Composition of n‐Alkanes in Natural Populations of Pinus nigra from Serbia – Chemotaxonomic Implications

This is the first report on the composition and variability of the needle‐wax n‐alkanes in natural populations of Pinus nigra in Serbia. Samples of 195 trees from seven populations belonging to several infraspecific taxa (ssp. nigra, var. gocensis, ssp. pallasiana, and var. banatica) were analyzed. In general, the size of the n‐alkanes ranged from C₁₆ to C₃₃, with the exception of ssp. nigra, for which it ranged from C₁₈ to C₃₃. The most abundant were C₂₃‐, C₂₅‐, C₂₇‐, and C₂₉‐alkanes. The needle waxes of Populations I–III and V were characterized by a higher content of C₂₃‐, C₂₅‐, and C₂₇‐alkanes and a lower content of C₂₄‐, C₂₆‐, C₂₈‐, and C₃₀‐alkanes, compared to the other populations, and the trees of these populations could be assigned to ssp. nigra. The samples of Population VI were characterized by higher amounts of C₂₂‐, C₂₄‐, C₃₀‐, and C₃₂‐alkanes and lower amounts of C₂₅‐ and C₂₇‐alkanes, and the trees could be considered as ssp. pallasiana. The samples of Population VII, consisting of trees belonging to var. banatica, were richer in C₂₉‐, C₃₁‐, and C₃₃‐alkanes. The wax compositions of Populations IV and V, both composed of trees previously determined as P. nigra var. gocensis, showed a tendency of splitting. Indeed, the alkane composition of Population IV was closer to that of ssp. pallasiana pines, while that of Population V was more similar to that of ssp. nigra pines. From the results presented here, it is obvious that in the central part of the Balkan Peninsula, significant diversification and differentiation of the populations of black pine exists, and these populations could be defined as different intraspecific taxa. Our results also indicate the validity of n‐alkanes as chemotaxonomic characters within this aggregate.     

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.     

Essential‐Oil Composition of the Needles Collected from Natural Populations of Macedonian Pine (Pinus peuce Griseb.) from the Scardo‐Pindic Mountain System

The needle‐terpene profiles of two natural Pinus peuce populations from the Scardo‐Pindic mountain system (Mt. O?ljak and Mt. Pelister) were analyzed. Among the 90 detected compounds, 87 were identified. The dominant constituents were α‐pinene (45.5%), germacrene D (11.1%), β‐pinene (10.8%), and camphene (10.3%). The following eight additional components were found to be present in medium‐to‐high amounts (0.5–10%): bornyl acetate (5.0%), β‐phellandrene (3.4%), β‐caryophyllene (2.9%), β‐myrcene (0.9%), germacrene D‐4‐ol (0.9%), tricyclene (0.7%), (E)‐hex‐2‐enal (0.7%), and bicyclogermacrene (0.6%). Although the general needle‐terpene profiles of the populations from Mt. O?ljak and Mt. Pelister were found to be similar to those of the populations from Zeletin, Sjekirica, and Mokra Gora (Dinaric Alps), principle component analysis (PCA) of eight terpenes (α‐pinene, β‐myrcene, α‐terpinolene, bornyl acetate, α‐terpinyl acetate, β‐caryophyllene, trans‐β‐farnesene, and germacrene D) in 139 tree samples suggested a divergence between the two population groups, i.e., the samples from the Scardo‐Pindic mountain system and those from the Dinaric Alps. Genetic analysis of the β‐pinene content demonstrated a partial divergence between the two geographical groups. The profiles of both population groups differed from those published for populations from the Balkan‐Rhodope mountains system (literature results), which were characterized by high contents of bornyl acetate and citronellol (Greek populations) or δ‐car‐3‐ene (Bulgarian populations).     

Essential‐Oil Composition of the Fruits of Six Heracleum L. Species from Iran: Chemotaxonomic Significance

