Showing papers on "Terpene published in 2009"

Total synthesis of eudesmane terpenes by site-selective C–H oxidations

Abstract: From menthol to cholesterol to Taxol, terpenes are a ubiquitous group of molecules (over 55,000 members isolated so far) that have long provided humans with flavours, fragrances, hormones, medicines and even commercial products such as rubber. Although they possess a seemingly endless variety of architectural complexities, the biosynthesis of terpenes often occurs in a unified fashion as a 'two-phase' process. In the first phase (the cyclase phase), simple linear hydrocarbon phosphate building blocks are stitched together by means of 'prenyl coupling', followed by enzymatically controlled molecular cyclizations and rearrangements. In the second phase (the oxidase phase), oxidation of alkenes and carbon-hydrogen bonds results in a large array of structural diversity. Although organic chemists have made great progress in developing the logic needed for the cyclase phase of terpene synthesis, particularly in the area of polyene cyclizations, much remains to be learned if the oxidase phase is to be mimicked in the laboratory. Here we show how the logic of terpene biosynthesis has inspired the highly efficient and stereocontrolled syntheses of five oxidized members of the eudesmane family of terpenes in a modicum of steps by a series of simple carbocycle-forming reactions followed by multiple site-selective inter- and intramolecular carbon-hydrogen oxidations. This work establishes an intellectual framework in which to conceive the laboratory synthesis of other complex terpenes using a 'two-phase' approach.

Air oxidation increases skin irritation from fragrance terpenes.

Abstract: Background: Linalool and limonene are common fragrance terpenes that autoxidize on air exposure. The pure compounds are not allergenic but their oxidation products can cause contact allergy. Little has been investigated regarding the irritancy of oxidized terpenes. Aim: The aim of this study was to investigate the irritating effect of pure and oxidized R-limonene and linalool in concentration series and to study the MNIC (Maximum Non Irritant Concentration) of autoxidized linalool and limonene. Patients/methods: Patch testing was performed in dermatitis patients and controls with sequentially diluted concentrations of oxidized and non-oxidized linalool, and oxidized and non-oxidized R-limonene. Readings were made with visual assessment and using laser Doppler imaging. Results: The non-oxidized terpenes were non-irritating in all tested concentrations. Both linalool and especially R-limonene were more irritating after oxidation compared with the pure compounds. No difference in response was seen between dermatitis patients and controls. Conclusion: Autoxidation of the fragrance terpenes linalool and R-limonene increases irritation. Oxidized linalool is less irritating than oxidized R-limonene. In this study, we found no advantages in using laser Doppler technique compared with visual assessment.

Terpenes from Eupatorium adenophorum and their allelopathic effects on Arabidopsis seeds germination.

Abstract: The invasive plant Eupatorium adenophorum Spreng. (or Ageratina adenophora (Spreng.) King and Robinson) (Compositae) has caused great economic loss in China, especially the southwestern region, and is gravely threatening the native biodiversity. The aerial part of this plant was phytochemically investigated for its allelochemicals. Eleven terpenes (2 monoterpenes and 9 sesquiterpenes) were isolated and identified, which include a new monoterpene, (-)-(1R*,2S,*4R*,5S*)-3,3-dimethyl-5-hydroxybicyclo[2,2,1]hept-2-ylmethanol (1), two new cadinane sesquiterpenes, (-)-(5S*,6S*,7S*,9R*,10S*)-7-hydroxy-5,7-epidioxycadinan-3-ene-2-one (2) and (+)-(5S*,6R*,9R*,10S*)-5,6-dihydroxycadinan-3-ene-2,7-dione (3), and eight known terpene compounds (4, 6-12). The new structures were established by spectroscopic studies such as 1D- and 2D-NMR and MS analyses. Meanwhile, the potential allelopathic effects of these compounds on the Arabidopsis seeds germination were tested. Compounds 3 and 7 retarded the Arabidopsis seeds germination at 0.5 mM and 1.0 mM concentrations, respectively, while other compounds showed no obvious inhibitory effects.

Yields of Carbonyl Products from Gas-Phase Reactions of Fragrance Compounds with OH Radical and Ozone

Abstract: Chamber studies to quantify formation yields of oxygenated organic reaction products were performed for gas-phase reactions of the hydroxyl radical (OH*) and ozone (03) with the common cleaning product terpene compounds limonene, alpha-terpineol, and geraniol. The reaction products observed were identified and quantified using derivatization by O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) and gas chromatography/mass spectrometry. Limonene rate constants and product mechanisms have been examined previously. Several of these investigations have measured productyields from limonene reactions and those results are compared with the results presented here. Although rate constants and product mechanisms have previously been investigated for alpha-terpineol and geraniol, yields of oxygenated organic reaction products have not been measured. Reactions from the fragrance compounds in this study produced several dicarbonyl reaction products such as glyoxal, methylglyoxal, and 4-oxopentanal which were observed from all three terpenes. Total carbonyl yields ranged from 5.1% for the limonene + O3 reaction to 92% for the geraniol + O3 reaction.

