Chemical Compostions of Essential Oils and Antimicrobial Activity of Hyptis suaveolens (L.) Poit. (Lamiaceae) from Vietnam

Aims: This present study described the chemical constituents and antimicrobial activity of essential oils hydrodistiled from the leaves and flowers of Hyptis suaveolens (L.) Poit.

Study Design: This research was designed to accommodate different stages such as collection of authentic sample of Hyptis suaveolens, obtain essential oil by hydrodistillation, chemical analysis of the oil samples by gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC/MS) and screening of the essential oils for antimicrobial activity.

Place and Duration of Study: School of Natural Science, Vinh University, Vinh City, Nghệ An Province, Vietnam, between August and December 2018.

Methodology: The leaves and flowers of H. suaveolens used for this study were gotten from Đồng Văn Commune, Pù Hoạt Nature Reserve, Vietnam. The collection was done in December 2018. Essential oils were distilled off using hydrodistillation method according to established procedure. The determination of antimicrobial efficacy of essential oils of H. suaveolens will be achieved by the method of microdilution broth susceptibility assay. The minimum inhibitory concentration (MIC) and IC50 were evaluated accordingly.

Results: The major compounds in the oil were b-caryophyllene (31.1% and 33.7%), caryophyllene oxide (17.6% and 3.9%), phytol (9.9% and 2.7%) and a-humulene (6.7% and 6.6%), respectively. The leaf oil displayed strong antimicrobial activity against Enterococcus faecalis ATCC299212, Bacillus cereus ATCC14579 and Candida albicans ATCC10231 with minimum inhibitory concentrations (MIC) of 16.0, 32.0 and 16.0 µg/mL respectively, while the IC50 values were 5.78, 9.35 and 6.78 µg/mL, respectively. The flower oil showed activity towards the same organisms with MIC values of 64.0, 64.0 and 16.0 µg/mL, respectively; with IC50 values of 20.45, 26.78 and 6.78 µg/mL, respectively. Both essential oils exhibited moderate activity towards Staphylococcus aureus ATCC25923 with MIC of 256.0 µg/mL.

Conclusion: The results are indication of the potential of H. suaveolens essential oils as source of antimicrobial agents.