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Monoterpenes
Kinds of Monoterpenes Terms modified by Monoterpenes Selected AbstractsP71 Metabolism of delta-3-Carene by human cytochrom 450 enzymesCONTACT DERMATITIS, Issue 3 2004Mike Duisken Occupational exposure to monoterpenes occurs in saw mills, particle-board plants, carpentry shops and other types of wood-treating industries. The bicyclic monoterpene delta-3-Carene, one of the components of turpentine, may irritate the skin and muceous membranes and prolonged exposure may result in allergic contact dermatitis or chronic lung function impairment. The effects of low concentrations of delta-3-Carene on alveolar macrophages in vitro were examined and a dose-dependent relationship between the cell viability and the delta-3-Carene concentration was found. Little is known about the metabolism of delta-3-Carene in mammalians. In order to determine the toxic potential of this monoterpene we studied the human metabolism of delta-3-Carene in vitro. Therefore we used pooled human liver S9 and human liver microsomal cytochrome P450 enzymes. By using GC-MS analysis we found one main metabolite produced at high rates. The structure was identified by its mass spectra. The mass fragmentation indicated hydroxylation in allyl position. After synthesis of the assumed product in a four step reaction, it was characterized as delta-3-Carene-10-ol. There was a clear correlation between the concentration of the metabolite production, incubation time and enzyme concentration, respectively. Kinetic analysis showed that Km and Vmax values for the oxidation of delta-3-Carene by human liver microsomes were 0.39 ,M and 0.2 nmol/min/nmol P450. It is the first time that delta-3-Carene-10-ol is described as human metabolite of delta-3-Carene. [source] Stability and detection of ,-pinene oxide in aqueous culture mediumENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2000Kimberly K. Kajihara Abstract Methane consumption by methanotrophic bacteria was previously shown to be temporarily inhibited by ,-pinene. Based on literature considerations, loss of inhibition may be due to bacterial degradation of the monoterpene to ,-pinene oxide, an anticipated metabolite. However, since ,-pinene oxide is unstable in aqueous media, detection of its production by methanotrophs or other bacteria is problematic. Therefore, we used gas chromatography-mass spectrometry analysis to study the chemical breakdown of ,-pinene oxide in various buffer systems (Tris[hydroxymethyl]am inomethane, 3-[N-morpholino]propanesulfonic acid, phosphate; pH 7-9) suitable for bacterial whole-cell and cell-free experiments. In every case, aqueous phase ,-pinene oxide was unstable and its disappearance was accompanied by the appearance of five decomposition products in a characteristic fingerprint that was in part buffer dependent. However, this fingerprint was adequately stable in phosphate buffer such that its appearance could be used to infer the intermediacy of ,-pinene oxide if produced by the bacteria at or near their optimal pH. [source] Secondary Metabolites of Phomopsis sp.EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 18 2009XZ-2, an Endophytic Fungus from Camptothecaacuminate Abstract Eleven new metabolites, including nine lovastatin analogues [oblongolides N,V (1,2 and 5,11), which were defined as naphthalene-type fungal polyketides], one linear furanopolyketide (13) and a monoterpene named dihydroxysabinane (14), together with four known compounds including oblongolides B (3) and C (4), one linear furanopolyketide (12) and the sesterterpene terpestacin (15), were isolated from the endophytic fungal strain Phomopsis sp. XZ-26 of Camptotheca acuminate. Their structures were elucidated by spectroscopic analyses including HR-ESI-MS, 1H and 13C NMR, 2D NMR (HMQC, HMBC, 1H- 1H COSY and NOESY), and X-ray single-crystal analysis. The antimicrobial activities of 1,5, 8, 10 and 13,15 were evaluated, but none showed a substantial effect. Additionally, a hypothetical biosynthetic pathway for oblongolides was proposed.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Volatile constituents of different organs of Psoralea bituminosa L.FLAVOUR AND FRAGRANCE JOURNAL, Issue 2 2004Alessandra Bertoli Abstract The essential oil and SPME samples of the leaves, ,owers and seeds of Psoralea bituminosa L. were analysed by GC and GC,MS. We have investigated also the presence of monoterpene or aliphatic alcohol glucosides. The essential oils showed both qualitative and quantitative differences. The main constituents of the leaf and the ,ower essential oils were caryophyllene (23% and 18%, respectively), , -farnesene (15% and 6%, respectively), and germacrene D (24% and 18%, respectively). Signi,cant amounts (7%) of the same compounds were also directed in the seed essential oil, but tricyclene (11%) and , -pinene (50%) were the most important constituents of this oil. The volatile fractions of remaining leaf aqueous extracts after treatment with , -glucosidase revealed qualitative differences in comparison with the composition of the corresponding essential oils, and high levels of 3-hexen-1-ol (37%) and 1-octen-3-ol (27%) were observed. The SPME analysis of the fresh leaves, ,owers and seeds of P. bituminosa con,rmed the qualitative composition of the volatile oils, even if we detected