involving anthocyanin secondary products (vitisins A) as precursors of new pigments in subsequent stages of wine aging that may contribute to its color evolution.
在通过 TSK Toyopearl HW-40(s) 和聚酰胺树脂的色谱组合获得的陈酿波特酒馏分中，检测到一类具有相似独特光谱特征的新型稳定黄色素，其在紫外-可见光谱中仅显示出在 370nm 左右的显著宽带。这些化合物通过液相色谱-二极管阵列检测器/电喷雾电离质谱（LC-DAD/ESI/MS）进行鉴定，并通过在葡萄酒模型溶液中进行的合成实验表明它们是羧酸吡喃基花色苷（vitisins A）的直接氧化衍生物。通过 MS 和 NMR 光谱（（1）H、gCOSY、gHSQC 和 gHMBC）对其结构进行了全面表征，并发现它们与α-吡喃酮-花色苷（内酯或吡喃-2-酮-花色苷）相对应。它们的形成首先涉及亲核攻击花色苷的正电荷 C-10 位置，然后是脱羧、氧化和脱水步骤，生成新的中性吡喃酮结构。这些新型色素在陈年老酒中的出现表明，一种新的途径涉及花色苷次级产物（vitisins A）作为随后葡萄酒陈化阶段中新色素前体的形成，这可能有助于其颜色演变。
