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At least 739 records · Page 41Linked to original sources
PubMed2001

Exogenous methyl jasmonate induces volatile emissions in cotton plants.

We investigated the effect of exogenous methyl jasmonate (MeJA) on the emission of herbivore-induced volatiles; these volatile chemicals can signal natural enemies of the herbivore to the damaged plant. Exogenous treatment of cotton cv. Deltapine 5415 plants with MeJA induced the emission of the same volatile compounds as observed for herbivore-damaged plants. Cotton plants treated with MeJA emitted elevated levels of the terpenes (E)-beta-ocimene, linalool, (3E)-4,8-dimethyl-1,3,7-nonatriene, (E,E)-alpha-farnesene, (E)-beta-farnesene, and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene compared to untreated controls. Other induced components included (Z)-3-hexenyl acetate, methyl salicylate, and indole. Methyl jasmonate treatment did not cause the release of any of the stored terpenes such as alpha-pinene, beta-pinene, alpha-humulene, and (E)-beta-caryophyllene. In contrast, these compounds were emitted in relatively large amounts from cotton due to physical disruption of glands by the herbivores. The timing of volatile release from plants treated with MeJA or herbivores followed a diurnal pattern, with maximal volatile release during the middle of the photoperiod. Similar to herbivore-treated plants, MeJA treatment led to the systemic induction of (Z)-3-hexenyl acetate, (E)-beta-ocimene, linalool, (3E)-4,8-dimethyl-1,3,7-nonatriene, (E,E)-alpha-farnesene, (E)-beta-farnesene, and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene. Our results indicate that treatment of cotton with MeJA can directly and systemically induce the emission of volatiles that may serve as odor cues in the host-search behavior of natural enemies.

Acetates↗
PubMed2003

Seasonal cycle of VOCs in apartments.

To assess the adverse health effects of volatile organic compounds (VOCs), epidemiological studies combine the health outcome of individuals with their concomitant VOC exposure. While the latter is representative of the studied period, health effects might also be the result of long-term exposure or emerge in consequence of a peak pollution throughout the year. To address these problems, additional information about the spatiotemporal distribution of VOCs is necessary. The present paper aims at elucidating the spatial and temporal variation of VOC concentrations in Leipzig, Germany. The analysis is based on 1499 indoor and 222 outdoor measurements taken in the period between 1994 and 2001. All data were collected in the frame of epidemiological studies (Diez et al., 1999; Fritz et al., 1998; Schulz et al., 1999). The analysis comprised concentrations of 30 VOCs belonging to the groups of alkanes, cycloalkanes, aromatics, volatile halogenated hydrocarbons, and terpenes. We found that the VOC load in indoor air is, on average, 10 times higher than outdoors. For the studied period there was a clear downward tendency for all VOCs in apartments in Leipzig, except for terpenes which show an upward trend in the period 1996-99. In indoor air we observe an annual cycle for the total VOC concentration as well as the sum concentrations of the above called groups. Highest concentrations occur during the winter months, approximately three times higher than the summer burden. We summarize this finding in a seasonal model, which is fitted to our measurements. Based on the model we develop a procedure for seasonal adjustment, which enables to roughly estimate the annual peak concentration utilizing one monthly observation.

Air Pollution, Indoor↗
PubMed2004

The role of vanadium bromoperoxidase in the biosynthesis of halogenated marine natural products.

Halogenated natural products are frequently reported metabolites in marine seaweeds. These compounds span a range from halogenated indoles, terpenes, acetogenins, phenols, etc., to volatile halogenated hydrocarbons that are produced on a very large scale. In many cases these halogenated marine metabolites possess biological activities of pharmacological interest. Given the abundance of halogenated marine natural products found in marine organisms and their potentially important biological activities, the biogenesis of these compounds has intrigued marine natural product chemists for decades. Over a quarter of a century ago, a possible role for haloperoxidase enzymes was first suggested in the biogenesis of certain halogenated marine natural products, although this was long before haloperoxidases were discovered in marine organisms. Since that time, FeHeme- and Vanadium-haloperoxidases (V-HPO) have been discovered in many marine organisms. The structure and catalytic activity of vanadium haloperoxidases is reviewed herein, including the importance of V-HPO-catalyzed bromination and cyclization of terpene substrates.