signi,cative differences in the percentage ratio between monoterpenes and sesquiterpenes in comparison with the oils, where sesquiterpenes were the main components. In fact the variation of the monoterpenes, tricyclene, , -pinene and camphene between the leaf oil and the corresponding headspace sample was remarkable: tricyclene increased from 0.1% to 8%, , -pinene from 0.1% to 16% and camphene from 0.3% to 10% in the SPME samples. Copyright © 2004 John Wiley & Sons, Ltd. [source] The essential oil co-distillation by superheated vapour of organic solvents from aromatic plantsFLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2001Josip Masteli Abstract A method of essential oil co-distillation by superheated vapour of solvents was developed and the apparatus was presented. As suitable solvents, pentane and ether (inert solvent with low boiling point) were used. The method was tested on sage, Salvia officinalis L., as an aromatic plant. The essential oil of this plant was also isolated by hydrodistillation as a standard method. The isolated volatiles obtained by two methods were analysed using gas chromatography (GC) and gas chromatography,mass spectrometry (GC,MS). The obtained results were compared. This method of distillation enables safe isolation of monoterpene and sesquiterpene compounds, as well as hydrodistillation. Copyright © 2001 John Wiley & Sons, Ltd. [source] Kinetics of the reactions of OH with 3-methyl-2-cyclohexen-1-one and 3,5,5-trimethyl-2-cyclohexen-1-one under simulated atmospheric conditionsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 1 2002James B. McQuaid Relative rate coefficients for the reactions of OH with 3-methyl-2-cyclohexen-1-one and 3,5,5-trimethyl-2-cyclohexen-1-one have been determined at 298 K and atmospheric pressure by the relative rate technique. OH radicals were generated by the photolysis of methyl nitrite in synthetic air mixtures containing ppm levels of nitric oxide together with the test and reference substrates. The concentrations of the test and reference substrates were followed by gas chromatography. Based on the value k(OH + cyclohexene) = (6.77 ± 1.35) × 10,11 cm3 molecule,1 s,1, rate coefficients for k(OH + 3-methyl-2-cyclohexen-1-one) = (3.1 ± 1.0) × 10,11 and k(OH + 3,5,5-trimethyl-2-cyclohexen-1-one) = (2.4 ± 0.7) × 10,11 cm3 molecule,1 s,1 were determined. To test the system we also measured k(OH + isoprene) = (1.11 ± 0.23) × 10,10 cm3 molecule,1 s,1, relative to the value k(OH + (E)-2-butene) = (6.4 ± 1.28) × 10,11 cm3 molecule,1 s,1. The results are discussed in terms of structure,activity relationships, and the reactivities of cyclic ketones formed in the photo-oxidation of monoterpene are estimated. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 34: 7,11, 2002 [source] Selective manipulation of predators using pheromones: responses to frontalin and ipsdienol pheromone components of bark beetles in the Great Lakes regionAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 3 2005Brian H. Aukema Abstract 1,One proposed approach to improving biological control of bark beetles (Coleoptera: Scolytidae; alt. Curculionidae: Scolytinae) is to manipulate predator movement using semiochemicals. However, selective manipulation is impeded by attraction of both predators and pests to bark beetle pheromones. 2,The primary bark beetle affecting pine plantations in Wisconsin, U.S.A., is the pine engraver, Ips pini (Say). Other herbivores include Ips grandicollis (Eichhoff) and Dryophthorus americanus Bedel (Curculionidae). The predominant predators are the beetles Thanasimus dubius (Cleridae) and Platysoma cylindrica (Histeridae). 3,We conducted field assays using two enantiomeric ratios of ipsdienol, and frontalin plus ,-pinene. Ipsdienol is the principal pheromone component of I. pini, and frontalin is produced by a number of Dendroctonus species. ,-Pinene is a host monoterpene commonly incorporated into commercial frontalin lures. 4,Thanasimus dubius was attracted to frontalin plus ,-pinene, and also to racemic ipsdienol. By contrast, I. pini was attracted to racemic ipsdienol, but showed no attraction to frontalin plus ,-pinene. Platysoma cylindrica was attracted to 97%-(,)-ipsdienol and, to a lesser extent, racemic ipsdienol, but not to frontalin plus ,-pinene. Ips grandicollis was attracted to frontalin plus ,-pinene but not to ipsdienol. Dryophthorus americanus was attracted to both ipsdienol and frontalin plus ,-pinene. 5,This ability to selectively attract the predator T. dubius without attracting the principal bark beetle in the system, I. pini, provides new opportunities for research into augmentative biological control and basic population dynamics. Moreover, the attraction of T. dubius, but not P. cylindrica, to frontalin plus ,-pinene creates opportunities for selective manipulation of just one predator. 6,Patterns of attraction by predators and bark beetles to these compounds appear to reflect various degrees of geographical and host tree overlap with several pheromone-producing species. [source] Effect of varying monoterpene concentrations on the response of Ips pini (Coleoptera: Scolytidae) to its aggregation pheromone: implications for pest management and ecology of bark beetlesAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 4 2003Nadir Erbilgin Abstract 1,Host plant terpenes can influence attraction of conifer bark beetles to their aggregation pheromones: both synergistic and inhibitory compounds have been reported. However, we know little about how varying concentrations of individual monoterpenes affect responses. 