Essential oils of the ginger plants Meistera caudata and Conamomum vietnamense: chemical compositions, antimicrobial, and mosquito larvicidal activities.

Abstract

The current study describes the chemical identification, antimicrobial, and mosquito larvicidal activities of essential oils from Meistera caudata and Conamomum vietnamense, growing in Vietnam. Essential oils were extracted from the leaves and rhizomes, and characterized by the GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry) analysis. Monoterpenes (33.1-89.2 %) were the main chemical class found in these oils. β-Pinene (30.8 %) and α-pinene (23.8 %) were two major compounds in M. caudata leaf oil. C. vietnamense leaf and rhizome essential oils were dominated by 1,8-cineole (47.9-62.0 %) and limonene (10.3-16.2 %). With the same MIC (minimum inhibitory concentration) value of 25 μg/mL, C. vietnamense leaf and rhizome essential oils strongly inhibited the growth of Gram-positive bacteria Staphylococcus aureus ATCC 29213 and Bacillus subtilis ATCC 6501, respectively. For 24 and 48-h treatments, C. vietnamense leaf essential oil strongly controlled the growth of mosquito Aedes aegypti with the respective LC₅₀ values of 7.67 and 6.73 μg/mL, and the respective LC₉₀ values of 13.37 and 10.83 μg/mL. In the same manner, C. vietnamense rhizome essential oil also showed strong mosquito larvicidal activity against Aedes albopictus with the LC₅₀ values of 12.37 and 12.00 μg/mL, and the LC₉₀ values of 20.56 and 18.58 μg/mL, respectively. C. vietnamense essential essential oils containing a high amount of 1,8-cineole are generally better than M. caudata essential essential oils in both two biological assays.