Essential Oils of Myrtaceae Species Growing Wild in Tunisia: Chemical Variability and Antifungal Activity Against Biscogniauxia mediterranea,the Causative Agent of Charcoal Canker

The chemical composition of five Eucalyptus species and five Myrtus communis L. populations was investigated using GC/MS and GC‐FID. For Eucalyptus essential oils, 32 compounds, representing 88.56 – 96.83% of the total oil according to species, were identified. The main compounds were 1,8‐cineole, α‐pinene, p‐cymene, γ‐gurjunene, α‐aromadendrene, and β‐phellandrene. For Myrtle essential oils, 26 compounds, representing 93.13 – 98.91% of the total oil were identified. α‐Pinene, 1,8‐cineole, linalool, and myrtenyl acetate were found to be the major compounds. Principal component analysis (PCA) showed chemical differentiation between Eucalyptus species and between Myrtle populations. Biscogniauxia mediterranea, the causative agent of charcoal canker, was identified according to its morphological and molecular characteristics. Essential oils of the investigated Eucalyptus species and Myrtle populations were tested for their antifungal capacity against this fungus. The antifungal activity varied according to the essential oil composition. Biscogniauxia mediterranea exhibited powerful resistance to some essential oils including them of Eucalyptus lehmannii and Eucalyptus sideroxylon but it was very sensitive to Eucalyptus camaldulensis oil (IC₅₀ = 3.83 mg/ml) and M. communis oil from Zaghouan (IC₅₀ = 1 mg/ml). This sensitivity was found to be correlated to some essential oil compounds such as p‐cymene, carvacrol, cuminaldehyde, and linalool.     

Essential‐Oil Diversity of Salvia tomentosa Mill. in Greece

Salvia tomentosa essential oils from Greece were studied for the first time here. The oils from five populations growing in Mediterranean pine forests on the island of Thassos (northern Aegean Sea) and from 14 populations situated in deciduous forests in Thrace (northeastern Greek mainland) were investigated. Their essential‐oil contents ranged from 1.1 to 3.3% (v/w, based on the dry weight of the plant material). The populations from Thassos had high contents of α‐pinene (18.0±2.9%), 1,8‐cineole (14.7±3.0%), cis‐thujone (14.0±6.9%), and borneol (12.8±2.2%) and smaller amounts of camphene, camphor, and β‐pinene, whereas the populations from Thrace showed high α‐pinene (16.7±4.0%), β‐pinene (22.8±4.5%), camphor (18.3±4.3%), and camphene (10.3±2.4%) contents, much lower 1,8‐cineole and borneol amounts, while cis‐thujone was completely lacking. The comparison of the present results with published data showed that oils having cis‐thujone as one of the main compounds were reported for the first time here. Multivariate statistical analyses indicate that the observed essential‐oil variation was related to geographical and environmental factors.     

Chemical Composition of the Essential Oils from Different Morphological Parts of Pinus cembra L.

The essential oils from needles, twigs, bark, wood, and cones of Pinus cembra were analyzed by GC‐FID, GC/MS, and ¹H‐NMR spectroscopy. More than 130 compounds were identified. The oils differed in the quantitative composition. The principal components of the oil from twigs with needles were α‐pinene (36.3%), limonene (22.7%) and β‐phellandrene (12.0%). The needle oil was dominated by α‐pinene (48.4%), whereas in the oil from bark and in the oil from twigs without needles there were limonene (36.2% and 33.6%, resp.) and β‐phellandrene (18.8% and 17.1%, resp.). The main constituents of the wood oil as well as cone oil were α‐pinene (35.2% and 39.0%, resp.) and β‐pinene (10.4% and 18.9%, resp.). The wood oil and the cone oil contained large amounts of oxygenated diterpenes in comparison with needle, twig, and bark oils.     

