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Background and Objectives: Syzygium (the family Myrtaceae) is a well-known genus in the field of food chemistry and medicinal purposes. The current study aims to provide a chemical analysis of essential oils from the fresh leaves of two Vietnamese Syzygium species Syzygium oblatum (Roxb.) Wall. ex Steudel and S. abortivum (Gagnep.) Merr. & L.M.Perry. Methods: Chemical compounds in essential oils were identified using GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry) analysis. The broth microdilution method was used for the antimicrobial assay. Docking stimulation aided experimental results. Results: (E)-Caryophyllene (27.89%), α -selinene (18.34%), β -selinene (17.48%), and α -pinene (5.20%) were identified to be the main compounds in S. oblatum leaf essential oil, whereas the leaf essential oil of S. abortivum was dominated by (E)-caryophyllene (19.56%), δ -cadinene (11.03%), germacrene D (10.34%), and γ -muurolene (5.50%). It noted that both studied oil samples with the MIC/IC50 values of 8-32 µg/mL/4.56-10.37 µg/mL were comparable to the standard drugs in antimicrobial experiments against the Gram-positive bacteria Bacillus cereus and Enterococcus faecalis, and yeast Candida albicans. Molecular docking results showed that the main compound (E)-caryophyllene primarily formed hydrophobic interactions with the microbial proteins C. albicans N-myristoyl transferase B. cereus patB1, and E. faecalis carbamate kinase with the binding affinities of −6.969, −6.342, and −5.530 kcal/mol, respectively Conclusion: It is advised to isolate the main chemicals and conduct in vivo antibacterial experiments for both essential oils and their main compounds. [ABSTRACT FROM AUTHOR]

Camellia pleurocarpa (Gagnep.) Sealy, a species of yellow camellia indigenous to Vietnam, was investigated for its essential oil properties in this study. Hydrodistillation of its leaves yielded a complex mixture rich in sesquiterpenes and diterpenes. Chemical analysis identified 50 constituents, with notable compounds including spathulenol (13.26%), phytol (9.94%), and α-selinene (5.34%). The essential oil exhibited significant antimicrobial activity against three Gram-positive bacteria Enterococcus faecalis, Staphylococcus aureus, and Bacillus cereus; one Gram-negative bacterium Pseudomonas aeruginosa; and one yeast Candida albicans, with minimum inhibitory concentration (MIC) values ranging from 16 to 32 μg/mL and half-maximal inhibitory concentration (IC50) values ranging from 7.26 to 16.23 μg/mL. Furthermore, it demonstrated larvicidal potential against Aedes aegypti and Culex quinquefasciatus mosquitoes, with LC50 values ranging from 13.49 to 28.95 μg/mL and LC90 values ranging from 28.29 to 53.24 μg/mL. These findings underscore the promising antimicrobial and mosquito larvicidal properties of C. pleurocarpa essential oil, suggesting its potential as a natural alternative in combating microbial infections and controlling mosquito-borne diseases. This study represents the first comprehensive report on the chemical compositions and bioactivities of C. pleurocarpa essential oil. [ABSTRACT FROM AUTHOR]

The present study aims to describe the chemical composition of essential oils from three Vietnamese Annonaceae species, Meiogyne virgata, M. vietnamica, and Orophea polycarpa, and their antimicrobial activity. Essential oils were extracted by hydro-distillation. From the GC-FID/MS (gas chromatography-flame ionization detection and mass spectrometry) analysis, the leaf essential oil of M. virgata was reported to contain the major compound germacrene D (42.48%). Spathulenol (24.51%), bicyclogermacrene (18.58%), β-selinene (11.14%), and germacrene D (8.20%) can be seen as the main compound in M. vietnamica leaf essential oil. α-Phellandrene (39.35%), bicyclogermacrene (13.07%), β-phellandrene (10.87%), and limonene (8.27%) represented O. polycarpa leaf essential oil. Essential oil of M. virgata leaves exhibited strong antimicrobial activity against the Gram (+) bacterium Bacillus subtilis ATCC 5230, the Gram (-) bacterium Escherichia coli ATCC 8739, and the fungus Aspergillus niger ATCC 9587 with the same MIC value of 16 μg/mL. The docking method showed that germacrene D has the ΔGbinding (binding affinity) values of –6.68, –5.265, and –5.602 kcal/mol with the proteins E. coli DNA gyrase, B. subtilis TasA, and A. niger PhyA, respectively. Alkyl and pi-alkyl interactions are the main contributors to the binding affinity between the studied proteins and ligands. Furthermore, germacrene D is predicted to have low toxicity and is not active against any of the considered organ targets. [ABSTRACT FROM AUTHOR]

Objective: Essential oils extracted from Syzygium species are known for various pharmacological purposes. Syzygium fluviatile (Hemsl.) Merr. & L.M.Perry is a flowering plant found in China and Vietnam. The current study aims to offer a comparison of chemical compositions in essential oils of S. fluviatile fruits and leaves, collected from five regions of Vietnam. The obtained oils were also taken into antimicrobial consideration, which was further aided by in silico approaches. Methods: Phytochemical analysis of essential oils was carried out using GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry) analysis. An antimicrobial assay was performed using broth micro-dilution for in vitro screening. In silico considerations are mainly based on docking studies and toxicity assessments using the AutoDock Vina v1.2.3 program and the ProTox 3.0 web server, respectively. Results: Hydro-distillation of S. fluviatile fresh fruits and leaves can lead to the production of yellow essential oil with yields of 0.21–0.32% v/w. In general, the obtained oils were dominated by monoterpene and sesquiterpene derivatives, as well as (E)-caryophyllene (8.40-47.12%) being the principal compound. The oil samples showed strong antimicrobial activity against the Gram (+) bacteria Enterococcus faecalis ATCC51299, Staphylococcus aureus ATCC29213, and Bacillus cereus ATCC11778, and the yeast Candida albicans ATCC 60193 with the MIC and IC50 values 16–64 µg/mL and 5.12–24.68 µg/mL. Docking results indicated that (E)-caryophyllene exhibited binding affinities from −6.728 kcal/mol to −5.729 kcal/mol with important amino acid residues in the DNA gyrase, PBP3, and SAP2 targets. The toxicity profile of (E)-caryophyllene is also discussed. Conclusion: The isolation of (E)-caryophyllene from Vietnamese Syzygium essential oils as a purified compound is necessary. In vivo antimicrobial studies and molecular mechanisms of action are needed. [ABSTRACT FROM AUTHOR]

