Simulation of Eucalyptus cinerea oil distillation: A study on optimization of 1,8-cineole production

Cineolic essential oils are used in medicinal, perfumery and flavour preparations. 1,8-Cineole, being an ecofriendly compound, has the potential to replace the ozone depleting industrial solvents. Optimized process parameters for hydrodistillation and production of essential oil enriched with 1,8-cineole from Eucalyptus cinerea grown in the mid-hills of western Himalaya, were reported. The effect of drying of the foliage prior to distillation with respect to oil composition and content was studied. The first order kinetic and Langmuir adsorption models were evaluated to simulate hydrodistillation of E. cinerea oil. The Langmuir model parameters that simulate the hydrodistillation process were determined. GCMS analysis revealed that the oil produced from fresh foliage contained higher 1,8-cineole content (84.4%) than the dried foliage (77.6%). The other major constituents were limonene and α-terpineol.     

Chemical composition of essential oils of four Eucalyptus species and their phytotoxicity on silverleaf nightshade (Solanum elaeagnifolium Cav.) in Australia

Phytotoxicity and chemical composition of essential oils from four selected Eucalyptus species in Australia were investigated. Essential oils had stronger inhibitory effects on germination and seedling growth of silverleaf nightshade (Solanum elaeagnifolium Cav.) when compared with a commercial eucalyptus oil and with 1,8-cineole. E. salubris oil had the highest inhibition index for silverleaf nightshade germination, root growth and shoot growth, while E. spathulata had the lowest inhibitory effect except root growth. Gas chromatography-mass spectrometry analysis revealed 56 compounds present in E. salubris oil, with 1,8-cineole (57.6?%), ??-pinene (10.9?%) and p-cymene (8.3?%) predominant. E. dundasii oil contained 55 identified compounds with 1,8-cineole (65.5?%) and ??-pinene (19.9?%) being the richest fractions. There were 56 compounds identified from E. brockwayii oil with ??-pinene (31.1?%), isopentyl isovalerate (20.2?%) and 1,8-cineole (16.9?%) as the most abundant components. E. spathulata oil contained 60 compounds, predominantly 1,8-cineole (52.9?%) and ??-pinene (31.0?%). Further study is required to determine the phytoxicity of the individual identified compounds on silverleaf nightshade and whether the observed phytotoxicity is attributable to a single compound or to the synergistic effects of several compounds.     

Influence of growth phase on the essential oil composition of Hyptis suaveolens

The chemical composition of the essential oils of seven populations of Hyptis suaveolens in vegetative, flowering and fruiting stages and their interpopulation variability were investigated by GC–MS. Sabinene, limonene, 1,8-cineole, (E)-caryophyllene and spathulenol were the principal constituents. The results from the chemical analysis were submitted to Principal Component and Chemometric Cluster Analysis which allowed five groups of populations to be distinguished with respect to the stage of growth and high content of bicyclogermacrene/terpin-4-ol, sabinene, 1,8-cineole/spathulenol, limonene/γ-terpinene and spathulenol/(E)-caryophyllene. Pattern of geographic-variation in essential oil composition indicated that monoterpene hydrocarbons were mainly produced in plants from sampling sites located in higher latitudes and altitudes regardless of the phase of growth, while sesquiterpenes were mainly produced in fruiting samples grown at lower ones. The Canonical Correlation Analysis between the soil sampling sites with the populations revealed a significant relationship between oil components and edaphic factors. Sesquiterpenes and potential acidity, Al, and Al saturation load fairly strong onto the first canonical variate and are related to fruiting samples collected at lower latitudes. On the other hand, monoterpene hydrocarbons are strongly related to chemical balance in soils (P, Zn, Cu, Mn, base saturation, neutral pH), which is related to the vegetative/flowering sampling at higher latitudes.     