Yield,chemical composition,and bioactivity of essential oils from 12 species of Eucalyptus on Aedes aegypti larvae

The insecticidal activity of essential oils from 12 species of Eucalyptus (Myrtaceae) was evaluated on larvae of Aedes aegypti (L.) (Diptera: Culicidae), the most important vector of dengue and yellow fever in the Americas. Oils were obtained by hydrodistillation and their chemical composition was determined by gas chromatography coupled to mass spectrometry; yields ranged from 0.2 to 2.5%. Essential oils were mainly composed of 1,8‐cineole, α‐pinene, α‐phellandrene, β‐phellandrene, γ‐terpinene, 4‐terpineol, α‐terpineol, p‐cymene, and spathulenol. Larvicidal effects were tested on susceptible third or fourth stage Ae. aegypti larvae, determining median lethal concentration (LC₅₀) and median effective concentration (EC₅₀). Essential oils from Eucalyptus dunnii (Maiden), Eucalyptus gunnii (Hook), Eucalyptus tereticornis (Smith), Eucalyptus camaldulensis (Dehn), and Eucalyptus saligna (Smith) showed the best larvicidal activities with LC₅₀ values of 25.2, 21.1, 22.1, 26.8, and 22.2, respectively. No significant differences were observed between LC₅₀ and EC₅₀ values of the same oil. Regression analysis revealed a significant relationship between total essential oil yields and 1,8‐cineole concentration. Significant relationships were also revealed between larval mortality and the concentration of 1,8‐cineole and p‐cymene. This indicated that Eucalyptus species with high oil yields have higher 1,8‐cineole concentrations and lower p‐cymene concentrations and have less effect on Ae. aegypti. Our results suggest the potential of controlled crossing methods to obtain Eucalyptus trees with chemical profiles having enhanced activity against this mosquito.     

Composition and Chemical Variability of Cleistopholis patens Trunk Bark Oil from Côte d'Ivoire

The chemical composition of trunk bark oil from Cleistopholis patens (Benth .) Engl . & Diels , growing wild in Côte d'Ivoire, has been investigated by GC (FID) in combination with retention indices, GC/MS and ¹³C‐NMR. Moreover, one oil sample has been subjected to CC and all the fractions analyzed by GC (RI) and ¹³C‐NMR. In total, 61 components have been identified, including various sesquiterpene esters scarcely found in essential oils. ¹³C‐NMR was particularly efficient for the identification of a component not eluted on GC and for the quantification of heat‐sensitive compounds. Then, 36 oil samples, isolated from trunk bark harvested in six Ivoirian forests have been analyzed. The content of the main components varied drastically from sample to sample: (E)‐β‐caryophyllene (0.4 – 69.1%), β‐pinene (0 – 57%), α‐phellandrene (0 – 33.2%), α‐pinene (0.1 – 30.6%), β‐elemol (0.1 – 29.9%), germacrene D (0 – 25.4%), juvenile hormone III (0 – 22.9%), germacrene B (0 – 20.6%) and sabinene (tr‐20.3%). Statistical analysis, hierarchical clustering and principal components analysis, carried out on the 36 compositions evidenced a fair chemical variability of the stem bark oil of this species. Indeed, three clusters have been distinguished: the composition of group I (ten samples) was dominated by β‐pinene and α‐pinene, group II (nine samples) was represented by α‐phellandrene and p‐cymene and group III (16 samples) by β‐elemol. A sample displayed an atypical composition dominated by (E)‐β‐caryophyllene.     

Variation in Volatile Leaf Oils of Eleven Eucalyptus Species Harvested from Korbous Arboreta (Tunisia)

Hydrodistillation of the dried leaves of eleven species of the genus Eucalyptus L 'Hér ., i.e., E. astringens Maiden , E. camaldulensis Dehnh ., E. diversifolia Bonpl ., E. falcata Turcz ., E. ficifolia F. Muell ., E. gomphocephala DC., E. lehmannii (Schauer ) Benth ., E. maculata Hook ., E. platypus Hook ., E. polyanthemos Schauer, and E. rudis Endl ., harvested from Korbous arboreta (region of Nabeul, northeast of Tunisia) in April 2006, afforded essential oils in yields varying from 0.1±0.1 to 3.8±0.1%, dependent on the species. E. astringens and E. ficifolia showed the highest and the lowest mean percentage of essential oil amongst all the species examined, respectively. Analysis by GC (RI) and GC/MS allowed the identification of 138 components, representing 74.0 to 99.1% of the total oil. The contents of the different samples varied according to the species. The main components were 1,8‐cineole, followed by trans‐pinocarveol ( 1 ), spathulenol ( 2 ), α‐pinene, p‐cymene, (E,E)‐farnesol, cryptone, globulol ( 3 ), β‐phellandrene, α‐terpineol, viridiflorol, and α‐eudesmol. The principal‐component and the hierarchical‐cluster analyses separated the eleven Eucalyptus leaf essential oils into seven groups, each constituting a chemotype.     

