Application of ionic liquid-based microwave-assisted extraction of flavonoids from Scutellaria baicalensis Georgi

• Four flavonoids extracted from Scutellaria baicalensis Georgi were analyzed by HPLC.
• The optimal ILMAE method offered the satisfaction extraction efficiency that was comparable to traditional extraction methods.
• The extraction mechanism was investigated by studying the microstructures of S. baicalensis powders before and after extraction with SEM, as well as the activity of the crude enzyme solution from S. baicalensis.

In the present work, a rapid ionic liquid-based microwave-assisted extraction (ILMAE) method was successfully applied to simultaneous extraction of baicalin, wogonoside, baicalein and wogonin from Scutellaria baicalensis Georgi. A series of 1-alkyl-3-methylirnidazolium ionic liquids with different anions and cations were assessed for extraction efficiency, and 1-octyl-3-methylimidazolium bromide was selected as the optimal solvent. In addition, the parameters of ILMAE procedure for the four flavonoids were optimized, and the optimal ILMAE method was validated in the linearity, stability, precision and recovery. Meanwhile, the microstructures of S. baicalensis powders were observed before and after extraction with the help of a scanning electron microscope (SEM) in order to explore the extraction mechanism, and the activity of the crude enzyme solution from S. baicalensis was determined through the hydrolysis of baicalin. Finally, the extraction yields and extraction time of WaterHRE, WaterMAE, ILHRE and Chp were 5.18% (30 min), 8.77% (90 s), 16.94% (30 min) and 18.58% (3 h), respectively. The results indicated that compared with the conventional extraction approaches, ILMAE possessed great advantages in extracting flavonoids, such as the highest extraction yield (22.28%), the shortest extraction time (90 s), etc.