Composition and chemical polymorphism of the essential oils from Piper lanceaefolium

Essential oils obtained by hydrodistillation from leaves and spikes of Piper lanceaefolium H.B.K. of Costa Rica were analysed by GC-FID, GC-MS and 13C-NMR methods. Main constituents found in the oil from leaves were sesquiterpene hydrocarbons - especially beta-caryophyllene and germacrene D - and phenylpropanoids, of which elemicin and parsley apiol were the major ones. The volatile oil from spikes showed monoterpene hydrocarbons, namely alpha- and beta-pinene, and the same phenylpropanoids as in the oil from leaves as the major constituents. Results obtained in the analysis by GC-FID and GC-MS of the essential oils from individual plants of different geographic origin were submitted to chemometric cluster analysis and principal component analysis, showing the presence of three different types of oils (i) parsley apiol/elemicin, (ii) elemicin/parsley apiol/dill apiol, and (iii) parsley apiol/dill apiol.     

Isotope ratio by HRGC-MS of citrus Junos tanaka (yuzu) essential oils: m/z 137/136 of terpene hydrocarbons

The isotope ratios of monoterpene hydrocarbons in Citrus junos Tanaka (yuzu) essential oils from different origins were determined by ordinary high-resolution gas chromatography-mass spectrometry (HRGC-MS). Both intensities of the molecular mass peaks (m/z 136) and of the isotope peaks (m/z 137) of monoterpene hydrocarbons were measured by single-ion monitoring with an MS analysis. The isotope ratios (m/z 137/136) of the ten monoterpene hydrocarbons commonly contained in citrus essential oils, alpha-pinene, beta-pinene, sabinene, myrcene, alpha-phellandrene, alpha-terpinene, limonene, gamma-terpinene, beta-phellandrene and terpinolene, were determined in yuzu samples of the highest commercial quality from 42 different production districts. Statistical treatment of these data by the t-test and sign test revealed significant differences of the isotope effects in each yuzu sample. It is suggested that this technique will be applicable for evaluating the quality, genuineness and origin of citrus fruits and their products. The isotope fingerprints were also demonstrated in several citrus fruits other than the yuzu samples.     

Effects of storage conditions on the composition of Citrus tamurana Hort. ex Tanaka (hyuganatsu) essential oil

Compositional changes of Citrus tamurana Hort. ex Tanaka (hyuganatsu) essential oil were analyzed after storage for 1, 3, 6, and 9 weeks at -21, 5, 20, and 30 degrees C. The total amount of oxides increased greatly. The contents of monoterpene alcohols and ketones also increased. The total amount of monoterpene hydrocarbons was unchanged up to 30 degrees C. However, the contents of myrcene, gamma-terpinene, and terpinolene decreased, while there was a considerable increase in p-cymene. Among the sesquiterpene hydrocarbons, considerable increases in the (-)-cedrene, gamma-elemene, and alpha-humullene contents were noted in samples stored at 30 degrees C, and the trans-beta-farnesene content decreased during storage. The total content of monoterpene alcohols was increased slightly. The content of trans-carveol increased during storage. p-Cymene, trans-carveol, isopiperitone, and limonene oxide contents increased, while gamma-terpinene, terpinolene, and citronellal contents decreased significantly during storage. The changes of these compounds during storage can serve as a quality index for hyuganatsu essential oil.     

Essential oil composition of two myrtus communis L. varieties grown in North Tunisia

Two Myrtus communis varieties (var. italica and baetica) were studied in order to investigate their essential oil yield and composition. Essential oil yield varied in leaves, fruits and stems. So, in leaves, it was 0.5% for italica and 0.3% for baetica and was higher than in fruits and stems with respectively 0.1% and 0.04% for italica and 0.07% and 0.03% for baetica. The essential oil analysis performed by GC and GC/MS showed a composition characterized by a high percentage of monoterpene hydrocarbons in leaves, largely due to alpha-pinene with 51.3% for italica and 27.7% for baetica; 1,8-cineole, the alone compound of ether class, was predominant in fruits and stems with respectively 31.6% and 34.7% for italica and 19.8% and 25.8% for baetica.     

