Essential Oils from Vietnamese Asteraceae for Environmentally Friendly Control of Aedes Mosquitoes.

Mosquitoes, in addition to being a biting nuisance, are vectors of several pathogenic viruses and parasites. As a continuation of our work identifying abundant and/or invasive plant species in Vietnam for use as ecologically friendly pesticidal agents, we obtained the essential oils of Blumea lacera, Blumea sinuata, Emilia sonchifolia, Parthenium hysterophorus, and Sphaeranthus africanus; analyzed the essential oils using gas chromatographic techniques; and screened the essential oils for mosquito larvicidal activity against Aedes aegypti and Aedes albopictus. The most active larvicidal essential oils were B. sinuata, which was rich in thymohydroquinone dimethyl ether (29.4%), (E)-ß-caryophyllene (19.7%), α-pinene (8.8%), germacrene D (7.8%), and α-humulene (4.3%), (24-h LC50 23.4 and 29.1 µg/mL) on Ae. aegypti and Ae. albopictus, respectively, and Emilia sonchifolia, dominated by 1-undecene (41.9%) and germacrene D (11.0%), (24-h LC50 30.1 and 29.6 µg/mL) on the two mosquito species. The essential oils of P. hysterophorus and S. africanus were also active against mosquito larvae. Notably, B. sinuata, P. hysterophorus, and S. africanus essential oils were not toxic to the non-target water bug, Diplonychus rusticus. However, E. sonchifolia essential oil showed insecticidal activity (24-h LC50 48.1 µg/mL) on D. rusticus. Based on these results, B. sinuata, P. hysterophorus, and S. africanus essential oils appear promising for further investigations.

Essential Oil Compositions of Three Invasive Conyza Species Collected in Vietnam and Their Larvicidal Activities against Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus.

Mosquito-borne infectious diseases are a persistent problem in tropical regions of the world, including Southeast Asia. Vector control has relied principally on synthetic insecticides, but these have detrimental environmental effects and there is an increasing demand for plant-based agents to control insect pests. Invasive weedy plant species may be able to serve as readily available sources of essential oils, some of which may be useful as larvicidal agents for control of mosquito populations. We hypothesize that members of the genus Conyza (Asteraceae) may produce essential oils that may have mosquito larvicidal properties. The essential oils from the aerial parts of Conyza bonariensis, C. canadensis, and C. sumatrensis were obtained by hydrodistillation, analyzed by gas chromatography-mass spectrometry, and screened for mosquito larvicidal activity against Aedes aegypti, Ae. albopictus and Culex quinquefasciatus. The essential oils of C. canadensis and C. sumatrensis, both rich in limonene (41.5% and 25.5%, respectively), showed notable larvicidal activities against Ae. aegypti (24-h LC50 = 9.80 and 21.7 µg/mL, respectively) and Ae. albopictus (24-h LC50 = 18.0 and 19.1 µg/mL, respectively). These two Conyza species may, therefore, serve as sources for alternative, environmentally-benign larvicidal control agents.

Integrated Analysis of the Wood Oil from Xanthocyparis vietnamensis Farjon & Hiep. by Chromatographic and Spectroscopic Techniques.

In order to get better knowledge about the volatiles produced by Xanthocyparis vietnamensis, a species recently discovered in Vietnam, its wood oil has been analyzed by a combination of chromatographic (GC, CC) and spectroscopic (GC-MS, (13)C-NMR) techniques. Forty components that accounted for 87.9% of the oil composition have been identified. The composition is dominated by nootkatene (20.7%), 11,12,13-tri-nor-eremophil-1(10)-en-7-one (17.2%), γ-eudesmol (5.1%), nootkatone (4.7%), valencene (3.5%) and 13-nor-eremophil-1(10)-en-11-one (2.6%). The structure of two new compounds-10-epi-nor-γ-eudesmen-11-one and 12-hydroxy-isodihydroagarofuran-has been elucidated, while 11,12,13-tri-nor-eremophil-1(10)-en-7-ol is reported as a natural product for the first time. The composition of X. vietnamensis wood oil varied drastically from those of leaf oils, dominated by hedycaryol (34.4%), phyllocladene (37.8%) or by pimara-6(14)-15-diene (19.4%).

