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.     

Variation in essential oil composition of Leonotis leonurus,an important medicinal plant in South Africa

Leonotis leonurus widely used by traditional healers in southern Africa for treatment of various ailments, is well known for its reported psychoactive properties. The present study was undertaken to investigate the variation in essential oil composition between geographically distinct populations of L. leonurus in South Africa using gas chromatography. Plant material (n = 50) was collected from three provinces of South Africa. Essential oils of the aerial parts were obtained by hydrodistillation and analysed using one and two dimensional gas chromatography. Twenty-six compounds accounted for more than 80% of the total composition of the oil. Eight major constituents in the oil, representing about 50% of the total oil composition, were identified by both GC–MS–FID and GCxGC–ToF–MS. These major compounds were trans-β-ocimene (0.1–5.0%), cis-β-ocimene (0.1–31.5%), β-caryophyllene (0.3–15.0%), caryophyllene oxide (0.1–5.0%), α-humulene (0.4–18.2%), γ-elemene (0.4–10.6%), α-cubebene (0.2–12.0%) and germacrene D (0.1–22.1%). Marked similarities exist in the essential oil composition between populations; differences are mostly quantitative when determined by GC–MS–FID, while GCxGC–ToF–MS data reveals both quantitative and qualitative differences.Untargeted multivariate analysis was performed using SIMCA-P + 14.0 PCA and OPLS-DA methods, identifying two distinct clusters, inland and coastal populations.     

An untargeted metabolomic approach in the chemotaxonomic assessment of two Salvia species as a potential source of α-bisabolol

α-Bisabolol is a commercially important aroma chemical currently obtained from the Candeia tree (Vanillosmopsis erythropappa). Continuous unsustainable harvesting of the Candeia tree has prompted the urgent need to identify alternative crops as a source of this commercially important sesquiterpene alcohol. A chemotaxonomic assessment of two Salvia species indigenous to South Africa is presented and recommended as a potential source of α-bisabolol. The essential oil obtained by hydrodistillation of the aerial parts was analysed by gas chromatography coupled to mass spectrometry (GC–MS) and mid-infrared spectroscopy (MIRS). Orthogonal projections to latent structures–discriminant analysis (OPLS–DA) were used for multivariate classification of the oils based on GC–MS and MIRS data. Partial least squares (PLS) calibration models were developed on the MIRS data for the quantification of α-bisabolol using GC–MS as the reference method. A clear distinction between Salvia stenophylla and Salvia runcinata oils was observed using OPLS–DA on both GC–MS and MIRS data. The MIR calibration model showed high coefficient of determination (R² = 0.999) and low error of prediction (RMSEP = 0.540%) for α-bisabolol content.     

Essential oil composition of four Lomatium Raf. species and their chemotaxonomy

The composition of the essential oils of Lomatium dasycarpum ssp. dasycarpum, Lomatium lucidum, Lomatium macrocarpum var. macrocarpum and Lomatium utriculatum is described. Identification of components was determined from their GC, GC/MS data and many were confirmed by coinjections with authentic samples. Several components were isolated by liquid and gas chromatographic techniques and their structures confirmed from their ¹H and ¹³C NMR spectral data. 2-Methyl and 3-methylbutanoates were the major components of L. dasycarpum fruits as well as stems and leaves oils. β-Phellandrene/limonene, decanal, dodecanal, bornyl acetate, germacrene D, α-humulene and bicyclogermacrene were the major components of the corresponding L. lucidum oils. α-Pinene and β-pinene were the major components of the fruit oil of L. macrocarpum. Its stem and leaf oil was rich in peucenin 7-methyl ether, β-caryophyllene, (Z)-3-hexenol, palmitic acid, linoleic acid and (E)-2-hexenal. Sabinene, (Z)-ligustilide, terpinen-4-ol, β-phellandrene/limonene, β-caryophyllene, myrcene, α-pinene and β-pinene were the major compounds in L. utriculatum fruit oil, while its stem and leaf oil was rich in (Z)-ligustilide, palmitic acid, terpinen-4-ol, linoleic acid and germacrene D. (Z)-Falcarinol was a major component of all the four root oils.     

Genetic relationships between some Tunisian Citrus species based on their leaf volatile oil constituents

Volatile oil constituents of Tunisian sweet orange (Citrus sinensis Osbeck) cv. Meski (MES), Valencia Late (VAL), Thomson Navel (THN) and Maltaise Blanc (MAB); mandarin (Citrus reticulata Blanco); sour orange (Citrus aurantium L. cv. Amara (AM)) and pummelo (Citrus grandis Osbeck) were obtained by hydrodistillation and analysed by gas chromatography (GC) combined with a flame ionisation detector (FID) and mass spectrometry (MS). A total of 41 components accounting for more than 95% of the total essential oils were identified, and oxygenated monoterpenes (69.5–99.9%) were found as the most prominent fraction in all oil samples. The main constituents were linalool (3.1–73%), isoborneol (0–55.8%) and tepinen-4-ol (1.1–19.2%). A high degree of inter-and intraspecific chemical variability between species and cultivars was found to be genetically determined, and a set of distinctive traits (chemical markers) in the essential oils profile was established. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) of all identified components grouped the oils into two main chemotypes (linalool/isoborneol and isoborneol/linalool).     