Chemical compositions in the leaf essential oils of four Syzygium species were first identified by the GC-FID/MS analysis. Monoterpene hydrocarbons (39.6-51.1%), and sesquiterpene hydrocarbons (27.0-37.8%) were the main chemical classes in S. formosum and S. syzygioides leaf oils, whereas sesquiterpene hydrocarbons (83.0-83.8%) were predominant in S. Megacarpum and S. chantaranothaianum leaf essential oils. Bicyclogermacrene (9.1-37.0%) was the principal compounds in these essential oils. All the tested essential oils with the MIC values of 16-128 µg/mL were comparable to the positive control streptomycin against Gram-positive bacteria Staphylococcus aureus and Bacillus cereus, and Gram-negative bacterium Pseudomonas aeruginosa. The leaf essential oils of S. formosum, S. syzygioides, and S. chantaranothaianum with the MIC values of 16-128 µg/mL were comparable to the positive control cycloheximide against the yeast Candida albicans. Four samples also exhibited good larvicidal activity against the mosquito Aedes aegypti with the 24-h and 28-h LC50 values of 25-40 µg/mL [ABSTRACT FROM AUTHOR]

This article discusses the chemical composition and antimicrobial activity of the essential oils of a newly discovered species of the Piper genus found in Central Vietnam. The study identifies 43 compounds in the oils, with terpenoids being the predominant chemical class. The oils exhibit strong antimicrobial activity against three Gram-positive bacteria. The research contributes to the understanding of the chemical properties and potential uses of Piper species. [Extracted from the article]

This article provides information on the chemical compositions of essential oils from the leaves of two species of Camellia plants, Camellia pukhangensis and Camellia quephongensis. The essential oils of these plants contain various compounds, including alkanes, esters, and ketones. The article specifically focuses on the chemical compositions of the leaf oils of C. pukhangensis and C. quephongensis, identifying the main compounds present in each. The two species differ significantly in the number of phytochemical classes and the presence of specific compounds. The document also provides information on the collection and analysis methods used. [Extracted from the article]

The chemical constituents and antimicrobial activity of the essential oils isolated from the leaves of Machilus cicatricosa S.K. Lee and Machilus bonii Lecomte from Vietnam were studied and reported. The techniques of gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC-MS) were used to characterize the chemical constituents of the essential oil while the microdilution assay was used to evaluate the antimicrobial activity. The main constituents of the leaf oil of M. cicatricosa were α-pinene (20.6%), bicyclogermacrene (15.2%), linalool (14.9%), and β-pinene (8.4%). On the other hand (E)-β-ocimene (26.3%), bicyclogermacrene (23.6%) and (E)-nerolidol (9.1%) were the major constituents of M. bonii leaf essential oil. The studied essential oils displayed antimicrobial activity against Enterococcus faecalis ATCC 29212, and Staphylococcus aureus ATCC 25923, with minimum inhibitory concentration (MIC) value of 64.0 μg/mL. In addition, essential oil from the leaf of M. bonii was the most active towards Bacillus cereus ATCC14579 with MIC value of 64.0 μg/mL, while M. cicatricosa showed stronger anti-candidal activity against Candida albicans ATCC 10231 with MIC value of 32.0 μg/mL. This is the first report on the chemical constituents and antimicrobial activity of the essential oils of M. cicatricosa and M. bonii. [ABSTRACT FROM AUTHOR]

"The Leaf Essential Oils of Neolitsea vuquangensis: A Rich Resource of β-(E)-Ocimene" is an article that explores the chemical composition and potential applications of the essential oils found in the leaves of Neolitsea vuquangensis, an evergreen tree in the Lauraceae family. The study reveals that these oils contain compounds such as α-pinene, myrcene, limonene, β-(Z)-ocimene, and β-(E)-ocimene, which have antimicrobial properties. The research provides valuable insights into the chemical properties of N. vuquangensis and its potential uses. The study was funded by Hanoi Pedagogical University 2. [Extracted from the article]

The essential oils of five Vietnamese Syzygium species (Syzygium levinei, S. acuminatissimum, S. vestitum, S. cumini, and S. buxifolium) were first hydro-distilled and analyzed using GC-FID/MS (gas chromatography–flame ionization detection/mass spectrometry). Monoterpene hydrocarbons, sesquiterpene hydrocarbons, and oxygenated sesquiterpenoids were the main chemical classes in these oils. All these essential oils showed good–excellent antimicrobial activities against Gram-positive bacteria Enterococcus faecalis, Staphylococcus aureus, and Bacillus cereus, and the yeast Candida albicans. S. levinei leaf essential oil, rich in bicyclogermacrene (25.3%), (E)-β-elemene (12.2%), (E)-caryophyllene (8.2%), and β-selinene (7.4%), as well as S. acuminatissimum fruit essential oil containing (E)-caryophyllene (14.2%), α-pinene (12.1%), caryophyllene oxide (10.9%), β-selinene (10.8%), α-selinene (8.0%), and α-humulene (5.7%), established the same MIC value of 8 µg/mL against E. faecalis and B. cereus, which were much better than the positive control streptomycin (MIC 128–256 µg/mL). The studied essential oils showed the potential to defend against mosquitoes since they caused the 24 and 48 h LC50 values of less than 50 µg/mL against the growth of Culex quinquefasciatus and Aedes aegypti larvae. Especially, S. buxifolium leaf essential oil strongly inhibited Ae. aegypti larvae with 24 and 48 h LC50 values of 6.73 and 6.73 µg/mL, respectively, and 24 and 48 h LC90 values of 13.37 and 10.83 µg/mL, respectively. These findings imply that Vietnamese Syzygium essential oils might have potential for use as supplemental antibacterial agents or as "green" alternatives for the control of mosquitoes. [ABSTRACT FROM AUTHOR]

The paper reports that the main constituent of essential oil from the leaves of Macclurodendron oligophlebia (Merr.) Hartl. growing in Vietnam was α-pinene (81.7%), while α-pinene (67.4%) and limonene (11.2%) were the major compounds in fruit essential oil. The composition of essential oils from the leaves and fruits of Melicope ptelefolia (Champ. ex Benth.) T.G. Hartley was characterized as germacrene D (34.0% and 31.1%, respectively), bicyclogermacrene (5.5% and 7.6%, respectively), d-elemene (9.9% and 9.0%, respectively) and α-pinene (6.5% and 9.8%, respectively). The fruit essential oil contains limonene (4.9%) and (E)-β-ocimene (8.1%). The fruit essential oils of M. oligophlebia and M. ptelefolia exhibited anti-candial activity towards Candida albicans ATCC 10231, with minimum inhibitory concentration (MIC) value of 8.0 μg/mL and 32.0 μg/mL, respectively. M. oligophlebia fruit oil also showed action against Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, and Bacillus cereus ATCC 14579, each with MIC value of 32.0 μg/mL. Also, M. oligophlebia leaf showed higher activity against Pseudomonas aeruginosa ATCC 27853 (MIC, 32.0 μg/mL). The other oil samples exhibited varying degrees of antimicrobial activity with MIC values of either 64.0 μg/mL or 128. 0 μg/mL. The leaf essential oil of M. oligophlebia displayed larvicidal activity against Aedes aegypti larvae with minimum lethal concentration (LC50) values of 16.71 μg/mL and 11.40 μg/mL, respectively at 24 h and 48 h. The fruit oil did not exhibit any larvicidal action. However, M. ptelefolia leaf and fruit showed activity at 24 h with LC50 values of 33.18 μg/mL and 35.06 μg/mL, respectively. [ABSTRACT FROM AUTHOR]