Environment‐Related Variations of the Composition of the Essential Oils of Rosemary (Rosmarinus officinalis L.) in the Balkan Penninsula

Composition of the essential oils of Rosmarinus officinalis of ten populations from the Balkan Peninsula were determined by GC/FID and GC/MS. The main constituents were 1,8‐cineole, camphor, α‐pinene, and borneol. Multivariate statistical analysis (UPGMA cluster analysis and principal‐component analysis (PCA)) revealed two major types of rosemary oil, i.e., 1,8‐cineole and camphor‐type, and two intermediate types, i.e., camphor/1,8‐cineole/borneol type and 1,8‐cineole/camphor type. The regression analyses (simple linear regression and stepwise multiple regression) have shown that, with respect to basic geographic, orographic, and 19 bioclimatic characteristics of each population, bioclimatic factor temperature of habitat represented the dominant abiogenetic factor, which, in chemical sense, led to differentiation of populations in the studied region. Also, the regression analysis have shown that some constituents of essential oils are independent of any single bioclimatic factors. However, some constituents display statistically significant correlations with some abiotic factors.     

Chemical Variability of Algerian Myrtus communis L.

The composition of 55 samples of essential oil isolated from the aerial parts of wild growing Myrtus communis L. harvested in 16 locations from East to West Algeria were investigated by GC (determination of retention indices) and ¹³C‐NMR analyses. The essential oils consisted mainly of monoterpenes, α‐pinene (27.4–59.2%) and 1,8‐cineole (6.1–34.3%) being the major components. They were also characterized by the absence of myrtenyl acetate. The compositions of the 55 oils were submitted to k‐means partitioning and principal component analysis, which allowed the distinction of two groups within the oil samples, which could be subdivided into two subgroups each. Groups I (78% of the samples) and II were differentiated on the basis of the contents of α‐pinene, linalool, and linalyl acetate. Subgroups IA and IB could be distinguished by their contents of α‐pinene and 1,8‐cineole. Subgroups IIA and IIB differed substantially in their contents of 1,8‐cineole and limonene. All the samples contained 3,3,5,5,8,8‐hexamethyl‐7‐oxabicyclo[4.3.0]non‐1(6)‐ene‐2,4‐dione (up to 4.9%).     

Corymbia leaf oils,latitude, hybrids and herbivory: A test using common‐garden field trials

Foliar oils, particularly monoterpenes, can influence the susceptibility of plants to herbivory. In plants, including eucalypts, monoterpenes are often associated with plant defence. A recent analysis revealed an increase in foliar oil content with increasing latitudinal endemism, and we tested this pattern using three eucalypt taxa comprising a latitudinal replacement cline. We also examined the relative concentrations of two monoterpenes (α‐pinene and 1,8‐cineole), for which meta‐analyses also showed latitudinal variation, using hybrids of these three taxa with Corymbia torelliana. These, and pure C. torelliana, were then assessed in common‐garden field plots for the abundance and distribution of herbivory by four distinct herbivore taxa. Differing feeding strategies among these herbivores allowed us to test hypotheses regarding heritability of susceptibility and relationships to α‐pinene and 1,8‐cineole. We found no support for an increase in foliar oil content with increasing latitude, nor did our analysis support predictions for consistent variation in α‐pinene and 1,8‐cineole contents with latitude. However, herbivore species showed differential responses to different taxa and monoterpene contents. For example, eriophyid mites, the most monophagous of our censused herbivores, avoided the pure species, but fed on hybrid taxa, supporting hypotheses on hybrid susceptibility. The most polyphagous herbivore (leaf blister sawfly Phylacteophaga froggatti) showed no evidence of response to plant secondary metabolites, while the distribution and abundance patterns of Paropsis atomaria showed some relationship to monoterpene yields.     

