Chemical study of Anthospermum emirnense (Rubiaceae)

Chemical study of the aerial parts of Anthospermum emirnense led to the isolation of one original iridoid glycoside (1) along with six known iridoids (2–7), three lignans (8–10), two flavonoids (11–12), one coumarin (13), two anthraquinones (14–15), two benzoic acids (16–17) and three triterpenoids (18–20). These results are the first chemical data on non-volatile constituents of this genus. The chemotaxonomic significance of these compounds is discussed.     

Contact toxicity, feeding reduction, and repellency of essential oils from three plants from the ginger family (Zingiberaceae) and their major components against Sitophilus zeamais and Tribolium castaneum

The essential oils from rhizomes of Alpinia conchigera Griff, Zingiber zerumbet Smitt, Curcuma zedoaria (Berg.) Roscoe; their major compounds (camphene, camphor, 1,8-cineole, alpha-humulene, isoborneol, alpha-pinene, beta-pinene and terpinen-4-ol); and synthetic essential oils comprised of mixtures of major pure compounds in the same ratios as the extracted essential oils were tested for contact, feeding reduction, and repellency against Sitophilus zeamais Motschulsky and Tribolium castaneum (Herbst) adults. Via topical applications, the three extracted oils had similar toxicity against S. zeamais (LD50 fiducial limits: 18-24 microg oil/mg insect). T. castaneum had similar sensitivity to all three oils (35-58 microg/mg), and it was less sensitive than S. zeamais. The LD50 values of synthetic A. conchigera and synthetic Z. zerumbet oils were similar to those of their corresponding extracted essential oils. The synthetic C. zedoaria oils showed lower contact toxicity than the extracted C. zedoaria oils to both insects. Sitophilus zeamais and T. castaneum were sensitive to terpinen-4-ol and isoborneol in contact toxicity tests. In antifeedant tests, the three extracted oils were able to decrease the consumption of flour disks, especially Z. zerumbet oils, whereas both insect species could feed on the flour disks treated with three synthetic essential oils. Only terpinen-4-ol deterred feeding in both insects. In repellency tests, A. conchigera oils at highest concentration repelled S. zeamais and T. castaneum. None of the synthetic essential oils repelled S. zeamais (315 microl/cm2) and T. castaneum (31 microl/cm2) Only terpinen-4-ol showed repellent activity against both insects.     

Fumigant activity of essential oils and components of Illicium verum and Schizonepeta tenuifolia against Botrytis cinerea and Colletotrichum gloeosporioides

To develop a natural fungicide against Botrytis cinerea and Colletotrichum gloeosporioides, a total of 25 essential oils were tested for their fumigant activity against post-harvest pathogens. The vaporous phases of oils were treated to each fungus on potato dextrose agar medium in half-plate separated Petri plates at 10 microg per plate. The essential oil of Illicium verum strongly inhibited the mycelial growth of both B. cinerea and C. gloeosporioides by over 90%. On the other hand, the essential oil of Schizonepeta tenuifolia showed inhibitory activity against mycelial growth of only B. cinerea by over 90%. Gas chromatography-mass spectrometry and bioassay indicated trans-anethole in I. verum and menthone in S. tenuifolia as a major antifungal constituent. The essential oils of I. verum and S. tenuifolia and their major constituents could be used to manage post-harvest diseases caused by B. cinerea and C. gloeosporioides.     

In-vitro antimicrobial activity and chemical composition of Sardinian Thymus essential oils

Essential oils and their components are becoming increasingly popular as naturally occurring antimicrobial agents. In this work the chemical composition and the antimicrobial properties of Thymus essential oils and of their main components were determined. Three essential oils obtained from different species of Thymus growing wild in Sardinia and a commercial sample of Thymus capitatus oil were analysed. The essential oil components were identified by GC/MS analysis. The antimicrobial activity of the oils and components was determined against a panel of standard reference strains and multiple strains of food-derived spoilage and pathogenic bacteria, using a broth microdilution method. The GC/MS analysis showed that the major constituents of the oils were monoterpene hydrocarbons and phenolic monoterpenes, but the concentration of these compounds varied greatly among the oils examined. The results of the antimicrobial assay showed that essential oils extracted from Sardinian Thymus species have an antimicrobial activity comparable to the one observed in other thyme oils. It seems also confirmed that the antimicrobial properties of thyme essential oils are mainly related to their high phenolic content. Among the single compounds tested carvacrol and thymol turned out to be the most efficient against both reference strains and food-derived bacteria. The results of this study confirmed the possibility of using thyme essential oils or some of their components in food systems to prevent the growth of foodborne bacteria and extend the shelf-life of processed foods.     

