Chemical Compositions and Antibacterial Activities of Litsea cubeba Essential Oil and Its Distillates Prepared by Vacuum Fractional Distillation and Molecular Distillation

Litsea cubeba essential oil (LCEO) has various bioactivities and wide applications. However, most reported LCEOs are directly extracted from plants, and studies on further processing of LCEO to enrich bioactive components using modern separation techniques are scarce. In this study, LCEO was extracted by hydrodistillation and further processed via vacuum fractional distillation (VFD) and molecular distillation (MD). The chemical compositions of LCEO and seven distillates were analyzed, and the activities of the EOs and eight individual constituents against seven bacteria were tested. Distillates VFD3 and MDH2 showed the best activity against Escherichia coli, Staphylococcus aureus, and Agrobacterium rhizogenes. VFD3 exerted antibacterial action against A. rhizogenes by inhibiting biofilms, damaging the cell membrane and cell wall, and perturbing metabolic pathways. VFD and MD are effective processing methods for changing the chemical composition and enhancing the bioactivity of LCEO, which might be used to improve the quality and extend the applications of LCEO and other EOs.