RNAi targeting the gene for 1,8-cineole synthase induces recomposition of leaf essential oil in lavandin (Lavandula × intermedia Emeric)

Recomposition of volatile compounds is an effective way to alter the fragrance of an essential oil. Using RNA interference (RNAi), we attempted to reduce the production of 1,8-cineole, a major monoterpene in essential oils, to alter the composition of the essential oil in lavandin. We obtained 12 transgenic regenerants via inoculation with Agrobacterium tumefaciens, including an RNAi inducing vector targeting five regions of the gene for 1,8-cineole synthase (CINS). Of these, two regenerants, targeting a coding region about 250 nt upstream with 5′-UTR and a coding region about 300 nt downstream of CINS mRNA (CINS I and V), respectively, showed a significant decrease of 1,8-cineole production in leaf essential oil, although the overall composition was barely altered because the production of other compounds decreased concurrently. By contrast, in two other regenerants, targeting a coding region about 1000 nt in the middle and a coding region about 300 nt downstream of CINS mRNA (CINS IV and V), respectively, 1,8-cineole production could be barely observed, without any decrease in production of other compounds. Expression of CINS in these transgenic regenerants was extremely suppressed to 0.02 and 0.08 of that of a nontransgenic regenerant control. The composition of leaf essential oil in the transgenic regenerants was changed by the RNAi. Specifically, the major compounds changed from 1,8-cineole, camphor, and borneol, to linalool, camphor, and borneol. Consequently, the fragrance of essential oils of these plants was perceived as more citrusy than the fragrance of the nontransgenic regenerant. These results suggest that the knockdown strategy was a useful tool for altering the fragrance in lavandin.

     

Essential oil variability within and among populations of Cunila incisa Benth.

To evaluate the intra- and interpopulational variability of volatile compounds in Cunila incisa, 72 samples representing 12 populations, were collected all over the distribution area of the species in Rio Grande do Sul State. The samples were extracted by steam distillation and analyzed using GC and GC–MS. A total of 19 volatile compounds were detected and identified. In average, the main compounds were 1,8-cineole, α-terpineol, p-cymene, sabinene, terpinene-4-ol, and γ-terpinene. Negative correlation was detected between the concentrations of 1,8-cineole and α-terpineol. Significant variation in the concentration of volatile compounds was detected within and among populations. Multivariate analysis of volatile oil composition identified three groups. Most populations exhibited low intra-populational variation indicating foundation effect. Relation between geographic distribution and chemical composition was observed.     

Investigation of monoterpenoids rich essential oils of two Ocimum basilicum L. varieties at different agro-climatic conditions in India

India is an emerging basil essential oil producer in South-east Asia. Two high essential oil yielding hybrids, namely one inter specific hybrid between of O. basilicum and O. kilimandscharicum Gürke (HYBL-1) and another intraspecific hybrid of O. basilicum × O. basilicum (OBL-1) of basil were analyzed using GC, enantiomeric GC, NMR, enantio-GC–MS and GC–MS methods. Inter specific hybrid HYBL-1 contained high essential oil-rich in linalool (68.5%), camphor (8%), and 1,8-cineole (4.6%) as characteristic constituents among monoterpenoids, whereas β-caryophyllene (1.9%), germacrene D (1.0%), and epi-α-cadinol (1.9%) were the sesquiterpenoids at the Lucknow (North Indian conditions) and linalool (71.8%), camphor (9.4%) and 1,8-cineole (4.3%) at Hyderabad (South Indian conditions) locations. Intraspecific hybrid (OBL-1) possessed linalool (66.1%), 1,8-cineole (5.4%) and geraniol (8.6%) with sesquiterpenoids in low proportions. Inter specific hybrid HYBL-1 showed superiority over OBL-1 in the multi-location trials conducted at Lucknow and Hyderabad. Average mean performance of inter specific hybrid over locations was: herb yield 44.80 t/ha, oil content 0.63%, oil yield 188.50 kg/ha, linalool content 67.65%, camphor content 8.90% v/s OBL-1 herb yield 21.32 t/ha, oil content 0.53%, oil yield 97.50 kg/ha, linalool content 65.55%, camphor content 0.00%, respectively. The essential oil of these two hybrids subjected to enantiomer differentiation revealed a high enantiomeric excess for (3R) -(?)-linalool, whereas (1R)- (+)-camphor was recorded exclusively in inter specific hybrid. The extensive NMR experiments were performed to confirm constituents in these hybrids and found that NMR spectroscopy could also be an ideal tool for the differentiation of essential oils from commercial samples declared as natural.     

