Deep eutectic solvent (DES) combined with ultrasonic-assisted extraction was employed as an environmentally friendly technique for extracting antioxidant phenolic compounds from Neem leaves in place of organic solvents. Choline chloride-Ethylene glycol (1:2) with 40% /V water content (DES-1) was investigated as a potential total phenolic content extractant (38.2 ± 1.2 mg GAE/g DW, where GAE: gallic acid equivalent, DW: dry weight). The optimal operational parameters assessed using single-factor experiments to maximize the total phenolic compounds content were as follows: extraction time of 30 min, 40% /V water content, liquid-solid ratio of 15:1, and room temperature. Additionally, the in-vitro antioxidant experiments (2,2-diphenyl-1- picrylhydrazyl radical scavenging assay and ferric reducing antioxidant power assay) demonstrated the DES-1-based extract of Neem leaves as a potent antioxidant agent, compared to traditional solvents. Moreover, microscopic morphological analysis supported the effectiveness of DES-1 for the noticeable alteration in the fiber surface structure of Neem leaves after extraction which benefited in the release of polyphenols from these leaves. Eventually, the mass analysis of the extract disclosed the presence of eleven polyphenols in the extract. The Green Analytical Procedure Index revealed the greenness of the extraction method.

中文翻译：

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基于超声波辅助萃取的低共熔溶剂绿色高效提取印楝叶酚类化合物


采用低共熔溶剂（DES）结合超声波辅助萃取作为一种环保技术，代替有机溶剂从印楝叶中提取抗氧化酚类化合物。研究了含水量为 40% /V 的氯化胆碱-乙二醇 (1:2) (DES-1) 作为潜在的总酚含量提取剂（38.2 ± 1.2 mg GAE/g DW，其中 GAE：没食子酸当量，DW：净重）。通过单因素实验评估最大化总酚类化合物含量的最佳操作参数如下：提取时间30分钟、含水量40%/V、液固比15:1、室温。此外，体外抗氧化剂实验（2,2-二苯基-1-苦基肼自由基清除测定和铁还原抗氧化能力测定）证明，与传统溶剂相比，基于 DES-1 的印楝叶提取物是一种有效的抗氧化剂。此外，显微形态分析支持 DES-1 在提取后显着改变印楝叶纤维表面结构的有效性，这有利于从这些叶子中释放多酚。最终，提取物的质量分析揭示了提取物中存在十一种多酚。绿色分析程序指数揭示了提取方法的绿色性。