Abstract: 【Objective】 This study aimed to solve the limitations of Litsea cubeba essential oil(LCEO) including poor aqueous solubility,high volatility and irritation, and improve its solubility and stability,thereby achieve the purpose of sustained release and strengthen the antibacterial efficacy in vitro. 【Method】 In this study,the β-cyclodextrin(β-CD) inclusion complex of LCEO was prepared through a saturated aqueous solution method with β-CD as coating material,and the optimal preparation conditions were systematically optimized via orthogonal design experiments.The structural and morphological properties of the inclusion compound were analyzed by Fourier transform infrared spectroscopy(FT-IR),inverted fluorescence microscope and scanning electron microscope(SEM).Furthermore,the stability test,dissolution test in vitro and antibacterial test against Escherichia coli,Salmonella,Staphylococcus aureus and Streptococcus suis in vitro were conducted to a comprehensive assessment. 【Result】 The optimal preparation process of clathrate was as follows:The ratio of β-CD to LCEO was 3∶1,the inclusion temperature was 40 ℃,the inclusion time was 4 h,and the volume ratio of anhydrous ethanol to LCEO was 1∶1.Under these conditions,the average yield of clathrate was 79.33% and the average inclusion rate was 84.40%.FT-IR analysis showed that the infrared spectral characteristic peaks of LCEO were hidden in the inclusion complexes,and the surface morphology and structure of β-CD and LCEO-β-CD inclusion complexes were significantly different under inverted fluorescence microscopy and SEM.The results of light and high temperature stability tests showed that under the condition of light intensity of (4 500±500) lx and 60 ℃,the performance of the clathrate was stable within 10 days,while the content of LCEO in the physical mixture decreased significantly,indicating that the clathrate had good light and thermal stability.The results of in vitro dissolution test showed that all the LCEO in the physical mixture of LCEO/β-CD were dissolved within 120 min,while the cumulative release of LCEO-β-CD clathrate was 84.36% within 240 min.The results of kinetic model showed that the release of clathrate in simulated intestinal fluid was about 2.7 times that in simulated gastric fluid,The results showed that the inclusion compound of LCEO-β-CD inclusion complexes had sustained release and enteric solubility.The results of in vitro antibacterial test showed that the MIC of LCEO against Escherichia coli,Salmonella,Staphylococcus aureus and Streptococcus suis were 1.56,1.56,0.78 and 0.39 μL/mL,respectively,while the MIC corresponding to LCEO-β-CD inclusion compound were 0.78,0.78,0.39 and 0.19 μL/mL,respectively.The results showed that clathrate could improve the bacteriostatic effect on Escherichia coli,Salmonella,Staphylococcus aureus and Streptococcus suis,and the bacteriostatic curve showed that clathrate could prolong the bacteriostatic time. 【Conclusion】 The LCEO-β-CD inclusion complexes prepared in this study effectively overcome the poor water solubility and strong volatility of LCEO.It had sustained-release and enteric-coated effects,which could enhance the antibacterial effect and prolong the antibacterial time in vitro.

Key words: Litsea cubeba essential oil; β-cyclodextrin; inclusion complex; bacteriostasis