The fruit essential oils of Heracleum persicum, H. rechingeri, H. gorganicum, H. rawianum, H. pastinacifolium, and H. anisactis from Iran were obtained by hydrodistillation and characterized by GC‐FID and GC/MS analyses. The oils of the six species were compared to determine the similarities and differences among their compositions. Overall, 36 compounds were identified in the fruit oils, accounting for 92.40–96.74% of the total oil compositions. Aliphatic esters constituted the main fraction of the oils (86.61–94.31%), with octyl acetate and hexyl butyrate as the major components. The oil compositions of species belonging to section Pubescentia (H. persicum, H. gorganicum, and H. rechingeri) were discriminated by equally high contents of both octyl acetate (13.84–20.48%) and hexyl butyrate (17.73–38.36%). On the other hand, the oils of H. rawianum, H. pastinacifolium and H. anisactis, belonging to section Wendia, showed lower hexyl butyrate contents (3.62–6.6%) and higher octyl acetate contents (48.71–75.36%) than the former. Moreover, isoelemicin was identified at low amounts (0.10–2.51%) only in the oils of the latter species. The differences in the oil composition among the six species were investigated by hierarchical cluster and principal component analyses, which indicated that the oil composition confirmed well the taxonomical classification based on the morphological and botanical data, and, thus, may provide a reliable marker to discriminate Heracleum species at the intersectional level.     

Variability of the needle essential oils of Pinus peuce from different populations in Montenegro and Serbia

The essential-oil composition of Pinus peuce Griseb. is reported at the population level. Macedonian pine is endemic high-mountain Balkan pine relict of an anthropogenically reduced area, with large morphological diversity and insufficiently clear taxonomic position. In the pine-needle terpene profile of two populations from Montenegro and one from Serbia, 78 compounds were detected, 56 of which are identified (Table 3). The dominant constituents were alpha-pinene (36.5%) and germacrene D (11.4%). The following 20 additional components were found to be present in medium-to-high amounts (0.5-10%): camphene (8.5%), bornyl acetate (6.8%), beta-pinene (6.8%), beta-caryophyllene (5.2%), beta-phellandrene (4.7%), terpinen-4-ol acetate (1.6%), (E)-hex-2-enal (1.5%), alpha-muurolene (1.2%), beta-gurjunene (1.1%), beta-myrcene (1.0%), alpha-terpinyl acetate (0.9%), alpha-phellandrene (0.8%), delta-cadinene (0.8%), alpha-humulene (0.8%), sabinene (0.7%), aromadendrene (0.6%), alpha-thujene (0.6%), gamma-muurolene (0.6%), gamma-cadinene (0.6%), alpha-terpinolene (0.5%), and one unknown component (0.5%). The similarity of the populations and the within-population variability were visualized by principle-component analysis (PCA) and genetic analysis of selected terpenes in 90 tree samples. Our study suggests a closer connection between populations II and III compared to population I. Based on the profile of the main terpene components, the studied populations are more similar to populations from Kosovo and Greece than to the population from Mt. Mokra (Montenegro) and the population in France.     

Variability in the Essential‐Oil Composition of Sideritis scardica Griseb. from Native Bulgarian Populations

The essential‐oil composition of six native populations of Sideritis scardica from Bulgaria was studied by GC‐FID and GC/MS analyses. Altogether, 37 components, representing 73.1 to 79.2% of the total oil content were identified. Among them, α‐pinene (4.4–25.1%), β‐pinene (2.8–18.0%), oct‐1‐en‐3‐ol (2.3–8.0%), phenylacetaldehyde (0.5–9.5%), β‐bisabolene (1.3–11.0%), benzyl benzoate (1.1–14.3%), and m‐camphorene ( 1 ; 0.3–12.4%) were the main compounds. All samples were characterized by low contents of oxygenated mono‐ and sesquiterpenes (≤1.6 and 2.3%, resp.). Principal component analysis (PCA) and cluster analysis (CA) showed a significant variability in the chemical composition of the studied samples as well as a correlation between the oil profiles and the ecological conditions of the natural habitats of S. scardica.     

Chemical Composition of the Essential Oils of Three Endemic Species of Anthemis Sect. Hiorthia (DC.) R.Fern. Growing Wild in Sicily and Chemotaxonomic Volatile Markers of the Genus Anthemis L.: An Update

