Chemical composition and larvicidal effects of essential oil of Dendropanax morbifera against Aedes aegypti L.

Essential oils obtained from the flowers of Dendropanax morbifera were extracted and the chemical composition and larvicidal effects were studied. The analyses were conducted by gas chromatography and mass spectroscopy (GC–MS) revealed that the essential oil of D. morbifera contained 27 compounds. The major chemical components identified were γ-elemene (18.59%), tetramethyltricyclohydrocarbon (10.82%), β-selinene (10.41%), α-zingibirene (10.52%), 2-isopropyl-5-methylbicylodecen (4.2%), β-cubebene (4.19), and 2,6-bis(1,1-Dimethylethyl)-4-phenol (4.01%). The essential oil had a significant toxic effect against early fourth-stage larvae of Aedes aegypti L. with an LC₅₀ value of 62.32 ppm and an LC₉₀ value of 131.21 ppm. The results could be useful in search for newer, safer, and more effective natural larvicidal agents against A. aegypti.     

Chemical composition and antimicrobial activity of the essential oils of the Amazon Guatteriopsis species

The essential oils of Guatteriopsis blepharophylla, Guatteriopsis friesiana and Guatteriopsis hispida were obtained by hydrodistillation and analysed by GC and GC/MS. The main compound found in the leaf oil of G. blepharophylla was caryophyllene oxide (1) (69.25%). The leaf oil of G. friesiana contained predominantly beta-eudesmol (2) (51.60%), gamma-eudesmol (3) (23.70%), and alpha-eudesmol (4) (14.56%). The major constituents identified in the leaf of G. hispida were beta-pinene (38.18%), alpha-pinene (30.77%) and (E)-caryophyllene (20.59%). The antimicrobial activity of the essential oils was evaluated against 11 species of microorganisms. The oil of G. friesiana exhibited significant antimicrobial activity for all microorganisms tested, whereas that of G. hispida and G. blepharophyla had potent activity against Rhodococcus equi with MIC of 50 microg mL(-1). The major constituents of each oil were also tested separately, and showed lower activity compared to the oils. Moreover, mixtures of the main constituents, in the same proportions found in G. friesiana and G. hispida oils, did not show the same activity as the original oils.     

Chemical composition and larvicidal activity of essential oils of three Artemisia species

Aedes aegypti L. (Diptera: Culicidae) is a vector for serious diseases in tropical regions. This pest is mainly controlled by commercial larvicides but the application of such products has led to environmental problems. Essential oils (EO) have been consistently reported as molecules with insecticidal activity and can be used to produce more environmentally friendly larvicides in the control of A. aegypti. In this study, the larvicidal effect of essential oils (EO) from the leaves of three Artemisia species was evaluated against A. aegypti. The oils were obtained from steam distillation and their chemical composition was determined by gas chromatography–mass spectrometry. The EO of Artemisia camphorata was the most active in the screening bioassay and presented LC₅₀ and LC₉₅ of 64.95 and 74.18 μg ml⁻¹, respectively. In addition, we found that germacrene D-4-ol was the constituent responsible for the toxicity of this EO. Artemisia camphorata EO and its major constituent, germacrene D-4-ol, are promising for the development of natural larvicides against A. aegypti.     

Chemical composition and antimicrobial activity of Cymbopogon citratus and Cymbopogon giganteus essential oils alone and in combination

As part of ongoing research on the chemical composition and the antimicrobial properties of Burkinabe plants essential oils alone and in combination, essential oils (EOs) from leaves of Cymbopogon citratus and Cymbopogon giganteus from Burkina Faso were analyzed by GC-FID and GC-MS. Five constituents, which accounted for 96.3% of the oil, were identified in the EO of C. citratus. Geranial (48.1%), neral (34.6%) and myrcene (11.0%) were the major constituents. For C. giganteus a total of eight compounds were identified which represented 86.0% of the oils extracted. The dominant compounds were limonene (42%) and a set of monoterpene alcohols: trans-p-mentha-1(7),8-dien-2-ol (14.2%), cis-p-mentha-1(7),8-dien-2-ol (12%), trans-p-mentha-2,8-dien-1-ol (5.6%) and cis-p-mentha-2,8-dien-1-ol (5.2%). The EOs were tested against nine bacteria by using disc diffusion and microdilution methods. C. giganteus EO showed antimicrobial effects against all microorganisms tested whereas C. citratus EO failed to inhibit Pseudomonas aeruginosa. The antimicrobial activity of combinations of the two EOs was quantified by the checkerboard method. Combinations of the two EOs exerted synergistic, additive and indifferent antimicrobial effects. Results of the present investigation provide evidence that the combinations of plant EOs could be assessed for synergistic activity in order to reduce their minimum effective dose.     