In recent years, essential oils (EOs) have gained popularity for their potential as natural antimicrobial agents and mosquito larvae control. This study aimed to explore the chemical composition of EOs extracted from the leaves and rhizomes of Distichochlamys benenica Q.B. Nguyen & Škorničk, and to evaluate their mosquito larvicidal and antimicrobial activities. The EOs were obtained using hydrodistillation and subjected to gas chromatography (GC) and GC-mass spectrometry to determine their chemical constituents. The main components identified in the leaf EO were β-pinene (47.7%), cis -β-elemene (8.5%), and α-pinene (7.8%), while the rhizome EO mainly consisted of geranyl acetate (25.7%), geranial (23.3%), neral (16.6%), and geraniol (8.4%). The mosquito larvicidal activity of the EOs was evaluated using larvae of Aedes aegypti and Culex quinquefasciatus during 24 and 48 h of treatment. The results demonstrated that these EOs effectively inhibited the mosquito larvae, with LC50 values ranging from 31.15 to 71.53 μg/mL and LC90 values ranging from 46.28 to 148.66 μg/mL. Additionally, the minimum inhibitory concentration (MIC) and half-maximal inhibitory concentration (IC50) values were used to evaluate the antimicrobial efficacy of EOs. Both EOs exhibited potent antimicrobial effects against Enterococcus faecalis ATCC 299212, Staphylococcus aureus ATCC 25923, Bacillus cereus ATCC 14579, Pseudomonas aeruginosa ATCC 27853, and Candida albicans ATCC 10231, with MIC values ranging from 16 to 64 μg/mL and IC50 values ranging from 4.67 to 45.67 μg/mL. Overall, the mosquito larvicidal and antimicrobial activities of D. benenica EOs highlight their potential as natural alternatives for combating mosquito-borne diseases and microbial infections. [ABSTRACT FROM AUTHOR]

However, monoterpene hydrocarbons (34.7%), oxygenated monoterpenes (4.7%), sesquiterpene hydrocarbons (49.8%), oxygenated sesquiterpenes (7.7%), and nonterpenes (1.4%) were the classes of compounds identified in the stem essential oil of I S. henryi i subsp I . hoatii i . However, the compositions of essential oils from other I Schisandra i plants have been described - essential oil from the berries of I S. chinensis i are comprised of I i I cis i -bergamotene (10.7%), selina-4,11-diene (5.2%), and I i -cadinol (5.1%), while the ylangene (10.1%), I i -himachalene (9.4%) and I di i I epi i I i -cedrene (8.9%) were found in the seed oil. The identities of these terpenes differ from species to species - for example, I i -ylangene, I cis i I i -bergamotene and I di i I epi i I i -cedrene, the major compounds of I S. chinesis i [[2]], were conspicuously absent in I S. henryi i subsp I . hoatii i essential oils. However, the fruit essential oil of I S. chinensis i isolated by simultaneous distillation extraction (SDE) showed good antibacterial activity against both Gram-positive ( I S. epidermidis i , I S. aureus i , I B. subtilis i ) and Gram-negative ( I E. coli i , I P. aeruginosa i , I Proteus vulgaris i ) bacteria [[3]]. [Extracted from the article]

The chemical compositions were determined by the leaf essential oils of 2 Vietnamese plants, Piper betle f. densum and Disepalum plagioneurum. The main chemical classes in the P densum leaf essential oil were sesquiterpene hydrocarbons (30.1%) and oxygenated sesquiterpenes (60.1%), with γ-elemene (12.7%), valeranone (9.3%), and ishwarone (6.0%) being the principal compounds. Disepalum plagioneurum leaf essential oil was dominated by monoterpene hydrocarbons (23.9%) and sesquiterpene hydrocarbons (59.8%). Bicyclogermacrene (26.8%), (E)-caryophyllene (12.7%), (E)- β -ocimene (8.4%), and (Z)- β -ocimene (6.0%) were the major compounds of this essential oil. With the same MIC of 64 µg/mL, the leaf essential oils of P betle f. densum and D plagioneurum strongly controlled the growth of the Gram (+) bacterium Clostridium sporogenes NCTC 12935 and the fungus Aspergillus niger ATCC 1015, respectively. It was also found that D plagioneurum leaf essential oil was cytotoxic to cancer cell lines MCF7 and HeLa with IC50 values of 63.2 and 41.4 µg/mL, respectively. [ABSTRACT FROM AUTHOR]

Background: Leaves, flowers and young shoots of yellow Camellia species are often used as a substitute for green tea in Vietnam. Yellow Camellia species contain high levels of polyphenol compounds, and have shown activities such as antioxidant, anticancer, and cytotoxic. Objectives: We qualitatively screened phytochemicals, quantified total polyphenols of 70% ethanol (EtOH) extracts of leaves, young shoots, and flowers of Camellia vuquangensis and Camellia hatinhensis in Ha Tinh Province, Vietnam. Furthermore, these extracts have been evaluated for lipid peroxidation inhibitory activities at the in vivo level in the BALB/c mouse model, and in vitro cytotoxic activities. Materials and Methods: Chemical methods and thin-layer chromatographic (TLC) analysis were used for the qualitative screening of phytochemicals. High-performance liquid chromatography (HPLC) was used to determine total polyphenols. Cell survival was determined through optical density (OD) measured when the protein composition of the cells was stained with sulforhodamine B (SRB). Inhibition of lipid peroxidation was evaluated by determining the content of malondialdehyde (MDA), which is a product of membrane lipid peroxidation. Results: The total polyphenol contents of all parts of the two species were comparable to that of green tea with values between 319.3 and 342.6 mg gallic acid equivalents (GAE/g) dry weight. Extracts of leaves, flowers of C. vuquangensis and C. hatinhensis showed strong lipid peroxidation inhibitory activities (IC50: 7.92–17.45 µg/mL) and moderate cytotoxic activities against cell lines HepG2, A549, MCF7, SK-Mel-2, HT-29, and AGS (IC50: 34.73–80.58 µg/mL). Conclusion: These two tea species may be considered as herbal teas with various health benefits. [ABSTRACT FROM AUTHOR]

