Influence of environmental and genetic factors on the stability of essential oil composition of Thymus pulegioides

Thymus pulegioides plants were collected from various natural habitats of Lithuania and transferred into a new uniform environment. The plants were cloned annually at controlled conditions and their essential oil composition was monitored by capillary GC and GC/MS. The geraniol/geranial/neral (G/G/N), thymol (T), linalool (L), carvacrol/γ-terpinene/p-cymene (C/γT/pC) and thymol/carvacrol/γ-terpinene/p-cymene (T/C/γT/pC) chemotypes of T. pulegioides were studied. It was found that according to the stability of essential oil composition on a sudden change of environmental conditions two types of T. pulegioides can be distinguished: (1) plants which preserve their chemical composition of the essential oils; (2) plants, which considerably change their chemical composition of the essential oils.     

Analysis of the volatile components of Lavandula canariensis (L.) Mill., a Canary Islands endemic species,growing in Australia

The essential oil of a Canary Islands endemic species, Lavandula canariensis (L.) Mill., gathered from Australia, was extracted by hydrodistillation and solid phase micro-extraction (SPME). The oils have been studied by GC and GC–MS. A total of 38 compounds have been identified in the leaf oil extracted by hydrodistillation, the principal components being carvacrol (23.6%), β-bisabolene (20.8%), (E,E)-α-farnesene (11.3%), β-caryophyllene (7.6%) and carvacrol methyl ether (7.3%), while the oil extracted by SPME showed carvacrol (42.6%) as the principal component with moderate amounts of (E,E)-α-farnesene (9.1%), β-bisabolene (7.5%), cis-hex-3-en-1-ol (5.6%) and carvacrol methyl ether (4.6%). SPME extracts indicated that carvacrol, cis-hex-3-en-1-ol and linalool were in greater concentration in the head space vapours than in the oil. This is the first report describing the essential oil composition of this species.     

Salvia verbenaca L. essential oil: Variation of yield and composition according to collection site and phenophase

The effect of the collection sites and phenophase on yield and chemical composition of Salvia verbenaca essential oils was evaluated. The essential oil constituents were assessed by gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS). The highest essential oil yields were observed for samples of the higher semi-arid bioclimate and at the flowering period. Eighty-five volatile constituents were identified and their percentages varied significantly (p < 0.05) depending on the collection site and the phenological stage. According to the plants origin, essential oils were dominated by monoterpene hydrocarbons, oxygenated monoterpenes and sesquiterpene hydrocarbons. The monoterpene hydrocarbons (31.9%) predominate at the flowering stage whereas oxygenated sesquiterpenes (27.5%) at the early fruiting stage. The sesquiterpene hydrocarbons (28.2%) was the most represented chemical class at late fruiting. On the basis of GC-MS data, the major identified volatile constituents were viridiflorol (3.4–17.7%), α-pinene (0.7–15.9%), β-caryophyllene (1.0–15.3%) and p-cymene (1.3–14.2%). S. verbenaca contains a diversity of bioactive constituents which shows large variations as affected by the collection sites and phenophase.     

Circadian and seasonal study of the cinnamate chemotype from Lippia origanoides Kunth

The leaves of Lippia origanoides Kunth are used in culinary as flavoring regional dishes and remedy for gastrointestinal and respiratory diseases in the Amazon region. The circadian and seasonal study of its essential oil was characterized by GC and GC–MS analysis. The oil components were grouped into monoterpenes, sesquiterpenes and phenylpropanoids, during the dry and rainy season. The main constituents were (E)-methyl cinnamate, (E)-nerolidol, p-cymene, 1,8-cineole, carvacrol, α-pinene, (E)-caryophyllene and γ-terpinene, with great variation throughout the year. In this work, we are reporting the occurrence of a new chemotype for L. origanoides, characterized by an essential oil rich in (E)-methyl cinnamate and (E)-nerolidol, with fruity-woody odor, reminiscent of cinnamon, strawberry and wood. The oil yield varied from 1.7% to 4.6%, which is considered a significant value for the production of essential oils on an industrial scale. This new chemotype may have ecological, chemosystematics and taxonomic significance in the management and economic utilization of the species.     