Content and composition of volatile terpenes, flavonoids and phenolic acids in Greek oregano (Origanum vulgare L. ssp. hirtum) at different development stages during cultivation in cool temperate climate.

Abstract: Plants of Origanum vulgare ssp. hirtum (Greek oregano) were cultivated in two years in a cool temperate climate and the aerial parts were harvested at up to five different development stages during the growing season (July to late August) in order to investigate how the content of volatile terpenes and polyphenols depends on the development stage of the plants. Volatile terpenes were identified and quantified in dichloromethane extracts by GC-MS and GC-FID, respectively. Polyphenols were quantified in aqueous methanol extracts by RP-HPLC-PDA and identified by LC-PDA-MS and NMR spectroscopy. Significant changes in the concentrations and composition of major volatile terpenes (carvacrol, γ-terpinene, p-cymene, myrcene, α-pinene, β-caryophyllene, thymol) were observed at the different development stages. The content of volatile terpenes varied from 3.7–4.9 % (year 1) and 2.6–4.6 % (year 2). The potential yields of total volatile terpenes varied from 74–165 kg ha–1 (year 1) and 31–79 kg ha–1 (year 2) being highest near full flowering stage (50–60 % open flowers). Major polyphenols were eriodictyol 6,8-di-C-glucoside, apigenin 6,8-di-C-glucoside, luteolin 7-O-glucuronide, epi-lithospermic acid B, lithospermic acid B and rosmarinic acid. The content of flavonoids varied from 4.8–7.7 mg g–1 dry matter (DM) (year 1) and 8.9– 12.4 mg g–1 DM (year 2), and phenolic acids from 1.4– 10.1 mg g–1 DM (year 1) and 23.4–51.5 mg g–1 DM (year 2). The highest content of flavonoids in aerial parts was obtained near full flowering stage and for phenolic acids earlier at around 10–20 % open flowers. The conclusion of this study is that also in a cool temperate climate the development stage has a significant impact on the content and composition of both volatile terpenes and polyphenols in O. vulgare ssp. hirtum, and that an optimal harvest time of aerial parts of this plant depends on the secondary metabolites of interest.

QCM sensor array for monitoring terpene emissions from odoriferous plants

Abstract: An e-nose comprised of six sensing channels each coated with a molecularly imprinted polymer (MIP) selectively interacting with alpha-pinene, thymol, estragol, linalool, and camphor, respectively, was designed. When applying it for continuous online surveillance of terpenes emitted from basil and peppermint leaves as a criterion of freshness, it very appreciably reproduced the emanation patterns from these plants as shown by GC-MS. Chromatography yielded a variety of terpenes in a concentration range below 70 ppm. Trend lines obtained from the e-nose were corroborated by GC-MS and also appreciably fit the usual conduct of these plants as observable by the human nose.

Disappearance of nine monoterpenes exposed in vitro to the rumen microflora of dairy goats: Effects of inoculum source, redox potential, and vancomycin

Abstract: This in vitro study evaluated the roles of diet type and redox potential in the degradation of linalool, (E)- and (Z)-β-ocimene, α-phellandrene, (−)-β-pinene, (−)-α-pinene, (+)-α-pinene, sabinene, and α-terpinene when incubated with rumen microflora, and it provided information on the time course of their disappearance. The 9 monoterpenes are found in the winter and spring diets of dairy goats in northwestern Mediterranean grazing systems. The diets were individually exposed to rumen microflora for 3 h in 17-mL culture tubes at a concentration of 4 μL/L. The mixed flora of the inoculum was controlled by the use of vancomycin (eliminating gram-positive bacteria) and by the energy source (starch vs. structural polysaccharides) on which rumen microflora had been grown. Redox potential was controlled by addition of l-cysteine-hydrochloride. The preliminary adaptation of microbial inoculum to a diet rich in structural carbohydrates reduced the recovery yields of (E)- and (Z)-β-ocimene, (−)-β-pinene, (−)-α-pinene, (+)-α-pinene, and sabinene (P < 0.01), whereas vancomycin was without effect. The effect of carbohydrate source likely stems from the specific composition of the microbial community rather than from its acidogenic capacity. Reducing the culture redox potential by 50 mV reduced the recovery yields of linear and monocyclic terpenes (P < 0.02), and the culture redox potential interacted with the inoculum source for (E)- and (Z)-β-ocimene and for α-phellandrene. The time course of terpene disappearance was studied by exposing terpenes to a rumen microflora adapted either to starch or to fiber for 3, 6, or 24 h. The degraded fraction reached a plateau within 3 h for α-phellandrene and for all the isomers of β-ocimene and pinene with the fiber-adapted microflora as well as with both inocula for α-terpinene. With the starch-adapted microflora, this steady state was reached for most other terpenes within 6 h of incubation. Sabinene was the only compound still disappearing after an incubation period of 6 h. Biotic and environmental variables in the rumen affected terpene degradation in a way that can alter the dietary terpene profile and possibly its influence on animal product characteristics.