Zingiber is a genus of medicinal plants containing a rich resource of essential oils. The current study aims to describe chemical analysis and antimicrobial assay for two Zingiber species Zingiber eberhardtii Gagnep. and Z. skornickovae N.S. Lý. The rhizome oils, which were obtained by hydro-distillation using a Clevenger apparatus, were analyzed by GC-MS (gas chromatography-mass spectrometry). Extraction of Z. eberhardtii rhizome gave a yellow oil with 41 identified compounds (96.3%), in which linalool (34.9%) and 1,8-cineole (12.7%) were the principal compounds. The yellow oil of Z. skornickovae rhizome included 53 identified compounds (97.8%), with β-pinene (25.0%), (E)-caryophyllene (8.8%), and α-pinene (7.9%) as the major agents. By broth dilution method, both oils moderately controlled the growth of Gram (+) bacteria Bacillus subtilis ATCC 6633 and Staphylococcus aureus ATCC 25923 with the same MIC (minimum inhibitory concentration) value of 128 μg/mL. In particular, Z. skornickovae rhizome oil showed the best antimicrobial activity against yeast Saccharomyces cerevisiae ATCC 4098 with a MIC value of 64 μg/mL. The obtained results are promising information for future research. [ABSTRACT FROM AUTHOR]

In this study, the antimicrobial activity and constituents of essential oils from the leaves of Cinnamomum auricolor Kosterm. and C. petelotii Kosterm collected from Pù Hoạt Natural Reserve (Hạnh Dịch Commune, Quế Phong District), Vietnam were reported. The essential oils obtained by separate hydrodistillation were analyzed by means of gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC-MS). The antimicrobial activities were evaluated by microbroth dilution susceptibility assay. The main constituents of C. auricolor comprised of oxygenated sesquiterpenes mainly caryophyllene oxide (26.0%), spathulenol (11.1%), and (E)-nerolidol (10.7%). However, oxygen-containing monoterpenes were the main compounds identified in S. petelotii and they are linalool (34.3%), 1,8-cineole (20.8%) and terpinene-4-ol (9.9%). The essential oil of C. auricolor displayed prominent antimicrobial activity towards Bacillus cereus ATCC14579 and Staphylococcus aureus ATCC25923 with minimum inhibitory concentration (MIC) value of 16.0 μg/mL. In addition, the essential oil of C. auricolor also exhibited antimicrobial activity against Enterococcus faecalis ATCC29212, and anti-candidal activity towards Candida albicans ATCC10231 with MIC value of 32.0 μg/mL. The leaf essential oil of C. petelotii only exhibited activity towards S. aureus and C. albicans with MIC value of 64.0 μg/mL. The chemical constituents and antimicrobial activity of both essential oils are being reported for the first time. [ABSTRACT FROM AUTHOR]

Syzygium plants are known as sources of biologically active substances. The essential oils constituents and antimicrobial activity of Syzygium petelotii Merr. & Perry and Syzygium syzygioides (Miq.) Merr. & Perry from Vietnam are being reported. Essential oils were obtained by hydrodistillation of the leaves of S. petelotii and S. syzygioides collected from Pù Hoạt Nature Reserve, Vietnam. The constituents of the essential oils were determined by using gas chromatography (GC) and gas chromatography-mass (GC/MS) spectrometry methods. The antimicrobial activity was evaluated by microdilution broth susceptibility assay. The results indicate that γ-guaiene (24.1%), β-caryphyllene (9.3%), α-pinene (7.8%), and β-pinene (6.1%) were the major compounds of S. petelotii. The main constituents of S. syzygioides were caryophyllene oxide (14.8%), α-pinene (10.6%), β-pinene (6.6%) and spathulenol (6.4%). The essential oil of S. petelotii showed pronounced antimicrobial activity against Pseudomonas aeruginosa ATCC27853 and Enterococcus faecalis ATCC299212, with minimum inhibitory concentration (MIC) values of 16.0 μg/mL and 64.0 μg/mL, respectively. The essential oil of S. syzygioides only displayed activity towards Pseudomonas aeruginosa ATCC27853 with MIC value of 32.0 μg/mL. Both essential oils exhibited antimicrobial activity towards Bacillus cereus ATCC14579 (MIC value, 128.0 μg/mL), and anti-candidal action against Candida albicans ATCC10231 with MIC value of 64.0 μg/mL. The chemical compositions and antimicrobial activity of essential oils of S. petelotii and S. syzygioides are being reported for the first time. [ABSTRACT FROM AUTHOR]

The major compounds of the essential oil of I T. odorum i were I i -pinene (20.4%), I i -caryophyllene (6.4%), and -humulene (5.6%). The essential oils of I M. hypolampra i were dominated by I i -pinene (36.5 and 41.3%), I i -pinene (23.7 and 24.4%), and germacrene D (14.6 and 5.8%) [[14]]. On the other hand, monoterpene hydrocarbons (5.6%), monoterpene oxygenated (3.9%), sesquiterpene hydrocarbons (61.4%), oxygenated sesquiterpenes (10.4%), and nonterpenes (2.0%) constitute the bulk of the essential oil of I M. chevalieri i . Compounds such as I i -pinene and I i -pinene have previously shown antimicrobial activity against broad-spectrum microorganisms [[15]]. [Extracted from the article]

Lindera chunii Merr. 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. chunii grown in Vietnam were reported. The essential oil was obtained by hydrodistillation of the leaves of L. chunii while 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. chunii were 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. chunii inhibited the growth of Enterococcus faecalis ATCC29212, Staphylococcus aureus ATCC25923 and Salmonella enterica ATCC13076, 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 IC50 value of 23.12 μg/mL. The antimicrobial activity of L. chunii essential 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 Lindera oil samples. [ABSTRACT FROM AUTHOR]

From hydro-distillation and GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry) analysis, chemical compositions in essential oils of two Vietnamese Piper plants Piper pendulispicum C. DC. and P. hymenophyllum Miq. were identified. Essential oils of P. pendulispicum leaf and stem are highlighted with the predominant amount of sesquiterpene hydrocarbons (73.21-78.06%), in which bicyclogermacrene (12.17-12.54%) and β-caryophyllene (12.10-14.51%) were the principal compounds. Monoterpene hydrocarbons (87.44%) are the main chemical class of P. hymenophyllum leaf oil, in which α-pinene (52.92%) and β-pinene (26.65%) are the principal compounds. These obtained essential oils with the MIC (minimum inhibitory concentration) values of 16-128 μg/mL are better than the positive control streptomycin ((MIC 128-256 μg/mL) in antimicrobial assay against three Gram-positive bacteria Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, and Bacillus cereus ATCC 14579. P. pendulispicum essential oils (MIC 16-32 μg/mL) are also comparable to the other standard cycloheximide (MIC 32 μg/mL) against the yeast Candida albicans ATCC 10231. In general, P. pendulispicum essential oil is better than P. hymenophyllum leaf oil for antimicrobial treatment. [ABSTRACT FROM AUTHOR]

