Comparative Chemotype Characterization and Antibacterial Activity of Essential Oils Obtained from the Leaves of Three Litsea species from Vietnam

The genus Litsea (family Lauraceae) is well known for its essential oils, which are traditionally valued for their richness in monoterpenes and sesquiterpenes—compounds with notable antibacterial and antioxidant properties. This study analyzed the chemical composition and antibacterial effects of essential oils obtained from the leaves of three Litsea species: Litsea cubeba (PH1), Litsea glutinosa (PH2), and Litsea verticillata (PH3). Essential oils were obtained through hydrodistillation and analyzed using gas chromatography–mass spectrometry (GC-MS) and gas chromatography-flame ionization detection (GC-FID). The results showed significant chemical differences among the three species. PH1 oil displayed a typical profile dominated by 1,8-cineole (22.60 %), sabinene (17.12 %), α-pinene (6.21 %), and β-pinene (5.01 %). In contrast, PH2 was dominated by β-elemene (12.78 %), β-caryophyllene (10.13 %), and linalool (9.60 %), while PH3 contained a high amount of β-caryophyllene (19.75 %), β-caryophyllene epoxide (15.05 %), α-caryophyllene (8.50 %), and much lower levels of 1,8-cineole (2.05 %). The antibacterial activity of the oils was evaluated against four bacterial strains: Escherichia coli, Salmonella typhi, Staphylococcus aureus, and Pseudomonas aeruginosa, using the agar well diffusion method. All essential oils demonstrated inhibitory activity, with the strongest effects (inhibition zone up to 20.1 ± 0.4 at 60 % against S. aureus) exhibited by PH1, which is rich in monoterpenes. These findings, therefore, highlight the chemical and biological diversity among Litsea species and emphasize their potential as sources of natural antibacterial agents for pharmaceutical and cosmetic applications.