Comparative larvicidal activity of essential oils from three medicinal plants against Aedes aegypti L

This work aimed at comparing larvicidal activity of essential oils extracted from the dried leaves of Alpinia speciosa, Cymbopogon citratus, and Rosmarinus officinalis against Ae. aegypti larvae. The larvae were observed for 4 h and at 24 h according to a completely randomized design with three replications and the following concentrations [μl/ml]: 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, and controls were distilled water, and commercial standard citral, camphor, eucalyptol, α‐pinene, and β‐myrcene. The essential oil of C. citratus had the lowest LC₅₀ (0.28) and LC₉₀ (0.56) values, followed by that of A. speciosa (0.94 and 1.2, resp.) and of R. officinalis (1.18 and 1.67, resp.), and only the commercial standards citral and α‐pinene were larvicidal.     

Chemical composition and antibacterial activities of seven Eucalyptus species essential oils leaves

Background

In this paper, we have studied the essential oils chemical composition of the leaves of seven Eucalyptus species developed in Tunisia. Eucalyptus leaves were picked from trees growing in different arboretums in Tunisia. Choucha and Mrifeg arboretums located in Sedjnene, region of Bizerte (Choucha: E. maideni, E. astrengens et E. cinerea; Mrifeg : E. leucoxylon), Korbous arboretums located in the region of Nabeul, North East Tunisia with sub-humid bioclimate, (E. lehmani), Souiniet-Ain Drahem arboretum located in region of Jendouba (E. sideroxylon, E. bicostata). Essential oils were individually tested against a large panel of microorganisms including Staphylococcus aureus (ATCC 6539), Escherichia coli (ATCC 25922), Enterococcus faecalis (ATCC29212), Listeria ivanovii (RBL 30), Bacillus cereus (ATCC11778).

Results

The yield of essential oils ranged from 1.2% to 3% (w/w) for the different Eucalyptus species. All essential oils contain α-pinene, 1,8-cineol and pinocarveol-trans for all Eucalyptus species studied. The 1,8-cineol was the major compound in all species (49.07 to 83.59%). Diameter of inhibition zone of essential oils of Eucalyptus species varied from 10 to 29 mm. The largest zone of inhibition was obtained for Bacillus cereus (E. astrengens) and the lowest for Staphylococcus aureus (E. cinerea). The essential oils from E. maideni, E. astrengens, E. cinerea (arboretum of Bizerte), E. bicostata (arboretum of Aindraham) showed the highest antibacterial activity against Listeria ivanovii and Bacillus cereus.

Conclusion

The major constituents of Eucalyptus leaves essential oils are 1,8-cineol (49.07 to 83.59%) and α-pinene (1.27 to 26.35%). The essential oils from E. maideni, E. astrengens, E. cinerea, E. bicostata showed the highest antibacterial activity against Listeria ivanovii and Bacillus cereus, they may have potential applications in food and pharmaceutical products.     

Inhibitory effect of essential oils of Allium sativum and Piper longum on spontaneous muscular activity of liver fluke, Fasciola gigantica

Effects of essential oil of Allium sativum (garlic) and Piper longum (Indian long pepper) were evaluated on muscular activity of whole Fasciola gigantica and its strip preparation. The whole flukes and longitudinal strip preparations of the flukes were isometrically mounted to record the spontaneous muscular activity (SMA) and to evaluate effects of cumulative doses (0.1, 0.3, 1.0 and 3.0 mg/ml) of the plant essential oils. Whole flukes and the strip preparations exhibited continuous SMA without any significant difference in its baseline tension, frequency and amplitude for 2 h. Essential oil of A. sativum produced significant reduction in the frequency and the amplitude of the SMA of whole fluke at 1 and 3 mg/ml concentrations. It caused complete paralysis of the fluke after 15 min of administration of 3 mg/ml concentration. Similar to whole fluke, essential oil of A. sativum (3 mg/ml) also produced flaccid paralysis in the strip preparations of the flukes. Essential oil of P. longum firstly induced marked excitatory effect and then there was flaccid paralysis of the whole fluke following 15 min exposure at 3 mg/ml concentration. Complete flaccid paralysis of the strip preparation was also ensued after 15 min of administration of 3 mg/ml concentration of P. longum. In both the essential oils, the whole fluke and strip preparations did not recover from paralysis following 2-3 washes. In conclusion, the observations demonstrated irreversible paralytic effect of essential oils of A. sativum and P. longum on F. giganticain vitro which might possibly help to developing herbal-based anthelmintic.     

