State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China.
State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China.
Food Chem. 2019 Mar 1;275:354-360. doi: 10.1016/j.foodchem.2018.09.135. Epub 2018 Sep 24.
The antioxidant capacity (AC) of six dihydrochalcone compounds was evaluated using DPPH and ABTS assays. In water-based solution 3-hydroxyphlorizin exhibited the highest AC among all dihydrochalcones. In acetone and acidic solutions (pH = 2.5 or 2.0), presence of an o-dihydroxyl at the B-ring increased AC, whereas glycosylation at the A-ring decreased AC of dihydrochalcones. By comparing the AC of dihydrochalcones with similar structures, it was found that the o-dihydroxyl at the B-ring and 2'-hydroxyl group at the A-ring were critical for maintaining the AC of dihydrochalcones by promoting hydrogen atom transfer or single electron transfer mechanism. Sequential proton-loss electron transfer commonly occurred during free radical scavenging in water-based solution. Moreover, we report a unique phenomenon in which glycosylation at the 2'-position enhanced the dissociation ability of the 4'-hydroxyl group and increased the AC of dihydrochalcones containing o-dihydroxyl. We speculate that this increase in AC might occur through intramolecular electron transfer.
采用 DPPH 和 ABTS 法评价了 6 种二氢查耳酮化合物的抗氧化能力 (AC)。在水基溶液中，3-羟基根皮素在所有二氢查耳酮中表现出最高的 AC。在丙酮和酸性溶液 (pH=2.5 或 2.0) 中，B 环上的邻二羟基增加了二氢查耳酮的 AC，而 A 环上的糖苷化降低了二氢查耳酮的 AC。通过比较具有相似结构的二氢查耳酮的 AC，发现 B 环上的邻二羟基和 A 环上的 2'-羟基是通过促进氢原子转移或单电子转移机制维持二氢查耳酮 AC 的关键。在水基溶液中清除自由基时，通常会发生连续的质子丢失电子转移。此外，我们报告了一种独特的现象，即在 2'-位的糖苷化增强了 4'-羟基的解离能力，从而提高了含有邻二羟基的二氢查耳酮的 AC。我们推测，这种 AC 的增加可能是通过分子内电子转移发生的。
