The antimicrobial activity and essential oil constituents of the leaves and trunks of Aquilaria banaensis P.H.Hô (Thymelaeceae) from Vietnam.

The aim of the present paper was to report the chemical constituents and antimicrobial activity of essential hydrodistilled from the leaves and trunk of Aquilaria banaensis P.H.Hô (Thymelaeceae) from Vietnam. The essential oils were analysed comprehensively for their constituents by using Gas chromatography coupled with Mass spectrometry (GC/MS). The antimicrobial activity was determined by agar well diffusion and broth microdilution methods. The leaf essential oil comprised mainly of sesquiterpenes while fatty acids constitutes the bulk of the trunk essential oil. The main constituents of the leaf essential oil were ß-caryophyllene (17.11%), α-selinene (10.99%), α-humulene (8.98%), ß-selinene (8.01%), ß-guaiol (6.69%) and ß-elemene (5.65%). However, hexadecanoic acid (48.46%), oleic acid (19.80%) and tetradecanoic acid (5.32%) were the major compounds identified in the trunk essential oil. The trunk essential oil displayed antimicrobial activity against Staphylococcus aureus, with the minimum inhibitory concentration (MIC) value of about 256.0 µg/mL.

Chemical composition and antimicrobial activity of essential oil from Popowia pisocarpa (Bl.) Endl., Walp. Repert. (Annonaceae).

The volatile compositions and antimicrobial activity of aerial parts of Popowia pisocarpa from Vietnam were reported for the first time. From the GC/MS spectral, spathulenol (35.9%), bicyclogermacrene (5.7%) and muurola-4,10(14)-dien-1ß-ol (4.2%) among the sesquiterpenoids, along with 4,4-dimethyl-3-(3-methylbut-3-enylidene)-2-methylenebicyclo[4,1,0]heptane (17.7%), an unsaturated cyclic compound, were the main constituents of the essential oil. Monoterpenoids were not identified in the essential oil. The essential oil displayed antimicrobial activity against the Gram-negative Escherichia coli ATCC 25922 with MIC value of 16.0 µg/mL and IC50 value of 8.52 µg/mL. In addition, the essential oil also exhibited activity towards the Gram-positive bacteria of Staphylococcus aureus ATCC 13709, Bacillus subtilis ATCC 6633, and Lactobacillus fermentum N4 with MIC value of 64.0 µg/mL each and corresponding IC50 values of 11.06 µg/mL, 26.47 µg/mL and 15.68 µg/mL, respectively. The essential oil did not inhibit the growth of Pseudomonas aeruginosa ATCC 15442, Salmonella enterica and the yeast Candida albicans ATCC 10231.

Chemical composition and acetylcholinesterase inhibitory activity of essential oil from the leaves of Mitrephora poilanei Weeras. & R.M.K. Saunders.

The present study provides the first information on the chemical composition and acetylcholinesterase inhibitory activity of the essential oil (EO) from the leaves of Mitrephora poilanei Weeras. & R.M.K.Saunders from Vietnam. Gas chromatography and gas chromatography-mass spectrometry analysis revealed that the main components of the M. poilanei EO were ß-caryophyllene (13.2%), α-humulene (10.5%), germacrene D (8.1%), ß-elemene (5.2%) and bicyclogermacrene (5.1%). The anti-acetylcholinesterase assay showed that the EO displayed moderate activity with IC50 value of 31.16 ± 3.06 µg/mL. These findings proposed that the plant can be exploited for its anti-acetylcholinestrate potential.

A Character Level Based and Word Level Based Approach for Chinese-Vietnamese Machine Translation.

Chinese and Vietnamese have the same isolated language; that is, the words are not delimited by spaces. In machine translation, word segmentation is often done first when translating from Chinese or Vietnamese into different languages (typically English) and vice versa. However, it is a matter for consideration that words may or may not be segmented when translating between two languages in which spaces are not used between words, such as Chinese and Vietnamese. Since Chinese-Vietnamese is a low-resource language pair, the sparse data problem is evident in the translation system of this language pair. Therefore, while translating, whether it should be segmented or not becomes more important. In this paper, we propose a new method for translating Chinese to Vietnamese based on a combination of the advantages of character level and word level translation. In addition, a hybrid approach that combines statistics and rules is used to translate on the word level. And at the character level, a statistical translation is used. The experimental results showed that our method improved the performance of machine translation over that of character or word level translation.