Terpenoid compositions, and antioxidant and antimicrobial properties of the rhizome essential oils of different Hedychium species

A phytochemical study of the rhizome essential oils of four different Hedychium species was performed by means of GC and GC/MS analyses. H. ellipticum mainly contained 1,8-cineole, sabinene, and terpin-4-ol, while H. aurantiacum possessed terpin-4-ol, para-cymene, and bornyl acetate as the major entities. Similarly, trans-meta-mentha-2,8-diene and linalool were noticed in H. coronarium. Three different collections (I-III) of H. spicatum showed amazing differences in the relative contents of their essential oils, 1,8-cineole and 10-epi-gamma-eudesmol being identified as markers for samples I and II, terpin-4-ol and sabinene being the major compounds in sample III. The rhizome essential oils of the above species were studied for their antioxidant activities by different methods, including their effect on the chelating properties of Fe(2+), DPPH radical-scavenging activity, and reducing power. Antimicrobial screenings of the oils by the paper-disc method were performed against Staphylococcus aureus, Shigella flexneri, Pasteurella multocida, Escherichia coli, and Salmonella enterica enterica, and the respective minimum-inhibitory-concentration (MIC) values were determined. The rhizome essential oils from all Hedychium species exhibited moderate-to-good Fe(2+) chelating activity. H. spicatum from collection site III showed a completely different DPPH radical-scavenging profile than the samples from the other collection sites.     

杉木心材精油抑菌活性及其化学成分研究

通过水蒸气蒸馏法提取杉木心材精油,并进行柱层析分离、气-质联用分析和抑菌活性试验,比较分析了精油含量、化学组成和抑菌活性成分.结果表明,杉木心材精油含量为1.794～2.076(w/w);气-质联用分析共分离出47个色谱峰,鉴定出27个化合物(占精油总量的99%),其中主要成分为柏木脑(76.27%);杉木心材精油对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌、伤寒沙门氏菌等均有较明显的抑制作用;柏木脑是杉木精油的主要抑菌活性成分.     

Chemoprevention by thyme oils of Aspergillus parasiticus growth and aflatoxin production

The essential oils from Thymus eriocalyx and Thymus X-porlock obtained by hydrodistillation were analyzed by GC/MS. The major components of T. eriocalyx and T. X-porlock oils were thymol (63.8, 31.7%), beta-phellandrene (13.30, 38.7%), cis-sabinene hydroxide (8.1, 9.6%), 1,8-cineole (2, 1.7%), and beta-pinene (1.31, 2%), respectively. Antifungal activities of the oils were studied with special reference to the inhibition of Aspergillus parasiticus growth and aflatoxin production. Minimal inhibitory (MIC) and minimal fungicidal (MFC) concentrations of the oils were determined. Static effects of the above oils against A. parasiticus were at 250 ppm and lethal effects of T. eriocalyx and T. X-porlock were 500 and 1000 ppm of the oils, respectively. Aflatoxin production was inhibited at 250 ppm of both oils with that of T. eriocalyx being stronger inhibitor. Transmission electron microscopy (TEM) of A. parasiticus exposed to MIC level (250 ppm) of the oils showed irreversible damage to cell wall, cell membrane, and cellular organelles. It is concluded that the essential oils could be safely used as preservative materials on some kinds of foods at low concentrations to protect them from fungal infections.     

