Essential Oils of Five Species Growing Wild in Vietnam: Chemical Compositions and Antimicrobial and Mosquito Larvicidal Potentials.

The essential oils of five Vietnamese species (, , , , and ) were first hydro-distilled and analyzed using GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry). Monoterpene hydrocarbons, sesquiterpene hydrocarbons, and oxygenated sesquiterpenoids were the main chemical classes in these oils. All these essential oils showed good-excellent antimicrobial activities against Gram-positive bacteria , , and , and the yeast leaf essential oil, rich in bicyclogermacrene (25.3%), ()--elemene (12.2%), ()-caryophyllene (8.2%), and -selinene (7.4%), as well as fruit essential oil containing ()-caryophyllene (14.2%), -pinene (12.1%), caryophyllene oxide (10.9%), -selinene (10.8%), -selinene (8.0%), and -humulene (5.7%), established the same MIC value of 8 µg/mL against and , which were much better than the positive control streptomycin (MIC 128-256 µg/mL). The studied essential oils showed the potential to defend against mosquitoes since they caused the 24 and 48 h LC values of less than 50 µg/mL against the growth of and larvae. Especially, leaf essential oil strongly inhibited larvae with 24 and 48 h LC values of 6.73 and 6.73 µg/mL, respectively, and 24 and 48 h LC values of 13.37 and 10.83 µg/mL, respectively. These findings imply that Vietnamese essential oils might have potential for use as supplemental antibacterial agents or as "green" alternatives for the control of mosquitoes.