Antiparasitic activity of prenylated benzoic acid derivatives from Piper species

Fractionation of dichloromethane extracts from the leaves of Piper heterophyllum and P. aduncum afforded three prenylated hydroxybenzoic acids, 3-[(2E,6E,10E)-11-carboxy-3,7,15-trimethyl-2,6,10,14-hexadecatetraenyl)-4,5-dihydroxybenzoic acid, 3-[(2E,6E,10E)-11-carboxy-13-hydroxy-3,7,15-trimethyl-2,6,10,14-hexadecatetraenyl]-4,5-dihydroxybenzoic acid and 3-[(2E,6E,10E)-11-carboxy-14-hydroxy-3,7,15-trimethyl-2,6,10,15-hexadecatetraenyl]-4,5-dihydroxybenzoic acid, along with the known compounds, 4,5-dihydroxy-3-(E,E,E-11-formyl-3,7,15-trimethyl-hexadeca-2,6,10,14-tetraenyl)benzoic acid (arieianal), 3,4-dihydroxy-5-(E,E,E-3,7,11,15-tetramethyl-hexadeca-2,6,10,14-tetraenyl)benzoic acid, 4-hydroxy-3-(E,E,E-3,7,11,15-tetramethyl-hexadeca-2,6,10,14-tetraenyl)benzoic acid, 3-(3,7-dimethyl-2,6-octadienyl)-4-methoxy-benzoic acid, 4-hydroxy-3-(3,7-dimethyl-2,6-octadienyl)benzoic acid and 4-hydroxy-3-(3-methyl-1-oxo-2-butenyl)-5-(3-methyl-2-butenyl)benzoic acid. Their structures were elucidated on the basis of spectroscopic data, including homo- and heteronuclear correlation NMR experiments (COSY, HSQC and HMBC) and comparison with data reported in the literature. Riguera ester reactions and optical rotation measurements established the compounds as racemates. The antiparasitic activity of the compounds were tested against three strains of Leishmania spp., Trypanosoma cruzi and Plasmodium falciparum. The results showed that 3-(3,7-dimethyl-2,6-octadienyl)-4-methoxy-benzoic acid exhibited potent and selective activity against L. braziliensis (IC₅₀ 6.5 μg/ml), higher that pentamidine used as control. Moreover, 3-[(2E,6E,10E)-11-carboxy-3,7,15-trimethyl- 2,6,10,14-hexadecatetraenyl)-4,5-dihydroxybenzoic acid and 4-hydroxy-3-(3-methyl-1-oxo-2-butenyl)-5-(3-methyl-2-butenyl)benzoic acid showed moderate antiplasmodial (IC₅₀ 3.2 μg/ml) and trypanocidal (16.5 μg/ml) activities, respectively.     

Chemical composition and antifungal activity of the essential oils of Lippia rehmannii from South Africa

Lippia rehmannii H.Pearson (Verbenaceae) is an aromatic bush, indigenous to the northern parts of South Africa. As far as could be ascertained, the essential oil composition has not been previously reported and forms the subject of this investigation. Aerial parts of the shrub were collected from two localities in Gauteng, South Africa, and the isolated essential oils were analysed by gas chromatography. Citral, a mixture of the E- and Z-isomers, was found to be the main constituent of the oils, while borneol, camphor, neryl acetate, isocaryophyllene, p-cymene, β-caryophyllene and β-caryophyllene oxide were other major compounds present. Oil compositions, within and between the two localities, did not differ significantly. The in vitro antifungal activity of L. rehmannii essential oil was compared to that of Cympopogon citratus (lemongrass) and pure citral, against a number of pre- and postharvest fungal food pathogens. At a concentration of 3000 µL/L, lemongrass oil and pure citral caused complete growth inhibition of all the pathogens tested. Lippia rehmannii, containing less citral than lemongrass oil, was effective at this concentration against the majority of pathogens, but only partially restricted the growth of Lasiodiplodia theobromae and Botrytis cinerea. This finding suggests that citral may be largely responsible for the observed antifungal activities. Essential oil from L. rehmannii appears to be a good candidate for the in vitro control of Fusarium oxysporum and Rhizoctonia solani and application of these oils in the field should be investigated.     