Chemotaxonomic study on Thymus villosus from Portugal

The composition of the essential oils of four populations of Thymus villosus subsp. lusitanicus (Boiss.) Coutinho from Portugal was investigated by GC and GC-MS. To study the chemical polymorphism the results obtained from GC analyses of the volatile oils from individual plants from four populations were submited to Principal Component and Cluster analyses. A comparision with the essential oil of T. villosus subsp. villosus, previously studied by us was done. Important differences with regard to the major constituents in these two taxa were found. Linalool, geranyl acetate, geraniol and terpinen-4-ol were the main components of the essential oils of T. villosus subsp. lusitanicus, whereas in the oil of T. villosus subsp. villosus p-cymene, myrcene and alpha-terpineol were the major ones. Although, both taxa showed chemical polymorphism, different types of essential oils were characterized in each one: linalool; linalool/ terpinen-4-ol/trans-sabinene hydrate; linalool/1,8-cineole; geranyl acetate/geraniol; geranyl acetate/geraniol/1,8-cineole in T. villosus subsp. lusitanicus and p-cymene/camphor/linalool; p-cymene/borneol; linalool/geraniol/geranyl acetate; alpha-terpineol/camphor/myrcene in T. villosus subsp. villosus. Thus, the two subspecies of T. villosus can be easely differenciated by the composition of their essential oils.     

Chemical Composition and Antimicrobial Activity of the Essential Oil from Aerial Parts and Roots of Eryngium barrelieri Boiss. and Eryngium glomeratum Lam. from Tunisia

The study of chemical composition and biological activity of unexplored essential oils may open new perspectives on their potential use in facing major health concerns such as drug‐resistant infections. The present study investigates the chemical composition and antimicrobial effects of previously unstudied essential oils obtained from genus Eryngium: Eryngium glomeratum Lam . and Eryngium barrelieri Boiss . The chemical compositions of the essential oils from aerial parts and roots of both species were studied using GC and GC/MS analytical technics. The analysis led to the identification of 102 compounds totalizing 85 – 94% of all detected compounds. Essential oils were characterized by the predominance of oxygenated sesquiterpenes. The oils obtained from aerial parts were tested against 36 microbial strains by agar dilution method and showed minimum inhibitory concentrations (MIC) in the range of 2 – 625 μg/ml. A strong antibacterial activity against multiresistant Pseudomonas aeruginosa was observed especially from E. glomeratum essential oil with MIC value up to 2 μg/ml. These findings give significant information about the pharmacological activity of these essential oils, which suggest their potential use to develop new remedies, or as sources of active compounds.     

In vitro antifungal, anti-elastase and anti-keratinase activity of essential oils of Cinnamomum-, Syzygium- and Cymbopogon-species against Aspergillus fumigatus and Trichophyton rubrum

This study was aimed to evaluate effects of certain essential oils namely Cinnamomum verum, Syzygium aromaticum, Cymbopogon citratus, Cymbopogon martini and their major components cinnamaldehyde, eugenol, citral and geraniol respectively, on growth, hyphal ultrastructure and virulence factors of Aspergillus fumigatus and Trichophyton rubrum. The antifungal activity of essential oils and their major constituents was in the order of cinnamaldehyde>eugenol>geraniol=C. verum>citral>S. aromaticum>C. citratus>C. martini, both in liquid and solid media against T. rubrum and A. fumigatus. Based on promising antifungal activity of eugenol and cinnamaldehyde, these oils were further tested for their inhibitory activity against ungerminated and germinated conidia in test fungi. Cinnamaldehyde was found to be more active than eugenol. To assess the possible mode of action of cinnamaldehyde, electron microscopic studies were conducted. The observations revealed multiple sites of action of cinnamaldehyde mainly on cell membranes and endomembranous structures of the fungal cell. Further, test oils were also tested for their anti-virulence activity. More than 70% reduction in elastase activity was recorded in A. fumigatus by the oils of C. verum, C. martini, eugenol, cinnamaldehyde and geraniol. Similar reduction in keratinase activity in A. niger was recorded for the oils of C. martini and geraniol. Maximum reduction (96.56%) in elastase activity was produced by cinnamaldehyde whereas; geraniol caused maximum inhibition (97.31%) of keratinase activity. Our findings highlight anti-elastase and anti-keratinase activity of above mentioned essential oils as a novel property to be exploited in controlling invasive and superficial mycoses.     

