Fast and green extraction and separation of main bioactive flavonoids from Radix Scutellariae

• Fast and green extraction and separation of flavonoids in R. Scutellariae was achieved.
• Green NADES systems were used as extraction solvent.
• Natural deep eutectic solvent microwave-assisted extraction was developed.
• The proposed approach was confirmed by higher yields and reproducibility.
• Resin was attempted for direct separation of flavonoids from NADES solution.

In this study, fast and green extraction and separation of four main flavonoids in Radix Scutellariae was achieved by natural deep eutectic solvent microwave-assisted extraction (NADES-MAE) and direct macroporous resin adsorption and desorption process. Multivariate data analysis revealed that the NADES system composed of choline chloride and lactic acid, possessed excellent extractability for baicalin, wogonoside, baicalein and wogonin. The influential parameters of NADES-MAE were investigated and optimized by single-factor experiment and Box–Behnken experimental design combined with response surface methodology. Well-fitting models for the extraction of baicalin, wogonoside, baicalein and wogonin were successfully established and verified. The proposed method had satisfactory extraction yields for the four flavonoids and high reproducibility. Moreover, the direct enrichment and separation of baicalin, wogonoside, baicalein and wogonin in NADES extraction solution was efficiently achieved using macroporous resin ME-2 with recovery yields of 84.1%, 79.5%, 85.0% and 81.8%, respectively. The developed procedure represents an excellent alternative for the extraction and separation of natural products from sample matrices.