Biological Products↗
PubMed2026

Dock & design: engineering specificity for an alternative pimaradiene outcome with the ent-kaurene synthase from Bradyrhizobium japonicum.

The complexity of the reactions catalyzed by terpene synthases has hindered enzymatic engineering. In most cases such efforts result in non-specific product outcome, with the targeted compound being produced alongside others, hindering further use. Previous work with the structurally characterized ent-kaurene synthase from Bradyrhizobium japonicum (BjKS) identified a serine for alanine substitution (A167S) that led to premature deprotonation, yielding a pair of ent-pimaradiene double-bond isomers, with retrospective analysis by the TerDockin computational approach indicating that the introduced hydroxyl acts as a catalytic base for both. Here this route to 'short-circuiting' the BjKS catalyzed reaction for ent-pimaradiene production was further explored, with prospective application of TerDockin, via design-build-test cycles, enabling specific production of a novel pimaradiene isomer via introduction of a water molecule as the catalytic base. The resulting mutants, BjKS:F72S and particularly BjKS:F72Y/Y280S specifically yield the targeted ent-pimara-8,15-diene with reasonable catalytic efficiency, demonstrating the applicability of this computationally inexpensive approach to engineering terpene synthase product outcomes.

Journal Article↗
PubMed2001

A plastid envelope location of Arabidopsis ent-kaurene oxidase links the plastid and endoplasmic reticulum steps of the gibberellin biosynthesis pathway.

We have used fusions of gibberellin biosynthesis enzymes to green fluorescent protein (GFP) to determine the subcellular localization of the early steps of the pathway. Gibberellin biosynthesis from geranylgeranyl diphosphate is catalysed by enzymes of the terpene cyclase, cytochrome P450 mono-oxygenase and 2-oxoglutarate-dependent dioxygenase classes. We show that the N-terminal pre-sequences of the Arabidopsis thaliana terpene cyclases copalyl diphosphate synthase (AtCPS1) and ent-kaurene synthase (AtKS1) direct GFP to chloroplasts in transient assays following microprojectile bombardment of tobacco leaves. The AtKS1-GFP fusion is also imported by isolated pea chloroplasts. The N-terminal portion of the cytochrome P450 protein ent-kaurene oxidase (AtKO1) directs GFP to chloroplasts in tobacco leaf transient assays. Chloroplast import assays with 35S-labelled AtKO1 protein show that it is targeted to the outer face of the chloroplast envelope. The leader sequences of the two ent-kaurenoic acid oxidases (AtKAO1 and AtKAO2) from Arabidopsis direct GFP to the endoplasmic reticulum. These data suggest that the AtKO1 protein links the plastid- and endoplasmic reticulum-located steps of the gibberellin biosynthesis pathway by association with the outer envelope of the plastid.

Arabidopsis↗
PubMed2001

Isolation and functional analysis of a cDNA encoding a myrcene synthase from holm oak (Quercus ilex L.).

An 859-bp cDNA segment of a terpene synthase gene was amplified by PCR from the evergreen sclerophyllous holm oak (Quercus ilex L.) using heterologous primers for conserved regions of terpene synthase genes (TPS) in dicotyledonous plants. Based on the sequence of this segment, homologous primers were designed for amplification by RACE-PCR of a cDNA segment carrying the monoterpene synthase gene myrS. The gene encodes a protein of 597 amino acids including an N-terminal putative plastid transit peptide. The gene without the segment encoding the transit peptide was cloned by PCR into a bacterial expression vector. Expression in Escherichia coli yielded an active monoterpene synthase, which converted geranyl diphosphate (GDP) predominantly into the acyclic monoterpene myrcene and to a very small extent into cyclic monoterpenes. Sequence comparison with previously cloned monoterpene synthases revealed that the myrcene synthase from Q. ilex belongs to the TPSb subfamily.