The essential oils from the leaves and rhizomes of I M. cristatissima i displayed moderate antimicrobial activity (Table 2). The obtained essential oils were light-yellow coloured and the yields were 0.16% (leaf) and 0.25% (rhizome), which is consistent with values reported previously for the majority of the I Amomum i essential oils from Vietnam - for example, essential oils from the leaf and rhizome I A. cinnamomeum i were obtained in yields of 0.12 and 0.19%, respectively [[1]], while the leaves and stems of I A. rubidum i afforded essential oils in yields of 0.22 and 0.15%, respectively [[2]]. It is well noted that terpene compounds predominate in the essential oils, and this has been previously reported for other I Amomum i essential oil samples grown in Vietnam [[1]]. [Extracted from the article]

The essential oil from the leaf oil of I L. annamensis i displayed promising antibacterial activity against I Enterococcus faecalis i ATCC299212 and I Staphylococcus aureus i ATCC25923, and anti-candidal action towards I Candida albicans i ATCC10231, with a minimum inhibitory concentration (MIC) value of 32.0 g/mL (Table 2). In our previous communications, the chemical compositions and antimicrobial activity of essential oils from I L. glauca i [[2]] and I L. rufa i [[3]] were reported. The leaves of I L. annamensis i afforded essential oil dominated by sesquiterpene hydrocarbons (76.1%) and monoterpene hydrocarbons (14.9%). [Extracted from the article]

Essential oils from the leaves of Fokienia hodginsii (Dunn) A. Henry & H. H. Thomas and Amentotaxus argotaenia (Hance) Pilg. from Vietnam were obtained by hydrodisitllation and the chemical components determined by gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC/MS). Also the microdilution broth assay was used to test the antimicrobial activity of the essential oil. The yield of the essential oil was 0.22% (v/w). The major components of F. hodginsii were α-pinene (73.2%), limonene (10.3%), myrcene (4.1%) and β-pinene (2.6%). Amentotaxus argotaenia feature essential oil with α-pinene (20.4%), δ-cadinene (7.8%) and β-selinene (7.6%) as main compounds. The leaf essential oil of F. hodginsii displayed potent antimicrobial activity towards the Gram-positive microorganisms of Enterococcus faecalis ATCC 29212 and Bacillus cereus ATCC 14579 with minimum inhibitory concentration (MIC) values of 32.0 μg/mL and 64.0 μg/mL, respectively. The essential oil of A. argotaenia showed activity against E. faecalis ATCC 29212, Staphylococcus aureus ATCC 25923 and Bacillus cereus ATCC 14579 with MIC value of 64.0 μg/mL; as well as Pseudomonas aeruginosa ATCC 27853 (MIC, 32.0 μg/mL). Additionally, the essential oil of A. argotaenia exhibited the most anti-candidal action towards Candida albicans ATCC 10231 with MIC value of 32.0 μg/mL. The chemical constituents and antimicrobial activity of the essential oils of F. hodginsii were being reported for the first time. [ABSTRACT FROM AUTHOR]

The current study describes chemical compositions and antimicrobial activity of essential oils from the rhizome of two Vietnamese ginger plants Newmania orthostachys N.S. Lý & Škorničk. and Newmania serpens N.S. Lý & Škorničk. 49 compounds (98.4%) were identified in N. orthostachys rhizome oil, whereas 54 compounds (93.4%) were identified in N. serpens rhizome oil. N. orthostachys rhizome essential oil was dominated by monoterpene hydrocarbons (74.2%), in which β-pinene (35.7%), α-pinene (13.4%), sabinene (8.0%), camphene (6.7%), and limonene (5.1%) were characteristic compounds. Monoterpene hydrocarbons (33.5%) and sesquiterpene hydrocarbons (44.1%) represented N. serpens rhizome essential oil, as well as β-pinene (18.5%), bicyclogermacrene (12.4%), β-selinene (8.2%) were the principal compounds. In an antimicrobial assay against three tested Gram-positive bacteria Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, and Bacillus cereus ATCC 14579, both two essential oils showed the minimum inhibitory concentration (MIC) values of 16-64 µg/mL lower than those of positive control Streptomycin (MIC 128-256 µg/ml). These two essential oils with the MIC values of 8-16 µg/mL are also better than the positive control cycloheximide (MIC 32 µg/mL) against the yeast Candida albicans ATCC 10231. [ABSTRACT FROM AUTHOR]

Essential oils of the leaves of 4 Vietnamese Zingiberaceae species were first obtained by hydro-distilled, and their chemical compositions were identified by gas chromatography-flame ionization detection/mass spectrometry. β -Pinene (21.7%), sabinene (12.8%), and α -pinene (8.0%) were the main compounds in Wurfbainia tenella leaf oil. The essential oil of Hedydium villosum var. tenuifolium leaf was dominated by β -pinene (23.7%), β -caryophyllene (21.6%), and 1,8-cineole (14.0%). β -Pinene (27.4%), α -pinene (21.2%), limonene (12.1%), and myrcene (8.6%) were the characteristic components of Meistera sudae leaf oil, and β -pinene (32.8%) and (E)-methyl cinnamate (15.8%) of Alpinia hongiaoensis leaf oil. The 4 oil samples exhibited antimicrobial activity against Bacillus subtilis (American Type Culture Collection [ATCC] 27212), Staphylococcus aureus (ATCC 12222), Escherichia coli (ATCC 8739), Pseudomonas aeruginosa (ATCC 25923), Aspergillus niger (ATCC 9763), Fusarium oxysporum (ATCC 48112), Candida albicans (ATCC 10231), and Saccharomyces cerevisiae (ATCC 2601) at different levels. Especially, the leaf oil of M sudae showed strong activity against B subtilis, S aureus, and S cerevisiae with a minimum inhibitory concentration (MIC) value of 25.0 µg/mL. [ABSTRACT FROM AUTHOR]

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)-β-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. [ABSTRACT FROM AUTHOR]

The compositional pattern of I M. cochinchinensis i was similar to that of I M. obovatifolia i [[10]] and I M. philippinensis i [[12]] owing to high contents of monoterpene and sesquiterpene hydrocarbons. The chemical constituents of essential oils from I Machilus i species of Vietnamese origin such as I M. velutina i [[3]], I M. grandifolia i [[4]], I M. balansae i [[4]], and I M. japonica i [[5]] have been reported. Monoterpene hydrocarbons were the main compounds in I M. velutina i [[3]] and I M. japonica i [[5]], whereas sesquiterpene hydrocarbons were found in I M. grandifolia i [[4]]. I M. zuihoensis i [[7]], I M. pseudolongifolia i [[8]], I M. mushaensis i [[9]], I M. obovatifolia i [[10]], and I M. kusanoi i [[11]] also showed moderate action toward the organisms mentioned. [Extracted from the article]

