Effects of natural deep eutectic solvent on the extraction efficiency and antioxidant activities of Toona sinensis seed polyphenols: Composition and mechanism

This study was designed to investigate the effects of natural deep eutectic solvents (NADESs) on extraction efficiency and antioxidant activities of phenolic compounds from Toona sinensis seeds (TSSs) compared with ethanol and water extraction methods. The single factor experiment was employed to optimize the extraction conditions of TSSs phenolic compounds on NADESs. Results indicate that the NADES of choline chloride-oxalic acid (CC-OA) with a molar ratio of 2:1 (solid/liquid ratio: 1:90 (m/v), extraction time: 30 min) showed the highest total phenolic content (32.58 mg GAE/g DW) and antioxidant activities (DPPH radical scavenging activity: 95.94%) compared with ethanol or water extraction. In addition, 15 main phenolic compounds were identified in the extracts of CC-OA solvent, while only 9 and 6 main compounds were identified in the extracts of ethanol and water solvents, respectively. The molecular dynamic simulation result illustrates that the high extraction efficiency of the NADES mainly attributing to their high compatibility as well as hydrogen interaction between ellagic acid (the main polyphenol in TSSs) and CC-OA solvent. In summary, the NADES (CC-OA at the ratio of 2:1) showed superior extraction efficiency on TSSs phenolic compound compared with ethanol or water extraction which could be an environmentally friendly method for the high-value utilization of TSSs.