Deep eutectic solvent combined with ultrasound-assisted extraction as high efficient extractive media for extraction...

Deep eutectic solvent (DES) combined with ultrasound-assisted extraction (UAE) was successfully developed and fully validated to simultaneously determine Icarrin, IcarisidⅡ, Epimcdin A, Epimcdin B and Epimcdin C for the quality evaluation of Herba Epimedii. Twelve kinds of DESs were initially screened, and then the effective extraction was achieved by the tailor-made DES consisting of the mixture of l-proline and ethylene glycol with the molar ratio of 1:4 in this study. The optimal conditions were further optimized by the orthogonal experimental design (OED). 0.2 g sample powder was ultrasonic extracted by using 4.00 mL of aqueous solution containing 70 % (v/v) the above DES for 45 min, resulting to the optimum extraction efficiency. The FT-IR and NMR spectra showed the chemical structural characteristic correlation between l-proline and ethylene glycol, and could infer the formation of hydrogen bonds between the hydroxyl group of ethylene glycol and the nitrogen atom of l-proline. The hierarchical cluster analysis (HCA) was further processed for the quality evaluation of Herba Epimedii. Finally, DES could be used to distinguish different origins and different kinds of Herba Epimedii, and to evaluate the quality of Herba Epimedii. This method provided good linearity, precision and accuracy. The recoveries of the five main bioactive flavonoids in Herba Epimedii were within the range of 88.5-107.7 % (RSD less than 3.4 %). Compared to the traditional extraction method of Icarin in the Chinese Pharmacopoeia (2015 edition), the solvent consumption was decreased by 80 % and the extraction time was shortened by 25 %, leading to more efficient and more convenient of this DES-UAE method. This work indicated that DES would be a promising high effective solvent for the analytical sample preparations of plant herbs, and it might have a broad application in the quality control of traditional Chinese medicines.