Composition of the essential oils of Tanacetum argyrophyllum (C. Koch) Tvzel. var. argyrophyllum and Tanacetum parthenium (L.) Schultz Bip. (Asteraceae) from Turkey

The aerial parts of Tanacetum argyrophyllum (C. Koch) Tvzel. var. argyrophyllum and T. parthenium (L.) Schultz Bip. were hydro-distilled to produce the oils in the yields of 0.78% (v/w) and 0.43% (v/w), respectively. The oils were analysed by GC and GC/MS. Twenty-two and twenty-three components were identified representing 94.2% and 90.1% of the oils, respectively. The main compounds of T. argyrophyllum were cis-thujone (69.9%), trans-thujone (5.6%) and 1,8-cineole (3.2%), whereas camphor (56.9%), camphene (12.7%) and p-cymene (5.2%) were the major constituents of T. parthenium.     

Constituents of essential oil of Boswellia frereana

The composition of the essential oil of Boswellia frereana was investigated by GC/MS. Ten terpenes were identified and p-cymene was by far the most abundant component of the oil.     

Chemotypes of Artemisia herba-alba in Israel based on their sesquiterpene lactone and essential oil constitution

Analysis of sesquiterpene lactones and essential oils of various Artemisia herba-alba populations growing in Israel revealed the existence of five different chemotypes. These vary in their chemical profile from populations of the Sinai Desert, Egypt, Morocco and Spain. On the basis of the substitution patterns of the sesquiterpene lactones isolated from the Israeli populations which bear a hydroxyl or acetoxy function at C-9 it is suggested that these constitute a chemotaxonomic subspecies in the A. herba-alba complex.     

The steam volatile leaf oils of some species of Eucalyptus subseries Strictinae

The volatile leaf oils of Eucalyptus stenostoma, E. fraxinoides, E. triflora, E. dendromorpha, E. burgessiana, E. rupicola, E. approximans subsp. approximans, E. approximans subsp. codonocarpa and E. paliformis were qualitatively very similar to each other but significantly different from the leaf oils of the remaining species of the subseries. Their leaf oils were characterized by high concentrations of p-cymene and by the presence of α- and β-phellandrene, variable amounts of piperitone, trans- and cis-piperitol and trans- and cis-p-menth- 2-en-1-ol. The three last named alcohols have not been previously reported from the Myrtaceae.     

Screening of the essential oil composition of wild Sicilian thyme

Thirty samples of wild thyme collected from as many Sicilian locations have been analysed for their qualitative and quantitative essential oil profiles. The oils, obtained by hydrodistillation, have been analysed by a combination of GC-FID-MS; in all, 46 components, representing more than 98% of the oils, were fully characterized. Monoterpenes, both hydrocarbons and oxygenated, were the most highly represented components: the former with a range of 8–61% and the latter with a range of 31–86%. Carvacrol was the main compound in 29 samples, ranging between 49 and 83%, suggesting that Thymus capitatus Hoff. et Link. [syn. Coridothymus capitatus (L.) Rchb.f., Satureja capitata L., Thymbra capitata (L.) Cav.] is the most widespread wild species in the Sicilian area. Only one sample, identified as Thymus longicaulis C. Presl., collected from the North-East of Sicily showed a different composition, p-cymene and thymol being the main compounds with 40 and 16%, respectively. Statistical analyses allowed establishing a single broad group, confirming the substantial compositional uniformity of the essential oil profiles of the wild Sicilian thyme.     

Chemical composition,antibacterial, antioxidant and insecticidal activities of moroccan Thapsia transtagana essential oil

IntroductionThe use of chemical products to neutralize microorganisms has always been a subject of discussion and research for alternative solutions, indeed, the use of essential oils has been a promising natural methodology.MethodsIn our study we used the essential oils from different parts of Thapsia transtagana (Apiaceae), obtained by hydrodistillation, were identified and using Gas chromatography–mass spectrometry (GC–MS) and Gas Chromatography-Flame Ionization Detection (GC/FID) methods and evaluated against several bacteria of Gram- and Gram + bacteria. Disk diffusion, Minimum Inhibitory Concentration (MIC) and Minimum Microbicidal Concentration (MMC) methods have been used. Free radical-scavenging activity and insecticidal activity of Thapsia transtagana essential oils were also identified.ResultsMajority products from different parts of Thapsia transtagana essential oil identified by GC–MS and GC/FID methods are 2,6-Dimethylnaphthalene, Pinane and Hexahydrofarnesyl acetone. The highest activity was found against Staphylococcus aureus using inflorescence essential oil with minimal inhibitory concentration value for 0,56 μg/μL. Insecticidal activity was also the subject of this study, roots and inflorescence essential oils demonstrated to have a remarkable potent against Acanthoscelides obtectus and Sitophilus oryzae using contact assessment, inhalation assessment and ingestion assessment tests. Insecticidal activity assay results showed a significant enhancement of mortality in both test insect pest on increasing the dose and exposure period. In the other hand, the different essential oils of Thapsia transtagana were evaluated for their radical scavenging activities by means of the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assay. The strongest scavenging activity was observed in inflorescences essential oil fraction scavenged radicals effectively at 100% using 500 mgL^-1 concentration.ConclusionIts essential oils were proved to have strong antimicrobial, insecticidal and antioxidant activities that allows it to be used by the pharmaceutical and cosmetic industries as natural preservative.     

