Extraction solvent is a very important factor in the recovery of antioxidants from natural matrices. In this study, the effect of three solvents (ethanol, ethanol/water and water) on the phenolic composition, antioxidant and anti-cholinesterase activities and electrochemical behaviour of four winemaking byproducts (seeds, skins, stems, and pomace) was evaluated. Phenolic composition was determined by the Folin–Ciocalteu method and ultra-high-performance liquid chromatography (UHPLC), antioxidant activity by the capacity to scavenge 2,2-diphenyl-1-picrylhydrazyl and hydroxyl radicals, anti-cholinesterase activity by the Ellman’s method, and electrochemical behaviour by cyclic voltammetry. Eight phenolic compounds were quantified with higher content in water/ethanol extracts (e.g., epicatechin in pomace: 17 mg/100 g vs. 7 and 6 mg/100 g in ethanol and water extracts, respectively), although there were some exceptions (e.g., gallic acid in seeds was most abundant in water extracts). Moreover, the highest total phenolic content (TPC) and antioxidant activity were found in ethanol/water extracts (between 2 and 30-fold the values of the other extracts). Overall, the most active extracts in inhibiting both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes were ethanol/water and ethanol extracts from seeds (between 31.11 and 53.90%). The electrochemical behaviour allowed for differentiating the extracts depending on the solvent and the byproduct. Our findings indicate that winemaking byproducts represent a source of phenolic compounds with antioxidant and anti-cholinesterase activities and suggest that cyclic voltammetry is a promising technique to evaluate the phenolic extraction process from these byproducts.

中文翻译：

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从酿酒副产品中提取抗氧化剂：溶剂对酚类成分、抗氧化和抗胆碱酯酶活性以及电化学行为的影响。


萃取溶剂是从天然基质中回收抗氧化剂的一个非常重要的因素。在本研究中，评估了三种溶剂（乙醇、乙醇/水和水）对四种酿酒副产品（种子、皮、茎和果渣）的酚类成分、抗氧化和抗胆碱酯酶活性以及电化学行为的影响。酚类成分通过 Folin-Ciocalteu 方法和超高效液相色谱 (UHPLC) 测定，抗氧化活性通过清除 2,2-二苯基-1-三硝基苯肼和羟基自由基的能力测定，抗胆碱酯酶活性通过 Ellman 法测定，以及循环伏安法的电化学行为。水/乙醇提取物中八种酚类化合物的含量较高（例如果渣中的表儿茶素：17 mg/100 g，乙醇和水提取物中分别为 7 和 6 mg/100 g），但也有一些例外（例如，种子中的没食子酸在水提取物中含量最高）。此外，乙醇/水提取物中的总酚含量 (TPC) 和抗氧化活性最高（是其他提取物的 2 至 30 倍）。总体而言，抑制乙酰胆碱酯酶 (AChE) 和丁酰胆碱酯酶 (BChE) 酶最有效的提取物是乙醇/水和种子乙醇提取物（31.11% 至 53.90%）。电化学行为允许根据溶剂和副产物来区分提取物。我们的研究结果表明，酿酒副产品是具有抗氧化和抗胆碱酯酶活性的酚类化合物的来源，并表明循环伏安法是评估从这些副产品中酚类提取过程的一种有前途的技术。