Enzyme-assisted extraction of essential oil from Cinnamomum longepaniculatum (Gamble) N. Chao ex H. W. Li and anxiolytic activity

This work was designed to evaluate the effect of four enzyme-assisted extraction (EAE) combined hydrodistillation (HD) methods on the yield, microstructure and chemical composition of essential oil (EO) from leaves of Cinnamomum longepaniculatum (Gamble) N. Chao ex H. W. Li. The chemical composition of EO was analyzed using gas chromatography-mass spectrometry. Changes in the microstructure of leaf residues were observed by scanning electron microscopy. Response surface methodology was used to predict the best conditions for the EO extraction with the most effective enzyme pretreatment. Further, the anxiolytic effect and mechanism of the optimized EO were investigated by the open-field test (OFT), elevated plus-maze test (EPMT), hole-board test (HBT) and the assay of neurotransmitter concentrations (5-hydroxytryptamine, 5-HT; γ-aminobutyric acid, GABA; norepinephrine, NE). The results showed that different enzyme pretreatments increased the yield and quality of EO and disrupted the cell wall. The circumscribed-β-glucan/hemicellulose enzyme (1:1) pretreatment (4.33%) was the most effective compared to the enzyme-free group (2.82%). The optimum extraction process conditions were: pH:5, enzymolysis time: 67 min and digestion temperature: 48.5 °C. Under these conditions, the maximum yield of EO was 4.37%. After inhalation of EO, mice showed significant anxiolytic effects in EPMT, HBT, and OFT. In addition, EO significantly down-regulated 5-hydroxytryptamine and NE levels and up-regulated GABA levels. Cinnamomum longepaniculatum EO may be related to 5-HTergic, GABAergic and NEergic neurotransmitter systems for better anxiolytic effect.