Green and Efficient Ultrasonic-Assisted Extraction of Bioactive Components from Salvia miltiorrhiza by Natural Deep Eutectic Solvents

Natural deep eutectic solvents (NaDESs) are recently developed green solvent alternatives to conventional fossil solvents. The present work systematically screened 22 different NaDESs for the ultrasonic-assisted extraction of bioactive components from Salvia miltiorrhiza (SM), a widely used traditional Chinese medical plant. The suitable solvent and extraction condition were optimized in a two-round screening. In comparison with fossil solvents, NaDESs, especially L-proline-lactic acid (L-Pro-Lac) showed significant advantages in the extraction of salvianolic acid B (SAB), tanshinone IIA (TIIA) and cryptotanshinone (CYT). The optimized yields of the three targeting compounds were 42.05, 1.485 and 0.839 mg/g, respectively. The present method was also applied to the pretreatment of SM samples from different geographic origins. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities of NaDES extracts were determined in the study to prove the feasibility of NaDES in bioactive component extraction. The application of NaDESs in the extraction of both hydrophilic and hydrophobic small molecules from SM is proved to be a green and efficient method for pretreatment of herbal materials.