2,We tested a gradient of ratios of ,-pinene, the predominant monoterpene in host pines in the Great Lakes region of North America, to Ips pini's pheromone, racemic ipsdienol plus lanierone. 3,Ips pini demonstrated a parabolic response, in which low concentrations of ,-pinene had no effect on attraction to its pheromone, intermediate concentrations were synergistic and high concentrations were inhibitory. These results suggest optimal release rates for population monitoring and suppression programmes. 4,Inhibition of bark beetle attraction to pheromones may be an important component of conifer defences. At terpene to pheromone ratios emulating emissions from trees actively responding to a first attack, arrival of flying beetles was low. This may constitute an additional defensive role of terpenes, which are also toxic to bark beetles at high concentrations. 5,Reduced attraction to a low ratio of ,-pinene to pheromone, as occurs when colonization densities become high and the tree's resin is largely depleted, might reflect a mechanism for preventing excessive crowding. 6,Thanasimus dubius, the predominant predator of I. pini, was also attracted to ipsdienol plus lanierone, but its response differed from that of its prey. Attraction increased across all concentrations of ,-pinene. This indicates that separate lures are needed to sample both predators and bark beetles effectively. It also provides an opportunity for maximizing pest removal while reducing adverse effects on beneficial species. This disparity further illustrates the complexity confronting natural enemies that track chemical signals to locate herbivores. [source] 1,8-Cineole induces relaxation in rat and guinea-pig airway smooth muscleJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 3 2009Nilberto Robson Falcão Nascimento Abstract Objectives 1,8-Cineole is a monoterpene with anti-inflammatory, vascular and intestinal smooth muscle relaxant activity. We have evaluated the potential bronchodilatatory activity of this compound. Methods 1,8-Cineole was tested against carbachol, histamine, K+ 80 mM and ovalbumin-induced bronchial contractions in Wistar rat or guinea-pig tissues. Some of the guinea-pigs had been previously sensitized with an intramuscular injection of 5% (w/v) ovalbumin/saline solution. Control animals received 0.3 ml saline. In separate experimental groups the response to 1,8-cineole (1,30 mg/kg), phenoterol (0.05,5 mg/kg) or vehicle (0.3% Tween in saline) was studied. Key findings 1,8-Cineole decreased, in vivo, rat bronchial resistance with similar efficacy as phenoterol (66.7 ± 3.2% vs 72.1 ± 5.3%). On the other hand, the maximal relaxant response to 1,8-cineole in carbachol-precontracted rat tracheas was 85.5 ± 5.7% (IC50 = 408.9 (328,5196) ,g/ml) compared with 80.2 ± 4.8% (IC50 = 5.1 (4.3,6.1) ,g/ml) with phenoterol. The addition of 1,8-cineole to guinea-pig tracheal rings tonically contracted with K+ 80 mM induced a concentration-related relaxation. The maximal relaxation elicited by 1,8-cineole was 113.6 ± 11.7% (IC50 127.0 (115.9,139.2) ,g/ml) compared with 129.7 ± 14.6% (IC50 0.13 (0.12,0.14) ,g/ml) achieved after phenoterol administration. In addition, the incubation of tracheal rings with 1,8-cineole (100, 300 or 1000 ,g/ml), 15 min before inducing phasic contractions with K+ 80 mM, decreased the maximal amplitude of the contraction by 31.6 ± 4.6, 75.7 ± 2.7 and 92.2 ± 1.5%, respectively. In another set of experiments, neither the maximal response nor the IC50 for the 1,8-cineole-induced relaxation were different between normal and ovalbumin-sensitized tissues. Moreover, the relaxation of bronchial rings contracted after exposure to 1 ,g/ml ovalbumin occurred at a faster rate in rings pre-incubated with 1,8-cineole when compared with rings pre-incubated with vehicle only (Tween 0.3%). Therefore, in the first minute after the antigen challenge, the tracheal tissue relaxed after the peak contraction by 6.5, 21.4 (P < 0.05 vs control) and 66.9% (P < 0.05 vs control) in the presence of 100, 300 or 1000 ,g/ml 1,8-cineole, respectively. Conclusions 1,8-Cineole relaxed rat and guinea-pig (nonsensitized and ovalbumin-sensitized) airway smooth muscle by a nonspecific mechanism. [source] Thermal transformation of monoterpenes within thionin-supported zeolite Na-Y.JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 1 2003Acid-catalyzed or electron transfer-induced? Abstract Several monoterpenes (monocyclic, bicyclic or acyclic) isomerize and finally transform to p -cymene in the dark upon loading within thionin-supported zeolite Na-Y. The same reactions occur in Na-Y dried under the same conditions as thionin/Na-Y. It is postulated that the thermal treatment of Na-Y generates ,electron holes' (probably acidic sites). The transformation of monoterpenes occurs more likely via an electron transfer-induced reaction subordinated to the occurrence of the acidic sites. The radical cation of the more thermodynamically stable monoterpene, ,-terpinene, eventually dehydrogenates to p -cymene. For comparison, the same reactions were performed within methyl viologen-supported Na-Y. Copyright © 2002 John Wiley & Sons, Ltd. [source] Enrichment of the thymoquinone content in volatile oil from Satureja montana using supercritical fluid extractionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2009Clara Grosso Abstract Supercritical fluid extraction (SFE) of the volatile oil from Satureja montana L. was performed under different conditions of pressure (90 and 100 bar), temperature (40 and 50°C), mean particle sizes (0.4, 0.6 and 0.8 mm) and CO2 flow rate (0.8, 1.1 and 1.3 kg/h) to understand the influence of these parameters on the composition and yield of this oil. The results were compared with those obtained for the essential oil isolated by hydrodistillation (HD). The volatile and the essential oil were analysed by GC and GC-MS. The main compounds are carvacrol (52.2,62.0% for HD vs. 41.7,64.5% for SFE), thymol (8.6,11.0% for HD vs. 6.0,11.3% for SFE), p -cymene (6.9,12.8% for HD vs. 6.0,17.8% for SFE), ,-terpinene (6.4,9.4% for HD vs. 2.3,6.0% for SFE) and ,-bisabolene (2.0,2.7% for HD vs. 2.2,3.5% for SFE). The major difference between SFE and HD was the relative amount of thymoquinone, an oxygenated monoterpene with important biological activities, which can be ten-fold higher in volatile oil (1.6,3.0 for SFE vs. 0.2% for HD). The morphology of the glandular trichomes of S. montana and the effect of the grinding process on them was also evaluated by SEM. [source] Every plant for himself; the effect of a phenolic monoterpene on germination and biomass of Thymus pulegioides and T. serpyllumNORDIC JOURNAL OF BOTANY, Issue 2 2009Catrine Grønberg Jensen Thyme plants are known for their production of aromatic oils, whose main component is terpenes. The plants leach terpenes to their surroundings and thereby affect the seed germination and biomass of associated plants, but also potentially themselves. A variation in the dominant terpenes produced by thyme plants is found both within and among species. In Denmark two thyme species (Thymus pulegioides and T. serpyllum) are naturally occurring. The essential oil of T. pulegioides in Denmark is mainly dominated by one monoterpene; ,carvacrol'. In contrast, the essential oil of T. serpyllum constitutes a mix of two,four different types of terpenes, both mono- and sesqui-terpenes. As the effects of terpenes on plant performance can vary with the type of terpene, and in order to study species-specific responses, we examined how the dominating T. pulegioides monoterpene ,carvacrol' affected germination and growth of both T. pulegioides and T. serpyllum. We compared the performance of seeds and seedlings of both thyme species on soil treated with carvacrol versus control soil. We found no effect of treatment on germination, but we detected a highly significant effect of treatment on seedling biomass. For both thyme species, seedling biomass was significantly higher on terpene soil compared to control soil, suggesting a general adaptation to the presence of terpenes in the soil for both thyme species. Moreover, while no difference in seedling biomass between species on control soil was found, T. pulegiodes seedlings were significantly larger than T. serpyllum when grown on soil treated with its ,home' terpene, suggesting an additional species specific response. Dividing the biomass into aboveground and root biomass showed that the increased biomass on terpene-soil was due to increased aboveground biomass, whereas no difference in root biomass was detected among treatments and species. We discuss whether this response may be caused by an adaptation to a predictable terpene-mediated alteration in nitrogen-availability. [source] Chemical composition and antiproliferative activity of essential oil from the leaves of a medicinal herb, Schefflera heptaphyllaPHYTOTHERAPY RESEARCH, Issue 1 2009Yao-Lan Li Abstract Schefflera heptaphylla (L.) Frodin is a medicinal herb widely used as a main ingredient of the popular health tea formulation against infections in Southern China. Twenty-seven volatile compounds were identified by GC-MS analysis from the essential oil obtained from the leaves of S. heptaphylla, and 17 of them belonged to monoterpenes or sesquiterpenes. The main volatile constituent in S. heptaphylla was found to be a monoterpene, , -pinene, comprising about 22% of the total volatile components. The essential oil showed significant antiproliferative activity against three cancer cell lines, MCF-7, A375 and HepG2 cells, with IC50 values of 7.3 µg/mL, 7.5 µg/mL and 6.9 µg/mL, respectively. The result of the cytotoxicity assay indicates that (,)- , -pinene and (+)- , -pinene (commercially available from Sigma) also possessed antiproliferative activity against the cancer cells MCF-7, A375 and HepG2 with IC50 values ranging from 147.1 to 264.7 µm. Copyright © 2008 John Wiley & Sons, Ltd. [source] Health monitoring of plants by their emitted volatiles: trichome damage and cell membrane damage are detectable at greenhouse scaleANNALS OF APPLIED BIOLOGY, Issue 3 2009R.M.C. Jansen Abstract Pathogen attack and herbivore infestation have a major impact on plant health. In a model study, these two plant health issues were simulated to study whether plant health can be monitored at greenhouse scale through the analysis of volatile organic compounds (VOCs) in greenhouse atmosphere. To simulate pathogen attack and herbivore infestation, we