Essential oils are promising as environmentally friendly and safe sources of pesticides for human use. Furthermore, they are also of interest as aromatherapeutic agents in the treatment of Alzheimer's disease, and inhibition of the enzyme acetylcholinesterase (AChE) has been evaluated as an important mechanism. The essential oils of some species in the genera Callicarpa, Premna, Vitex and Karomia of the family Lamiaceae were evaluated for inhibition of electric eel AChE using the Ellman method. The essential oils of Callicarpa candicans showed promising activity, with IC50 values between 45.67 and 58.38 μg/mL. The essential oils of Callicarpa sinuata, Callicarpa petelotii, Callicarpa nudiflora, Callicarpa erioclona and Vitex ajugifolia showed good activity with IC50 values between 28.71 and 54.69 μg/mL. The essential oils Vitex trifolia subsp. trifolia and Callicarpa rubella showed modest activity, with IC50 values of 81.34 and 89.38, respectively. trans-Carveol showed an IC50 value of 102.88 µg/mL. Molecular docking and molecular dynamics simulation were performed on the major components of the studied essential oils to investigate the possible mechanisms of action of potential inhibitors. The results obtained suggest that these essential oils may be used to control mosquito vectors that transmit pathogenic viruses or to support the treatment of Alzheimer's disease. [ABSTRACT FROM AUTHOR]

The main constituents of I A. calcicola i leaf essential oil were I i -pinene (14.4%), I i -cadinene (9.7%), I i -caryophyllene (7.7%), I i -cadinol (7.0%), and 9 I epi i -( I E i )-caryophyllene (5.1%), whereas I i -cadinol (19.1%), I i -pinene (15.3%), I i -cadinene (10.1%), and I epi i I i -muurolol (9.4%) were found in the rhizome essential oil. It could be seen that terpene compounds predominate in the essential oils, as was previously reported for other I Alpinia i oil samples grown in Vietnam, such as I A. napoensis i [[2], [4]], I A. menghaiensis i [[3]], I A. maclurei i [[3]], I A. globosa i [[5]], and I A. tonkinensis i [[5]]. Moreover, terpenes were also the predominant compounds of other I Alpinia i essential oils reported from other parts of the world, which include I A. kwangsiensis i [[15]] and I A. zerumbet i [[16]]. For example, the yields of the hydrodistilled essential oils of I A. napoensis i leaves, stems, and roots were 0.21%, 0.17%, and 0.25% respectively [[2]], whereas I A. napoensis i rhizome gave oil in a yield of 0.26% [[4]]. [Extracted from the article]

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. rubella and C. sinuata) and 4 species of Premna (P. chevalieri, P. corymbosa, P. maclurei, and P. tomentosa) were screened for mosquito larvicidal activity against Aedes albopictus and Culex quinquefasciatus and for molluscicidal activity against 3 freshwater snail species, Gyraulus convexiusculus, Pomacea canaliculata, and Tarebia granifera. Callicarpa rubella essential oil showed exceptional larvicidal activity against Cx. quinquefasciatus with 24-h LC50 of 9.8 μg/mL. In addition to C. rubella, the essential oils of P. chevalieri and P. tomentosa showed notable molluscicidal activities against P. canaliculata with LC90 values ≤ 20 μg/mL. These Callicarpa and Premna essential oils were all rich in sesquiterpenes and should be considered for continued investigation as botanical pesticidal agents. [ABSTRACT FROM AUTHOR]

The present paper reports for the first time the chemical composition and antimicrobial activity of essential oil from the leaves of Phoebe macrocarpa C. Y. Wu. The yield of the essential oil was 0.28% (w/w). The essential oil features monoterpene hydrocarbons (3.3%), oxygenated monoterpenes (2.8%), sesquiterpene hydrocarbons (31.9%) and oxygenated sesquiterpenes (46.0%). The major compounds of the essential oil were β-caryophyllene (16.6%) and spathulenol (12.6%). The essential oil showed moderate antimicrobial activity towards Enterococcus faecalis ATCC299212 with minimum inhibitory concentration (MIC) value of 128 µg/mL, Staphylococcus aureus ATCC25923 (MIC 256 µg/mL) and Bacillus cereus ATCC14579 (MIC 1280 µg/mL). The essential oil did not display anti-candidal activity. [ABSTRACT FROM AUTHOR]

Essential oil from the leaves of Vitex axillariflora (Merr.) Bramley distributed in Sao La Nature Reserve - Quang Nam was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). The main chemical constituents of the essential oil were (E)-β-caryophyllene (54.3 %), α-humulene (15.6 %), bicyclogermacrene (7.9 %) and α-copaene (3.3 %). For the first time, the chemical composition of Vitex axillariflora (Merr.) Bramley was studied. [ABSTRACT FROM AUTHOR]

The compositions and antimicrobial activity of essential oils from the leaves and rhizomes of Zingiber magang N.S. Lý & Škornièk sp. nov. and Zingiber tamii N.S. Lý & Škornièk. sp. nov. from Vietnam were reported. The essential oils from Z. magang were obtained in yields of 0.12 % (leaf) and 0.18 % (rhizome), while Z. tamii afforded essential oils with yields of 0.15 % and 0.20 %, respectively, for the leaf and rhizome. The leaf essential oil of Z. magang consists of β-pinene (12.3 %) and (E)-nerolidol (10.3 %), while α-selinene (10.5 %), caryophyllene oxide (9.7 %), and neo-intermedeol (7.5 %) were found in the rhizome essential oil. However, the compositions of essential oils from the leaf and rhizome of Z. tamii comprised mainly of β-pinene (53.8 % and 55.4 %), and sabinene (12.3 % and 12.5 %), respectively. The rhizome essential oil of Z. magang displayed promising antimicrobial activity against Enterococcus faecalis ATCC 299212 and Staphylococcus aureus ATCC 25923 with the Minimum inhibitory concentration (MIC) values of 9.99 μg/mL and 9.67 μg/mL, respectively. In addition, essential oil from the leaf of Z. tamii was the most active against Escherichia coli ATCC 25922 (MIC 44.38 μg/mL) and Candida albicans ATCC 10231 (MIC, 45.62 μg/mL). This is the first report on the chemical compositions and antimicrobial activity of essential oils of Z. magang and Z. tamii. [ABSTRACT FROM AUTHOR]