Composition of the essential oils in various organs at different developmental stages of Ammi visnaga (L.) Lam. from Tunisia

The composition of the essential oils isolated by hydrodistillation from various organs at different development stages of Ammi visnaga (L.) Lam. growing in Tunisia was determined by GC/MS analysis. In particular, the oil profiles of the leaves, stems, flower buds, roots, umbels, and fruits have been examined during the whole life cycle. The oil from the flowering aerial parts was characterized by a high content of isoamyl 2-methylbutanoate. After flowering and during desiccation and fructification, the umbels and fruits expressed a high content of linalool. The oils, extracted from the roots collected in the vegetatif, buds floral, and floral stages, were rich in monoterpene aldehydes, oxygenated monoterpenes, and monoterpene hydrocarbons. The highest level of non-terpene hydrocarbons was found at the flower-bud stage, represented by 61.3% of nonane. Among the monoterpenes, sabinene (12.5%) and β-pinene (8.5%) were identified in the flower buds.     

Allelopathic effect of Schinus molle essential oils on wheat germination

Gas chromatography-flame ionisation detection (GC-FID) and gas chromatography–mass spectrometry (GC–MS) analyses of the essential oils of leaves and fruits of the ornamental Shinus molle L. were reported and their allelopathic effect on wheat (Triticum aestivum L.) was evaluated. Qualitative and quantitative differences between fruit and leaf oils were observed. Both oils were rich in monoterpene hydrocarbons and the major constituents were limonene and β-phellendrene (35.9–65.4%), α-phellendrene (24.3–20.1%), myrcene (12.8–7.7%) and α-pinene (5.9–1.7%) for fruits and leaves, respectively. Both essential oils showed a dose-dependent allelopathic activity on wheat germination and radicle elongation with leaf oil being the more phytotoxic.     

Chemical composition and in vitro evaluation of antioxidant effect of free volatile compounds from Satureja montana L

As a part of an investigation of natural antioxidants from Dalmatian aromatic plants, in this paper we report a study of the antioxidant activity related to the chemical composition of savory free volatile compounds. Twenty-one compounds were identified in the essential oil without fractionation, representing 97.4% of the total oil. The major compound was phenolic monoterpene thymol (45.2%). Other important compounds were monoterpenic hydrocarbons p-cymene (6.4%) a nd gamma-terpinene (5.9%)and oxygen-containing compounds carvacrol methyl ether (5.8%), thymol methyl ether (5.1%), carvacrol (5.3%), geraniol (5.0%) and borneol (3.9%). The evaluation of antioxidant power was performed in vitro by the beta-carotene bleaching and thiobarbituric acid (TBA) methods. As determined with both methods, the total savory essential oil as well as different fractions or pure constituents containing hydroxyl group exhibited relatively strong antioxidant effect. The hydrocarbons, when isolated as CH fraction, showed the poorest effectiveness in spite the fact that this fraction contained gamma-terpinene, alpha-terpinene, p-cymene and terpinolene which previously were identified as potential antioxidants.     

Characterization of gamma-terpinene synthase from Citrus unshiu (Satsuma mandarin)

Gamma-terpinene is a monoterpene and a major component of essential oils made from citrus fruits and shows strong antioxidant activity in various assay systems. Plant gamma-terpinene synthase is a member of the monoterpene cyclase family, which produces a specific monoterpene through cyclization of geranyl diphosphate (GPP), but the monoterpene cyclases have not been fully characterized. It is necessary to prepare large amounts of gamma-terpinene synthase from Citrus unshiu (Satsuma mandarin) for the characterization, on this purpose we expressed the protein in Escherichia coli (E. coli) cells. As most monoterpene synthases have plastid-targeting signals, a gene lacking these signals was prepared and functionally expressed in E. coli cells harboring extra copies of the argU gene. The purified enzyme was incubated with GPP and the main product was confirmed to be gamma-terpinene by GC/MS.     