repeatedly stroked the stems of tomato plants (Lycopersicon esculentum) and repeatedly removed their side shoots. In addition, we studied the effect of fruit picking on the concentration of plant-emitted VOCs in greenhouse atmosphere. Analysis of air samples obtained before these treatments revealed up to 17 VOCs that are known to be released from tomato plants, of which the most dominant one was the monoterpene ,-phellandrene. When plants were 7 weeks old, the concentration of this VOC was approximately 0.06 ppbv before treatment. When plants were 12 weeks old, this concentration was raised to approximately 0.14 ppbv. Stroking of the stems, removing the side shoots and fruit picking resulted in an increase in the concentrations of all mono- and most sesquiterpenes up to 60-fold, which was expected because these VOCs are well-known constituents of trichomes. The treatments did not result in substantially increased concentrations of the stress-related compounds ,-copaene, methyl salicylate and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene. In contrast to stroking and fruit picking, shoot removal resulted in the emission of the lipoxygenase-derived product (Z)-3-hexenol in greenhouse atmosphere expressing cell membrane degradation. The findings presented in this paper focus on the feasibility of monitoring plant health through the analysis of VOCs in greenhouse air, but findings might also be relevant for atmospheric chemistry. [source] Density-mediated responses of bark beetles to host allelochemicals: a link between individual behaviour and population dynamicsECOLOGICAL ENTOMOLOGY, Issue 4 2002Kimberly F. Wallin Abstract ,1. Bark beetles (Coleoptera: Scolytidae) accept or reject host conifers based partly on concentrations of phloem monoterpenes. They colonise trees in aggregations, in response to pheromones that attract flying beetles to trees undergoing colonisation. A series of entry and gallery construction assays was conducted to determine whether responses by individual beetles to monoterpenes are altered by pheromones and/or the presence of other beetles. 2. Entry into the amended media by Ips pini and the length of time until entry were not influenced by the presence of aggregation pheromones. 3. Entry into amended media was influenced by the presence of other beetles on the surface of, or constructing galleries in, the substrate. The effects of alpha-pinene and limonene on host entry behaviour were mediated by the density of beetles on the surface of the assay arena, and by the density of beetles constructing galleries within the medium. 4. The percentage of beetles entering medium amended with higher concentrations of monoterpenes increased with increased density of beetles on the surface of the assay arena, until a threshold density of three or four beetles per assay arena, after which entrance rate declined. 5. The presence of other beetles constructing galleries elicited more rapid entry by the test beetles. 6. Gallery lengths were generally higher in the presence of aggregation pheromones. 7. Gallery lengths increased with increased density of beetles within the assay arena. 8. These results suggest a link between the density of bark beetles and responses of individuals. This linkage may partially explain behavioural changes observed during population eruptions. [source] The evolution of floral scent and insect chemical communicationECOLOGY LETTERS, Issue 5 2010Florian P. Schiestl Ecology Letters (2010) 13: 643,656 Abstract Plants have evolved a range of strategies to manipulate the behaviour of their insect partners. One powerful strategy is to produce signals that already have a role in the animals' own communication systems. To investigate to what extent the evolution of floral scents is correlated with chemical communication in insects, I analyse the occurrence, commonness, and evolutionary patterns of the 71 most common ,floral' volatile organic compounds (VOCs) in 96 plant families and 87 insect families. I found an overlap of 87% in VOCs produced by plants and insects. ,Floral' monoterpenes showed strong positive correlation in commonness between plants (both gymnosperms and angiosperms) and herbivores, whereas the commonness of ,floral' aromatics was positively correlated between angiosperms and both pollinators and herbivores. According to a multivariate regression analysis the commonness of ,floral' aromatics was best explained by their commonness in pollinators, whereas monoterpenes were best explained by herbivores. Among pollinator orders, aromatics were significantly more common in Lepidoptera than in Hymenoptera, whereas monoterpenes showed no difference among the two orders. Collectively, these patterns suggest that plants and insects converge in overall patterns of volatile production, both for attraction and defence. Monoterpenes seem to have evolved primarily for defence under selection by herbivores, whereas aromatics evolved signalling functions in angiosperms, primarily for pollinator attraction. [source] Prior encounters modulate subsequent choices in host acceptance behavior by the bark beetle Ips piniENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2002Kimberly F. Wallin Abstract Laboratory bioassays indicate that the bark beetle Ips pini employs flexible, rather than absolute, responses to phytochemicals in its host