Antifungal activity of essential oils and their synergy with fluconazole against drug-resistant strains of Aspergillus fumigatus and Trichophyton rubrum

The aim of this study was to screen certain plant essential oils and active compounds for antifungal activity and their in vitro interaction with fluconazole against drug-resistant pathogenic fungi. The methods employed in this work included disc diffusion, broth macrodilution, time kill methods and checkerboard microtiter tests. Oil compositions were evaluated by gas chromatography-mass spectrometry (GC-MS) analysis. Transmission electron microscopy was used to assess the effect of essential oils on cellular structures of test fungi. Test fungal strains exhibited resistance to at least two drugs (fluconazole and itraconazole). Among the 21 essential oils or active compounds tested, ten showed promising antifungal activity. GC-MS analysis revealed the presence of major active compounds in the essential oils used. Cinnamaldehyde showed the most promising antifungal activity and killing potency against Aspergillus fumigatus MTCC2550 and Trichophyton rubrum IOA-9. Cinnamaldehyde showed strongest synergy with fluconazole against A. fumigatus and T. rubrum by reducing the minimum inhibitory concentration of fluconazole up to 8-fold. Zones of lysis of the cell wall and cell membrane appeared to be where cinnamaldehyde acted on fungi. This study highlights the broad spectrum antifungal activity of essential oils and active compounds and their synergy with fluconazole against drug-resistant fungi.     

Bactericidal activities of essential oils of basil and sage against a range of bacteria and the effect of these essential oils on Vibrio parahaemolyticus

Basil and sage essential oils were examined for bactericidal activity against a range of Gram-positive and Gram-negative bacteria by viable count determinations. Generally, Gram-positive bacteria showed higher resistance to basil and sage essential oils than Gram-negative bacteria. Vibrio species showed a high sensitivity to both essential oils. Stationary growth phase cells of selected bacteria showed higher resistance to these essential oils than exponential growth phase cells. Basil-resistant (b21) and sage-resistant (s20) strains of Vibrio parahaemolyticus were isolated. Both strains showed higher resistance to heat and H2O2 than parent strain. Conversely, heat-adapted V. parahaemolyticus also showed a higher resistance to these essential oils than nonadapted cells.     

北细辛挥发油对二斑叶螨的毒性及其酶的影响

采用气相/质谱分析了北细辛挥发油的化学成分,并研究了北细辛挥发油对二斑叶螨的薰蒸毒性,以及对谷胱甘肽巯基转移酶(GSTs)与Na+,K+-ATP酶活性的影响。结果表明:有9种含量大于1%的化学成分占北细辛挥发油总量的86.1%,其中甲基丁香酚含量最高(22.9%),其次为黄樟醚(19.8%);北细辛挥发油在8μg/mL时对二斑叶螨的熏蒸毒性最强,其24和48 h的螨死亡率分别为72.6%和100%;以4μg/mL北细辛挥发油薰蒸,在24 h内螨Na+,K+-ATP酶活性下降、GSTs活性升高。本研究结果提示北细辛挥发油有开发为农业用杀螨剂的潜在价值。     

Essential oils of Schinus terebinthifolius and S. molle (Anacardiaceae): Mitodepressive and aneugenic inducers in onion and lettuce root meristems

Essential oils constitute an important group of plant products and include a mixture of volatile low-molecular-weight terpenes. The present study aimed to determine the phyto- and cytotoxicity of essential oils from leaves of Schinus molle and Schinus terebinthifolius on lettuce and onion. These essential oils affected germination, initial growth, and mitotic and metaphasic indexes of the target species. Compared to negative controls, essential oils of S. molle and S. terebinthifolius reduced the mitotic index of onion by 21.05% and 82.03%, respectively. Similar results were observed for lettuce. The volatiles also induced chromosomal abnormalities such as spindle disturbance at late prophase, sticky metaphase, c-mitosis, micronucleus, and nuclear buds. Although the essential oils of both species shared the same major compound (α-pinene), more pronounced effects were observed in S. terebinthifolius treatments. The results suggest that major and minor compounds of these essential oils act in synergy, causing the inhibitory effects observed on onion and lettuce.     