In vitro degradation by mixed rumen bacteria of 17 mono- and sesquiterpenes typical of winter and spring diets of goats on Basilitica rangelands (southern Italy).

Abstract: BACKGROUND: Nine monoterpenes (δ-3-carene, p-cymene, limonene, β-myrcene, (E)- and (Z)-β-ocimene, α-phellandrene, α-terpinene, γ-terpinene), seven oxygenated monoterpenes (1,8-cineole, linalool, (E)- and (Z)-linalool oxide, 4-terpinenol, α-terpineol, α-terpinolene) and one sesquiterpene (β-cedrene) were investigated for their degradability in the rumen microbial ecosystem. These molecules were identified as dominant terpenes in the winter and spring diets of milking goats in Basilicata (southern Italy). RESULTS: All terpenes were tested at 3.33 µL L−1 for 24 h using in vitro incubation with mixed rumen bacteria from dairy goats. Oxygen-containing compounds were those recovered at the highest levels (89% of (E)-linalool oxide, 93% of (Z)-linalool oxide, 91% of 1,8-cineole, 82% of terpineol and 72% of 4-terpinenol), except linalool. The linear alkenes β-myrcene and β-ocimene almost completely disappeared. Results were more variable among cyclic alkenes, with recovery rates ranging from 50% in the case of limonene to less than 1% for α-phellandrene. 17% of the only sesquiterpene of the group, β-cedrene, was recovered. CONCLUSION: Recovery rates differed markedly among terpenes, partly in relation to the presence of oxygen and rings in the molecules. These observations should contribute to a better understanding of the changes in composition between the diet and milk terpenes. Copyright © 2008 Society of Chemical Industry

Chemical Compositions of Aerial Part of Tagetes minuta L. Chemotype Essential Oils From Madagascar

Abstract: The chemical composition of 18 essential oil samples of the aerial parts of various flower color types of Tagetes minuta from Madagascar has been characterized by GC and GC/MS. The main components were limonene (3.6–11%), (Z)-β-ocimene (1.0–17.1%), (E)- β-ocimene (0.5–14.6%), p-cymene (0.3–20.4%), β-caryophyllene (1.1–12.7%), (Z)- tagetenone (tr-26.7%), (E)-tagetenone (tr-31.3%), α-muurolene (tr-36.5%), and verbenone (1.4–15.4%). Results show the occurrence of various chemotypes reach in tagete derivatives (up to 80%) or in terpene derivatives (up to 76%).

Thienyl analogues of acyclic monoterpene alcohols and their biological activity

Abstract: BACKGROUND: Thienyl analogues of linalool, geraniol, nerol and citronellol were synthesised and their sensory and antimicrobial activities were investigated. RESULTS: The thienyl analogues of linalool, geraniol, nerol and citronellol, in which the isobutenyl moiety was replaced by a thiophene substituent, were synthesised from commercially available 2- and 3-methylthiophenes and 2- and 3-thiophenecarboxaldehydes. The olfactory properties of the new compounds were generally of the corresponding parent terpene type; however, their relative volatility determined by the headspace gas chromatography method was lower by a factor of 34 – 42 compared with the parent alcohols. Antimicrobial activity against Aspergillus niger and Penicillium expansum of some thienyl analogues of linalool was 1.5 – 3 times higher than that of linalool, with a minimum inhibitory concentration of 0.2 – 0.1 µ Lm L −1 . CONCLUSION: Replacement of the isobutenyl moiety in acyclic monoterpene alcohols by a thienyl substituent results in the formation of new terpene analogues, some of which are interesting for perfumery and cosmetology because of their odour quality, tenacity and antimicrobial action. c � 2009 Society of Chemical Industry

Efficient synthesis of azo dye labeled terpenes, sugars, and steroids using N-(4-arylazobenzoyl)-1H-benzotriazoles

Abstract: N-(4-Arylazobenzoyl)-1H-benzotriazoles react with hydroxyterpenes, sugars, and steroids in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) at room temperature in tetrahydrofuran to afford azo dye labeled terpenes, sugars, and steroids (45-82% yield).

GC-MS Analysis of Terpenes from Ficus mucuso

Abstract: Fractionation of the CH2Cl2/MeOH extract of the stem bark of Ficus mucuso, a western Cameroonian plant species lead to five main fractions from which eleven terpenes previously reported from other species of the genus were identified. These were based on GC-MS analysis and comparison with the Willey database.