Amino Acid Sequence↗
PubMed2000

In vitro effect of essential oils and isolated mono- and sesquiterpenes on Leishmania major and Trypanosoma brucei.

The effect of different essential oils as well as of isolated mono- and sesquiterpenes on the viability of bloodstream forms of Trypanosoma brucei, promastigotes of Leishmania major and human HL-60 cells was evaluated using the Almar Blue assay. Of the 12 essential oils and 8 terpenes investigated, only three essential oils, Melissa officinalis (balmmint) oil, Thymus vulgaris (thyme) oil, and Melaleuca alternifolia (tea tree) oil were about 50-fold and 80-fold more toxic to bloodstream forms of T. brucei than to HL-60 cells, respectively. Terpinen-4-ol, the main compound of the Australian tea tree oil, was even 1000-fold more toxic to trypanosomes than to the human cells. On the other hand, none of the essential oils and terpenes tested were more toxic to promastigotes of L. major than to HL-60 cells.

Animals↗
PubMed2003

Pharmacokinetics of Ginkgo biloba extracts.

EGb 761 (definition see editorial) Ginkgo extract is produced by a validated production process. Its pharmacologically active constituents, flavonol glycosides and terpene lactones, are kept within a narrow range of 22 to 27 % and 5 to 7 %, respectively, by standardisation. The concentration of ginkgolic acids is below 5 ppm. The constant production process also maintains the concentrations of other constituents such as proanthocyanidins, carboxylic acids and non-flavone glycosides at a fairly constant level. In this article, we will summarise the data on the pharmacokinetics of flavonol glycosides and terpene lactones.

Adult↗
PubMedDate not supplied

Effect of in situ composting on reducing offensive odors and volatile organic compounds in swineries.

Seven swine farms were studied to find out how the in situ composting system, compared to the slatted floor pit system, influences the concentration and occurrence of malodorous compounds. Ammonia concentrations were measured with diffusion tubes. Small molecular sulfur compounds were analyzed using laminated bags and a gas chromatograph with a FP-detector. All other volatile organic compounds were analyzed by gas chromatography/mass spectrometry with simultaneous sniffing of the eluted compounds. About 400 organic compounds were identified from the air samples, and 94 suspect odorous compounds are listed in the present article. The most intense and unpleasant odors were caused by p-cresol, carboxylic acids (C2-C7), and some ketones such as 3-hydroxy-2-butanone, 2,3-butanedione, and 2-butanone. Terpenes (alpha-pinene, beta-pinene, 3-carene, and limonene), which originate from sawdust, caused the main peaks in the chromatograms of compost swineries. In swine confinement buildings where the composting system was functioning properly, the concentration of sulfur compounds, and especially of carboxylic acids, ketones, and p-cresol, fell effectively. The use of sawdust as composting material caused elevated concentrations of terpenes in the ambient air. There was clearly less airborne ammonia and hydrogen sulfide in the well-functioning compost swineries than in the poorly functioning ones. Elevated hydrogen sulfide levels were measured during turning work, however. In one composting swinery, the hydrogen sulfide level was as high as 15 mg/m3 during turning work. All the other concentrations of odorous compounds did not exceed occupational exposure limit values, but several compounds exceeded the respective threshold odor concentrations.

Air Pollutants, Occupational↗
PubMed2003

The telltale structures of epoxide hydrolases.