Assessment of the repellent effect of Lippia alba essential oil and major monoterpenes on the cattle tick Rhipicephalus microplus

The control of Rhipicephalus microplus (Ixodida: Ixodidae) is achieved using synthetic acaricides. However, resistant tick populations are widespread around the world. Plant essential oils can act as repellents, keeping ticks away from hosts and decreasing the selection pressure on synthetic acaricides. The aim of this study was to evaluate the in vitro repellent effect of Lippia alba essential oil on R. microplus larvae. Leaves from two L. alba genotypes maintained under the same agronomic and environmental conditions were collected. Essential oil was extracted by hydrodistillation and analysed by gas chromatography–mass spectrometry (GC‐MS). The major monoterpenes detected in the chemical analysis were commercially acquired and tested. For the repellency test, a glass rod was vertically fixed to measure active climbing of approximately 30 R. microplus larvae aged 14–21 days in response to essential oils and monoterpenes. Repellency was evaluated at 1 h, 3 h and 5 h after treatment. Variation in repellent action was detected between the genotypes. The major monoterpenes identified in the essential oils (limonene and carvone) showed low repellent effects in comparison with intact essential oils. Thus, the present results showed that L. alba essential oil contains bioactive compounds with great repellent activity against ticks that varies according to the plant genotype.     

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.     

Chemotaxonomic significance of the essential oils of 18 Ferula species (Apiaceae) from Iran

To evaluate the chemotaxonomic significance of the essential oils of 23 populations of 18 Iranian Ferula species, the chemical composition of the oils was investigated by GC/FID and GC/MS. Altogether, 84 constituents, representing 81.3-99.7% of the total composition of the oils, have been identified. The composition of six species of the genus, i.e., F. oopoda, F. foetida, F. behboudiana, F. diversivittata, F. galbaniflua, and F. hezarlalehzarica, has been reported for the first time. The main constituents identified were α-terpinyl acetate (73.3%), 2,3,4-trimethylthiophene (2; 49.0%), sabinene (75.3%), verbenone (5; 69.4%), β-pinene (59.0-66.3%), and (Z)-β-ocimene (41.7%). Cluster analysis (CA) of the percentage content of the essential oil components of the Ferula species resulted in the characterization of four groups, i.e., taxa containing either i) monoterpene hydrocarbons, ii) oxygenated monoterpenes, iii) organosulfur compounds, or iv) monoterpene, sesquiterpene, and aliphatic hydrocarbons as the principal classes of compounds. Based on the results obtained, the chemical independence of F. hirtella from F. szowitsiana and of F. galbaniflua from F. gummosa at the specific level was concluded and their positions as distinct species were confirmed. The chemotaxonomic relationships among the representatives of the genus Ferula have been discussed in detail.     

Chemical diversity in the essential oil of Indian valerian (Valeriana jatamansi Jones)

To explore the diversity in the essential oil yield and composition of Valeriana jatamansi Jones (syn. V. wallichii DC) growing wild in Uttarakhand (Western Himalaya), 17 populations were collected from different locations and grown under similar conditions. Comparative results showed considerable variations in the essential oil yield and composition. The essential oil yield varied from 0.21 to 0.46% in the fresh roots and rhizomes of different populations of V. jatamansi. Analysis of the essential oils by GC (RI) and GC/MS and the subsequent classification by principal component analysis (PCA) resulted in six clusters with significant variations in their terpenoid composition. Major components in the essential oils of the different populations were patchouli alcohol (1; 13.4-66.7%), α-bulnesene (3; <0.05-23.5%), α-guaiene (4; 0.2-13.3%), guaiol (5; <0.05-12.2%), seychellene (6; 0.2-9.9%) viridiflorol (<0.05-7.3%), and β-gurjunene (7; 0.0-7.1%). V. jatamansi populations with contents of 1 higher than 60% may be utilized commercially in perfumery.     