Meliternatin: a feeding deterrent and larvicidal polyoxygenated flavone from Melicope subunifoliolata

We screened more than 60 Malaysian plants against two species of insects and found that Melicope subunifoliolata (Stapf) T.G. Hartley (Rutaceae) showed strong feeding deterrent activity against Sitophilus zeamais Motsch. (Curculionidae) and very good larvicidal activity against Aedes aegypti L. (Diptera). One anti-insect compound, meliternatin (3,5-dimethoxy-3',4',6,7-bismethylendioxyflavone) (6) and six other minor polyoxygenated flavones were isolated from M. subunifoliolata.     

Chemical and biological profiles of Lavandula luisieri essential oils from western Iberia Peninsula populations

The chemical composition and biological activity of wild Lavandula luisieri (Rozeira) Rivas-Martínez populations from the south Beira interior region in central eastern Portugal are described. The essential oils of these four populations have been analyzed by GC–MS, and their antifeedant effects evaluated against Spodoptera littoralis, Myzus persicae and Rhopalosiphum padi. Relative concentration data (% values) was subjected to principal component and cluster analysis. Relative concentration data and antifeedant effects were subjected to a stepwise multiple regression analysis. Additionally, one of these populations has been adapted to experimental field cultivation.     

Chemical composition,intraspecies variation and seasonal variation in essential oils of Calendula arvensis L.

The essential oil composition of Calendula arvensis was established for the first time using GC and GC/MS. Eighty-five essential oil components were identified, which accounted for 90.3 g/100 g of essential oil. The oil contained a high concentration of sesquiterpenes, of which δ-cadinene and α-cadinol were the main components. The chemical composition of 25 Corsican C. arvensis oils was analyzed to determine intraspecies variation in essential oil composition. A matrix linking essential oil composition to sample location was composed to identify relationships between concentrations of volatile samples and the geographical origins of samples. Two main groups of compounds were identified according to the amount of sesquiterpenic compounds (hydrocarbons and alcohols) and soil characteristics. Seasonal variation (winter vs. spring) in the concentrations of two major compounds during the flowering period was observed.     

几种典型植物精油的化学成分与其抗菌活性

【目的】植物精油萃取自天然植物, 因具有抗菌活性, 近年来受到广泛关注。论文的目的是分析植物精油的化学成分, 测试其抗菌活性, 并研究其化学成分与抗菌活性之间的联系。【方法】实验选取了肉桂、山苍子、丁香、香茅、迷迭香和大蒜精油等6种典型植物精油, 通过气质联用分析方法研究了其化学组分, 并通过污染食物技术研究了其对黑曲霉和绳状青霉的抗真菌活性, 以及对大肠杆菌和金黄色葡萄球菌的抗细菌活性。【结果】气质联用分析结果表明, 肉桂、山苍子、香茅和迷迭香等4种植物精油的化学成分主要是醛类和醇类, 丁香精油的主要化学成分是丁香油酚, 大蒜精油化学成分基本上都是含硫的醚类, 其中二烯丙基三硫醚(大蒜素)含量最高。抗菌活性结果显示, 不同植物精油的抗菌活性不同, 6种植物精油的抗真菌活性由强到弱依次为: 肉桂>大蒜>丁香>山苍子=香茅>迷迭香, 抗细菌活性由强到弱依次为: 肉桂>山苍子>丁香>香茅=迷迭香>大蒜。【结论】植物精油的抗真菌、细菌活性与其化学组分密切相关, 肉桂、山苍子、香茅和迷迭香等4种精油的抗菌活性可能主要与其化学成分中的醛类和醇类有关, 丁香精油较高的抗菌活性可能主要源于丁香油酚; 大蒜精油具有高效的抗真菌活性主要源于其化学成分中的含硫醚。不同植物精油化学成分不同, 抗真菌、细菌活性也不同, 表明其可能有不同的抗真菌与抗细菌机制。     

Composition and antimicrobial activity of essential oils from Centaurea sessilis and Centaurea armena

The essential oils of air-dried Centaurea sessilis and Centaurea armena obtained by hydrodistillation were analyzed by gas chromatography-mass spectrometry (GC-MS). Forty and twenty components were identified in the essential oils and the main component of these taxons was beta-eudesmol in the ratios of 12.4% and 19.3% from C. sessilis and C. armena, respectively. The antimicrobial activity of the isolated essential oil of the plants was also investigated. They showed moderate antibacterial activity against Gram-positive and Gram-negative bacteria, but no antifungal activity was observed against two yeastlike fungi.     