Traditionally, epoxide hydrolases (EH) have been regarded as xenobiotic-metabolizing enzymes implicated in the detoxification of foreign compounds. They are known to play a key role in the control of potentially genotoxic epoxides that arise during metabolism of many lipophilic compounds. Although this is apparently the main function for the mammalian microsomal epoxide hydrolase (mEH), evidence is now accumulating that the mammalian soluble epoxide hydrolase (sEH), despite its proven role in xenobiotic metabolism, also has a central role in the formation and breakdown of physiological signaling molecules. In addition, a certain class of microbial epoxide hydrolases has recently been identified that is an integral part of a catabolic pathway, allowing the use of specific terpens as sole carbon sources. The recently available x-ray structures of a number of EHs mirror their respective functions: the microbial terpen EH differs in its fold from the canonical alpha/beta hydrolase fold of the xenobiotic-metabolizing mammalian EHs. It appears that the latter fold is the perfect solution for the efficient detoxification of a large variety of structurally different epoxides by a single enzyme, whereas the smaller microbial EH, which has a particularly high turnover number with its prefered substrate, seems to be the better solution for the hydrolysis of one specific substrate. The structure of the sEH also includes an additional catalytic domain that has recently been shown to possess phosphatase activity. Although the physiological substrate for this second active site has not been identified so far, the majority of known phosphatases are involved in signaling processes, suggesting that the sEH phosphatase domain also has a role in the regulation of physiological functions.

Animals↗
PubMed2005

Chemical and histochemical analysis of 'Quatre Saisons Blanc Mousseux', a Moss Rose of the Rosa x damascena group.

BACKGROUND AND AIMS: Moss roses are old garden roses covered with a mossy growth on flower pedicel and calyx. This moss releases a pine-scented oleoresin that is very sticky and odoriferous. Rosa x centifolia 'muscosa' was the first moss rose to be obtained by bud-mutation but, interestingly, R. x damascena 'Quatre Saisons Blanc Mousseux' was the first repeat-blooming cultivar, thus interesting breeders. In the present study, the anatomy of these sports (i.e. bud-mutations) is characterized and the volatile organic compounds (VOCs) produced by the moss versus the petals are identified. They are compared between the two lines and their respective parents. METHODS: Anatomy of the moss is studied by environmental scanning electron microscopy and histochemical light microscopy. Sudan Red IV and Fluorol Yellow 088 are used to detect lipids, and 1-naphthol reaction with N,N-dimethyl-p-phenylenediamine to detect terpenes (Nadi reaction). Head-space or solid/liquid extraction followed by gas chromatography and mass spectrometry are used to identify VOCs in moss, trichomes and petals. KEY RESULTS: Moss of the two cultivars has the same structure with trichomes on other trichomes but not exactly the same VOCs. These VOCs are specific to the moss, with lots of terpenes. An identical VOC composition is found in leaves but not in petals. They are nearly the same in the moss mutants and in the respective wild types. CONCLUSIONS: Sepals of moss roses and their parents have a specific VOC pattern, different from that of the petals. The moss corresponds to a heterochronic mutation with trichomes developing on other trichomes. Such a mutation has probably appeared twice and independently in the two lines.

Chromatography, Gas↗
PubMed2001

Antibacterial activity of essential oils and their major constituents against respiratory tract pathogens by gaseous contact.

The antibacterial activity of 14 essential oils and their major constituents in the gaseous state was evaluated against Haemophilus influenzae, Streptococcus pneumoniae, Streptococcus pyogenes and Staphylococcus aureus. For most essential oils examined, H. influenzae was most susceptible, followed by S. pneumoniae and S. pyogenes, and then S. aureus. Penicillin-susceptible and -resistant S. pneumoniae were comparable in susceptibility. Escherichia coli, which was used as a control, showed least susceptibility. A minimal inhibitory dose (MID) was introduced as a measure of the vapour activity. Among 14 essential oils, cinnamon bark, lemon-grass and thyme oils showed the lowest MID, followed by essential oils containing terpene alcohols as major constituents. The essential oils containing terpene ketone, ether and, in particular, hydrocarbon had high MIDS. The vapour activity on short exposure was comparable to that following overnight exposure, and rapid evaporation was more effective than slow evaporation of essential oils. The vapour concentration and absorption into agar of essential oils reached a maximum 1 or 2 h after rapid evaporation. These results indicate that the antibacterial action of essential oils was most effective when at high vapour concentration for a short time.