Variation in volatile leaf oils of five Eucalyptus species harvested from Jbel Abderrahman arboreta (Tunisia)

Hydrodistillation of the dried leaves of five species of the genus Eucalyptus L' Hér ., viz., E. dundasii Maiden , E. globulus Labill ., E. kitsoniana Maiden , E. leucoxylon F. Muell ., and E. populifolia Hook ., harvested from Jbel Abderrahman arboreta (region of Nabeul, northeast of Tunisia) in April 2006, afforded essential oils in yields varying from 0.9±0.3 to 3.8±0.6%, dependent on the species. E. globulus and E. Kitsoniana provided the highest and the lowest percentage of essential oil amongst the species examined, respectively. Analysis by GC (RI) and GC/MS allowed the identification of 127 compounds, representing 93.8 to 98.7% of the total oil composition. The contents of the different samples varied according to the species. The main components were 1,8‐cineole ( 2 ; 4.7–59.2%), followed by α‐pinene ( 1 ; 1.9–23.6%), trans‐pinocarveol ( 6 ; 3.5–21.6%), globulol ( 8 ; 4.3–12.8%), p‐cymene ( 3 ; 0.5–6.7%), α‐terpineol (1.5–4.5%), borneol (0.2–4.4%), pinocarvone (1.1–3.8%), aromadendrene (1.4–3.4%), isospathulenol (0.0–1.9%), fenchol ( 4 ; 0.1–2.5%), limonene (1.0–2.4%), epiglobulol (0.6–2.1%), viridiflorol ( 9 ; 0.8–1.8%), and spathulenol (0.1–1.6%). E. leucoxylon was the richest species in 2 . Principal component analysis (PCA) and hierarchical cluster analysis (HCA) separated the five Eucalyptus leaf essential oils into four groups, each constituting a chemotype.     

Phytochemical Investigation of Male and Female Hedyosmum scabrum (Ruiz & Pav.) Solms Leaves from Ecuador

This article reports the chemical composition of the essential oils obtained by hydrodistillation of male and female H. scabrum fresh leaves. The essential oils, HSMO and HSFO, respectively, were analyzed by GC/MS and GC‐FID. A total of 93 components were detected, accounting for 94.8% and 95.3% of HSMO and HSFO, respectively. The prevalent constituents of HSMO were pinocarvone (13.1%), d ‐germacren‐4‐ol (12.6%), 1,8‐cineole (10.8%), α‐pinene (6.4%), and β‐pinene (4.8%), whereas the major components of HSFO were 1,8‐cineole (20.5%), linalool (16.5%), α‐pinene (15.0%), β‐pinene (6.4%), and sabinene (6.3%). The different enantiomeric distribution of β‐pinene, sabinene, limonene, linalool in the two oils, was determined. The non‐volatile esters of p‐coumaric and ferulic acids with borneol ( 1 and 4 ), cis‐chrysanthenol ( 2 and 5 ), and cis‐pinocarveol ( 3 and 6 ) were identified in the leaves after basic hydrolysis and analysis of the NMR spectra of the free acids, and GC/MS spectra of the monoterpene alcohols, respectively. Compounds 2 , 3 , 5 , and 6 have been found in nature for the first time. These findings demonstrated that, from a chemical point of view, male and female individuals of H. scabrum collected in Ecuador seem quite differentiated between each other and from samples of the same species growing in Bolivia and in Peru.     

Genetic and Chemical Diversity in Perovskia abrotanoides Kar. (Lamiaceae) Populations Based on ISSRs Markers and Essential Oils Profile