Variation of Salvia fruticosa Essential Oils on the Island of Crete (Greece)

The essential oil content and composition of Salvia fruticosa (Greek sage) plants growing wild in 20 localities scattered on the island of Crete are studied. The results of our analyses have shown a noticeable variation in the essential oil content (ranging from 1.1 up to 5.1 %) and the amount of the four main oil components: 1,8-cineole (22.7 ? 64.2% of total oil), α-thujone (1.0 ? 19.2%) β-thujone (0.9 ? 25.6%) and camphor (0.8 ? 30.3%). Discriminant analysis revealed that the variation pattern of the essential oil content and the amount of the four main oil components is geographically related, following a W → E direction. Plants grown in Western Crete show a lower essential oil content and their oils are characterised by the predominance of 1,8-cineole. On the other hand, those collected from Eastern Crete exhibit higher values in essential oil content and their oils, besides 1,8-cineole, are rich in α- and β-thujone or camphor. Our findings are further discussed in relation to literature data.     

Association genetics of essential oil traits in <Emphasis Type="Italic">Eucalyptus loxophleba</Emphasis>: explaining variation in oil yield

York gum (Eucalyptus loxophleba Benth) is widely planted in semi-arid regions of Australia for the production of Eucalyptus oil, a mixture of terpenes dominated by the monoterpene 1,8-cineole. Increasing oil yield in this species would improve the profitability of this crop and enhance its use in sustainable land management systems in Australia. To this end, we sequenced ten structural genes in the terpene biosynthetic pathway of ~400 individuals of E. loxophleba. Of the 4353 allelic variants identified, 1347 had a minor allele frequency >0.01. These were associated with three key traits of essential oil yield (concentration of 1,8-cineole, α-pinene and total terpenes). Three variants associated with α-pinene, two with 1,8-cineole and eight with total terpenes (13 total). The variants were mostly located in introns of the final three biosynthetic steps of the 2-C-methyl-d-erythritol-4-phosphate (MEP) pathway (mcs, hds and hdr). Effect size varied from 2.7 to 6.8%, comparable to similar studies in forest trees. The cumulative effect size of the unlinked variants was 34.8% for total terpenes, although this is likely to be a high estimate. These results provide the basis for the development of molecular breeding methods for improving essential oil yield in this industrially important species.     

The inflorescence and leaf essential oils of Tanacetum vulgare L. var. vulgare growing wild in Lithuania

Forty samples of inflorescences and leaves of wild Tanacetum vulgare L. var. vulgare were collected in 20 habitats from Lithuania. The essential oils were analyzed by GC and GC/MS. The 57 identified compounds in the oils made up 80.7–99.6%. According to the cluster analysis the volatile oils were divided into four groups with 1,8-cineole (23.6–46.3%, 11 oils), trans-thujone (35.7–78.4%, 6 samples), camphor (19.8–61.8%, 17 oils) and myrtenol (13.1–24.9%, 6 samples) as main constituents. The inflorescences and leaves of tansy plants formed the oils with the same dominating constituent in 15 of the 20 habitats investigated. The leaves in five localities produced oils of the 1,8-cineole chemotype, while the inflorescences biosynthesized oils of the camphor type in three habitats and of the myrtenol type in two habitats. Amounts of the 1,8-cineole in all leaf oils were greater than that in inflorescence oils of the plants from the same locality. An opposite correlation was determined for camphor, myrtenol, cis- and trans-thujone. The myrtenol chemotype was not noticed earlier in the essential oils of T. vulgare.     

Chemical Variability of Moroccan Myrtle Oil

Thirty-three oil samples isolated from aerial parts of Myrtus communis L. harvested in seven localities, from Northern to Central Morocco, have been analyzed by combination of chromatographic and spectroscopic techniques. The 33 compositions have been subjected to statistical analysis, hierarchical cluster analysis (HCA) and principal component analysis (PCA). Two groups have been differentiated on the basis of their myrtenyl acetate and α-pinene contents and each one was sub-divided in two sub-groups according to the contents of 1,8-cineole and linalool. The compositions of our 33 myrtle oil samples may be named as follow by their main components: sub-group IA (13/33): α-pinene/1,8-cineole/linalool; sub-group IB (6/33): 1,8-cineole/α-pinene; sub-group IIA (10/33): 1,8-cineole/myrtenyl acetate; sub-group IIB (4/33): myrtenyl acetate.     