The chemical composition of the essential oils isolated from the aerial parts of Anthemis pignattiorum Guarino, Raimondo & Domina and A. ismelia Lojac . and the aerial parts and flowers of Anthemis cupaniana Tod . ex Nyman , three endemic Sicilian species belonging to the section Hiorthia, was determined by GC‐FID and GC/MS analyses. (Z)‐Muurola‐4(14),5‐diene (27.3%) was recognized as the main constituent of the A. pignattiorum essential oil, together with isospathulenol (10.6%), sabinene (7.7%), and artemisyl acetate (6.8%), while in the oil obtained from the aerial parts of A. ismelia, geranyl propionate (8.8%), bornyl acetate (7.9%), β‐thujone (7.8%), neryl propionate (6.5%), and τ‐muurolol (6.5%) prevailed. α‐Pinene was the main compound of both the aerial part and flower oils of A. cupaniana (18.4 and 13.2%, resp.). Also noteworthy are the considerable amounts of artemisyl acetate (12.7%) and β‐thujone (11.8%) found in the oil from the aerial parts and those of tricosane (9.8%) and sabinene (7.6%) evidenced in the flower oil. Furthermore, an update on the main compounds identified in the essential oils of all the Anthemis taxa studied so far was presented, and cluster analyses were carried out, to compare the essential oils of these taxa.     

Variability of the Root Essential Oils of Seseli rigidum Waldst. & Kit. (Apiaceae) from Different Populations in Serbia

The chemical compositions of the essential oils of seven natural populations of Seseli rigidum were analyzed. The essential‐oil yield ranged from 0.16 to 2.09%. Analysis of variance (ANOVA) revealed that there were no statistically significant differences in the mean essential‐oil yields between the populations, and no significant influence of the climate or soil type on the oil yield was observed. In all 67 analyzed samples, the polyacetylene falcarinol was the main compound, followed by octanal, methyl linoleate, α‐muurolene, 3‐butylphthalide, falcarinone, muurola‐4,10(14)‐dien‐1β‐ol, β‐sesquiphellandrene, salvial‐4(14)‐en‐1‐one, δ‐amorphene, spathulenol, and isospathulenol. The principal component analysis (PCA), the canonical discriminant analysis (CDA), and the cluster analysis (CA) revealed differentiation between the populations based on the climate. Three groups of populations were formed; the first group was composed of samples growing in regions with a humid climate, with oils having high falcarinol and low sesquiterpene contents, and the second and third groups comprised samples exposed to semi‐arid climate, with oils characterized by a lower falcarinol and higher α‐muurolene, δ‐amorphene, β‐sesquiphellandrene, and salvial‐4(14)‐en‐1‐one contents. The semi‐arid populations were divided into two groups, which were distinguished based on the oil contents of sesquiterpenes, falcarinone, and 3‐butylphthalide. On the other hand, no clear separation between populations based on the different soil types could be observed.     

Chemotaxonomic Implications of the n‐Alkane Composition and the Nonacosan‐10‐ol Content in Picea omorika,Pinus heldreichii,and Pinus peuce

The n‐alkane composition and the nonacosan‐10‐ol content in the needle cuticular waxes of Serbian spruce (Picea omorika), Bosnian pine (Pinus heldreichii), and Macedonian pine (Pinus peuce) were compared. The amount of nonacosan‐10‐ol in the needle waxes of P. omorika was higher than those in P. heldreichii and P. peuce. The range of n‐alkanes was also wider in P. omorika (C₁₈–C₃₅) than in P. heldreichii and P. peuce (C₁₈–C₃₃). The dominant n‐alkanes were C₂₉ in the needle waxes of P. omorika, C₂₃, C₂₇, and C₂₅ in those of P. heldreichii, and C₂₉, C₂₅, C₂₇, and C₂₃ in those of P. peuce. The waxes of P. omorika contained higher amounts of n‐alkanes C₂₉, C₃₁, and C₃₃, while those of P. heldreichii and P. peuce had higher contents of n‐alkanes C₂₁, C₂₂, C₂₃, C₂₄, and C₂₆. The principal component analysis of the contents of nine n‐alkanes showed a clear separation of the Serbian spruce populations from those of the two investigated pine species, which partially overlapped. The separation of the species was due to high contents of the n‐alkanes C₂₉ and C₃₁ (P. omorika), C₁₉, C₂₀, C₂₁, C₂₂, C₂₃, and C₂₄ (P. heldreichii), and C₂₈ (P. peuce). Cluster analysis also showed a clear separation between the P. omorika populations on one side and the P. heldreichii and P. peuce populations on the other side. The n‐alkane and terpene compositions are discussed in the light of their usefulness in chemotaxonomy as well as with regard to the biogeography and phylogeny of these rare and endemic conifers.     