acceptance behavior. Each beetle's decision to enter substrate was influenced by the types and concentrations of monoterpenes present. However, previous rejection of a simulated host containing a moderate concentration of monoterpenes increased the likelihood that the same concentration would be accepted upon a second or third encounter. This flexibility more than offsets any loss of vigor due to starvation and age that accompanies a process of trial and error. Starvation decreased beetles' total lipid content, but beetles can recover some energetic losses by a small amount of feeding during each trial. In addition to its adaptive value, a flexible host acceptance strategy may yield population level consequences. That is, bark beetles preferentially enter trees having low concentrations of monoterpenes, but may modify their acceptance thresholds when cues associated with stressed trees are not available. This could partially explain how some tree-killing bark beetles colonize a broader physiological range of trees during outbreaks. The adaptive value of relating individual decisions to population density may arise from two ecological relationships: first, as populations rise, the pool of stressed trees is rapidly depleted; secondly, healthy trees are attainable through pheromone , mediated mass attacks when adequate numbers of beetles are present. Flexible host acceptance behaviors may also reduce the advantage of relying exclusively on pre-landing cues to distinguish between susceptible and non-susceptible trees. [source] Thermal Behaviour of Selected C10H16 MonoterpenesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 15 2006Achim Stolle Abstract The presented work investigates the thermal behaviour of selected monoterpenes under various reactor temperatures and residence times (carrier gas, reactor inserts). In addition to the analysis of the liquid products by capillary GC and GC-MS, chemical derivatisation techniques (Diels,Alder reaction, hydrogenation) were used to identify the liquid-phase products. A thermal conversion of ,-pinene (1), myrcene (2) and limonene (4) in a reaction network is presented and the experimental evidence for the formation of pyrolysis products by a biradical pathway is discussed. The reaction network was modified based on the identification of additional C10H16 terpene isomers. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Monoterpene biosynthesis in lemon (Citrus limon)FEBS JOURNAL, Issue 13 2002cDNA isolation, functional analysis of four monoterpene synthases Citrus limon possesses a high content and large variety of monoterpenoids, especially in the glands of the fruit flavedo. The genes responsible for the production of these monoterpenes have never been isolated. By applying a random sequencing approach to a cDNA library from mRNA isolated from the peel of young developing fruit, four monoterpene synthase cDNAs were isolated that appear to be new members of the previously reported tpsb family. Based on sequence homology and phylogenetic analysis, these sequences cluster in two separate groups. All four cDNAs could be functionally expressed in Escherichia coli after removal of their plastid targeting signals. The main products of the enzymes in assays with geranyl diphosphate as substrate were (+)-limonene (two cDNAs) (,)-,-pinene and ,-terpinene. All enzymes exhibited a pH optimum around 7; addition of Mn2+ as bivalent metal ion cofactor resulted in higher activity than Mg2+, with an optimum concentration of 0.6 mm. Km values ranged from 0.7 to 3.1 µm. The four enzymes account for the production of 10 out of the 17 monoterpene skeletons commonly observed in lemon peel oil, corresponding to more than 90% of the main components present. [source] Identification of the aceA gene encoding isocitrate lyase required for the growth of Pseudomonas aeruginosa on acetate, acyclic terpenes and leucineFEMS MICROBIOLOGY LETTERS, Issue 2 2007Alma Laura Díaz-Pérez Abstract Pseudomonas aeruginosa PAO1 mutants affected in acyclic monoterpenes, n-octanol, and acetate assimilation were isolated using transposon mutagenesis. The isocitrate lyase gene (aceA) corresponding to ORF PA2634 of the PAO1 strain genome was identified in one of these mutants. The aceA gene encodes a protein that is 72% identical to the isocitrate lyase (ICL) characterized from Colwellia maris, but is less than 30% identical to their homologues from pseudomonads. The genetic arrangement of aceA suggests that it is a monocistronic gene, and no adjacent related genes were found. The ICL protein was detected as a 60-kDa band in sodium dodecyl sulfate polyacrylamide gel electrophoresis from cultures grown on acetate, but not in glucose-grown PAO1 cultures. Genetic complementation further confirmed that the aceA gene encodes the ICL enzyme. The ICL enzyme activity in crude extracts from cultures of the PAO1 strain was induced by acetate, citronellol and leucine, and repressed by growth on glucose or citrate. These results suggest that ICL is involved in the assimilation of acetate, acyclic monoterpenes of the citronellol family, alkanols, and leucine, in which the final intermediary acetyl-coenzyme A may be channelled to the glyoxylate shunt. [source] Rhodotorula cycloclastica sp. nov., Rhodotorula retinophila sp. nov., and Rhodotorula terpenoidalis sp. nov., three limonene-utilizing yeasts