Abstract：
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/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/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.
摘要：
低共熔溶剂（DES）与超声辅助提取相结合，作为一种环保技术，用于代替有机溶剂从印em叶中提取抗氧化剂酚类化合物。研究了具有40％V/V水含量（DES-1）的氯化胆碱-乙二醇（1：2）作为潜在的总酚含量萃取剂（38.2±1.2mgGAE/gDW，其中GAE：没食子酸当量，DW：干重）。使用单因素实验评估的最佳操作参数，以最大化总酚类化合物含量如下：提取时间为30分钟，40%V/V含水量，液固比为15:1，室温。此外,体外抗氧化实验（2,2-二苯基-1-吡啶基肼基自由基清除测定和三价铁还原抗氧化能力测定）证明了基于DES-1的Neem叶提取物作为有效的抗氧化剂，与传统溶剂相比。此外，微观形态分析支持DES-1在提取后对Neem叶的纤维表面结构发生明显改变的有效性，这有利于从这些叶中释放多酚。最终,提取物的质量分析揭示了提取物中存在11种多酚。绿色分析程序指数揭示了提取方法的绿色性。