Flavonoids from Anoectochilus annamensis and their Anti-inflammatory Activity.

One new flavonol diglycoside, 4',5-dihydroxy-3,3',7-trimethoxyflavone 4'-O-α-L-rhamnopyranosyl-(1 --> 6)-ß-D-glucopyranoside (1), and two known compounds (2-3) were isolated from the methanolic extract of Anoectochilus annamensis Aver. aerial parts. The effects were evaluated of all isolated compounds (1-3) on LPS-induced production of the inflammatory mediator nitric oxide (NO) by RAW264.7 cells. 4',5-Dihydroxy-3,3',7-trimethoxyflavone (2) was the most active while the addition of a rutinoside at C4' (compound 1) decreased the inhibitory activity. This is the first report on the chemical composition and biological activity of A. annamensis.

Composition of essential oils from Euodia lepta (Spreng.) Merr and Euodia calophylla Guill., grown in Vietnam / Composición de los aceites esenciales de Euodia lepta (Spreng.) Merr y Euodia calophylla Guill., crecidas en Vietnam

The chemical compositions of essential oils obtained by hydrodistillation of the leaves, stems and flowers of Euodia lepta and Euodia callophylla grown in Vietnam and then analysed by gas chromatography-flame ionization detector (GC-FID) and gas chromatography/mass spectrometry (GC-MS) were being reported. The main compounds of the leaves oil of E. lepta were (E)-beta-ocimene (24.4 percent), alpha-pinene (9.8 percent), (Z)-beta-ocimene (6.3 percent) and delta-cadinene (5.2 percent), while the stems oil comprised of spathulenol (26.0 percent), (E)-beta- ocimene (9.9 percent) and (Z)-9-octadecenamide (7.7 percent). However, ciscarane (19.2 percent), alpha-cadinol (10.8 percent), alpha-pinene (10.5 percent) and (E)-beta-ocimene (9.0 percent) were present in the flowers oil of E. lepta. On the other hand, alpha-pinene (8.3 percent), trans-alpha-bergamotene (7.5 percent), (E)-beta-ocimene (7.0 percent) and (E)-nerolidol (6.6 percent) were the major constituents of the leaves oil of E. calophylla. The quantitatively significant compounds of the stems oil were (E,E)-alpha-farnesene (11.9 percent), alpha-terpinolene (11.3 percent) and alpha-pinene (8.2 percent), while alpha-pinene (21.6 percent), limonene (19.0 percent) and sabinene (15.5 percent) were obtained from the flowers oil...

La composición químicas de los aceites esenciales obtenidos por hidrodestilación de las hojas, tallos y flores de Euodia lepta y Euodia callophylla cultivadas en Vietnam, fueron analizados por cromatografía de gases-detector de ionización de llama (GC-FID) y la cromatografía de gases/espectrometría de masas (GC-MS). Los principales compuestos del aceite de hojas de E. lepta fueron (E) -beta-ocimeno (24,4 por ciento), alfa-pineno (9,8 por ciento), (Z)-beta- ocimeno (6,3 por ciento) y delta-cadineno (5.2 por ciento), mientras que los tallos de aceite estaban compuestos de spatulenol (26,0 por ciento), (E) -beta-ocimeno (9,9 por ciento) y (Z) -9- octadecenamida (7,7 por ciento). Sin embargo, cis-carano (19,2 por ciento), alfa-cadinol (10,8 por ciento), alfa-pineno (10,5 por ciento) y (E) -beta-ocimeno (9,0 por ciento) estaban presentes en el aceite de flores de E. lepta. Por otro lado, alfa-pineno (8,3 por ciento), trans-alfa-bergamoteno (7,5 por ciento), (E) - beta-ocimeno (7,0 por ciento) y (E) -nerolidol (6,6 por ciento) fueron los principales constituyentes del aceite de las hojas de E. calophylla. Los compuestos cuantitativamente significativos del aceite de los tallos fueron (E, E)-farneseno -alfa (11,9 por ciento), alfa-terpinoleno (11,3 por ciento) y alfa-pineno (8,2 por ciento), mientras que alfa-pineno (21,6 por ciento), limoneno (19,0 por ciento) y sabineno (15,5 por ciento) se obtuvieron del aceite de las flores...