Essential oil chemotypes in Hyptis suaveolens from Brazilian Cerrado

The composition of nine samples of essential oil of individual plants in fruiting stage of Hyptis suaveolens from Brazilian Cerrado was investigated by GC–MS. Spathulenol, 1,8-cineole and (E)-caryophyllene were the principal constituents. The results were submitted to Principal Component and Chemometric Cluster Analysis which allowed three groups of essential oils to be distinguished with respect to the content of 1,8-cineole/sabinene, β-bourbonene and α-bulnesene. Latitude seems to be the most important environmental factor influencing the oil contents. Pattern of geographic-variation in essential oil composition indicated that sesquiterpenes are mainly produced in the samples grown at lower latitudes and altitudes.     

Chemical composition of the essential oils of ripe berries of Juniperus oxycedrus L., growing wild in Kosovo

The main objective of this work was to study the essential oil composition of ripe Juniperus oxycedrus L. berries and its natural variation among wild populations in Kosovo. Essential oil was analysed using GC-FID and GC–MS. Plant materials were collected from five locations in Kosovo in August and September of 2011. In total, twenty-seven compounds were identified in the essential oils. The main components were β-myrcene (45.5–56.9%), α-pinene (10.2–36.6%), dl-limonene (3.6–13.8%) and germacrene D (1.7–8.7%). Of the total identified compounds, monoterpenes constituted the highest percentage of all components (70.24–88.22%), followed by oxygenated sesquiterpenes (4.9–11.4%), sesquiterpenes (3.5–11.0%), oxygenated monoterpenes (0.2–2.7%) and oxygenated diterpenes (0.0–1.7). Hierarchical Cluster Analysis (HCA) and Principal Component Analyses (PCA) were used to identify any geographical variations in essential oil composition. Statistical analysis suggests that the clustering of populations is not related to their geographic location, but rather seemed to be linked to local selective forces acting on chemotype diversity.     

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.     

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%).     

Essential oil composition and variability of Hypericum perforatum L. growing in Lithuania

The composition of essential oils obtained from flowers and leaves in 11 accessions of Hypericum perforatum L. was analysed by GC and GC–MS. All the analysed oils were dominated by their oxygenated sesquiterpene fraction. Differences were attributed to the main components: caryophyllene oxide, spathulenol and viridiflorol. There were only a few monoterpenes in essential oil of all accessions. The data indicated some differences in sesquiterpene and aliphatic hydrocarbons, as well as in oxygenated aliphatics biosynthesis in flowers and leaves. The concentrations of β-caryophyllene and caryophyllene oxide in essential oils from leaves were higher than those from flowers, whereas dodecanol, spathulenol, viridiflorol, carotol and tetradecanol were present in higher quantities in flowers. Cluster analysis of all identified components grouped oils from flowers and from leaves into three clusters that corresponded with their major components: caryophyllene oxide, tetradecanal, tetradecanol and manool. Chemical variability of the analysed accessions seems likely to result from the genetic variability, since the influence of different environmental factors has been eliminated.     

Chemical composition,intraspecies variation and seasonal variation in essential oils of Calendula arvensis L.

The essential oil composition of Calendula arvensis was established for the first time using GC and GC/MS. Eighty-five essential oil components were identified, which accounted for 90.3 g/100 g of essential oil. The oil contained a high concentration of sesquiterpenes, of which δ-cadinene and α-cadinol were the main components. The chemical composition of 25 Corsican C. arvensis oils was analyzed to determine intraspecies variation in essential oil composition. A matrix linking essential oil composition to sample location was composed to identify relationships between concentrations of volatile samples and the geographical origins of samples. Two main groups of compounds were identified according to the amount of sesquiterpenic compounds (hydrocarbons and alcohols) and soil characteristics. Seasonal variation (winter vs. spring) in the concentrations of two major compounds during the flowering period was observed.     

(−)-5,6-Dehydrocamphor from the antifungal essential oil of Zuccagnia punctata

The essential oils from aerial parts of nine populations of Zuccagnia punctata Cav. (Fabaceae) were obtained by hydrodistillation and analyzed by GC–FID, GC–MS and ¹³C NMR. A total of 80 constituents, mainly oxygenated monoterpenes, were identified representing from 79.0 to 95.2% of the total oils which showed different composition patterns. The unusual compound (?)-5,6-dehydrocamphor, the major constituent in six of the samples investigated with percentages ranging from 12.3% to 56.5%, was isolated for the first time from nature and its structure was completely defined from NMR spectrometric data. Microscope studies of leaves indicated that not only capitate glands but also non-glandular trichomes, not previously described in this species, were present on the leaf surfaces.The essential oil showed antifungal activity against the dermatophytes Microsporum gypseum, Tricophyton rubrum and T. mentagrophytes with MIC values between 15.6 and 125 μg ml^?1, being T. rubrum the most susceptible species.     

