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Nine cembranoid diterpenes 1-9, including four new compounds, crassumols D-G (1-4), were isolated from the methanol extract of the Vietnamese soft coral Lobophytum crassum. Spectroscopic methods were used to elucidate the structures of these compounds. Compound 5 exhibited a potent inhibitory effect on tumor necrosis factor-alpha (TNFα)-induced nuclear factor-kappa B (NF-κB) transcriptional activation in HepG2 cells and significantly inhibited the mRNA expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in a dose-dependent manner.

Leaf essential oil of Magnolia coriacea (Hung T. Chang & B. L. Chen) Figlar growing wild in the Bat Dai Son Nature Reserve, Ha Giang Province, Viet Nam was obtained by hydrodistillation and its chemical composition was analyzed using GC/MS. In total, 45 compounds were detected in the essential oil, accounting for 87.1% of the oil, in which 37 compounds were identified accounting for 66.9%. Bicyclogermacrene (12.6%) and spathulenol (17.0%) were the main components of the leaf essential oil of M. coriacea. Antimicrobial activity of the essential oil sample was tested against three microorganism strains using an agar disk diffusion method. The results show that the inhibitory zone diameters ranged from 8.5 to 20.5 mm. Median inhibitory concentration (IC50) and minimum inhibitory concentration (MIC) of the essential oil was determined using microdilution broth susceptibility assay against seven test microorganism strains. Bacillus subtilis had the highest sensitivity with IC50 and MIC values of 185.9 and 512 µg/mL, respectively.

Plants of the genus Polyalthia can be seen as a rich resource of essential oils type terpenoids. In this study, the essential oils obtained by hydro-distillation from the leaf and stem of Polyalthia viridis were analysed by gas chromatography/mass spectrometry–flame ionization detection. Thirty-nine constituents (95.3%) were identified in the leaf oils and 42 constituents (90.9%) in the stem oils. Sesquiterpene hydrocarbons and oxygenated sesquiterpenes were the main constituents of both oils, in which 2 sesquiterpene hydrocarbons, germacrene D (45.1%-47.4%) and bicyclogermacrene (8.2%-17.1%), were the 2 major compounds. The stem oils inhibited the growth of 3 cancer cell lines, HepG2, MCF7, and A549, with half inhibitory concentration (IC50) values of 56.7 to 68.4 μg/mL. The stem oils also successfully suppressed the growth of the filamentous fungus Aspergillus niger and the yeast Candida albicans with minimum inhibitory concentration values of 50 μg/mL. P viridis oils suppressed NO production in lipopolysaccharide-stimulated BV2 microglial cells, with IC50 values of 57.6 to 76.7 μg/mL.

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Background. Inhibition ofα-glucosidase is an important factor to control postprandial hyperglycemia in type 2 diabetes mellitus.Citrusessential oils (CEO) are among the most widely used essential oils, and some of them exhibited promising antidiabetic effect. However, theα-glucosidase inhibition of CEO has not been investigated so far. The present work aims to evaluate theα-glucosidase inhibition of essential oils from six VietnameseCitruspeels.Methods. The chemical composition of essential oils obtained by hydrodistillation from sixCitruspeels was analyzed by GC-MS. All essential oils were tested for their inhibitory activity onα-glucosidase usingp-nitrophenyl-α-D-glucopyranoside as substrate.Results. In Buddha’s hand and lime peels, the major components were limonene (59.0–61.31%) andγ-terpinene (13.98–23.84%) while limonene (90.95–95.74%) was most abundant in pomelo, orange, tangerine, and calamondin peels. Among the essential oils, the Buddha’s hand oil showed the most significantα-glucosidase inhibitory effect with the IC50value of 412.2 μg/mL. The combination of the Buddha’s hand essential oil and the antidiabetic drug acarbose increased the inhibitory effect.Conclusions. The results suggested the potential use of Buddha’s hand essential oil as an alternative in treatment of type 2 diabetes mellitus.

Essential oils from the leaf and twig of Polyalthia suberosa (Roxb.) Thwaites were analyzed using GC/MS/FID. A total of sixty‐three constituents were namely identified accounting for 96.03 and 94.12 % in the hydrodistilled oils of the leaf and twig, respectively. Monoterpenes, monoterpenoids, sesquiterpenes, and sesquiterpenoids were characteristic derivatives of P. suberosa essential oils. Sesquiterpenes bicyclogermacrene (26.26 %) and (E)‐caryophyllene (7.79 %), and monoterpene β‐pinene (12.71 %) were the major constituents of the leaf oil. Sesquiterpenes (E)‐caryophyllene (17.17 %) and α‐humulene (9.55 %), sesquiterpenoid caryophyllene oxide (9.41 %), and monoterpenes camphene (8.16 %) and tricyclene (6.35 %) were to be main components in the twig oil. The leaf oil indicated cytotoxic activity against three cancer cell lines HepG2, MCF7 and A549 with the IC50 values of 60.96–69.93 μg/mL, while the twig oil inhibited MCF7 with the IC50 value of 66.70 μg/mL. Additionally, the twig oil successfully suppressed the growth of the negative Gram bacterium Pseudomonas aeruginosa, fungus Aspergillus niger, and yeast Candida albicans with the same MIC value of 50 μg/mL, whereas the leaf oil had the same result on the negative Gram bacterium Escherichia coli.

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