Xia Bo-Hou, Xiong Su-Hui, Tang Jie, Zhang Zhi-Min, Li Ya-Mei, Li Ming-Juan, Lin Li-Mei
College of Pharmacy， Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province， Collaborative Innovation Center for the Protection and Utilization of Chinese Herbal Medicine Resources in Hunan Province, Hunan University of Chinese Medicine, Changsha 410208, China.
College of Pharmacy， Shaoyang University, Shaoyang 422000, China.
Zhongguo Zhong Yao Za Zhi. 2018 Sep;43(17):3484-3492. doi: 10.19540/j.cnki.cjcmm.20180702.002.
Flavonoids have attracted much attention due to their good anti-inflammatory, anti-oxidation and anti-tumor effects. At present, the extraction of flavonoids is mainly based on organic solvent, while the researches on the use of green and safe solvents are quite limited. Therefore, in the present study, different types of deep eutectic solvents (DESs) were applied to investigate their effect on extraction of flavonoids and optimize the process, also investigate the recovery efficiency of DESs and evaluate the recovery method for total flavonoids. The extraction yield of the total flavonoids acted as the comprehensive evaluation indexes, and a central composite design (CCD) of response surface methodology (RSM) was employed to further optimize the alcohol-based DES extraction conditions. The results showed that the optimized extraction conditions were as follows: water-DES ratio of 27%, solid-liquid ratio of 15 mL·g⁻¹, extraction temperature of 83 °C and extraction time of 42 min in ChCl-glycerol at 1:4 ratio. Under these conditions, the mean experimental value of the extraction yield (75.05 mg·g⁻¹) corresponded well with the predicted value (77.86 mg·g⁻¹). Moreover, these experimental results showed more advantages such as in higher efficiency, economy and environmental protection as compared with previously reported conventional extraction methods. In addition，the recovery yield of the total flavonoids from the DESs extraction solution achieved 97.88% by using AB-8 macroporous resin, and 88.12% desorption ratio can be achieved by 100% ethanol with 5 times resin content. After the above treated DESs were collected, the extraction yield with the same method reached 95.23%, indicating that the method of macroporous resin can be used for efficient and simple recovery and reuse. This study suggests that DESs can be used as a kind of sustainable and efficient natural extraction solvents for extraction of flavonoids from Prunella vulgaris.
黄酮类化合物因其良好的抗炎、抗氧化和抗肿瘤作用而备受关注。目前，黄酮类化合物的提取主要基于有机溶剂，而关于使用绿色安全溶剂的研究相当有限。因此，在本研究中，应用了不同类型的深共熔溶剂（DESs）来研究它们对黄酮类化合物提取的影响并优化提取工艺，同时研究DESs的回收效率并评估总黄酮的回收方法。以总黄酮的提取率作为综合评价指标，采用响应面法（RSM）的中心复合设计（CCD）进一步优化基于醇类的DES提取条件。结果表明，优化后的提取条件如下：在1:4比例的氯化胆碱-甘油体系中，水与DES的比例为27%，固液比为15 mL·g⁻¹，提取温度为83℃，提取时间为42分钟。在此条件下，提取率的平均实验值（75.05 mg·g⁻¹）与预测值（77.86 mg·g⁻¹）吻合良好。此外，与先前报道的传统提取方法相比，这些实验结果显示出更高的效率、经济性和环保性等更多优势。另外，使用AB-8大孔树脂从DESs提取液中回收总黄酮的回收率达到97.88%，用5倍树脂体积的100%乙醇可实现88.12%的解吸率。收集上述处理后的DESs后，采用相同方法的提取率达到95.23%，表明大孔树脂法可用于高效简便的回收和再利用。本研究表明，DESs可作为一种可持续且高效的天然提取溶剂用于从夏枯草中提取黄酮类化合物。