Genetic and the essential oil composition variability among twelve Perovskia abrotanoides populations (PAbPs) growing wild in Iran were assessed by ISSR markers, GC‐FID and GC/MS, respectively. Nine selected ISSR primers produced 119 discernible bands, of them 96 (80.7%) being polymorphic. Genetic similarity values among populations ranged between 0.07 and 0.79 which indicated a high level of genetic variation. Polymorphic information content, resolving power and marker index generated by ISSR primers were, 0.31, 6.14, and 3.32, respectively. UPGMA grouped PAbPs into four main clusters. Altogether, 38 chemical compounds were identified in the oils, and a relatively high variation in their contents was found. Camphor (11.9 – 27.5%), 1,8‐cineole (11.3 – 21.3%), α‐bisabolol (0.0 – 13.1%), α‐pinene (5.9 – 10.8%), and δ‐3‐carene (0.1 – 10.5%) were the major compounds. Oxygenated monoterpenes (32.1 – 35.8%) and monoterpene hydrocarbons (25.7 – 30.4%) were the main groups of compounds in the oils studied. Cluster analysis and principal‐component analysis were used to characterize the samples according to oil components. Four main chemotypes were found to be Chemotype I (camphor/1,8‐cineol), Chemotype II (1,8‐cineole/camphor), Chemotype III (camphor/1,8‐cineol/α‐bisabolol), and Chemotype IV (camphor/δ‐3‐carene/α‐bisabolol). The information, provided here on P. abrotanoides populations, will be useful to introduce this plant into agricultural systems.     

Essential‐Oil Variability of Juniperus deltoides R.P.Adams along the East Adriatic Coast – How Many Chemotypes Are There?

The composition of the essential oils isolated from twigs of ten Juniperus deltoides R.P . Adams populations from the east Adriatic coast was determined by GC‐FID and GC/MS analyses. Altogether, 169 compounds were identified, representing 95.6–98.4% of the total oil composition. The oils were dominated by monoterpenes (average content of 61.6%), which are characteristic oil components of species of the Juniperus section. Two monoterpenes, α‐pinene and limonene, were the dominant constituents, comprising on average 46.78% of the essential oils. Statistical methods were deployed to determine the diversity of the terpene classes and the common terpenes between the investigated populations. These statistical analyses revealed the existence of three chemotypes within all populations, i.e., a α‐pinene, limonene, and limonene/α‐pinene type.     

Chemotaxonomic Importance of the Essential‐Oil Composition in Two Subspecies of Teucrium stocksianum Boiss. from Iran

The hydrodistilled essential oils obtained from aerial flowering parts of Teucrium stocksianum ssp. stocksianum (TSS) and T. stocksianum ssp. gabrielae (TSG) from Iran were analyzed by capillary GC and GC/MS. The oil analysis of two subspecies led to the identification of 65 compounds that accounted for 93.3 and 95.1% of the total oil compositions, respectively. Sesquiterpenoids (52.9%) constituted the main compounds in the essential oil of TSS represented mainly by cis‐sesquisabinene hydrate (12.0%), followed by epi‐β‐bisabolol (6.6%), guaiol (5.4%), and β‐eudesmol (4.4%), whilst monoterpenoids (61.2%) were found to be the major components of the oil of TSG, represented by α‐pinene (23.0%), β‐pinene (13.0%), myrcene (6.3%), and sabinene (6.3%). The principal component in both subspecies, TSS and TSG, was α‐pinene (22.0 and 23.0%, resp.) and β‐pinene (6.5 and 13.0%, resp.). epi‐α‐Cadinol, myrcene, and sabinene, which were detected as principal compounds of TSG, were characterized in lower amounts (<1.5%) in the oil of TSS. Seven components were identified in the oil of TSS corresponding to 25.9% of total oil, which were totally absent in the oil of TSG, of which cis‐sesquisabinene hydrate (12.0%), guaiol (5.4%), and β‐eudesmol (4.4%) were in considerable amounts. Taxonomic position of the subspecies is discussed on the basis of phytochemical data.     

Chemical Variability of the Essential Oil of Juniperus phoenicea var. turbinata from Algeria

The chemical composition of 50 samples of leaf oil isolated from Algerian Juniperus phoenicea var. turbinata L. harvested in eight locations (littoral zone and highlands) was investigated by GC‐FID (in combination with retention indices), GC/MS, and ¹³C‐NMR analyses. The composition of the J. phoenicea var. turbinata leaf oils was dominated by monoterpenes. Hierarchical cluster and principal component analyses confirmed the chemical variability of the leaf oil of this species. Indeed, three clusters were distinguished on the basis of the α‐pinene, α‐terpinyl acetate, β‐phellandrene, and germacrene D contents. In most oil samples, α‐pinene (30.2–76.7%) was the major compound, associated with β‐phellandrene (up to 22.5%) and α‐terpinyl acetate (up to 13.4%). However, five out of the 50 samples exhibited an atypical composition characterized by the predominance of germacrene D (16.7–22.7%), α‐pinene (15.8–20.4%), and α‐terpinyl acetate (6.1–22.6%).     