Anti-Bacterial Agents↗
PubMedDate not supplied

Controls over monoterpene emissions from boreal forest conifers.

We investigated controls over the emission of monoterpenes from two species of boreal forest conifers, black spruce (Picea mariana Miller (B.S.P.)) and jack pine (Pinus banksiana Lamb). Monoterpenes are important in plants as carbon-based defensive compounds and in the atmosphere as photochemically reactive compounds that affect ozone and carbon monoxide concentrations. We examined ecological theories of plant allocation to defensive compounds in relation to emission rates of monoterpenes from the foliage of these two species. Monoterpene emission from plants is controlled by the vapor pressure of the monoterpenes within plant tissues, and vapor pressure is controlled by two parameters, air temperature and terpene concentration within the tissues. We measured the concentration of terpenes and nitrogen within foliage and the emission rate from foliage, and demonstrated that emission rate was linearly related to nitrogen concentration and exponentially related to air temperature. Current theories of plant allocation to carbon-based defenses predict an inverse relationship between foliar nitrogen and carbon-based defenses. We found that, under certain circumstances, these theories were sufficient to predict concentrations and emissions, but under other circumstances, the theories did not predict monoterpene concentrations or emissions. These results are discussed in the context of landscape/regional modeling of hydrocarbon emission from vegetation.

Journal Article↗
PubMed1997

De Novo Biosynthesis of Volatiles Induced by Insect Herbivory in Cotton Plants.

In response to insect feeding on the leaves, cotton (Gossypium hirsutum L.) plants release elevated levels of volatiles, which can serve as a chemical signal that attracts natural enemies of the herbivore to the damaged plant. Pulse-labeling experiments with [13C]CO2 demonstrated that many of the volatiles released, including the acyclic terpenes (E,E)-[alpha]-farnesene, (E)-[beta]-farnesene, (E)-[beta]-ocimene, linalool, (E)-4,8-dimethyl-1,3,7-nonatriene, and (E/E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene, as well as the shikimate pathway product indole, are biosynthesized de novo following insect damage. However, other volatile constituents, including several cyclic terpenes, butyrates, and green leaf volatiles of the lipoxygenase pathway are released from storage or synthesized from stored intermediates. Analysis of volatiles from artificially damaged plants, with and without beet armyworm (Spodoptera exigua Hubner) oral secretions exogenously applied to the leaves, as well as volatiles from beet armyworm-damaged and -undamaged control plants, demonstrated that the application of caterpillar oral secretions increased both the production and release of several volatiles that are synthesized de novo in response to insect feeding. These results establish that the plant plays an active and dynamic role in mediating the interaction between herbivores and natural enemies of herbivores.

Journal Article↗
PubMed1967

Effects of light and temperature on the monoterpenes of peppermint.

Peppermint (Mentha piperita L.) was grown in a growth chamber under several combinations of temperature and illumination, and the monoterpenes of each leaf pair were analyzed by gas chromatography. Effects on the monoterpenes could be seen in the new leaves after a few days in the growth chamber. Long-day conditions enhanced growth, with a corresponding increase in the total amount of monoterpenes. Either short nights or cool nights, combined with full light intensity during the day, enhanced the formation of menthone and depressed the accumulation of menthofuran and pulegone. Experiments with interrupted night and with low light intensity indicated that photoperiod, as such, does not directly influence the terpene composition. It is suggested that the oxidation-reduction level of the monoterpenes reflects the oxidation-reduction state of the respiratory coenzymes of the terpene-producing cells, and that this, in turn, depends on the concentrations of respiratory substrates in the cells. This suggestion is based on the likelihood that warm nights cause depletion of respiratory substrates, resulting in oxidizing conditions, while cool nights preserve high levels of respiratory substrates, and thus maintain reducing conditions.

Journal Article↗
PubMed1987

Triterpene Biosynthesis in the Latex of Euphorbia lathyris: Calmodulin Antagonists Are Ineffective in Whole Latex.