Essential oils from the rhizomes of Boesenbergia quangngaiensis N.S. Lý were obtained by hydrodistillation and the chemical components were determined by gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC/MS). In addition, the microdilution broth assay was used to test the antimicrobial activity of essential oils. The yield of the B. quangngaiensis rhizome essential oils was 0.16 % (w/w). The major components identified from the rhizome essential oil of B. quangngaiensis were cis-β-elemene (18.4 %), zerumbone (11.4 %) and myrtenyl acetate (10.6 %). The antimicrobial activity test indicated that B. quangngaiensis rhizome essential oil displayed good activity against Pseudomonas aeruginosa ATCC 27853 with a Minimum inhibitory concentration (MIC) value of 7.68 μg/mL and IC50 value of 16.0 μg/mL. Also, the essential oil inhibited the growth of other tested bacteria and yeast, except Escherichia coli ATCC 25922 and Salmonella enterica ATCC 13076, with MIC value of about 30 μg/mL. The chemical components and antimicrobial activity of the B. quangngaiensis rhizome essential oil were reported for the first time. [ABSTRACT FROM AUTHOR]

In the present communication, the composition and antimicrobial activity of essential oil from the leaves of Acorus macrospadiceus (Yam.) F. N. Wei & Y. K. Li from Vietnam were reported. The yield of the essential oil was 0.25 % (w/w). The main constituents of the essential oil were β-caryophyllene (31.1 %), α-selinene (12.6 %), α-asarone (12.0 %) and α-humulene (8.0 %). The essential oil displayed anti-candidal activity against Candida albicans ATCC 10231 with a minimum inhibitory concentration (MIC) value of 8.67 μg/ mL. In addition, the essential oil exhibited a broad spectrum of antimicrobial activity against the other tested microorganisms with MIC in the range 17.33 μg/mL (Enterococcus faecalis ATCC 299212) to 100.33 μg/mL (Escherichia coli ATCC 25922). The antimicrobial activities of A. macrospadiceus are being reported for the first time. [ABSTRACT FROM AUTHOR]

This paper reports the chemical compounds and antimicrobial activity of essential oils isolated from the leaves, stem, and rhizomes of Alpinia kwangsiensis T. 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 faecalis ATCC 299212 with a minimum inhibitory concentration (MIC) value of 1.60 μg/mL, while the leaf oil displayed pronounce activity towards Bacillus cereus ATCC 14579 (MIC 3.20 μg/mL). All the essential oils inhibited the growth of Staphylococcus aureus ATCC 25923 and Candida albicans ATCC 10231, with MIC value of 6.40 μg/mL. Therefore, the essential oils obtained from A. kwangisensis may have potential applications as antimicrobial agents. [ABSTRACT FROM AUTHOR]

Amomum velutinum X.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. velutinum were 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 faecalis ATCC299212 with minimum inhibitory concentration value (MIC) of 3.98-25. 56 μg/mL), Staphylococcus aureus ATCC25923 (MIC 32.87-100.56 μg/mL), Bacillus cereus ATCC14579 (MIC19. 78-20.45 μg/mL) and a strain of yeast, Candida albicans ATCC10231 (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. velutinum essential oils as a source of antimicrobial agents. [ABSTRACT FROM AUTHOR]

The rhizome essential oil of Curcuma sahuynhensis from Quang Ngãi Province, Vietnam, was obtained by hydrodistillation and analyzed by gas chromatographic techniques. The major components in the essential oil were β-pinene (52.7 %), β-caryophyllene (11.1 %), α-pinene (8.6 %), caryophyllene oxide (6.5 %), and (Z)-β-farnesene (5.9 %). The rhizome essential oil was screened for antimicrobial activity and showed good activity against the Gram-positive bacteria Enterococcus faecalis, Staphylococcus aureus, and Bacillus cereus, and the pathogenic yeast Candida albicans with minimum inhibitory concentrations of 64 μg/mL against each of the microorganisms. This study represents the first phytochemical analysis and bioactivity screening of C. sahuynhensis. [ABSTRACT FROM AUTHOR]

Essential oil hydrodistilled from the rhizomes of Alpinia naopensis H.G. Dong & G.J. Xu was characterised by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The antimicrobial activity was evaluated by microdilution broth susceptibility assay while the larvicidal efficacy on Aedes albopictus and Culex quinquefasciatus was determined by the World Health Organization protocol. The main constituents of the essential oil were 1,8-cineole (18.2 %), γ-terpinene (12.5 %), terpinene-4-ol (9.6 %), β-pinene (9.2 %) and fenchyl acetate (7.7 %). From the antimicrobial study, the essential oil showed activity towards six of the eight tested microorganisms with MIC < 50.0 μg/mL. At concentration 100 μg/mL, the essential oil exhibited 100 % mortality towards Ae. albopictus and Cx. quinquefasciatus under 24 h and 48 h. The oil displayed larvicidal activity against Ae. albopictus with median lethal concentrations (LC50) values of 56.39 μg/mL (24 h) and 53.85 μg/mL (48 h), as well LC50 values of 46.67 μg/mL (24 h) and 38.29 μg/mL (48 h) towards Cx. quinquefasciatus. [ABSTRACT FROM AUTHOR]

This paper reports the chemical constituents and the antimicrobial activity of essential oils hydrodisitlled from the leaves of Alpinia globosa Hour (syn. Amomum globosum Lour.) and Alpinia tonkinensis Gagnep. The essential oils were analysed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC/MS) techniques. The minimum inhibitory concentration (MIC) values were measured by the microdilution broth susceptibility assay. The absolute yields of the essential oils were 0.16 % (v/w, ± 0.01) and 0.21 % (v/w, ± 0.02), respectively for A. globosa and A. tonkinensis, calculated on a dry weight basis. The major constituents of A. biglobosa were β-pinene (12.1 %), α-gurjunene (10.5 %) and (Z)-13-docosenamide (9.0 %). The compounds occurring in higher amount in A. tonkinensis includes β-pinene (33.5 %), (E)-β-ocimene (9.6 %), γ-terpinene (9.2 %) and α-pinene (8.4 %). The essential oil of A. tonkinensis inhibited the growth of Saccharomyces cerevisiae (ATCC 16404) with MIC value of 25.0 μg/mL. In addition, both essential oils displayed antimicrobial activity against Escherichia coli (ATCC 25922), Staphylococcus aureus subsp. aureus (ATCC 11632) and Fusarium oxysporum (ATCC 48112) with MIC value of 50.0 μg/mL. The chemical constituents and antimicrobial activity of the studied essential oils were being reported for the first time. [ABSTRACT FROM AUTHOR]