Compositions comprising terpene compounds for treating negative sensory phenomena

Abstract: Compositions comprising terpene compounds for the treatment of negative sensory phenomena (NSP). Negative sensory phenomena is characterized by a decreased ability to sense light touch, pin prick, vibration, temperature, pain and/or reduced proprioception. The terpene compounds are preferably aromatic terpene compounds such as geraniol and citronellol and analogs thereof. The terpenes may also be used in combination. The terpenes are derived form plant essential oils or are manufactured synthetically.

Post-modification Enzymes Involved in the Biosynthesis of Plant Terpenoids

Abstract: Terpenoids are called "terpenome" for their structural diversities. Besides their important roles in plant growth, development and environmental responses, terpenoids have been widely used in medicine and organic chemicals. The biosynthesis of terpenoids in plants can be conceptually divided into three discrete processes: the formation of terpene precursors, the construction of terpene skeletons, followed by the complex post-modifications. After the skeleton construction by terpene synthases (TPS), diverse reactions catalyzed by the responsible post-modification enzymes result in tens of thousands of terpenoids. In this paper, with our preliminary studies on the biosynthesis of Isodon diterpenes, a number of representative post-modification enzymes of plant terpenoids formation reported in recent years are reviewed, which include P450 monooxidases, double-bond reductases, acyltransferases and glycosyltransferases.

Hydrogenation of CO(2)-Expanded Liquid Terpenes: Phase Equilibrium-Controlled Kinetics

Abstract: The hydrogenation of two liquid terpenes, alpha-pinene and limonene, was carried out in the presence of high-pressure carbon dioxide, using carbon-supported Pt catalysts. Phase equilibrium data on terpene + CO(2) + hydrogen were used to interpret the kinetics of hydrogenation in liquid + vapor systems close to the critical lines of the mixtures.

A Biomimetic Approach to Some Specifically Functionalized Cyclic Terpenoids

Abstract: The paper relates on the current advancements in the synthesis of complex cyclic terpenoids by superacidic induced cyclization of open chain precursors. It is shown that functional groups disposal in the initial substrate strongly influences the reaction outcome. Possible variations of the investigated compound structures include particularly alpha-functionalization and alpha,omega-bifunctionalization. This approach allowed a selective initiation of cyclization sequence from an internal double bond or suspending the ring closure cascade to partially cyclized compounds. The reported synthetic schemes are attempts to mimic the biogenetical processes postulated in the living systems.

Enhanced biotransformation of TCE using plant terpenoids in contaminated groundwater.

Abstract: Aims: To examine plant terpenoids as inducers of TCE biotransformation by an indigenous microbial community originating from a plume of TCE-contaminated groundwater. Methods and Results: One-litre microcosms of groundwater were spiked with 100 mol 1-1 of TCE and amended weekly for 16 weeks with 20 l 1-1 of the following plant monoterpenes: linalool, pulegone, R- (+)-carvone, S- (-)carvone, farnesol, cumene. Yeast extract- and un-amended control treatments were also prepared. The addition of R- and S-carvone, linalool and cumene resulted in the biotransformation of upwards of 88 % of the TCE, significantly more than the unamendment control (61 %). The aforementioned group of terpenes also significantly (P < 0.05) allowed more TCE to be degraded than the remaining two terpenes (farnesol and pulegone) and the yeast extract treatment which biotransformed 74-75 % of the TCE. The microbial community profile was monitored by denaturing gradient gel electrophoresis and demonstrated much greater similarities between the microbial communities in terpene-amended treatments than in the yeast extract or unamended controls. Conclusions: TCE biotransformation can be signficantly enhanced through the addition of selected plant terpenoids. Significance and Impact of Study: Plant terpenoid and nutrient supplementation to groundwater might provide an environmentally benign means of enhancing the rate of in situ TCE bioremediation.

Analysis of Leaf Essential Oil Constituents of Cinnamomum zeylanicum Grown in Nigeria

Abstract: Cinnamomum zeylanicum Blume (Luraceae) of Nigerian origin was investigated for the essential oil constituents of its leaves by combined gas chromatographic (GC) and gas chromatographic-mass spectrometry (GC-MS). Thirty one compounds representing 99.1 % of total oil were fully characterized. The plant oil was dominated by the non-terpene compound, benzyl benzoate (74.8 %). Terpenes were represented mainly by α-pinene (2.6 %), linalool (2.4 %), β-pinene (1.4 %), camphene (1.3 %), limonene (1.3 %) and α-phellandrene (1.2 %) in the monoterpene class; and by β-caryophyllene (3.2 %) in the sesquiterpene class. The plant belongs to a different chemical variety compared with similar species from elsewhere.