Green extraction of five target phenolic acids from Lonicerae japonicae Flos with deep eutectic solvent

• DES-MAE was used to extract phenolic acids for the first time.
• DES-MAE method was effective and environmental friendly.
• Green and efficient extraction of phenolic acids from Lonicerae japonicae Flos was optimized.
• The recovery of active compounds from DES was also investigated.

In this study, a deep eutectic solvent based microwave assisted extraction (DES-MAE) method was developed. This method was used for the extraction of five target phenolic acids, namely chlorogenic acid, caffeic acid, 3,5-dicaffeoylquinic acid, 3,4-dicaffeoylquinic acid, and 4,5-dicaffeoylquinic acid from Lonicerae japonicae Flos. Twelve kinds of aqueous deep eutectic solvents were investigated. The results indicated that deep eutectic solvents (DESs) showed remarkable effects on the extraction efficiency of phenolic acids. In addition, the parameters of DES-MAE, including concentration of water in DES, liquid/solid ratio, extraction temperature, and extraction time were optimized. The proposed approach was evaluated by comparison with the conventional heat-reflux extraction (HRE) and ultrasound assisted extraction (UAE). Finally, the recovery of active compounds from DES was also investigated. Recovery rates of chlorogenic acid, caffeic acid, 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid, and 4,5-dicaffeoylquinic acid reached 79.25%, 80.03%, 85.96%, 86.01% and 85.52%, respectively.