Essential oil production in shoot cultures versus field-grown plants of Thymus caespititius

Thymus caespititius Brot. is an important aromatic species, due to synthesis and production of essential oils for the pharmaceutical and food industries. In the present study, levels of essential oils from two chemotypes, including carvacrol/thymol (CT) and sabinene/carvacrol (SC), were evaluated in proliferating shoot cultures (6–12 subcultures following establishment) and compared to those from field-grown plants. The essential oils were isolated by hydrodistillation and analysed by gas chromatography (GC) and GC–mass spectrometry (GC–MS). Cultures grown under in vitro culture conditions, evaluated over six subcultures, were found to maintain stable composition of essential oils. For the CT chemotype, carvacrol (42 %) and thymol (23 %) were the main essential oil components detected in field-grown plants; in proliferating shoot cultures the levels detected attained 17–25 % in the case of carvacrol and 18–23 % in that of thymol, closely followed by carvacryl acetate (15–23 %) and thymyl acetate (11–15 %). For the SC chemotype, carvacrol (13–28 %), sabinene (18–45 %), and thymol (9–12 %) were the main essential oil components detected in both field-grown and proliferating shoot cultures. Our experiments showed that the essential oil composition in proliferating shoot cultures was not only stable, but also qualitatively similar to that of field-grown plants, notwithstanding minor quantitative differences.     

Composition and Chemical Variability of the Essential Oil from Aerial Parts of Cladanthus scariosus,an Endemic Species to the Moroccan High Atlas

Cladanthus scariosus (Ball) Oberpr. & Vogt is endemic to Moroccan High Atlas. It is known under the vernacular names Irezghi or Irezgui. Three essential oil samples have been isolated from aerial parts and analyzed by combination of chromatographic and spectroscopic techniques [gas chromatography (GC) in combination with retention indices (RI), gas chromatography-mass spectrometry (GC/MS) and ¹³C-NMR spectroscopy]. The compositions of oil samples were dominated by monoterpenes: α-pinene sabinene, and terpinen-4-ol. Chamazulene and dihydrochamazulene isomers as well as various hemiterpene esters and analogs have been identified. To evidence a chemical variability, statistical analysis performed on 13 oil sample compositions allowed partitioning into three groups, mainly differentiated by their contents of sabinene, camphor, borneol, terpinen-4-ol, and germacrene D.     

Chemical variation of essential oil constituents of Ocimum gratissimum L. from Benin, and impact on antimicrobial properties and toxicity against Artemia salina leach

To determine the period of harvest that optimizes the antimicrobial activities of the essential oil of Ocimum gratissimum L. from Benin, aerial plant parts were collected at two vegetative stages (pre- and full-flowering) and three sampling times (7?am, 1?pm, and 7?pm). Extraction by hydrodistillation yielded between 0.65 and 0.78% of essential oils. Characterization of the oils by GC-FID and GC/MS analysis revealed the presence of monoterpenes (87.26-93.81%), sesquiterpenes (5.57-11.34%), and aliphatic compounds (0.15-0.18%), with p-cymene (1; 28.08-53.82%), thymol (2; 3.32-29.13%), γ-terpinene (3; 1.11-10.91%), α-thujene (4; 3.37-10.77%), and β-myrcene (5; 4.24-8.28%) as major components. Two chemotypes were observed, i.e., a p-cymene/thymol and a p-cymene chemotype, for plants harvested at 7?am for the former and at 1?pm or 7?pm for the latter, respectively. The oils were fungicidal against Candida albicans, with the sample from full-flowering plants collected at 7?am being the most active (MIC?=?0.06±0.00?mg/ml). The chemical variation of the oils also influenced the antimicrobial effect against Staphylococcus aureus; the most active oil was obtained from plants at the pre-flowering stage collected at 7?am (MIC=0.24±0.01?mg/ml). Escherichia coli was insensitive to the chemical variation of the oils (MICs of ca. 0.48±0.02?mg/ml for all oils). Moreover, the essential oils showed low toxicity against Artemia salina Leach larvae, with LC(50) values in the range of 43-146?μg/ml. This is the first study of the interaction between the daytime of collection and vegetative stage of the plants and the antimicrobial properties and toxicity of the essential oil of O. gratissimum from Benin.     

Composition and variability of essential oils of Platycladus orientalis growing in China

Essential oils were isolated from the leaves of Platycladus orientalis growing in 16 areas of China. The essential oils were analyzed by gas chromatography and gas chromatography-mass spectrometry. In total, 98 volatile compounds were identified. Chemical variability in essential oil composition was evaluated using cluster analysis and principal component analysis. The two analyses led to the identification of four chemotypes: α-pinene, α-pinene/3-carene, cedrol, and cedrol/terpinyl acetate. Geographically, the populations growing in close proximity had similar essential oil composition. The chemical variability could possibly be attributed to genetic and environmental factors.