The calmodulin antagonists chlorpromazine, fluphenazine, trifluoperazine, and 2-(pentachlorophenoxy)ethyl N,N-diethylamine are not inhibitors of acetate incorporation into triterpenols (TOH) and their fatty acid esters (TE) in whole tapped latex from Euphorbia lathyris, although prior work demonstrated that these antagonists are good inhibitors of mevalonate incorporation into TOH and TE in a centrifuged pellet from the latex. Antagonist absorption into the endogenous terpene pool is the primary reason for antagonist ineffectiveness in whole latex; changes in the utilized substrate or chemical deactivation of the antagonists were ruled out as factors. A biosynthetically inactive, latex supernatant fraction containing the endogenous terpene pool was prepared. This fraction blocks antagonist action when added to the latex pellet, and proved to be a useful tool for demonstrating that inhibition of triterpene biosynthesis by a calmodulin antagonist is partially reversible.

Journal Article↗
PubMed1990

Site of clomazone action in tolerant-soybean and susceptible-cotton photomixotrophic cell suspension cultures.

Studies were conducted to determine the herbicidal site of clomazone action in tolerant-soybean (Glycine max [L.] Merr. cv Corsoy) (SB-M) and susceptible-cotton (Gossypium hirsutum [L.] cv Stoneville 825) (COT-M) photomixotrophic cell suspension cultures. Although a 10 micromolar clomazone treatment did not significantly reduce the terpene or mixed terpenoid content (microgram per gram fresh weight) of the SB-M cell line, there was over a 70% reduction in the chlorophyll (Chl), carotenoid (CAR), and plastoquinone (PQ) content of the COT-M cell line. The tocopherol (TOC) content was reduced only 35.6%. Reductions in the levels of Chl, CAR, TOC, and PQ indicate that the site of clomazone action in COT-M cells is prior to geranylgeranyl pyrophosphate (GGPP). The clomazone treatment did not significantly reduce the flow of [(14)C]mevalonate ([(14)C]MEV) (nanocuries per gram fresh weight) into CAR and the three mixed terpenoid compounds of SB-M cells. Conversely, [(14)C]MEV incorporation into CAR and the terpene moieties of Chl, PQ, and TOC in COT-M cells was reduced at least 73%, indicating that the site of clomazone action must be after MEV. Sequestration of clomazone away from the chloroplast cannot account for soybean tolerance to clomazone since chloroplasts isolated from both cell lines incubated with [(14)C]clomazone contained a similar amount of radioactivity (disintegrations per minute per microgram of Chl). The possible site(s) of clomazone inhibition include mevalonate kinase, phosphomevalonate kinase, pyrophosphomevalonate decarboxylase, isopentenyl pyrophosphate isomerase, and/or a prenyl transferase.

Journal Article↗
PubMed1989

Structure of columbin, a diterpenoid furanolactone from Tinospora cordifolia Miers.

(1S,4R,5R,8S,10R,12S)-4-Hydroxy-15,16-epoxycleroda-2,12(16),14- trieno-17,12: 18,1-biscarbolactone, C20H22O6, Mr = 358.2, m.p. = 453-454 K, orthorhombic, P2(1)2(1)2(1), a = 7.3869 (6), b = 11.986 (1), c = 19.896 (2) A, V = 1761.65 A3, Z = 4, Dx = 1.351, Dm(by flotation) = 1.349 g cm-3, lambda(Cu K alpha) = 1.5418 A, mu = 8.36 cm-1, F(000) = 760, T = 295 K, R = 0.0432 for 1662 observed reflections. Two terpene rings, two delta-lactones, two methyl groups, a tertiary hydroxyl group and a beta-substituted furan ring are present in the structure. The H atoms at C(12) and C(8) are alpha- and beta-oriented. The terpene ring A is locked into a boat conformation by the C(1)-C(4) lactone bridge. The furan ring is attached equatorially at atom C(12). The hydroxyl group is involved in intramolecular hydrogen bonding.

Crystallization↗