Chemical Compositions and Antimicrobial Activity of Essential Oils from Amomum velutinum X.E.Ye, Škornièk. & N.H.Xia (Zingiberaceae) from Vietnam

Abstract

Amomum velutinum X.E.Ye, Škornièk. & N.H.Xia (local name: Sa nhân lông hung) has been used in ethnomedicine for the amelioration of fever, rheumatism and microbial infections among others. In this study, the chemical constituents and antimicrobial activity of essential oils from the leaf, pseudo-stem and rhizome of A. velutinum were described. The study includes hydrodistillation of essential oils from the plant parts, instrumental analysis of the essential oils by gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC/MS) and the determination of the antimicrobial activity of the essential oils by the microdilution broth susceptibility assay. The essential oils were obtained in yields of 0.18 %, 0.11 and 0.21 % (v/w,±0.01) respectively for the leaf, pseudo-stem and rhizomes. β-Pinene (43.5 %-46.3 %) and α-pinene (5.2 %-8.1 %) were the main constituents of the essential oils. The leaf oil contained a significant quantity of myrtenyl acetate (10.5 %) and thymol (6.8 %), while β-caryophyllene (14.0 %), cis-β-elemene (9.8 %) and α-pinene (5.2 %) were found in the pseudo-stem oil in sizeable amount. The essential oils inhibited the growth of gram-positive bacteria namely Enterococcus faecalis ATCC299212 with minimum inhibitory concentration value (MIC) of 3.98-25. 56 μg/mL), Staphylococcus aureus ATCC25923 (MIC 32.87-100.56 μg/mL), Bacillus cereus ATCC14579 (MIC19. 78-20.45 μg/mL) and a strain of yeast, Candida albicans ATCC10231 (MIC 20.56-55.67 μg/mL). This was the first report on the chemical compositions and antimicrobial activity of essential oils from A. velutinum. The results are an indication of the potential of A. velutinum essential oils as a source of antimicrobial agents.