Isotope Ratio by HRGC-MS of Citrus junos Tanaka (Yuzu) Essential Oils: m/z 137/136 of Terpene Hydrocarbons

The isotope ratios of monoterpene hydrocarbons in Citrus junos Tanaka (yuzu) essential oils from different origins were determined by ordinary high-resolution gas chromatography-mass spectrometry (HRGC-MS). Both intensities of the molecular mass peaks (m/z 136) and of the isotope peaks (m/z 137) of monoterpene hydrocarbons were measured by single-ion monitoring with an MS analysis. The isotope ratios (m/z 137/136) of the ten monoterpene hydrocarbons commonly contained in citrus essential oils, α-pinene, β-pinene, sabinene, myrcene, α-phellandrene, α-terpinene, limonene, γ-terpinene, β-phellandrene and terpinolene, were determined in yuzu samples of the highest commercial quality from 42 different production districts. Statistical treatment of these data by the t-test and sign test revealed significant differences of the isotope effects in each yuzu sample. It is suggested that this technique will be applicable for evaluating the quality, genuineness and origin of citrus fruits and their products. The isotope fingerprints were also demonstrated in several citrus fruits other than the yuzu samples.     

Cosuppression of limonene-3-hydroxylase in peppermint promotes accumulation of limonene in the essential oil

cDNA clones encoding limonene synthase and limonene-3-hydroxylase, both driven by the CaMV 35S promoter, were independently transformed into peppermint (Menthaxpiperita) to alter the production and disposition of (-)-limonene, the first committed intermediate of essential oil biosynthesis in this species. Although both genes were constitutively expressed in leaves of transformed plants, the corresponding enzyme activities were not significantly increased in the glandular trichome sites of essential oil biosynthesis; thus, there was no effect on oil yield or composition in the regenerated plants. Cosuppression of the hydroxylase gene, however, resulted in the accumulation of limonene (up to 80% of the essential oil compared to about 2% of the oil in wild type plants), without influence on oil yield. These results indicate that limonene does not impose negative feedback on the synthase, or apparently influence other enzymes of monoterpene biosynthesis in peppermint, and suggests that pathway engineering can be employed to significantly alter essential oil composition without adverse metabolic consequences.     

Volatile flavor components of ripe and overripe ki-mikans (Citrus flaviculpus Hort. ex Tanaka) in comparison with Hyuganatsu (Citrus tamurana Hort. ex Tanaka)

The volatile flavor components of ripe and overripe ki-mikan (Citrus flaviculpus Hort. ex Tanaka) peel oil samples, which had been isolated by cold-pressing, were investigated by capillary GC and GC-MS, and compared with the Hyuganatsu (Citrus tamurana Hort. ex Tanaka) flavor. Limonene (ripe fruit, 82.44%; overripe fruit, 73.10%) was the most abundant compound in the ki-mikan oil, this being followed by gamma-terpinene (8.83% and 13.74%), trans-beta-farnesene (1.76% and 3.12%) and myrcene (1.54% and 1.13%). The composition of overripe ki-mikan oil was characterized by higher amounts of aliphatic and sesquiterpene hydrocarbons, monoterpene and sesquiterpene alcohols, ketones and esters than that of ripe ki-mikan oil. Monoterpene hydrocarbons, especially limonene (84.78%), were predominant in Hyuganatsu oil. The CPO composition of ki-mikan was qualitatively similar to that of Hyuganatsu, but differed quantitatively. The content of sesquiterpene hydrocarbons was higher in the ki-mikan oil samples than in Hyuganatsu oil, while ketones showed the opposite predominance. These differences were more evident in the trans-beta-farnesene and l-carvone contents. The ratio of both these compounds could be used to distinguish ki-mikan oil from Hyuganatsu oil.     

