Chemotypic Diversity, Antimicrobial Activities, and Molecular Docking Analysis of Essential Oils from Four Elsholtzia Species in Northern Vietnam

An ethnobotanical survey in the northern mountainous region of Vietnam identified four Elsholtzia species, E. blanda, E. ciliata, E. communis, and E. penduliflora, growing naturally above 1500 m and traditionally used by local ethnic communities to treat skin-related ailments. This study investigates their essential oil possible chemotypes, antimicrobial properties, and potential mechanisms of action through molecular docking. Essential oils obtained by steam distillation were analyzed using GC–MS. E. blanda (yield 1.17%) was characterized by high levels of 1,8-cineole (29.0%) and camphor (17.0%). E. ciliata (1.02%) represented a possible limonene-dominant chemotype (71.0%). E. communis (1.91%) contained an exceptionally high proportion of rosefuran oxide (86.2%), whereas E. penduliflora (0.91%) exhibited a pronounced 1,8-cineole chemotype (92.1%). All essential oils showed antimicrobial activity against Staphylococcus aureus (MSSA and MRSA), Escherichia coli, and Candida albicans, with MIC values ranging from 0.4% to 3.2%. Except for E. ciliata against C. albicans, MBC/MIC and MFC/MIC ratios ≤ 4 indicated predominantly bactericidal or fungicidal effects. Molecular docking further identified nine of twenty-eight detected constituents as strong binders to microbial target proteins. These findings expand current knowledge on possible chemotypic diversity within the genus, particularly the discovery of a high-altitude limonene chemotype in E. ciliata and the identification of E. penduliflora as a rich natural source of 1,8-cineole. The convergence of chemical, biological, and in silico evidence supports the ethnomedicinal relevance of Elsholtzia species and highlights their potential as candidates for developing natural antimicrobial agents.