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

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 LC ₅₀ values of 7.67 and 6.73 μg/mL, and the respective LC ₉₀ 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 LC ₅₀ values of 12.37 and 12.00 μg/mL, and the LC ₉₀ 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.
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