Chemical Composition of Essential Oils and Aromatic Waters from Different Italian Anthemis maritima Populations

The chemical composition of the essential oils and aromatic waters isolated from six Italian Anthemis maritima populations was determined by GC‐FID and GC/MS analyses. In total, 122 and 100 chemical compounds were identified in the essential oils and the aromatic waters, respectively. The main compound classes represented in the oils were monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpene hydrocarbons, oxygenated sesquiterpenes, and terpene esters. Multivariate chemometric techniques such as cluster analysis (CA) and principal coordinate analysis (PCO) were used to classify the samples according to the geographical origin. Statistical analysis allowed the attribution of the analyzed populations to different chemotype groups.     

Chemotaxonomic Analysis of the Aroma Compounds in Essential Oils of Two Different Ocimum basilicum L. Varieties from Iran

Hydrodistilled essential oils of 21 accessions of Ocimum basilicum L. belonging to two different varieties (var. purpurascens and var. dianatnejadii) from Iran were characterized by GC‐FID and GC/MS analyses. The oil yield was found to be between 0.6 and 1.1% (v/w). In total, 49 compounds, accounting for 96.6–99.7% of the oil compositions, were identified. Aromatic compounds, represented mainly by methyl chavicol (33.6–49.1%), and oxygenated monoterpenes, represented by linalool (14.4–39.3%), were the main components in all essential oils. Monoterpene hydrocarbons were present in the essential oils of all accessions of the purpurascens variety, whereas they were completely absent in those of the dianatnejadii variety, indicating that monoterpene hydrocarbons might be considered as marker constituents of the purpurascens variety. The chemotaxonomic value of the essential‐oil compositions was discussed according to the results of the cluster analysis (CA). The CA showed a clear separation of the O. basilicum var. purpurascens accessions and the O. basilicum var. dianatnejadii accessions, although the data showed no major chemotype variation between the studied varieties. Indeed, the CA revealed only one principal chemotype (methyl chavicol/linalool) for both varieties. In conclusion, GC/MS analyses in combination with CA showed to be a flexible and reliable method for the characterization of the chemical profiles of different varieties of Ocimum basilicum L.     

Population Variability of Essential Oils of Pinus heldreichii from the Scardo‐Pindic Mountains Ošljak and Galičica

The needle‐terpene profiles of two natural Pinus heldreichii populations from Mts. O?ljak and Gali?ica (Scardo‐Pindic mountain system) were analyzed. Among the 68 detected compounds, 66 were identified. The dominant constituents were germacrene D (28.7%), limonene (27.1%), and α‐pinene (16.2%). β‐Caryophyllene (6.9%), β‐pinene (5.2%), β‐myrcene (2.3%), pimaric acid (2.0%), α‐humulene (1.2%), and seven additional components were found to be present in medium‐to‐high amounts (0.5–10%). Although the general needle‐terpene profile of the population from Gali?ica was similar to those of the populations from Lov?en, Zeletin, Bjelasica, and Zlatibor‐Pe?ter (belonging to the Dinaric Alps), the principle‐component analysis (PCA) of seven terpenes (β‐myrcene, limonene, β‐elemene, β‐caryophyllene, α‐humulene, δ‐cadinene, and germacrene D‐4‐ol) in 121 tree samples suggested a partial divergence in the needle‐terpene profiles between the populations from the Scardo‐Pindic mountain system and the Dinaric Alps. According to previously reported data, the P. heldreichii samples from the Balkan‐Rhodope mountains lack β‐caryophyllene and germacrene D, but contain γ‐muurolene in their terpene profile. Differences in the terpene composition between populations growing in the three above‐mentioned mountain systems were compared and discussed.     

Essential‐Oil Variability in Natural Populations of Pinus mugo Turra from the Julian Alps

The composition and variability of the terpenes and their derivatives isolated from the needles of a representative pool of 114 adult trees originating from four natural populations of dwarf mountain pine (Pinus mugo Turra ) from the Julian Alps were investigated by GC‐FID and GC/MS analyses. In total, 54 of the 57 detected essential‐oil components were identified. Among the different compound classes present in the essential oils, the chief constituents belonged to the monoterpenes, comprising an average content of 79.67% of the total oil composition (74.80% of monoterpene hydrocarbons and 4.87% of oxygenated monoterpenes). Sesquiterpenes were present in smaller amounts (average content of 19.02%), out of which 16.39% were sesquiterpene hydrocarbons and 2.62% oxygenated sesquiterpenes. The most abundant components in the needle essential oils were the monoterpenes δ‐car‐3‐ene, β‐phellandrene, α‐pinene, β‐myrcene, and β‐pinene and the sesquiterpene β‐caryophyllene. From the total data set of 57 detected compounds, 40 were selected for principal‐component analysis (PCA), discriminant analysis (DA), and cluster analysis (CA). The overlap tendency of the four populations suggested by PCA, was as well observed by DA. CA also demonstrated similarity among the populations, which was the highest between Populations I and II.     

