Ternary mixed enzyme pretreatment combined with microwave-assisted hydrodistillation for extracting essential oil from fresh Acanthopanax trifoliatus (L.) Merr. stems: Enhancement of yield and biological activity

Abstract

In this study, a ternary enzyme mixture (comprising cellulase, pectinase, and papain) was used for pretreatment, which was combined with microwave-assisted hydrodistillation (EP-MHD) to extract essential oil from the stems of Acanthopanax trifoliatus. Each parameter of the EP-MHD method was optimized through the sequential optimization approach. Subsequently, the optimized EP-MHD method was compared with the hydrodistillation (HD) method and the microwave-assisted hydrodistillation (MHD) method in terms of both the yield and chemical composition of essential oil. The essential oil yield from the EP-MHD method (2.19 ± 0.07 mg/g) was significantly higher compared to both the MHD method (1.62 ± 0.05 mg/g) and the HD method (1.39 ± 0.09 mg/g), showing increases by 1.35 and 1.58 times, respectively. The results of GC/MS analysis showed that the main components of the essential oil were alcohols, aldehydes, and terpenoids, including isopimarinal, sandaracopimaral, sandaracopimarinol, 5,8,11-heptadecatrien-1-ol, pentadecanal, 2,4-di-tert-butylphenol, β-(Z)-curcumen-12-ol, and spatulenol. Particularly, the essential oil obtained by EP-MHD method had the highest alcohol components content (45.61 %), which significantly higher than those obtained by the MHD (25.17 %) and HD methods (23.95 %). Moreover, the essential oil extracted by the EP-MHD method exhibited superior scavenging ability against DPPH and ABTS⁺ radicals (with IC₅₀ values of 1.14 and 1.03 mg/mL, respectively). Additionally, it demonstrated antidepressant activity with IC₅₀ values of 3.77 mg/mL and 4.46 mg/mL against acetylcholinesterase and butyrylcholinesterase, respectively, which surpassed those obtained from the HD and MHD methods. Furthermore, the essential oil obtained through EP-MHD displayed notably stronger antibacterial activity against Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes with IC₅₀ values of 1.70 mg/mL, 1.03 mg/mL, and 2.30 mg/mL, respectively. In summary, EP-MHD method not only increased the yield of essential oil, but also significantly enhanced its biological activity. Therefore, our results provided evidence to the extraction, development and utilization of essential oil from fresh stems of Acanthopanax trifoliatus by EP-MHD method.