isolated from soilFEMS YEAST RESEARCH, Issue 8 2004Vu Nguyen Thanh Abstract During a search for yeasts that hydroxylate monoterpenes, four yeast strains were isolated from soil and plant residue in monoterpene-rich environments using enrichment techniques with cyclohexanedioic acid or cyclohexanedimethanol as sole carbon source. These strains were able to utilize (+)-limonene supplied as a vapor as only carbon source. The yeasts have a CoQ-10 system. Morphology and physiological properties of the strains did not fit any known yeast species. Recent analysis of the 26S D1/D2 and ITS-5.8S rDNA sequences of basidiomycetous yeasts showed that these strains represented three hitherto unknown species of Rhodotorula and fell in a cluster consisting of Rhodotorula philyla and the mycoparasitic fungus Colacogloea peniophorae. Descriptions of three new species Rhodotorula cycloclastica (type strain TVN 309=UOFS Y 2046=CBS 8448), Rhodotorula retinophila (type strain TVN 295=UOFS Y 2043=CBS 8446), Rhodotorula terpenoidalis (type strain TVN 310=UOFS Y 2042=CBS 8445) are proposed to accommodate these isolates. [source] Plasmodium falciparum growth is arrested by monoterpenes from eucalyptus oilFLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2008Vanessa Su Abstract Cerebral malaria is a major health problem in the developing world. Widespread resistance to existing drugs by the parasite Plasmodium falciparum has coincided with an increase in mortality, particularly in children. One potential source of new drugs comes from plant natural products. We found that commercially available, pharmaceutical grade eucalyptus oil and its principal component 1,8-cineole inhibited the growth and development of chloroquine-sensitive and chloroquine-resistant P. falciparum. This was true both when the oil was added directly to the parasite cultures and when cultures were exposed to the vapours. The development of the parasite was arrested at the early trophozoite stage, irrespective of when the oil was introduced. We used a new approach where the concentration of monoterpenes actually taken up by the cultures was measured directly using HS,GC. We found that the critical concentration required to inhibit and kill the parasite did not adversely affect the host erythrocytes, placing it in the range suitable for drug development. Given the ready availability and existing quality control of eucalyptus oils, this may represent an economically viable adjunct to current antimalarial therapies. Copyright © 2008 John Wiley & Sons, Ltd. [source] Volatile composition and olfactory profile of pennyroyal (Mentha pulegium L.) plantsFLAVOUR AND FRAGRANCE JOURNAL, Issue 2 2007M. Consuelo Díaz-Maroto Abstract The composition of volatile oil extracts of pennyroyal (Mentha pulegium L.) plants was investigated by gas chromatography,mass spectrometry. Those volatiles responsible for the characteristic minty and pungent aroma of this plant were determined by gas chromatography,olfactometry. Volatile oil extracts were found to be rich in oxygenated monoterpenes, mainly pulegone and piperitone oxide, followed by isopulegol, piperitone and piperitenone. Major monoterpenes hydrocarbons were limonene and , -pinene, while sesquiterpenoids were detected in low levels. With respect to the aroma characteristics, pulegone was found to have an intense mint, balsamic and pungent aroma. Other compounds with minty notes were isopulegone, piperitol and 1,8-cineole. Copyright © 2006 John Wiley & Sons, Ltd. [source] Composition of the essential oils from the leaves of nine Pinus species and the cones of three of Pinus speciesFLAVOUR AND FRAGRANCE JOURNAL, Issue 1 2007Kohsuke Kurose Abstract The essential oils from leaves of Pinus koraiensis, P. merkusii, P. palustris, P. parviflora, P. petula, P. ponderosa, P. pumila, P. rigida and P. rudis and cones of P. densiflora, P. rigida and P. taeda were investigated by GC,MS. Yields of the oils were 0.08,2.33 (w/w). , -Pinene (0.2,51.8%) and , -pinene (0.1,38.2%) were contained in both the leaf and cone oils of Pinus species. The monoterpene fractions of Pinus leaf oils comprised mainly pinanes and menthanes. Pinanes were present in greater amounts than menthanes in the leaf oils of all the species except P. petula. The leaves of P. pumila contained caranes as major components, whereas those of P. parviflora contained camphanes as major components. As for sesquiterpenes in the leaf oils, caryophyllane and/or the cadinane group were the major components. The leaf oils of P. merkusii, P. petula and P. rudis contained larger amounts of caryophyllanes than those of the cadinane group. The sesquiterpenes of these three species were mainly caryophyllanes, while in the sesquiterpene fraction of other Pinus species the content of the cadinane group was larger than that of caryophyllanes. Concerning cone oils, P. rigida and P. taeda cones were mainly composed of monoterpenes, while P. densiflora contained sesquiterpenes as the main components. Copyright © 2006 John Wiley & Sons, Ltd. [source] Composition of the essential oil of Abies koreana Wils.FLAVOUR AND FRAGRANCE JOURNAL, Issue 1 2007Szymon Baran Abstract The volatile constituents of Abies koreana Wils. from Poland have been investigated by GC, GC,MS, 1H- and 13C-NMR. The essential oils were obtained by hydrodistillation of needles, twigs and cones, as