Chemical composition and antimicrobial activity of the essential oil of endemic Dalmatian black pine (Pinus nigra ssp. dalmatica)

The chemical composition and the antimicrobial activity of the essential oil isolated from the needles of endemic Dalmatian black pine (Pinus nigra ssp. dalmatica) from Croatia were investigated. The chemical composition of the essential oil was determined by GC and GC/MS analyses, and the main compounds identified were α-pinene, β-pinene, germacrene D, and β-caryophyllene. Disc-diffusion and broth-microdilution assays were used for the in vitro antimicrobial screening. The Dalmatian black pine essential oil exhibited a great potential of antibacterial activity against Gram-positive bacteria (MIC=0.03-0.50% (v/v)) and a less pronounced activity against Gram-negative bacteria (MIC=0.12-3.2% (v/v)). The volatile compounds also inhibited the growth of all fungi tested, including yeast.     

Terpene chemodiversity of relict conifers Picea omorika, Pinus heldreichii, and Pinus peuce, endemic to Balkan

Terpenes are often used as ecological and chemotaxonomic markers of plant species, as well as for estimation of geographic variability. Essential oils of relic and Balkan endemic/subendemic conifers, Picea omorika, Pinus heldreichii, and P. peuce, in central part of Balkan Peninsula (Serbia and Montenegro), on the level of terpene classes and common terpene compounds were investigated. In finding terpene combinations, which could show the best diversity between species and their natural populations, several statistical methods were applied. Apart from the content of different terpene classes (P. omorika has the most abundant O-containing monoterpenes and sesquiterpenes; P. heldreichii and P. peuce have the largest abundance of sesquiterpene and monoterpene hydrocarbons, resp.), the species are clearly separated according to terpene profile with 22 common compounds. But, divergences in their populations were established only in combination of several compounds (specific for each species), and they were found to be the results of geomorphologic, climatic, and genetic factors. We found similarities between investigated species and some taxa from literature with respect to terpene composition, possibly due to hybridization and phylogenetic relations. Obtained results are also important regarding to chemotaxonomy, biogeography, phylogeny, and evolution of these taxa.     

Essential‐Oil Composition and Chemical Variability of Senecio vulgaris L. from Corsica

The chemical composition of the essential oils isolated from the aerial parts of Senecio vulgaris plants collected in 30 Corsican localities was characterized using GC‐FID and GC/MS analyses. Altogether, 54 components, which accounted for 95.2% of the total oil composition, were identified in the 30 essential‐oil samples. The main compounds were α‐humulene ( 1 ; 57.3%), (E)‐β‐caryophyllene ( 2 ; 5.6%), terpinolene ( 3 ; 5.3%), ar‐curcumene ( 4 ; 4.3%), and geranyl linalool ( 5 ; 3.4%). The chemical composition of the essential oils obtained from separate organs and during the complete vegetative cycle of the plants were also studied, to gain more knowledge about the plant ecology. The production of monoterpene hydrocarbons, especially terpinolene, seems to be implicated in the plant‐flowering process and, indirectly, in the dispersal of this weed species. Comparison of the present results with the literature highlighted the originality of the Corsican S. vulgaris essential oils and indicated that α‐humulene might be used as taxonomical marker for the future classification of the Senecio genus. A study of the chemical variability of the 30 S. vulgaris essential oils using statistical analysis allowed the discrimination of two main clusters according to the soil nature of the sample locations. These results confirmed that there is a relation between the soil nature, the chemical composition of the essential oils, and morphological plant characteristics. Moreover, they are of interest for commercial producers of essential oil in selecting the most appropriate plants.     