Chemical variability of peel and leaf essential oils of 15 species of mandarins

Peel and leaf oils of 58 mandarin cultivars, belonging to 15 different species were obtained from fruits and leaves collected on mandarin-trees submitted to the same pedoclimatic and cultural conditions. Their chemical composition was investigated by capillary GC, GC/MS and 13C NMR and the results were submitted to a cluster analysis and a discriminant analysis. Three major chemotypes, limonene, limonene/gamma-terpinene and linalyl acetate/limonene, were distinguished for peel oils while three other chemotypes, sabinene/linalool, gamma-terpinene/linalool and methyl N-methylanthranilate, were observed for leaf oils.     

Purification and characterization of the monoterpene cyclase gamma-terpinene synthase from Thymus vulgaris

The monoterpene cyclase, gamma-terpinene synthase, from Thymus vulgaris (thyme) leaves was purified to apparent homogeneity by isoelectric focusing and dye-ligand, anion-exchange, hydrophobic interaction, and gel permeation chromatography. The enzyme has a native molecular weight of 96,000 as determined by gel permeation chromatography, and exhibited a specific activity of 538 nmol/h.mg protein (turnover number of approximately 0.01/s). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed the enzyme to be composed of two apparently identical subunits of Mr approximately 55,000. The protein was very hydrophobic, and possessed a pI value of 4.85 as determined by isoelectric focusing. Maximum activity was observed at pH 6.8 in the presence of 20 mM Mg2+; 5 mM Mn2+ could support catalysis, albeit at a much lower rate. The Km value for the substrate, geranyl pyrophosphate, was 2.6 microM. Cyclase activity was inhibited by cysteine- and histidine-directed reagents. Purified gamma-terpinene synthase also possessed the ability to cyclize geranyl pyrophosphate to small amounts of alpha-thujene and to lesser quantities of myrcene, alpha-terpinene, limonene, linalool, terpinen-4-ol, and alpha-terpineol, all of which appear to be coproducts of the reaction sequence leading to gamma-terpinene. In general properties, the gamma-terpinene synthase from thyme leaves resembles other monoterpene cyclases as well as sesquiterpene and diterpene cyclases.     

Natural compounds of Palestine flora. Comparison analysis by static headspace and steam distillation GC-MS of semivolatile secondary metabolites from leaves of cultivated Palestinian Majorana syriaca

BACKGROUND: A comparative analysis by using static headspace (HS) and steam distillation (SD) GC-MS of the volatile and the semi-volatile secondary metabolites from leaves of cultivated Majorana syriaca. METHODS: The essential oils endogenous to cultivated thyme were isolated and identified by HS-GC-MS technology and compared to those from SD-GC-MS. RESULTS: The HS-GC-MS results showed that the Palestinian cultivated thyme is rich in monoterpene hydrocarbons and phenolic monoterpenes such as alpha-phellandrene, alpha-pinene, beta-myrcene, m-cymene, p-cymene, gamma-terpinene, thymol and carvacrol. In all the samples gamma-terpinene, p-cymene, thymol and carvacrol were the most abundant compounds. CONCLUSIONS: HS and SD-GC-MS have proved that most of the cultivated thyme samples examined has thymol isomer as the major phenolic constituent.     

Effect of Growth Stage on Essential‐Oil Yield and Composition of Daucus sahariensis

The essential oils obtained by hydrodistillation from Daucus sahariensis Murb . harvested at three different growth stages were characterized by GC/MS analysis. In total, 88 compounds were identified, with myristicin (29.8–51.7%), myrcene (6.7–31.1%), α‐pinene (11.6–14.8%), and limonene (5.3–11.5%) as main constituents. Monoterpene hydrocarbons were the most represented compounds in the oils of the plant samples collected during the flower‐budding and full‐flowering periods. On the contrary, during the fruiting stage, the oils were dominated by phenylpropanoids. The essential oils were subject of considerable variation in their composition during the various developmental stages, particularly concerning the content of myrcene that decreased significantly passing from the vegetative to the fruiting stage. Conversely, for myristicin, the opposite trend was observed. Furthermore, the essential‐oil yields were quite low during the flower‐budding phase (0.27%), but rapidly increased during plant development (0.63 and 0.68% for the flowering and fruiting phases, resp.).     