well as twigs with needles, with yields of 1.0%, 0.64%, 0.42% and 0.83%, respectively. Eighty-four compounds were identified in the essential oil, which consisted mainly of monoterpenes, such as , -pinene, camphene, limonene and bornyl acetate, and sesquiterpenes such as intermedeol and the new (+)-(1R,4R,5R,7S)-guaia-10(14),11-diene. Copyright © 2006 John Wiley & Sons, Ltd. [source] Volatile constituents of Dorema aucheri Boiss., Seseli libanotis (L.) W. D. Koch var. armeniacum Bordz. and Conium maculatum L. three Umbelliferae herbs growing wild in IranFLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2006Shiva Masoudi Abstract The composition of the essential oils from three Umbelliferae species of Iran,Dorema aucheri Boiss., which is endemic to Iran, Seseli libanotis (L.) W. D. Koch var. armeniacum Bordz. and Conium maculatum L.,obtained by hydrodistillation were analyzed by GC and GC[sol ]MS. , -Eudesmol (31.2%) and , -cadinene (10.9%) were the main components among the 35 constituents characterized in Dorema aucheri, representing 89.2% of the total components detected. Twenty-five compound were identified in the oil of Seseli libanotis, repesenting 90.6% of the total oil with acorenone (35.5%) as the major constituents. The oil of Conium maculatum was characterized by higher amount of germacrene D (46.1%), , -caryophyllene (15.3%) and (E,E)- , -farnesene (10.1%) among the 17 components comprising 91.0% of the total oil detected. All oils were richer in sesquiterpenes than monoterpenes. Copyright © 2006 John Wiley & Sons, Ltd. [source] Flavour volatiles of flowers and stalks of Murraya koenigii L.FLAVOUR AND FRAGRANCE JOURNAL, Issue 4 2006S. G. Walde Abstract The volatiles of fresh leaf stalks and flowers of Murraya koenigii (curry leaf plant), grown in Hyderabad, India, were isolated by simultaneous distillation and extraction method and analysed by GC,MS. Thirty-one components were identified in the leaf stalk oil, constituting 88.1% of the volatile oil. The major components were the mono- and sesquiterpene hydrocarbons (66.7%), of which the major ones were , -pinene (24.2%), , -pinene (6.9%), , -phellandrene (7.3%) and , -copaene (8.9%). In addition, the oil had nine oxygenated monoterpenes (14.2%) and four sesquiterpene alcohols (8.1%). In the flower oil, 24 components were identified, constituting 91.8% of the volatile oil. Here, too, the major constituents were mono- and sesquiterpenes (87%), of which cis -ocimene (34.1%), , -pinene (19.1%), , -terpinene (6.7%) and , -caryophyllene (9.5%) were predominant. It also contained seven oxygenated monoterpenes and three oxygenated sesquiterpenes, constituting 4.7% of the oil. The larger number of oxygenated mono- and sesquiterpenes present appear to be responsible for the intense odour associated with the stalk and flower parts of Murraya koenigii as compared to the leaf. Copyright © 2006 John Wiley & Sons, Ltd. [source] Composition of the essential oil of aerial parts of an endemic species of the Apiaceae of Algeria, Daucus reboudii Coss.FLAVOUR AND FRAGRANCE JOURNAL, Issue 4 2006L. Djarri Abstract Water-distilled essential oil of the aerial parts of Daucus reboudii Coss. was analysed by GC,MS and GC,FID. Twenty-four compounds were identified, corresponding to 87.2% of the oil, mainly represented by monoterpenes. The major constituents were , -pinene (39.7%) and sabinene (21.2%). Copyright © 2006 John Wiley & Sons, Ltd. [source] Volatile constituents of Achillea pachycephala, A. oxyodonta and A. biebersteinii from IranFLAVOUR AND FRAGRANCE JOURNAL, Issue 2 2006Akbar Esmaeili Abstract The water-distilled essential oils from aerial parts of Achillea pachycephala Rech.f. and Achillea oxyodonta Boiss., which are endemic to Iran, and stems, leaves and flowers of Achillea biebersteinii Afan., were analysed by GC and GC,MS. The oil of A. pachycephala was found to contain 1,8-cineole (27.7%) and camphor (27.4%) as the major constituents. The oil of A. oxyodonta was characterized by higher amounts of 1,8-cineole (38.5%) and artemisia ketone (23.0%). The oils obtained from stems and leaves of A. biebersteinii were rich in camphor (38.1% and 33.7%, respectively) and borneol (22.6% and 20.8%, respectively). The other main component of the stem oil was 1,8-cineole (13.5%). In the flower oil of the plant, camphor (36.3%) and 1,8-cineole (22.3%) were the predominant compounds. All oils were richer in oxygenated monoterpenes. Copyright © 2005 John Wiley & Sons, Ltd. [source] Volatile compositions of two Asteraceae from the north-east of Brazil: Ageratum conyzoides and Acritopappus confertus (Eupatorieae)FLAVOUR AND FRAGRANCE JOURNAL, Issue 6 2005Mary Anne Sousa Lima Abstract Essential oils obtained by hydrodistillation of leaves from specimens of Ageratum conyzoides and Acritopappus confertus were investigated by GC,MS. The leaf essential oil of A. conyzoides consisted exclusively of the chromenes precocene I (95.4%) and II (4.5%). The essential oil of A. confertus consisted predominantly of monoterpenes, representing 81.0% of the total. The main component was myrcene (52.0%), with reasonable amounts of , -pinene (16.8%) and limonene (8.2%). The essential oil of A. conyzoides from the north-east of Brazil has been reported as the major source of precocene I to date. Copyright © 2005 John Wiley & Sons, Ltd. [source] | ||||||||||||||||