Enhanced phenolic compounds extraction from Morus alba L. leaves by deep eutectic solvents combined with ultrasonic-assisted extraction

It is of great significance to develop green solvents for promoting green and sustainable technology. Deep eutectic solvents (DESs) as new extraction solvents are emerging in the search for efficient the extraction of bioactive compounds or drugs. In this study, twelve types of DESs including choline chloride-, betaine-, and Lproline-based DESs were investigated in combination with ultrasonic-assisted extraction (UAE) for the extraction of phenolic compounds from Morus alba L. leaves. Compared with conventional extraction system, DESs composed of choline chloride/citric acid showed more effective extraction yields (22.66 mg/g vs. 15.29 mg/g). The operation conditions were also optimized systematically. In addition, liquid-liquid extraction was an effective approach to recover the major phenolic compounds in the extracts. The recovery and recyclability of DESs were also evaluated. A broad extractability of phenolic compounds in the certain designed DESs systems was observed according to principal component analysis (PCA). The developed DESs can be an alternative procedure for the green and efficient extraction of phenolic compounds from natural sources.