Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Fuyang 311400, PR China; Nanjing Forestry University, Nanjing 210037, PR China.
Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Fuyang 311400, PR China.
Food Chem. 2021 Jul 15;350:129217. doi: 10.1016/j.foodchem.2021.129217. Epub 2021 Feb 9.
The free, esterified and bound forms of 37 phenolic compounds (including hydroxybenzoic acid, hydroxycinnamic acids, flavanols, flavonols and flavones) from walnut kernel (Juglans regia L.) were investigated in this study. Results showed that the majority of walnut phenolics were presented in the free form (51.1%-68.1%), followed by bound (21.0%-38.0%) and esterified forms (9.7%-18.7%). Ellagic acid, gallic acid, ferulic acid, sinapic acid and caffeic acid were widely distributed in three forms. Differently, jeuglone, kaempferol, quercetin-7-o-β-d-glucoside and dihydroquercetin were only found in free phenolics. Among the three forms, free phenolics had the highest radical scavenging activity (IC: DPPH, 15.5 µg/ml; ABTS, 13.6 µg/ml). The correlation coefficients between the antioxidant activities of phenolics and their corresponding contents were 0.82-0.92. More soluble phenolics (free and esterified forms) could be extracted by acetone, while methanol was better at extracting insoluble bound phenolics.
本研究对核桃仁（Juglans regia L.）中 37 种酚类化合物（包括羟基苯甲酸、羟基肉桂酸、黄烷醇、黄酮醇和黄酮）的游离、酯化和结合形式进行了研究。结果表明，大多数核桃酚以游离形式（51.1%-68.1%）存在，其次是结合形式（21.0%-38.0%）和酯化形式（9.7%-18.7%）。鞣花酸、没食子酸、阿魏酸、芥子酸和咖啡酸广泛分布于三种形式中。不同的是，胡桃醌、山柰酚、槲皮素-7-O-β-D-葡萄糖苷和二氢槲皮素仅存在于游离酚类中。在这三种形式中，游离酚类具有最高的自由基清除活性（IC：DPPH，15.5μg/ml；ABTS，13.6μg/ml）。酚类化合物抗氧化活性与其含量之间的相关系数为 0.82-0.92。丙酮更有利于提取可溶的游离和酯化酚类，而甲醇更有利于提取不溶性结合酚类。