Carvacrol Induces Heat Shock Protein 60 and Inhibits Synthesis of Flagellin in Escherichia coli O157:H7

The essential oils of oregano and thyme are active against a number of food-borne pathogens, such as Escherichia coli O157:H7. Carvacrol is one of the major antibacterial components of these oils, and p-cymene is thought to be its precursor in the plant. The effects of carvacrol and p-cymene on protein synthesis in E. coli O157:H7 ATCC 43895 cells were investigated. Bacteria were grown overnight in Mueller-Hinton broth with a sublethal concentration of carvacrol or p-cymene, and their protein compositions were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and confirmed by Western blotting. The presence of 1 mM carvacrol during overnight incubation caused E. coli O157:H7 to produce significant amounts of heat shock protein 60 (HSP60) (GroEL) (P < 0.05) and inhibited the synthesis of flagellin highly significantly (P < 0.001), causing cells to be aflagellate and therefore nonmotile. The amounts of HSP70 (DnaK) were not significantly affected. p-Cymene at 1 mM or 10 mM did not induce HSP60 or HSP70 in significant amounts and did not have a significant effect on flagellar synthesis. Neither carvacrol (0.3, 0.5, 0.8, or 1 mM) nor p-cymene (0.3, 0.5, or 0.8 mM) treatment of cells in the mid-exponential growth phase induced significant amounts of HSP60 or HSP70 within 3 h, although numerical increases of HSP60 were observed. Motility decreased with increasing concentrations of both compounds, but existing flagella were not shed. This study is the first to demonstrate that essential oil components induce HSP60 in bacteria and that overnight incubation with carvacrol prevents the development of flagella in E. coli O157:H7.     

Chemical composition and antifungal activity of the essential oils of Lippia rehmannii from South Africa

Lippia rehmannii H.Pearson (Verbenaceae) is an aromatic bush, indigenous to the northern parts of South Africa. As far as could be ascertained, the essential oil composition has not been previously reported and forms the subject of this investigation. Aerial parts of the shrub were collected from two localities in Gauteng, South Africa, and the isolated essential oils were analysed by gas chromatography. Citral, a mixture of the E- and Z-isomers, was found to be the main constituent of the oils, while borneol, camphor, neryl acetate, isocaryophyllene, p-cymene, β-caryophyllene and β-caryophyllene oxide were other major compounds present. Oil compositions, within and between the two localities, did not differ significantly. The in vitro antifungal activity of L. rehmannii essential oil was compared to that of Cympopogon citratus (lemongrass) and pure citral, against a number of pre- and postharvest fungal food pathogens. At a concentration of 3000 µL/L, lemongrass oil and pure citral caused complete growth inhibition of all the pathogens tested. Lippia rehmannii, containing less citral than lemongrass oil, was effective at this concentration against the majority of pathogens, but only partially restricted the growth of Lasiodiplodia theobromae and Botrytis cinerea. This finding suggests that citral may be largely responsible for the observed antifungal activities. Essential oil from L. rehmannii appears to be a good candidate for the in vitro control of Fusarium oxysporum and Rhizoctonia solani and application of these oils in the field should be investigated.     