Variation in Volatile Leaf Oils of Twelve Eucalyptus Species Harvested from Hajeb Layoun Arboreta (Tunisia)

Hydrodistillation of the dried leaves of twelve species of the genus Eucalyptus L' Hér ., i.e., E. brockwayi C. A. Gardn ., E. gracilis F. Muell ., E. gillii Maiden , E. largiflorens F. Muell ., E. loxophleba Benth ., E. occidentalis Endl ., E. oldfieldii F. Muell ., E. salmonophloia F. Muell ., E. sargentii Maiden , E. stricklandii Maiden , E. torquata Luehm ., and E. woodwardii Maiden , harvested from Hajeb Layoun arboreta (region of Kairouan, central Tunisia) in January 2005, afforded essential oils in yields varying from 0.5±0.1 to 5.7±0.5%, dependent on the species. E. sargentii and E. brockwayi provided the highest and the lowest percentage of essential oil amongst all the species examined, respectively. Analysis by GC (RI) and GC/MS allowed the identification of 133 components, representing 92.9–98.8% of the total oil. The contents of the different samples varied according to the species. The main components were 1,8‐cineole, terpinen‐4‐ol, α‐pinene ( 2 ), p‐cymene, aromadendrene ( 1 ), globulol ( 5 ), trans‐pinocarveol ( 6 ), spathulenol ( 7 ), β‐eudesmol, torquatone ( 3 ), and 4‐methylpentan‐2‐yl acetate ( 8 ). The principal component analysis and the hierarchical clustering indicated that the volatile leaf oil composition of the twelve Eucalyptus species could be clearly differentiated.     

High Diversity of Indigenous Populations of Dalmatian Sage (Salvia officinalis L.) in Essential‐Oil Composition

Essential oils of 25 indigenous populations of Dalmatian sage (Salvia officinalis L.) that represent nearly half of native distribution area of the species were analyzed. Plantlets collected from wild populations were grown in the same field under the same environmental conditions and then sampled for essential‐oil analysis. The yield of essential oil ranged from 1.93 to 3.70% with average of 2.83%. Among the 62 compounds detected, eight (cis‐thujone, camphor, trans‐thujone, 1,8‐cineole, β‐pinene, camphene, borneol, and bornyl acetate) formed 78.13–87.33% of essential oils of individual populations. Strong positive correlations were observed between camphor and β‐pinene, β‐pinene and borneol, as well as between borneol and bornyl acetate. The strongest negative correlation was detected between camphor and trans‐thujone. Principal component analysis (PCA) on the basis of eight main compounds showed that first main component separated populations with high thujone content, from those rich in camphor, while the second component separated populations rich in cis‐thujone from those rich in trans‐thujone. Cluster analysis (CA) led to the identification of three chemotypes of S. officinalis populations: cis‐thujone; trans‐tujone, and camphor/β‐pinene/borneol/bornyl acetate. We propose that differences in essential oils of 25 populations are mostly genetically controlled, since potential environmental factors were controlled in this study.     

Variation in Volatile Leaf Oils of 13 Eucalyptus Species Harvested from Souinet Arboreta (Tunisia)

