Antifungal and repellent efficacy of Boesenbergia rotunda and Kaempferia galanga essential oils: In vitro and field tests

This study investigated the chemical composition and bioactivities of essential oils derived from the rhizomes of Boesenbergia rotunda and Kaempferia galanga growing in Viet Nam. Essential oils (EOs) were obtained via steam distillation with extraction yields of approximately 1.95–2.03 %. GC-MS analysis revealed distinct chemical profiles; B. rotunda oil was dominated by monoterpenes, notably 1,8-cineole, camphor, and geraniol, whereas K. galanga oil contained high concentrations of phenylpropanoid esters, particularly ( E )-ethyl cinnamate and ethyl p -methoxycinnamate. Both EOs exhibited potent antifungal activity against Rhizoctonia solani and Sclerotium rolfsii , with K. galanga EO demonstrating complete inhibition at a lower concentration (312 ppm, 99.52 %) compared to B. rotunda EO (1250 ppm, 99.28 %). Scanning electron microscopy confirmed notable morphological disruptions of fungal hyphae following treatment with the EOs. Molecular docking studies further visualized favorable interactions between major EO components and critical fungal targets, including chitin synthase and beta-1,3-glucan synthase of R. solani , as well as EF1α and RPB2 of S. rolfsii . Additionally, significant insect-repellent effects against red imported fire ants were noted for both EOs, particularly with K. galanga EO achieving an impressive repellency rate of 81.93 % at 1000 ppm under in vitro and 85.69 % at 4000 ppm under field conditions. Overall, these findings emphasize the promising role of B. rotunda and K. galanga EOs in developing sustainable and effective agricultural pest control solutions.