Chemical composition and antimicrobial activity of the essential oil of Scutellaria barbata

The essential oil of Scutellaria barbata was obtained by hydrodistillation with a 0.3% (v/w) yield and analysed by GC and GC-MS. The main compounds in the oil were hexahydrofarnesylacetone (11.0%), 3,7,11,15-tetramethyl-2-hexadecen-1-ol (7.8%), menthol (7.7%) and 1-octen-3-ol (7.1%). The antimicrobial activity of the oil was evaluated against 17 microorganisms using disc diffusion and broth microdilution methods. The gram-positive bacteria, including methicillin-resistant Staphlococcus aureus, were more sensitive to the oil than gram-negative bacteria and yeasts.     

Composition and variability of essential oils of Platycladus orientalis growing in China

Essential oils were isolated from the leaves of Platycladus orientalis growing in 16 areas of China. The essential oils were analyzed by gas chromatography and gas chromatography-mass spectrometry. In total, 98 volatile compounds were identified. Chemical variability in essential oil composition was evaluated using cluster analysis and principal component analysis. The two analyses led to the identification of four chemotypes: α-pinene, α-pinene/3-carene, cedrol, and cedrol/terpinyl acetate. Geographically, the populations growing in close proximity had similar essential oil composition. The chemical variability could possibly be attributed to genetic and environmental factors.     

Nematicidal activity of Haplophyllum tuberculatum and Plectranthus cylindraceus oils against Meloidogyne javanica

The potentials of Haplophyllum tuberculatum and Plectranthus cylindraceus oils to control Meloidogyne javanica were investigated in vitro and in a greenhouse. A mixture of Haplophyllum and Plectranthus oils (1:1) was highly toxic to M. javanica in vitro, as it killed all nematode juveniles and inhibited hatching of eggs at 12.5 μg/ml concentration after 24 h exposure time, as did carbofuran at the same concentration. In the green-house, tomatoes grown in soil treated with a combination (1:1) of the two oils developed fewer root galls than those grown in soil treated with higher doses of either oil. The oil mixture, at 2.5 and 5.0 μg/ml of soil, was not phytotoxic to tomato plants as evident from the appearance and height of plants after 12 weeks exposure time, compared to treatment over the same period at lower effective doses. The nematicidal activity of the combined essential oils was suggested by the presence of C₁₀ dienes, C₁₀ trienes and C₁₀ phenol.     

Chemotaxonomy of Hypericum genus from Portugal: Geographical distribution and essential oils composition of Hypericum perfoliatum, Hypericum humifusum, Hypericum linarifolium and Hypericum pulchrum

The geographical distribution and analysis of the essential oils of species from three sections of Hypericum L. (Guttiferae/Clusiaceae/Hypericaceae) from Portugal are presented. Hypericum perfoliatum (section Drosocarpium) grows wild in the centre and south of Portugal; Hypericum humifusum and Hypericum linarifolium are both from section Oligostema, the former occurring throughout the country, while the second is distributed mainly in the north and centre; Hypericum pulchrum (section Taeniocarpium) is confined to the littoral north of Portugal. The essential oils were obtained by distillation–extraction, hydrodistillation and distillation in a modified Marcusson apparatus from the dried aerial parts of the different populations and were analysed by GC and GC–MS. Monoterpene hydrocarbons constituted the main fraction in all oils (43–69%, 53–85%, 28–45% and 48–65% for H. perfoliatum, H. humifusum, H. linarifolium and H. pulchrum, respectively). Sesquiterpene hydrocarbons (2–13%, 6–18%, 21–27% and 16–18%, respectively) and a third fraction of non-terpenic compounds (20–29%, 3–16%, 2–14% and 5–11%, respectively) from the four species attained relatively high amounts in all oils. Within each species, no major differences were detected in the essential oil composition, despite the fact that different locations, phenological phases and extraction methodologies were used. Notwithstanding the dominance of α-pinene in all four species' oils, cluster and principal components analysis on the identified components showed that the range of α-pinene, β-pinene and n-nonane supported a separation of the four species. The essential oil composition of the four species showed some qualitative resemblances, which correlate well with the taxonomical classification based on morphological characters.     

Chemical composition and antibacterial activities of the essential oils of Lippia chevalieri and Lippia multiflora from Burkina Faso

The chemical composition of the essential oils of Lippia chevalieri and Lippia multiflora obtained from the air-dried leaves by hydrodistillation were analysed using GC and GC-MS. L. chevalieri and L. multiflora belonged to thymol/p-cymene/2-phenyl ethyl propionate and thymol/p-cymene/thymyl acetate chemotypes, respectively. The essential oils were also tested against 09 strains using a broth microdilution method. The Gram-negative bacteria were the most sensitive. The essential oil of L. multiflora was the most active.