Mosquito-borne diseases are a large problem in Vietnam as elsewhere. Due to environmental concerns regarding the use of synthetic insecticides as well as developing insecticidal resistance, there is a need for environmentally-benign alternative mosquito control agents. In addition, resistance of pathogenic microorganisms to antibiotics is an increasing problem. As part of a program to identify essential oils as alternative larvicidal and antimicrobial agents, the leaf, stem, and rhizome essential oils of several Zingiber species, obtained from wild-growing specimens in northern Vietnam, were acquired by hydrodistillation and investigated using gas chromatography. The mosquito larvicidal activities of the essential oils were assessed against Culex quinquefasciatus, Aedes albopictus, and Ae. aegypti, and for antibacterial activity against a selection of Gram-positive and Gram-negative bacteria, and for activity against Candida albicans. Zingiber essential oils rich in α-pinene and β-pinene showed the best larvicidal activity. Zingiber nudicarpum rhizome essential oil showed excellent antibacterial activity against Enterococcus faecalis, Staphylococcus aureus, and Bacillus cereus, with minimum inhibitory concentrations (MIC) of 2, 8, and 1 μg/mL, respectively. However, the major components, α-pinene and β-pinene, cannot explain the antibacterial activities obtained. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Essential oils have emerged as viable alternatives to synthetic insecticides for control of mosquito-borne pathogens. The leaf essential oils of eight species of Premna (Lamiaceae) growing in central Vietnam have been obtained by hydrodistillation and analyzed by gas chromatography–mass spectrometry. Sesquiterpene hydrocarbons dominated most of the Premna essential oils, with the notable exception of Premnamekongensis from Ngoc Linh Nature Reserve, which had α-pinene as the major component. Larvicidal activities against Aedes aegypti have been determined and all of the Premna essential oils showed larvicidal activity with 24-h LC50 < 65 μg/mL. The leaf essential oils of Premnacambodiana from Chu Mom Ray National Park and Premnamekongensis from Ngoc Linh Nature Reserve showed the best larvicidal activities with 24-h LC50 of 16.8 and 18.0 μg/mL, respectively. The essential oil compositions and larvicidal activities of P. cambodiana, Premna flavescens, Premnamaclurei, P. mekongensis, and Premnapuberula are reported for the first time. Although the larvicidal activities of Premna leaf essential oils are promising, the essential oil yields are relatively low (0.10–0.25%). [ABSTRACT FROM AUTHOR]

The Lauraceae is a family rich in aromatic and medicinal plants. Likewise, essential oils derived from members of this family have demonstrated a myriad of biological activities. It is hypothesized that members of the Lauraceae from Vietnam will yield essential oils that may be useful in controlling mosquito populations and treating microbial infections. In this work, the leaf essential oils of eleven species of Lauraceae (Beilschmiedia erythrophloia, B. robusta, B. yunnanensis, Cryptocarya concinna, C. impressa, C. infectoria, Litsea viridis, Machilus balansa, M. grandifolia, Neolitsea ellipsoidea, and Phoebe angustifolia) have been obtained by hydrodistillation and the chemical compositions analyzed by gas chromatography – mass spectrometry (GC-MS) and gas chromatography with flame ionization detection (GC-FID). The essential oils were screened for larvicidal activity against Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus, and for antimicrobial activity against Enterococcus faecalis, Staphylococcus aureus, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, and Candida albicans. The leaf essential oil of N. ellipsoidea, rich in (E)-β-ocimene (87.6%), showed excellent larvicidal activity against Ae. aegypti with a 24 h LC50 of 6.59 μg/mL. The leaf essential oil of C. infectoria, dominated by germacrene D (55.5%) and bicyclogermacrene (11.4%), exhibited remarkable larvicidal activity against Cx. quinquefasciatus (48 h LC50 = 0.40 μg/mL). N. ellipsoidea leaf essential oil also demonstrated notable antibacterial activity against E. faecalis and B. cereus with minimum inhibitory concentration (MIC) values of 16 μg/mL, while the leaf essential oil of C. impressa showed excellent anticandidal with an MIC of 16 μg/mL. Leaf essential oils from the Lauraceae should be considered for utilization as alternative agents for controlling mosquito populations and as antimicrobial agents. [ABSTRACT FROM AUTHOR]

Mosquitoes are important vectors of several diseases, and control of these insects is imperative for human health. Insecticides have proven useful in controlling mosquito populations, but insecticide resistance and environmental concerns are increasing. Additionally, emerging and re-emerging microbial infections are problematic. Essential oils have been shown to be promising mosquito larvicidal agents as well as antimicrobial agents. In this work, the essential oils from four species of Myrtaceae (Baeckea frutescens, Callistemon citrinus, Melaleuca leucadendra, and Syzygium nervosum) growing wild in central Vietnam have been obtained by hydrodistillation and analyzed by gas chromatographic techniques. The essential oils have been screened for mosquito larvicidal activity against Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus, and for antimicrobial activity against Enterococcus faecalis, Staphylococcus aureus, and Candida albicans. Callistemon citrinus fruit essential oil, rich in α-pinene (35.1%), 1,8-cineole (32.4%), limonene (8.2%), and α-terpineol (5.8%) showed good larvicidal activity with 24-h LC50 = 17.3 μg/mL against both Ae. aegypti and Cx. quinquefasciatus, and good antibacterial activity against E. faecalis (minimum inhibitory concentration (MIC) = 16 μg/mL) The 48-h larvicidal activities of M. leucadendra leaf essential oil, rich in α-eudesmol (17.6%), guaiol (10.9%), linalool (5.1%), (E)-caryophyllene (7.0%), and bulnesol (3.6%) were particularly notable, with LC50 of 1.4 and 1.8 μg/mL on Ae. aegypti and Cx. quinquefasciatus. Similarly, M. leucadendra bark essential oil, with α-eudesmol (24.1%) and guaiol (11.3%), showed good antibacterial activity against. E. faecalis. Both B. frutescens and C. citrinus leaf essential oils demonstrated anti-Candida activities with MIC values of 16 μg/mL. The results of this investigation suggest that essential oils derived from the Myrtaceae may serve as "green" alternatives for the control of mosquitoes and/or complementary antimicrobial agents. [ABSTRACT FROM AUTHOR]

Mosquitoes are the deadliest animals on earth and are the vectors of several neglected tropical diseases. Recently, essential oils have emerged as potential renewable, cost-effective, and environmentally benign alternatives to synthetic pesticides for control of mosquitoes. In this work, thirteen species of Piper were collected from different areas of central Vietnam. The essential oils were obtained by hydrodistillation and analyzed by gas chromatography–mass spectrometry. The essential oils were screened for mosquito larvicidal activity against Aedes aegypti. Four of the Piper essential oils showed outstanding larvicidal activity against Ae. aegypti, namely P. caninum, P. longum, P. montium, and P. mutabile, with LC50 and LC90 values less than 10 µg/mL. Multivariate analysis has correlated concentrations of β-caryophyllene, β-bisabolene, α-pinene, and β-pinene with mosquito larvicidal activity. [ABSTRACT FROM AUTHOR]