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AbstractLindera chuniiMerr. is an important member of the Lauraceae family of plants which are known for their medicinal values. In this research article, the chemical constituents and antimicrobial activity of essential oils from the leaves of L. chuniigrown in Vietnam were reported. The essential oil was obtained by hydrodistillation of the leaves of L. chuniiwhile the constituents were determined by using gas chromatography (GC) and gas chromatography-mass (GC/MS) spectrometry methods. The antimicrobial activity was evaluated using a microdilution broth susceptibility assay. The constituents occurring in higher amounts in the leaf essential oil of L. chuniiwere mainly the monoterpene hydrocarbons comprising terpinolene (13.0%), α-pinene (8.0%), β-pinene (7.6%), camphene (7.3%), β-phellandrene (7.1%) and myrcene (5.0%). The leaf essential oil of L. chuniiinhibited the growth of Enterococcus faecalisATCC29212, Staphylococcus aureusATCC25923 and Salmonella entericaATCC13076, each with minimum inhibitory concentration (MIC) value of 64.0 μg/mL. The corresponding median lethal concentration (IC50) values were 19.45 μg/mL, 20.45 μg/mL and 18.78 μg/mL, respectively. The essential oil also displayed anti-candidal activity towards Candida albicans ATCC10231 with MIC value of 64.0 μg/mL, and IC50value of 23.12 μg/mL. The antimicrobial activity of L. chuniiessential oil was reported for the first time as a confirmation of the traditional uses of the plant in the treatment of microbial infections. Furthermore, the paper discusses the chemotaxonomy of Linderaoil samples.

AbstractThis paper reports the chemical compounds and antimicrobial activity of essential oils isolated from the leaves, stem, and rhizomes of Alpinia kwangsiensisT. L. Wu and S. J. Chen (Zingiberaceae). The essential oils were separately isolated using hydrodistillation of the pulverized samples (2 kg each) materials in an all- glass Clevenger-type apparatus and characterized by GC-FID and GC/MS. The yields of the essential oils were 0.16, 0.11 %, and 0.21 % (w/w), respectively, calculated on a dry weight basis. The main constituents of the essential oils (percentages, respectively) were 1,8-cineole (16.9 %, 14.3 % and 5.8 %), terpinene-4-ol (16.0 %, 13.6 % and 14.3 %), (E)-methyl cinnamate (9.4 %, 15.4 % and 4.6 %) and β-pinene (7.6 %, 9.9.% and 3.1 %). The study found out that the rhizome essential oil was the most active against Enterococcus faecalisATCC 299212 with a minimum inhibitory concentration (MIC) value of 1.60 μg/mL, while the leaf oil displayed pronounce activity towards Bacillus cereusATCC 14579 (MIC 3.20 μg/mL). All the essential oils inhibited the growth of Staphylococcus aureusATCC 25923 and Candida albicansATCC 10231, with MIC value of 6.40 μg/mL. Therefore, the essential oils obtained from A. kwangisensismay have potential applications as antimicrobial agents.

AbstractAmomum velutinumX.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. velutinumwere 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 faecalisATCC299212 with minimum inhibitory concentration value (MIC) of 3.98-25. 56 μg/mL), Staphylococcus aureusATCC25923 (MIC 32.87-100.56 μg/mL), Bacillus cereusATCC14579 (MIC19. 78-20.45 μg/mL) and a strain of yeast, Candida albicansATCC10231 (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. velutinumessential oils as a source of antimicrobial agents.

Mosquito-borne diseases are a consistent problem in Vietnam. Additionally, freshwater snail species are agricultural pests and are known to be intermediate hosts for several parasitic worms. There is a need for new and complementary botanical pesticidal agents for controlling these pests and essential oils have shown promise. In this work, essential oils from 2 species of Callicarpa(C. rubellaand C. sinuata) and 4 species of Premna(P. chevalieri, P. corymbosa, P. maclurei, and P. tomentosa) were screened for mosquito larvicidal activity against Aedes albopictusand Culex quinquefasciatusand for molluscicidal activity against 3 freshwater snail species, Gyraulus convexiusculus, Pomacea canaliculata,and Tarebia granifera. Callicarpa rubellaessential oil showed exceptional larvicidal activity against Cx. quinquefasciatuswith 24-h LC50of 9.8 μg/mL. In addition to C. rubella, the essential oils of P. chevalieriand P. tomentosashowed notable molluscicidal activities against P. canaliculatawith LC90values ≤ 20 μg/mL. These Callicarpaand Premnaessential oils were all rich in sesquiterpenes and should be considered for continued investigation as botanical pesticidal agents.