scispace - formally typeset
Search or ask a question

Showing papers on "Terpene published in 1997"


Journal ArticleDOI
19 Sep 1997-Science
TL;DR: These structures reveal an unexpected enzymatic mechanism for the synthesis of the bicyclic product, 5-epi-aristolochene, and provide a basis for understanding the stereochemical selectivity displayed by other cyclases in the biosynthesis of pharmacologically important cyclic terpenes.
Abstract: Terpene cyclases catalyze the synthesis of cyclic terpenes with 10-, 15-, and 20-carbon acyclic isoprenoid diphosphates as substrates. Plants have been a source of these natural products by providing a homologous set of terpene synthases. The crystal structures of 5-epi-aristolochene synthase, a sesquiterpene cyclase from tobacco, alone and complexed separately with two farnesyl diphosphate analogs were analyzed. These structures reveal an unexpected enzymatic mechanism for the synthesis of the bicyclic product, 5-epi-aristolochene, and provide a basis for understanding the stereochemical selectivity displayed by other cyclases in the biosynthesis of pharmacologically important cyclic terpenes. As such, these structures provide templates for the engineering of novel terpene cyclases.

663 citations


Journal ArticleDOI
TL;DR: 13C Enrichment and 13C13C coupling patterns showed conclusively that 1-deoxy-D-xylulose and not mevalonate is the predominant isoprenoid precursor of phytol, beta-carotene, and lutein.
Abstract: The incorporation of [1-13C]- and [2,3,4,5-13C4]1-deoxy-d-xylulose into β-carotene, lutein, phytol, and sitosterol in a cell culture of Catharanthus roseus was analyzed by NMR spectroscopy. The labeling patterns of the isoprene precursors, isopentenyl pyrophosphate and dimethylallyl pyrophosphate, were obtained from the terpenes by a retrobiosynthetic approach. 13C Enrichment and 13C13C coupling patterns showed conclusively that 1-deoxy-d-xylulose and not mevalonate is the predominant isoprenoid precursor of phytol, β-carotene, and lutein. Label from 1-deoxyxylulose was also diverted to phytosterols to a minor extent (6% relative to carotene and phytol formation). The data demonstrate that the formation of isopentenyl pyrophosphate from pentulose occurs strictly by an intramolecular rearrangement process.

383 citations


Journal ArticleDOI
TL;DR: In this article, 17 kinds of monoterpenoids (hydrocarbons, alcohols, and ketones) with p-menthane skeletons were studied for inhibition of AChE.
Abstract: Inhibition of acetylcholinesterase (AChE) activity by 17 kinds of monoterpenoids (hydrocarbons, alcohols, and ketones) with p-menthane skeletons was studied. Inhibition of AChE was measured by the colorimetric method. The terpene ketones showed stronger inhibition than the terpene alcohols. The terpene hydrocarbon compounds showed identical inhibitory activity with the terpene alcohols, but α-terpinene and (+)-p-menth-1-ene were equally strong inhibitors as the terpene ketones. Monoterpenoids used in this study were found to be competitive inhibitors. Keywords: Acetylcholinesterase; monoterpenoids; p-menthane skeleton; inhibition of enzyme activity; competitive inhibitor

205 citations


Journal ArticleDOI
TL;DR: In this article, four strains of Saccharomyces cerevisiae and native yeasts were evaluated for their influence on White Riesling-conjugated aroma precursors, which were measured using three analytical procedures.

82 citations


Journal ArticleDOI
TL;DR: The glycosides in mono-, di- and trihydroxylated terpene and norisoprenoid alcohols and also those in the related shikimate pathway have been isolated on C18 reversed-phase cartridges and fractionated into classes of different polarity at increasing percentages of methanol.

70 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of terpenes as penetration enhancers (e.g. carvone, 1,8-cineole and thymol) was studied on the in vitro percutaneous absorption of the model hydrophilic compound 5-fluorouracil through porcine epidermis.

62 citations


Journal ArticleDOI
TL;DR: In this paper, the ozone scrubber was tested for sampling of terpene oxidation products on Tenax and dinitrophenylhydrazine impregnated C 18 -silicagel cartridges.

32 citations


Journal ArticleDOI
TL;DR: The photohydroperoxidation of the stereoisomers of three terpenes has been performed by using photocatalysts such as zinc oxide, or sensitizers, such as anthracene or rose Bengal, supported on cross-linked polystyrene as discussed by the authors.
Abstract: The photohydroperoxidation of the stereoisomers of three terpenes ((+) and (−) α-pinene, (+) and (−) β-pinene and (+) and (−) limonene) has been performed by using photocatalysts, such as zinc oxide, or sensitizers, such as anthracene or rose Bengal, supported on cross-linked polystyrene. Hydroperoxides accumulated alone in the first stages of sensitized oxidation but were always associated with alcoholic and carbonyl products in the case of ZnO. Secondary products obtained for longer exposure times in sensitized oxidations were identified by gas chromatography/mass spectrometry and mechanisms for their formation, deriving from the photolysis of parent hydroperoxides, were suggested.

