The Leaf Oils of Beilschmiedia tonkinensis (Lecomte) Ridl. and Lindera gracilipes H. W. Li: Chemical Composition, Cytotoxicity, Antimicrobial Activity, and Docking Study

The Lauraceae plants comprised high amounts of essential oils, some of which established pharmacological potentials such as anticancer and antimicrobial activities. The Lauraceae essential oils are also used in cuisines and perfumes. The present study provides the chemical analysis of the leaf oils of Beilschmiedia tonkinensis and Lindera gracilipes, collected from Vietnam. Chemical components in the obtained oils were identified by the GC-FID/MS. The MTT and broth microdilution assays were used to evaluate cytotoxic and antimicrobial effects, respectively. The protein interactions were viewed by a docking study. Beilschmiedia tonkinensis leaf oil was characterized by sesquiterpene hydrocarbons (66.0%), in which bicyclogermacrene (23.3%), ( E)-caryophyllene (21.9%), caryophyllene oxide (9.9%), and spathulenol (6.0%) were the main components. The major chemical class in L gracilipes leaf oil was still sesquiterpene hydrocarbons (64.2%) with bicyclogermacrene (32.2%) being the principal component. Both 2 oil samples (IC50 41.2-44.12 µg/mL) were actively cytotoxic against the proliferation of A-549 cancer cells. In particular, B tonkinensis leaf oil strongly controlled Hep-G2 and MCF-7 cancerous cells with the IC50 values of 20.6 and 9.36 µg/mL, respectively. Beilschmiedia tonkinensis leaf oil also strongly inhibited the Gram (–) bacterium Pseudomonas aeruginosa and the fungus Aspergillus niger with the MIC values of 16 and 32 µg/mL, respectively. By molecular docking approach, bicyclogermacrene interacted with the p38α MAPK cancer protein (PDB ID: 4FA2) with a potential binding affinity of −8.019 kcal/mol, whereas ( E)-caryophyllene tends to bind 2 bacterial proteins P aeruginosa QS regulator (PDB ID: 6B8A) and glucosamine-6-phosphate synthase (GlmS) (PDB ID: 2VF5) with the better binding affinities of −6.740 and −6.521 kcal/mol, respectively. The most preferable binding mode was due to hydrophobic π-alkyl and alkyl interactions. The current result can be seen as a basic foundation in the applications of essential oils of B tonkinensis and L gracilipes for anticancer and antimicrobial treatments. Further phytochemical studies and mechanisms of action are needed.