Influence of herbicides and growth regulators on the growth and essential oil content of sage

Foliar application of a wide range of herbicides provided suggestive evidence for a direct correlation between growth and essential oil production in sage (Salvia officinalis) grown under controlled environmental conditions. Conversely, foliar application of the growth regulators AMO-1618 and DCPA indicated that moderate stunting of growth was associated with an increase in essential oil yield. Quantitative changes in the principle monoterpenes of sage oil, β-pinene, 1,8-cineole, 3-isothujone and camphor, were also observed in response to the various treatments. However, attempts to correlate the changes in oil composition with alteration in growth or oil yield also failed to establish any definitive relationships. Since the four monoterpene components examined arise by independent routes from a common precursor, the changes in oil composition observed indicate that the applied bioregulators exert a direct effect on terpene metabolism by a means independent of growth or development.     

Comparative determination of the essential oil composition in Bulgarian endemic plant Achillea thracica Velen. during the process of ex situ conservation

Ex situ conservation of Bulgarian endemic plant Achillea thracica Velen. was achieved by successful in vitro cultivation of mono-nodal segments on MS-B5 medium supplemented with 1.0 mg/L BA for 20 days and subsequent transferring of regenerated plants on hormone free basal MS-B5 medium for root development and accumulation of leaf biomass. In vitro multiplicated plants were successfully acclimated in a growth chamber with 100% survival. GC–MS analysis of the essential oils resulted in the identification of 30, 10 and 28 compounds in in situ grown, in vitro cultivated and ex vitro adapted plants, respectively, constituting 77.7%, 99.9% and 84.1% of the total oils. The wider variety of compounds was found in the essential oils of in situ and ex vitro adapted plants where santolina alcohol, β-eudesmol, 1,8-cineole, germacrene D, α-cadinol and artemisia alcohol were the principal components comprising 68.7% and 69.3 of the oil, respectively. In vitro cultivated plants consist of mainly 1,8-cineole, germacrene D and artemisia alcohol representing 87% of the oil. Different growth conditions affect the composition of essential oils, suggesting their possible involvement in the process of adaptation and surviving in changing environmental conditions.     

Composition and intraspecific chemical variability of the essential oil from Artemisia herba-alba growing wild in a Tunisian arid zone

The intraspecific chemical variability of essential oils (50 samples) isolated from the aerial parts of Artemisia herba-alba Asso growing wild in the arid zone of Southeastern Tunisia was investigated. Analysis by GC (RI) and GC/MS allowed the identification of 54 essential oil components. The main compounds were β-thujone and α-thujone, followed by 1,8-cineole, camphor, chrysanthenone, trans-sabinyl acetate, trans-pinocarveol, and borneol. Chemometric analysis (k-means clustering and PCA) led to the partitioning into three groups. The composition of two thirds of the samples was dominated by α-thujone or β-thujone. Therefore, it could be expected that wild plants of A. herba-alba randomly harvested in the area of Kirchaou and transplanted by local farmers for the cultivation in arid zones of Southern Tunisia produce an essential oil belonging to the α-thujone/β-thujone chemotype and containing also 1,8-cineole, camphor, and trans-sabinyl acetate at appreciable amounts.     

1,8-cineole and castor oil in sodium lauryl ether sulphate disrupt reproduction and ovarian tissue of Rhipicephalus (Boophilus) microplus