Chemical Composition of the essential oils from Vietnamese Clausena indica and C. anisum-olens.

The chemical composition of Vietnamese oil samples of the aerial parts of Clausena indica (Dalz.) Oliver and C. anisum-olens (Blanco) Merryll have been investigated using a combination of chromatographic and spectroscopic techniques. C. indica essential oil contained mainly terpinolene (53.9 and 56.1%), and myristicin (17.9 and 7.3%), whereas the major components of C. anisun-olens essential were citronellal (22.8%), geranial (21.4%) and neral (16.8%). The compositions of the investigated samples have been compared with those of essential oils from various origins.

Chemical composition of the essential oils from two Vietnamese Asarum species: A. glabrum and A. cordifolium.

The essential oil isolated from Asarum cordifolium C. E. C. Fischer recently discovered in Vietnam, and A. glabrum Merr., an endangered species listed as vulnerable in the Red Data Book of Vietnam, have been analyzed by a combination of chromatographic and spectroscopic techniques including 13C NMR spectroscopy. The composition of A. cordifolium essential oil, investigated for the first time, was dominated by elemicin (82.5%). The essential oil isolated from A. glabrum contained safrole (41.9%) as its major component and was characterized by the diversity of phenylpropanoids contained in this oil (10 compounds).

The leaf essential oils of five Vietnamese Desmos species (Annonaceae).

The leaf essential oils of five Desmos species from Vietnam have been extracted by steam distillation and subjected to GC and GC-MS analyses. The plant samples were Desmos cochinchinensis Lour., D. penduculosus (A. DC.) Ban, D. penducolosus var. tonkinensis Ban, D. chinensis Lour., and D. dumosus (Roxb.) Saff. The oils were rich in sesquiterpene hydrocarbons (65.9%-88.9%) and monoterpene hydrocarbons (6.3%-30.9%). The oxygenated counterparts were less common. The quantitatively significant constituents of the oils were alpha-pinene (2.4%-12.1%), beta-elemene (2.2-39.5%), beta-caryophyllene (13.9-26.3%), germacrene D (9.9-15.5%), bicyclogermacrene (2.0-11.4%) and alpha-humulene (3.8-7.5%). The studied oils could be classified into two chemical forms: oils with abundance of beta-caryophyllene, germacrene D and alpha-pinene (D. cochinchinensis, D. penducolosus var. tonkinensis, D. chinensis and D. Dumosus) and oil with high amounts of beta-elemene, beta-caryophyllene and germacrene D (D. penduculosus).

Composition and antimicrobial activity of the essential oil of Acronychia pedunculata (L.) Miq. from Vietnam.

The chemical composition and the antimicrobial activity of the essential oil isolated from aerial parts of Acronychia pedunculata (L.) Miq. from Vietnam are reported. Analysis was carried out by GC (RI), GC-MS and 13C NMR. Thirty-four compounds were identified, accounting for 92.8% of the oil. The major constituents were alpha-pinene (57.4%) and (E)-beta-caryophyllene (13.6%). The essential oil of A. pedunculata was shown to possess a broad spectrum of antimicrobial activity against various bacteria, particularly Salmonella enterica and Staphylococcus epidermidis.