Effect of soil application of humic acid on nutrients uptake,essential oil and chemical compositions of garden thyme (<Emphasis Type="Italic">Thymus vulgaris</Emphasis> L.) under greenhouse conditions

Humic acid is natural biological organic, which has a high effect on plant growth and quality. However, the mechanisms of the promoting effect of humic acid on the volatile composition were rarely reported. In this study, the effects of soil application of humic acid on the chemical composition and nutrients uptake of Thymus vulgaris were investigated. Treatments comprised 0, 50, 75 and 100 g m^?2. Essential oil was extracted by hydrodistillation and analyzed using GC–MS and GC–FID. Essential oil content was enhanced by increase of the humic acid level and its content ranged from 0.8% (control) to 2.0% (75 g m^?2). Thirty-two volatile compounds were identified and these compounds were considerably affected by humic acid. The highest percentage of thymol (74.15%), carvacrol (6.20%), p-cymene (4.24%), borneol (3.42%), trans-caryophyllene (1.70%) and cis-sabinene hydrate (1.35%) as major compounds were observed in T. vulgaris under 100 g m^?2 humic acid. There was a linear relationship (R² = 97%) between humic acid levels and thymol as a major compound. The oils were dominated by oxygenated monoterpenes followed by monoterpene hydrocarbons and sesquiterpene hydrocarbons. Based on the path coefficient analysis, the highest direct effects on essential oil content were observed in monoterpene esters (3.465) and oxygenated sesquiterpenes (3.146). The humic acid application also enhanced the uptake of N, P, K, Mg and Fe in garden thyme. The highest N (2.42%), P (0.75%), K (2.63%), Mg (0.23%) and Fe (1436.58 ppm) were observed in medium supplemented with 100 g m^?2 humic acid. In all, the utilization of humic acid could positively change nutrients uptake, essential oil content and its major constituents in T. vulgaris.     

Screening the essential oil composition of wild Sicilian oregano

The qualitative and quantitative composition of the essential oils obtained from wild Sicilian oregano plants has been investigated. Samples were collected from three areas of Sicily namely Val Mazara (M), Val di Noto (N) and Val Demona (D). These areas are based on historical territorial subdivision. The essential oils were obtained by hydrodistillation and analyzed by GC-FID-MS. Seventy eight compounds were identified representing more than 98% of the compounds in the oils. All samples are thymol-chemotype with variable percentage of γ-terpinene, p-cymene, trans-sabinene hydrate, terpinen-4-ol and carvacrol. Statistical analyses were performed in order to evaluate the variability of the essential oils. Six groups were formed reflecting the compositional differences of the essential oil profiles of the wild Sicilian oregano samples.     

Chemical Polymorphism of Essential Oils of Artemisia vulgaris Growing Wild in Lithuania

Compositional variability of mugwort (Artemisia vulgaris L.) essential oils has been investigated in the study. Plant material (over ground parts at full flowering stage) was collected from forty‐four wild populations in Lithuania. The oils from aerial parts were obtained by hydrodistillation and analyzed by GC(FID) and GC/MS. In total, up to 111 components were determined in the oils. As the major constituents were found: sabinene, 1,8‐cineole, artemisia ketone, both thujone isomers, camphor, cis‐chrysanthenyl acetate, davanone and davanone B. The compositional data were subjected to statistical analysis. The application of PCA (Principal Component Analysis) and AHC (Agglomerative Hierarchical Clustering) allowed grouping the oils into six clusters. AHC permitted to distinguish an artemisia ketone chemotype, which, to the best of our knowledge, is very scarce. Additionally, two rare cis‐chrysanthenyl acetate and sabinene oil types were determined for the plants growing in Lithuania. Besides, davanone was found for the first time as a principal component in mugwort oils. The performed study revealed significant chemical polymorphism of essential oils in mugwort plants native to Lithuania; it has expanded our chemotaxonomic knowledge both of A. vulgaris species and Artemisia genus.     

Essential oils of Bidens tripartita L. collected during period of 3 years composition variation analysis

The aim of this study was to evaluate the variation of essential oils composition of Bidens tripartita L. collected during three successive years (2009–2011). Essential oils were obtained by supercritical CO₂ extraction, applying gas chromatographic–mass spectrometric (GC–MS) analysis for identification of volatile compounds afterwards. The essential oils of B. tripartita showed a characteristic chemical composition from year to year, observing both quantitative and qualitative compounds differences. The yield of essential oils was 22 and 35 % higher in 2010 year material than in 2009 and 2011 year, respectively. The main compounds found in the B. tripartita essential oils were α-pinene (3.7–12.1 %), p-cymene (2.8–8.0 %), β-ocimene (40.5–45.9 %), β-elemene (9.9–15.6 %), iso and α-caryophyllenes (4.3–6.8 % and 5.2–8.2 %), and α-bergamotene (3.3–9.4 %). To determine the significance of changes in the identified compounds in the samples, representing different plant collection year, statistical hypothesis testing was applied. For classification of these samples to the groups and evaluation of similarity between them principal component analysis, multivariate analysis of variance and hierarchical cluster analysis techniques were used. The correlation analysis helped to find out the strength of linear relationship between amount of each compound and meteorological data (temperature and precipitations).     

