为了探索一种高效、环保的桂花黄酮提取方法，本文设计并制备了6种低共熔溶剂，通过比较醇提、冻融、超声波及微波四种技术，确定了超声波辅助-低共熔溶剂的提取工艺。通过单因素试验考察液料比、摩尔比、含水量、超声功率以及超声时间对桂花黄酮提取量的影响。在单因素的基础上，采用响应面法对提取工艺进一步优化。结果表明：桂花黄酮最优提取工艺为超声波辅助-三元低共熔溶剂提取（氯化胆碱/山梨醇/1,2-丙二醇）；最佳工艺条件为：液料比60:1 (mL/g)，氯化胆碱:山梨醇:1,2-丙二醇=2:1:4，含水量62 mol，超声波功率150 W，超声时间16 min，在此条件下提取量达到了10.06 mg/g，比传统醇提法提高了8.93 mg/g，证实超声波辅助-绿色低共熔溶剂技术提取桂花黄酮的高效性。实验结果与响应面模型预测值接近，证实模型的有效性。本研究为低共熔溶剂在天然产物绿色提取方面的应用提供参考。

Six kinds of deep eutectic solvents were designed and prepared, and four extraction techniques, namely, ethanol extraction, freeze-thaw extraction, ultrasonic extraction, and microwave extraction were compared to develop an efficient and environmentally friendly method for extracting flavonoids from Osmanthus fragrans. Ultrasound-assisted extraction using deep eutectic solvents was determined to be the optimal method. The effects of molar ratio of solvents, liquid-to-raw material ratio, water content, ultrasonic power, and extraction time on the yield of flavonoids were investigated through single-factor tests. Based on the results, response surface curves were drawn to obtain the optimal conditions for flavonoid extraction from Osmanthus fragrans. Optimal extraction can be achieved by ultrasound-assisted extraction using a ternary deep eutectic solvent (choline chloride/sorbitol/1,2-propanediol) under the following conditions: liquid-to-raw material ratio, 60:1 (mL/g); choline chloride-to-sorbitol-to-1,2-propanediol ratio, 2:1:4 (mol/mol/mol); water content, 62 mol; ultrasonic power, 150 W; and extraction time, 16 min. Under these conditions, the maximum yield of total flavonoids reaches 10.06 mg/g, which is 8.93 mg/g higher than that achieved using the traditional ethanol extraction method. This proves that ultrasound-assisted extraction using an environmentally friendly deep eutectic solvent is highly efficient. The good agreement between the experimental results and the proposed response surface model indicated the effectiveness of the model. The findings of this study provide a reference for the future utilization of deep eutectic solvents for green extraction from natural products.

江苏省高校优秀科技创新团队项目（2017-31）；南京科技职业学院科研课题（NHKY-2020-05）