Essential and fixed oils have been researched as alternatives to chemical acaricides. The activity of volatile compounds from essential oils (1,8-cineole, citral and eugenol) at 1.0% (w/v) and fixed oil (castor oil) at 0.3% (w/v) dissolved in 2.0% (v/v) dimethyl sulfoxide (DMSO) + 0.2% (w/v) Tween 80^® was assessed against Rhipicephalus microplus using immersion tests. 1,8-cineole (29.0%) and castor oil (30.2%) had the highest reproductive inhibition rate. A second experiment was performed to verify the effect of the 1,8-cineole (10.0% w/v) and, or castor oil (0.3% w/v) on tick reproduction using different solubilizing agents. The highest reproductive inhibition was observed for the combination of 1,8-cineole/castor oil (94.1%) and 1,8-cineole in 2.0% (w/v) sodium lauryl ether sulphate (SLES) (92.8%). A third experiment showed morphological changes in R. microplus oocytes at different stages of development, as well as in pedicel cells. The most intense effects were observed when ticks were immersed in the formulation containing 1,8-cineole (10.0% w/v) and castor oil (0.3% w/v) dissolved in 2% (w/v) SLES. These findings highlight the potential of this formulation as an alternative for managing cattle ticks as their cytotoxic effects can reduce R. microplus reproductive success.     

Variation in the leaf oil of Eucalyptus punctata

The steam-volatile leaf oil of Eucalyptus punctata. ssp. punctata has been shown to contain α-pinene, β-pinene, 1,8-cineole, p-cymene and cryptone. Several minor components have been tentatively identified by GLC. The wide variation in the leaf oil composition between individual trees indicated no grounds for the establishment of chemical varieties within the subspecies.     

Chemical compositions of Casuarina equisetifolia L., Eucalyptus toreliana L. and Ficus elastica Roxb. ex Hornem cultivated in Nigeria

Essential oils were obtained by separate hydrodistillation of three different plants cultivated in Nigeria and analysed comprehensively for their constituents by means of gas chromatography (GC) and gas chromatography-mass spectrometry (GC–MS). The leaf essential oil of Casuarina equisetifolia L. (Casuarinaceae) comprised mainly of pentadecanal (32.0%) and 1,8-cineole (13.1%), with significant amounts of apiole (7.2%), α-phellandrene (7.0%) and α-terpinene (6.9%), while the fruit oil was dominated by caryophyllene-oxide (11.7%), trans-linalool oxide (11.5%), 1,8-cineole (9.7%), α-terpineol (8.8%) and α-pinene (8.5%). On the other hand, 1,8-cineole (39.4%) and α-terpinyl acetate (10.7%) occurred in large quantities in the essential oils of the leaf of Eucalyptus toreliana L. (Myrtaceae). The oil also features high levels of sabinene (5.9%), caryophyllene-oxide (4.7%) and α-pinene (4.2%). The main compounds identified in the leaf oil of Ficus elastica Roxb. ex Hornem. (Moraceae) were 6,10,14-trimethyl-2-pentadecanone (25.9%), geranyl acetone (9.9%), heneicosene (8.4%) and 1,8-cineole (8.2%).     

Composition and infraspecific variability of Artemisia herba-alba from southern Spain

The composition of the essential oils of 16 individual plants of Artemisia herba-alba Asso ssp. valentina (Lam.) Marcl. (at the full bloom stage) growing wild in four different locations from southern Spain were investigated by capillary GC and GC–MS in combination with retention indices. Among the 60 identified constituents (accounting for 80.6–95.0% of the oils), 33 have been reported for the first time in Spanish A. herba-alba oil and 17 of them have not been previously described in A. herba-alba oil. From the analysis of the oil samples, it could be deduced that a noticeable chemical polymorphism typified this taxon. Four groups of essential oils exhibited a single compound with percentages near 30% or higher: davanone, 1,8-cineole, chrysanthenone and cis-chrysanthenol. Two further oil types showed p-cymene and cis-chrysanthenyl acetate as major components in moderate amounts (ca. 20%). All of these types of essential oils have not been previously found in A. herba-alba from Spain and the appearance of such considerable amount of p-cymene is described here for the first time in A. herba-alba.     

Composition of essential oils from turkish Salvia species

The chemical composition of the essential oils from five Salvia species from Turkey was determined by GC. The species were S. candidissima, S. cryptantha, S. fruticosa, S. officinalis and S. tomentosa. 24, 22, 20, 19, and 22 components were identified, respectively, the major ones being β-pinene (candidissima), borneol (cryptantha), 1,8-cineole (fruticosa), camphor (officinalis) and β-pinene (tomentosa). α-Pinene in candidissima, camphor in cryptantha, α-thujone in officinalis and 1,8-cineole in tomentosa were the other important components.