Enzyme-deep eutectic solvent pre-treatment for extraction of essential oil from Mentha haplocalyx Briq. leaves: Kinetic, chemical composition and inhibitory enzyme activity

In this study, an improved method, enzyme-deep eutectic solvent pre-treatment followed by microwave-assisted hydrodistillation (EDP-MAHD), was applied to extract essential oil from the leaves of M. haplocalyx Briq. The synergistic effects of enzymatic hydrolysis, deep eutectic solvent, and microwave irradiation on the extraction kinetics and composition of essential oil were systematically evaluated. The yield of essential oil was improved under the pre-treatment conditions of mixed enzymes (cellulase and pectinase of 1:1) and choline chloride/glucose. By investigating the pre-treatment and microwave-assisted hydrodistillation processes, the yield of essential oil was enhanced to 2.19%. The results of GC-MS showed that menthol was the most important component in essential oil, with the content of 62.43%, and other components including menthone, piperitone, isomenthone, germacrene D, etc. Compared with other methods, EDP-MAHD could produce a higher yield of essential oil and make the essential oil have higher inhibitory activity on acetylcholinesterase and α-amylase (IC50 value of 6.36 and 34.32 mg/mL, respectively).