Phytochemical diversity of Origanum vulgare L. subsp. vulgare (Lamiaceae) from Austria

This investigation was aiming at the phytochemical characterisation of Origanum vulgare subsp. vulgare from Austria. To study the qualitative and quantitative composition of essential oil compounds 374 individual plants were analysed via GC. The volatiles of Austrian O. vulgare subsp. vulgare were found to be complex mixtures of 53 mono- and sesquiterpenes. Among the sesquiterpenes β-caryophyllene, germacrene D, E-E-α-farnesene, germacrene D-4-ol and caryophyllene oxide were frequently present in higher amounts. The monoterpenes were mainly made up of sabinyl-compounds [mainly sabinene (up to 48.4%) and cis-sabinene hydrate (up to 57.8%)] and/or cymyl-compounds [mainly p-cymene (up to 49.7%), γ-terpinene (up to 21.5%) and carvacrol (up to 32.9%)] that were accompanied by usually smaller amounts of bornyl-compounds and acyclic compounds. Some exceptional (in O. vulgare rare) chemotypes were detected. The essential oil content of Austrian O. vulgare subsp. vulgare ranged between 0.1 and 1.8%. The content of rosmarinic acid was analysed by HPLC and ranged from 0.6 mg/g dry mass up to 37.2 mg/g dry mass. No arbutin could be detected in the analysed populations.     

The essential oil of greater galanga (Alpinia galanga) from Malaysia

The essential oil of A. galanga, a common spice in Malaysia, was prepared from fresh and dried rhizomes and analysed by means of capillary GC and GC/MS. Forty components were identified (only three of which were previously reported), accounting for 83–93% of the oil, depending on its method of preparation. Apart from monoterpenes, monoterpene alcohols and esters, and sesquiterpenes, also methyleugenol, eugenol acetate, chavicol (4-allylphenol) and chavicol acetate were present. This is the first time the latter substance has been reported in nature. Standardization of GC is proposed and tentatively applied towards a more systematic use of the Kováts indices as an aid in the identification of the constituents of essential oils.     

Volatile aroma constituents of Sri Lankan ginger

Two types of Sri Lankan ginger were examined (Sidda and Chinese varieties) and essential oils of both fresh and dried samples were prepared by standard procedures. Both varieties yielded relatively high percentages of oil (between 1.8 and 4.3%) and total aroma volatiles (ca 5 mg/g for dried samples). Analysis by GC and GC/MS showed terpenes to be the main aroma components (ca 99% for all samples). A number of the identified compounds have not previously been reported as ginger volatiles, including trans-β-ocimene, thujyl alcohol, terpinen-4-ol, myrtenal, guaiene, α-cubebene, δ-cadinene and farnesol. On drying, both varieties of Sri Lankan ginger showed considerable decrease in monoterpene content and very high increase in sesquiterpene concentration. Comparing the aroma volatiles of Sri Lankan dried ginger with those previously reported for dried ginger from some other countries, it was concluded that Sri Lankan ginger was as good as, if not superior to, other types. In particular, SriLankan dried ginger showed high levels of ar-curcumene together with reasonable levels of citral isomers and all other constituents previously claimed to be important to ginger aroma. Sri Lankan ginger would appear to be unusual in containing very low amounts of zingiberene but very high amounts of β-bisabolene.     

Analysis of leaf oils from a Eucalyptus species trial

The volatile leaf oils were analysed from adult leaves of five Eucalyptus species growing in a common environment. The trial consisted of two provenances of the species E. globulus and one provenance each of E. nitens and E. denticulata from the southern blue gum group and two provenances each of the species E. delegatensis and E. regnans from the ash group. Oil yields from adult leaves of E. nitens (0.7% dry wt.) and E. denticulata (0.8%) were markedly lower than those from the other three species (3.0–6.1%). Volatile leaf oils of E. delegatensis and E. regnans were rich in α- and β-phellandrene, cis- and trans-p-menth-2-en-1-ol, while E. regnans was also rich in α-, β- and γ-eudesmol. In contrast, volatile leaf oils of E. globulus were rich in 1,8-cineole and α-pinene and E. denticulata rich in γ-terpinene and p-cymene. Oil composition of E. nitens was intermediate between E. globulus and E. denticulata. Differences in oil yield and oil composition between species indicated a strong genetic basis for these variables.