Identification of alkaline-induced thiolyl-chlorogenic acid conjugates with cysteine and glutathione
Identification of alkaline-induced thiolyl-chlorogenic acid conjugates with cysteine and glutathione
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DOI：
10.1016/j.foodchem.2023.136267
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发表时间：
2023-05-13
期刊：
影响因子：
8.8
通讯作者：
Senger，Lilian W.
中科院分区：
文献类型：
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作者：
Drucker，Charles T.;Cicali，Amanda R.;Senger，Lilian W.
绿原酸（CGA）的碱性反应产生不期望的棕色或绿色色素，限制了富含碱性CGA的食品的利用。巯基如半胱氨酸和谷胱甘肽通过几种机制减轻色素形成，包括还原CGA醌的氧化还原偶联和巯基缀合，其形成不容易参与颜色产生反应的无色巯基-CGA化合物。这项工作提供的证据表明，除了假设与羟基自由基反应产生的羟基化缀合物物质外，在碱性条件下，还形成了与半胱氨酸和谷胱甘肽形成的芳香族和苄基硫醇基-CGA缀合物物质。这些缀合物的形成比CGA二聚化和胺加成反应更快地进行，从而减轻颜料显影。芳香族和苄基共轭物之间的区别是由特征断裂的C单键S键。巯基-CGA缀合物的奎尼酸部分的酰基迁移和水解产生了多种异构体物质，也通过非靶向LC-MS方法鉴定。
Alkaline reactions of chlorogenic acid (CGA) yield undesirable development of brown or green pigments, limiting the utilization of alkalized CGA-rich foods. Thiols such as cysteine and glutathione mitigate pigment formation through several mechanisms, including redox coupling to reduce CGA quinones, and thiol conjugation, which forms colorless thiolyl-CGA compounds that do not readily participate in color-generating reactions. This work provided evidence of the formation of both aromatic and benzylic thiolyl-CGA conjugate species formed with cysteine and glutathione under alkaline conditions in addition to hydroxylated conjugate species hypothesized to arise from reactions with hydroxyl radicals. Formation of these conjugates proceeds more quickly than CGA dimerization and amine addition reactions mitigating pigment development. Differentiation between aromatic and benzylic conjugates is enabled by characteristic fragmentation of Csingle bondS bonds. Acyl migration and hydrolysis of the quinic acid moiety of thiolyl-CGA conjugates yielded a variety of isomeric species also identified through untargeted LC-MS methods.