Deep
eutectic solvents (DESs) play important roles in the extraction
of active constituents in traditional Chinese medicine. Ultrasound-assisted
DES has been used to extract flavonoids from
Scutellaria
baicalensis
. Using the contents of scutellarin, baicalin,
baicalein, wogonoside, wogonin, and oroxylin A as quantitative indices,
different kinds of DESs have been optimized for extraction and betaine/acetic
acid has shown the highest yield. The Box–Behnken response
surface method (RSM) was utilized to select the extraction conditions
with the highest yields. The optimal extraction conditions were as
follows: the molar ratio of betaine/acetic acid was 1:4, the water
content was 40%, the solid/liquid ratio was 1:100 g/mL, the extraction
temperature was 52 °C, and the extraction time was 23 min. Compared
with traditional reflux extraction using 70% ethanol as the solvent,
ultrasound-assisted DES has a shorter extraction time and higher yields.
Furthermore, anti-inflammatory activities of the two extracts by ultrasound-assisted
DES and reflux were compared using RAW264.7 cells and the methyl thiazolyl
tetrazolium (MTT) method, and they showed equal anti-inflammatory
activities. The results demonstrated that the ultrasound-assisted
DES method for extraction of flavonoids from scutellariae radix is
simple, green, efficient, and reproducible. This research provides
good method guides for the rapid and efficient extraction of flavonoids
from natural sources.