Hydrodistillation of the dried leaves of 13 species of the genus Eucalyptus L' Hér ., viz., E. bicostata Maiden, Blakely & Simmonds , E. cinerea F. Muell . ex Benth ., E. exerta F. Muell ., E. gigantea Hook . f ., E. gunnii Hook . f ., E. macarthurii Deane & Maiden ., E. macrorrhyncha F. Muell ., E. maidenii F. Muell ., E. odorata Behr ., E. pauciflora Sieber ex Sprengel , E. sideroxylon A. Cunn . ex Woolls , E. tereticornis Sm ., and E. viminalis Labill ., harvested from Souinet arboreta (region of Ain Draaham, north of Tunisia) in June 2006, afforded essential oils in yields varying from 0.5±0.2 to 3.9±0.4%, dependent on the species. E. cinerea and E. exerta provided the highest and the lowest percentage of essential oil amongst all the species examined, respectively. Analysis by GC (RI) and GC/MS allowed the identification of 142 components, representing 81.5 to 98.9% of the total oil. The contents of the different samples varied according to the species. The main components were 1,8‐cineole ( 1 ), followed by cryptone, spathulenol ( 4 ), p‐cymene ( 2 ), viridiflorol ( 6 ), globulol ( 7 ), β‐eudesmol, α‐terpineol ( 5 ), limonene ( 8 ), D ‐piperitone, α‐pinene ( 3 ), cuminal, and γ‐eudesmol. The principal component and the hierarchical cluster analyses separated the 13 Eucalyptus leaf essential oils into three groups, each constituting a chemotype.     

Essential Oils and Chemical Diversity of Southeast European Populations of Salvia officinalis L.

The essential oils of 25 populations of Dalmatian sage (Salvia officinalis L.) from nine Balkan countries, including 17 indigenous populations (representing almost the entire native distribution area) and eight non‐indigenous (cultivated or naturalized) populations were analyzed. Their essential‐oil yield ranged from 0.25 to 3.48%. Within the total of 80 detected compounds, ten (β‐pinene, 1,8‐cineole, cis‐thujone, trans‐thujone, camphor, borneol, trans‐caryophyllene, α‐humulene, viridiflorol, and manool) represented 42.60 to 85.70% of the components in the analyzed essential oils. Strong positive correlations were observed between the contents of trans‐caryophyllene and α‐humulene, α‐humulene and viridiflorol, and viridiflorol and manool. Principal component analysis (PCA) on the basis of the contents of the ten main compounds showed that four principal components had an eigenvalue greater than 1 and explained 79.87% of the total variation. Performing cluster analysis (CA), the sage populations could be grouped into four distinct chemotypes (A–D). The essential oils of 14 out of the 25 populations of Dalmatian sage belonged to Chemotype A and were rich in cis‐thujone and camphor, with low contents of trans‐thujone. The correlation between the essential‐oil composition and geographic variables of the indigenous populations was not significant; hence, the similarities in the essential‐oil profile among populations could not be explained by the physical proximity of the populations. Additionally, the southeastern populations tended to have higher EO yields than the northwestern ones.     

Chemical Variability and Antioxidant Activity of Limbarda crithmoides L. Essential Oil from Corsica

The chemical compositions of 25 Corsican Limbarda crithmoides ssp. longifolia essential oils were investigated for the first time using GC‐FID, GC/MS, and NMR analyses. Altogether, 65 compounds were identified, accounting for 90.0–99.3% of the total oil compositions. The main components were p‐cymene ( 1 ; 15.1–34.6%), 3‐methoxy‐p‐cymenene ( 4 ; 11.8–28.5%), 2,5‐dimethoxy‐p‐cymenene ( 5 ; 5.9–16.4%), thymol methyl ether ( 6 ; 1.3–14.9%), α‐phellandrene ( 2 ; 0.9–11.9%), and α‐pinene ( 3 ; 0.2–13.4%). The chemical variability of the Corsican oil samples was studied using multivariate statistical analysis, which allowed the discrimination of two main clusters. A direct correlation between the water salinities of the plant locations and the chemical compositions of the L. crithmoides essential oils was evidenced. Indeed, essential oils rich in 1 (30.4–34.6%) were found in samples growing in the wetlands of the southern oriental coast, which exhibit high salinity levels (24.4±0.2–33.9±0.2 ppt), and essential oils with lower contents of 1 (15.1–27.3%) were isolated form samples growing in the wetlands of northern Corsica, which exhibit lower salinity levels (10.90±0.20–15.47±0.15 ppt). The antioxidant potential of L. crithmoides essential oil was also investigated, by assessing the DPPH^.‐ and ABTS^.+‐scavenging activities and the reducing power of ferric ions, and was found to be interesting. Moreover, using bioassay‐guided fractionation of the essential oil, a higher antioxidant activity was obtained for the oxygenated fraction and both ester and alcohol subfractions.