Antifungal activities of essential oils and their constituents from indigenous cinnamon (Cinnamomum osmophloeum) leaves against wood decay fungi

Cinnamomum osmophloeum Kaneh is one of the hardwood species indigenous to Taiwan that possesses significant antifungal activity. To examine the antifungal activity of leaf essential oils and dominant constituents from C. osmophloeum, the essential oils of leaves from three clones (A, B, and C) collected from Haw-Lin experimental forest were extracted and their components analyzed by gas chromatography. Results from the antifungal tests demonstrated that the essential oils of both B and C leaves had strong inhibitory effects. The antifungal indices of these two leaf oils at 100 ppm against five strains of white rot fungi and four strains of brown rot fungi were all 100%. Cinnamaldehyde, the major compound in C. osmophloeum leaf essential oils, possessed the strongest antifungal activities compared with the other components. Its antifungal indices against both Coriolus versicolor and Laetiporus sulphureus were 100%. The MIC (minimum inhibitory concentration) of cinnamaldehyde against C. versicolor and L. sulphureus was 50 and 75 ppm, respectively. In addition, comparisons of the antifungal indices of cinnamaldehyde's congeners proved that cinnamaldehyde exhibited the strongest antifungal activities.     

Essential oil composition and antimicrobial activity of wild and cultivated Moroccan Achillea ageratum L.: a rare and threatened medicinal species

The essential oils of leaves and flowers of the wild and cultivated Moroccan Achillea ageratum L., a rare and threatened medicinal species, were examined by GC/MS, and their chemical compositions were compared. At least nine components were identified in both wild and cultivated A. ageratum oils, representing more than 95% of the oils. Artemisyl acetate (62.34-78.79%), yomogi alcohol (4.89-12.40%), santolina alcohol (4.86-11.77%), and artemisia alcohol (3.36-7.04%) were the major compounds. Terpene-alcohol proportion was higher in wild A. ageratum than in cultivated A. ageratum. The antibacterial analysis showed that both oils presented high activity against all the studied Gram-positive strains in a range of MIC values from 2.55 to 7.02?mg/ml, but they appeared not effective against the tested Gram-negative ones (MIC values 20.40-41.10?mg/ml). They also exhibited remarkable antifungal activities against Candida species with MIC values ranging from 5.83 to 8.42?mg/ml. From these results, it was concluded that domestication of this threatened medicinal species using clonal propagation did not significantly affect its chemical composition and consequently its antimicrobial properties.     

Essential oil composition and variability of Thymus lotocephalus and Thymusxmourae

The composition of the essential oils of four populations of Thymus lotocephalus G. López and R. Morales and one population of T.xmourae Paiva and Salgueiro, two endemic taxa from Portugal, was investigated mainly by GC and GC-MS. Txmourae is a natural hybrid between T. lotocephalus and T. mastichina (L.) L. subsp. donyanae R. Morales, which essential oil was analysed for the first time. In its oil, it was possible to find compounds of both parents, which could enable us to confirm its intermediate status between those two taxa. 1,8-Cineole and borneol were the main constituents in the essential oil of T.xmourae, whereas linalool, geranyl acetate and 1,8-cineol were the major ones in T. lotocephalus. Intermedeol was also an important constituent in the oils of both taxa. Nevertheless, the volatile oils of the four populations investigated of T. lotocephalus showed important differences among the main constituents. In order to study their infraspecific variability, the results obtained in the analysis of individual plants were submitted to a Principal Component and Chemometric Cluster Analyses. Five types of essential oils were found: linalool, 1,8-cineole, linalool/1,8-cineole, linalyl acetate/linalool and geranyl acetate.     