23 citations



DOI
01 Jan 1997
TL;DR: The terpenoid language as mentioned in this paper is a language of compounds containing an integer number of 5C units, the "syllables", resulting from the sequential combination of these basic five-carbon units in the familiar categories of C10 (mono), C15 (sesqui-), C20 (di-), c30 (tri-) C40 (tetra-) and C>40 (poly-) terpenoids.
Abstract: Terpenoids are compounds containing an integer number of 5C units, the «syllables». There is an astonishing array of structures, the «words», resulting from the sequential combination of these basic five-carbon units in the familiar categories of C10 (mono-), C15 (sesqui-), C20 (di-), C30 (tri-) C40 (tetra-) and C>40 (poly-) terpenoids. Terpenoids are induced and emitted in response to internal (genetic and biochemical) and external (ecological) factors, both abiotic and biotic. They are emitted in quantitatively and qualitatively diverse blends, the «messages», that arrive to the environment either through volatilization (monoand sesquiterpenes), leaching or decomposition of plant debris. Their information or effect is received and responded by other parts of the plant, other plants, animals and microorganisms. Part of such terpenoid «words» are common to all plants. For example, carotenoids, chlorophylls or hormones such as cytokinins, gibberellins, or abscicic acid, are terpenoid derivatives. But there are also «dialects» of the terpenoid «language» that are qualitatively or quantitatively characteristic of each family and each species, or even each cultivar and each organ of the plant. They even seem to be kept in «memory». Some plants might remember previous exposures and produce terpenes (and compounds of other chemical languages such as phenolics or alkaloids) when they are needed. Thus, plants also have languages, and that of terpenoids is one of them.

13 citations


Patent
16 May 1997
TL;DR: Citrus terpene-containing composition contains 40 - 60 wt. % citrus terpenes, 15 - 30 wt% water-soluble solvent, 10 - 20 wt % surfactant and 1 - 5 wt%.
Abstract: Citrus terpene-containing composition contains 40 - 60 wt. % citrus terpene, 15 - 30 wt. % water-soluble solvent, 10 - 20 wt. % surfactant and 1 - 5 wt. % quaternary ammonium compound, with water making up the remainder.


Journal ArticleDOI
TL;DR: In this article, a cluster analysis was applied to the GC data on oxygenated terpenes of various samples of young leaves and green fruits of Japanese pepper (Xanthoxyum piperitum DC.) to select superior cultivars rich in flavoring potency.
Abstract: Cluster analysis was applied to the GC data on oxygenated terpenes of various samples of young leaves and green fruits of Japanese pepper (Xanthoxyum piperitum DC.) to select superior cultivars rich in flavoring potency. Of 74 leaf samples, six samples were rich in citronellal, linalool, isopulegol, piperitone, geranyl acetate, citronellol, and geraniol. Of 71 fruit samples, three samples were rich in isopulegol, piperitone, geranyl acetate, methoxycitronellal, and geraniol, and nine samples were rich in citronellal, linalool, citronellyl acetate, γ-terpineol, and citronellol. Similarity in the clusterings of the leaf and fruit samples were not observed. Of 78 plants, only one plant gave young leaves and green fruits rich in citronellal, linalool, isopulegol, geranyl acetate, and citronellol. Keywords: Japanese pepper; volatile compounds; cluster analysis

Journal Article
TL;DR: Toha-jeot, a traditional salt-fermented seafood in Korea, was purchased on the market in order to analyze the flavor compounds Volatile flavor compounds were detected by vacuum simultaneous steam distillation-solvent extraction/gas chromatography/mass spectrometry.
Abstract: Toha-jeot, a traditional salt-fermented seafood in Korea, was purchased on the market in order to analyze the flavor compounds Volatile flavor compounds in unfermented and fermented Toha-jeot were compared by vacuum simultaneous steam distillation-solvent extraction/gas chromatography/mass spectrometry A total of 104 volatile flavor compounds were detected in both samples Of these, 66 were positively identified, composed of aldehydes(14), ketones(8), alcohols(30), terpenes(20), sulfur-containing compounds(10), aromatic compounds (6), esters(12) and miscellaneous compounds(8) Levels of several other compounds such as aldehydes, terpenes, sulfur-containing compounds and esters decreased with fermentation time, whereas alcohols, ketone and aromatic compounds increased Particularly, levels of alcohols in fermented Toha-jeot was 21 times higher than those of unfermented one Major volatile flavor compounds in both samples were composed of terpenes, sulfur-containing compounds, esters and ethanol




Journal Article
TL;DR: In this article, a Rosin-terpene-maleic resins were prepared from an intermediate product of rosin and turpentine production, crude turpentines, in the presence of LiI, NaI, and KI as catalysts.
Abstract: Rosin-terpene-maleic resins were prepared from an intermediate product of rosin and turpentine production, crude turpentine, in the presence of LiI, NaI, and KI as catalysts. The optimum synthesis conditions were determined, and the physicochemical properties of the resins were studied.









01 Jan 1997
TL;DR: In this article, the authors present a screening for microorganisms converting limonene into carvone, showing that the degradation pathway used by the seven microorganisms unable to grow on perillyl alcohol is obtained by performing oxygen uptake experiments.
Abstract: Publisher Summary This chapter presents screening for microorganisms converting limonene into carvone. Terpenes are natural, unsaturated hydrocarbons derived from isoprene units. They are widely distributed in nature and their oxygenated derivatives, commonly named “terpenoids,” are important flavor compounds. The tools of molecular genetics provide the opportunity to express individual terpene-oxidizing enzymes in new bacterial hosts, or to selectively knock out steps in the host strain. Limonene is an important by-product of the citrus processing industry. Potentially, this compound can be used as a substrate for the production of several terpenoids with important flavor characteristics such as menthol, carvone and dihydrocarvone. Monoterpenes are hydrophobic compounds which diffuse freely over the cell membrane. Therefore, microorganisms degrading limonene via carvone should also be able to grow on carvone. An indication for the degradation pathway used by the seven microorganisms unable to grow on perillyl alcohol is obtained by performing oxygen uptake experiments.