Chemical Studies on the Essential Oils of Foeniculum vulgare

Twenty seven chemical constituents of oils from sweet leaves, flowers and fruits of Foeniculum vulgare Mill. are examined by GC and GC-MS with both different chromatographic columns. They are 1,1-diethoxyethane, α-thujene, α-pinene, camphene, sabinene, β-pinene, myrcene, α- phellandrene, p-cymene, limonene, cineole, γ-terpinene, fenchone, camphor, terpinen-4-ol, α-terpineol, estragole, verbenone, fenchol acetate, carveol, trans-fenchol acetate, carvone, anethole, anisaldehyde, trans-anethole, methoxyphenyl acetone and benzoic acid, 4-methoxy-, othylester. The limonene is 57.8% in the essential oil from leaves, 34.2% from flowers, 13.1% from fruits, The trans-anethole is 21.8% in the essential oil from leaves, 41.2% from flowers, 63.4% from fruits.     

Chemical composition and biological activity of the essential oils of Senecio aegyptius var. discoideus Boiss

The essential oil of Senecio aegyptius var. discoideus flowers, leaves, stems and roots were isolated by hydrodistillation. Analysis of the oils by capillary GLC and GLC-mass spectrometry were performed and 34 out of 37 compounds were identified. The main component was isolated and characterized as 1,10-epoxyfuranoeremophilane using a combination of GLC, GLC-MS, and NMR analyses. The oils of flowers, leaves and stems were rich in monoterpene hydrocarbons while the root oil mainly contains furanoeremophilanes. Flower and leaf volatile oils showed significant level of antifungal activity against C. albicans, moderate effect against Gram positive bacteria, however, it has weak activity against Gram negative bacteria. The isolated sesquiterpene (1,10-epoxyfuranoeremophilane) exhibited substantial inhibitory activity against Gram negative bacteria.     

Increased and altered fragrance of tobacco plants after metabolic engineering using three monoterpene synthases from lemon

Wild-type tobacco (Nicotiana tabacum) plants emit low levels of terpenoids, particularly from the flowers. By genetic modification of tobacco cv Petit Havana SR1 using three different monoterpene synthases from lemon (Citrus limon L. Burm. f.) and the subsequent combination of these three into one plant by crossings, we show that it is possible to increase the amount and alter the composition of the blend of monoterpenoids produced in tobacco plants. The transgenic tobacco plant line with the three introduced monoterpene synthases is emitting beta-pinene, limonene, and gamma-terpinene and a number of side products of the introduced monoterpene synthases, from its leaves and flowers, in addition to the terpenoids emitted by wild-type plants. The results show that there is a sufficiently high level of substrate accessible for the introduced enzymes.     

Analysis of essential oil of Coridothymus capitatus (L.) and its antibacterial and antifungal activity

The water-distilled essential oil the leaves of Coridothymus capitatus were analyzed by GC/MS and also analyzed by direct thermal desorption GC/MS. Comparison was made between two analyses techniques. The essential oil consisted mainly of monoterpenes 98.9%, while oxygenated hydrocarbons were identified as 55.6 % and non-oxygenated hydrocarbons as 43.6%. As major components were found carvacrol (35.6%), p-cymene (21.0%), thymol (18.6%), gamma-terpinene (12.3%), alpha-terpinene (3.2%), beta-myrcene (3.0%) and alpha-thujene (1.3%) by hydrodistillation and by the GC/MS method. The direct thermal desorption GC/MS analysis also showed the same major components, namely carvacrol (51.6%), thymol (21.7%), p-cymene (9.7%) gamma-terpinene (8.2%), alpha-terpinene (1.64%). The essential oil of C. capitatus showed strong activity against S. aureus, P. vulgaris, P. aeruginosa, E. coli, K. pneumonia, B.