Chemical composition and biological activities of essential oils extracted from Korean endemic citrus species

The aim of this study was to analyze the chemical composition of 14 kinds of citrus oils and to test their biological activities. Citrus essential oils were obtained by steam distillation from immature fruits collected from Jeju Island and were analyzed using gas chromatograph (GC)- flame ionization detectors (FID) and GC-MS. Limonene (55.4% to 91.7%), myrcene (2.1% to 32.1%), alpha-pinene (0.6% to 1.6%) and linalool (0.4% to 6.9%) were the major components in most citrus species. To evaluate in vitro antibacterial activity, all essential oils were tested against Propionibacterium acnes and Staphylococcus epidermidis. Nine out of fourteen citrus oils exhibited antibacterial activity against P. acnes, but not against S. epidermidis. The effects of the citrus oils on DPPH radical scavenging, superoxide radical anion scavenging, nitric oxide radical, and cytotoxicity were also assessed. Three essential citrus oils, Joadeung, Dongjunggyul, and Bujiwha, exhibited potent inhibitory effects on nitric oxide production. Two essential oils, Dongjunggyul and Joadeung, showed potent free radical scavenging activities in the DPPH assay. For future applications in cosmetic products, we also performed MTT assays in a human dermal fibroblast cell line. The majority of the essential oils showed no cytotoxicity. The results indicate that citrus essential oils can be useful natural agents for cosmetic application.     

Susceptibility of the bruchid Callosobruchus maculatus (Coleoptera: Bruchidae) and its parasitoid Dinarmus basalis (Hymenoptera: Pteromalidae) to three essential oils

The bruchid Callosobruchus maculatus (F.) causes major losses during the storage of seeds of Vigna unguiculata (Walp.) in West Africa. An endemic parasitoid, the pteromalid Dinarmus basalis (Rond.) reduces the increase in bruchid populations in stores and could be used for biological control. African farmers often introduce essential oils into granaries at harvest time. In Togo, essential oils were extracted from two Gramineae, Cymbopogon nardus (L.) and Cymbopogon schoenanthus (L.) and from a Lamiaceae, Ocimum basilicum (L.). The major components of these essential oils were citronellal in C. nardus, carene-2 and piperitone in C. schoenanthus and estragol in O. basilicum. Cymbopogon schoenanthus was the most toxic oil for C. maculatus adults. D. basalis adults were more susceptible to the three essential oils than the adults of their hosts C. maculatus. In the presence of cowpea seeds, the LC50s of the three essential oils were lower than in their absence, suggesting that the seeds may absorb a part of the volatiles. High doses of three essential oils slightly affected the survival of the fourth instar or the pupae of C. maculatus. This high survival was due to protection of larvae from volatiles by the surrounding seeds. The D. basalis were more affected by the oil volatiles than their hosts. Sub-lethal doses of essential oils reduced the duration of the adult life of both insect species and fecundity of the females. The differences in sensitivity of the host and its parasitoid could influence their population dynamics. The introduction of the essential oils into storage systems potentially could reduce density of parasitoid populations and increase seed losses.     

栽培地区、采收季节和株龄对迷迭香精油成分和抑菌活性的影响

采用气相色谱-质谱联用的方法,研究了不同提取部位、栽培地区、采收季节和株龄对迷迭香精油提取率、成分和抑菌活性的影响。结果表明,在贵州栽培的迷迭香叶子中精油的主要成分为α-蒎烯（31.88%–39.09%）、1,8-桉叶素（8.82%–10.97%）和樟脑（7.63%–11.59%）;茎中精油的主要成分为龙脑（26.62%–39.05%）、樟脑（11.41%–15.27%）和α-蒎烯（7.23%–17.80%）;茎中精油的抑菌活性强于叶中精油。北京地区栽培的迷迭香,其叶子中精油的主要成分为樟脑（27.92%）和L-β-蒎烯（25.28%）,抑菌活性强;茎中精油和贵州栽培的成分和活性均相似。对于采收季节,夏季采收的迷迭香精油提取率高,抑菌活性强。而株龄对精油的成分和抑菌活性影响不大。该研究为我国引种迷迭香的合理配置栽培、采收、生产条件和高效开发利用其抑菌活性提供了科学的依据。