Extraction of bioactive compounds from cinnamon residues with deep eutectic solvents and its molecular mechanism

Recycling of bioactive compounds from Chinese herb residue is facing challenges of low extraction efficiency and high energy environment impact. To improve extraction yield in a green and economic way, microwave-assisted deep eutectic solvent (DES) extraction was developed for bioactive compounds extraction from cinnamon twigs residue. A maximal extraction yield of 0.593 and 12.290 mg·g−1 for cinnamic acid and cinnamic aldehyde, were observed in an optimal choline chloride/ethylene glycol DES system, in which an increase of 41.528 % and 41.443 % than traditional extraction process was obtained. Kinetic analysis indicated that microwave-assisted DES extraction fitted with second-order reaction model, and was a spontaneous, exothermic and irreversible process. Quantum chemistry analysis verified that extraction capacity mainly depended on hydrogen bonding force. The difference of binding energy between the solvent and cinnamic aldehyde or cinnamic acid unraveled the reason for the variation of extraction yields for the two compounds.