Volatile Compounds in Thymus sect. Teucrioides (Lamiaceae): Intraspecific and Interspecific Diversity,Chemotaxonomic Significance and Exploitation Potential

Thymus sect. Teucrioides comprises three species, namely, T. hartvigii, T. leucospermus, and T. teucrioides, distributed in Greece and Albania. The volatile constituents of all species of the section were obtained by hydrodistillation and investigated by GC‐FID and GC/MS analyses. Twenty populations were sampled and a total of 103 compounds were identified, representing 98.0–99.9% of the oil compositions. The oils were mainly characterized by high contents of monoterpene hydrocarbons (42.7–92.4%), with the exception of three oils for which oxygenated monoterpenes were the dominating constituents, viz., that of T. hartvigii ssp. macrocalyx, with linalool as main compound (89.2±0.5%), and those of T. hartvigii ssp. hartvigii and of one population of T. teucrioides ssp. candilicus, containing thymol as major component (46.4±3.1 and 38.2±3.9%, resp.). The most common compound in the oils of the 20 populations of the section was p‐cymene. Considerable variation was detected within and among populations, and seven chemotypes were distinguished, i.e., p‐cymene, linalool, p‐cymene/thymol, p‐cymene/γ‐terpinene, p‐cymene/borneol, p‐cymene/γ‐terpinene/borneol, and p‐cymene/linalool chemotypes. Different chemotypes may exist in the same population. Multivariate statistical analyses enabled the segregation of the oils within Thymus sect. Teucrioides into two groups, one consisting of the three subspecies of T. teucrioides and the second comprising the species T. hartvigii and T. leucospermus. A linalool‐rich chemotype, unique within the section, distinguished the oil of T. hartvigii ssp. macrocalyx from all other oils. The high oil content of p‐cymene and the preference for serpentine substrates render T. teucrioides species promising for future exploitation.     

Biochemical Characterization of Helichrysum italicum (Roth) G.Don subsp. italicum (Asteraceae) from Montenegro: Phytochemical Screening,Chemotaxonomy, and Antioxidant Properties

The chemical composition and antioxidant properties of the essential oil and EtOH extract of immortelle (Helichrysum italicum (Roth) G.Don subsp. italicum, Asteraceae) collected in Montenegro were evaluated. The essential oil was characterized by GC/MS analysis, and the content of total phenolics and flavonoids in the EtOH extract was determined using the Folin? Ciocalteu reagent. The free‐radical‐scavenging capacity (RSC) of both the essential oil and the EtOH extract was assessed with the 2,2‐diphenyl‐1‐pycrylhydrazyl (DPPH) method. Moreover, the inhibition of hydroxyl radical (^.OH) generation by the EtOH extract of immortelle was evaluated for the first time here. Neryl acetate (28.2%) and γ‐curcumene (18.8%) were the main compounds in the essential oil, followed by neryl propionate (9.1%) and ar‐curcumene (8.3%). The chemical composition of the oils of the examined and additional 16 selected Helichrysum italicum taxa described in literature were compared using principal component (PCA) and cluster (CA) analyses. The results of the statistical analyses implied the occurrence of at least four different main and three subchemotypes of essential oils. Considering the antioxidant properties, the EtOH extract of immortelle exhibited similar potential as propyl gallate and quercetin, while the essential oil exhibited relatively weak DPPH^.‐scavenging capacity.     

Chemical Diversity among the Essential Oils of Wild Populations of Stachys lavandulifolia Vahl (Lamiaceae) from Iran

The variation of the essential‐oil composition among ten wild populations of Stachys lavandulifolia Vahl (Lamiaceae), collected from different geographical regions of Iran, was assessed by GC‐FID and GC/MS analyses, and their intraspecific chemical variability was determined. Altogether, 49 compounds were identified in the oils, and a relatively high variation in their contents was found. The major compounds of the essential oils were myrcene (0.0–26.2%), limonene (0.0–24.5%), germacrene D (4.2–19.3%), bicyclogermacrene (1.6–18.0%), δ‐cadinene (6.5–16.0%), pulegone (0.0–15.1%), (Z)‐hex‐3‐enyl tiglate (0.0–15.1%), (E)‐caryophyllene (0.0–12.9), α‐zingiberene (0.2–12.2%), and spathulenol (1.6–11.1%). For the determination of the chemotypes and the chemical variability, the essential‐oil components were subjected to cluster analysis (CA). The five different chemotypes characterized were Chemotype I (germacrene D/bicyclogermacrene), Chemotype II (germacrene D/spathulenol), Chemotype III (limonene/δ‐cadinene), Chemotype IV (pulegone), and Chemotype V (α‐zingiberene). The high chemical variation among the populations according to their geographical and bioclimatic distribution imposes that conservation strategies of populations should be made appropriately, taking into account these factors. The in situ and ex situ conservation strategies should concern all populations representing the different chemotypes.