Essential oil chemical diversity of twenty Iranian Origanum vulgare L. subsp. viride populations

Origanum vulgare L. belonging to the Lamiaceae family, commonly known as oregano, is one of the most traded and consumed medicinal plants worldwide. It is a rich natural source of specialized metabolites including essential oils. The present study is the first comprehensive account of the essential oil profile of wild O. vulgare subsp. viride plants in Iran. Twenty native populations from four provinces of northern Iran were investigated for the content and composition of essential oils. Essential oil contents were found to vary from 0.1 to 0.5% (v/w) based on dry weight. Analysis of these oils by GC-FID and GC-MS resulted in a total of forty-nine constituents, representing 96.2–99.7% of the total compositions. The subsequent classification of the studied populations by multivariate statistical procedures characterized four chemotypes: i) γ-terpinene/p-cymene; ii) linalool/α-phellandrene; iii) sabinene; and iv) carvacrol/trans-caryophyllene. These data may be useful in the future selection of populations comprising specific chemical characteristics for industrial purposes, and furthermore contribute beneficial information for developing conservation strategies, domestication and breeding programs of Iranian O. vulgare subsp. viride germplasm.     

Ecotypic variation in plant characteristics for Origanum vulgare subsp. hirtum populations

Origanum vulgare L. subsp. hirtum (Link) Ietsw. is a polymorphic taxon with respect to essential oil production and glandular trichome density. Here it is examined whether the natural populations that are indigenous in continental Greece may be considered as different ecotypes (i.e. populations with different genetic variation) and whether evidence regarding a fitness cost from essential oil production could be obtained. Samples from 30 different natural populations, differing in climatic conditions, were collected across continental Greece in 1998–2000 and were studied for essential oil production and glandular trichome density. Additionally, individual plants, derived from propagated rhizomes, originated from the natural populations, were transplanted in pots in two gardens that varied in terms of mean temperature and aridity. In these experimental populations, the above-ground phytomass and ratio of leaves and inflorescences to above-ground phytomass were additionally measured. The main findings of the study were (a) a strong positive correlation between essential oil concentration and glandular trichome density, (b) a high positive correlation between natural and experimental populations in essential oil concentration (or glandular trichome density), (c) a negative correlation between essential oil concentration and phytomass and (d) a positive relationship between the essential oil concentration and the factors thermal status and summer drought of the location of origin. Results suggest that the examined populations of O. vulgare subsp. hirtum are different ecotypes, the production of essential oils has a cost to plant growth and that the prime target of selection, by producing these oils, is to increase the resistance to drought and heat stresses.     

Variability of Essential Oil Content and Composition of Origanum vulgare L. Populations from a North Mediterranean Area (Liguria Region, Northern Italy)

Native populations of Origanum vulgare L. from the Liguria andEmilia regions of northern Italy were analysed for essentialoil content and composition. Morphological characters suggestedthat the Ligurian samples belonged to the ssp. viride. The essentialoil content of inflorescences ranged from less than 5 mg g^-1inthe samples from Emilia, to more than 50 mg g^-1in some Liguriansamples, values similar to those reported for ssp. hirtum fromsouthern Italy. Sixty-four compounds were identified in theessential oil. The samples were allotted to three main groupson the basis of oil composition: the first group had a highcontent of components belonging to the carvacrol/thymol biosyntheticpathway; the second was characterized by a different sesquiterpenecomposition and a high linalool content; and the third, includingthe two samples of ssp. vulgare from Emilia, was characterizedby the presence of abundant sesquiterpenes. The high essentialoil content of the samples studied, and the presence of someparticular morphological characters suggest that the taxonomyof O. vulgare, especially in its western distribution area,needs further investigation. Linalool types, although oftennot considered as ‘typical oregano’, may be usefulin promoting wider utilization of the biodiversity of this species.Copyright 2000 Annals of Botany Company Oregano, Origanum vulgare L., ssp. viride, ssp. vulgare, ssp. hirtum, essential oil, gas chromatography, mass spectrometry, genetic resources, chemotypes, quality, Mediterranean     

Capitula essential oil composition of seven Centaurea species (sect. Acrocentron,Asteraceae) – Taxonomic implication and ecological significance

In this paper, we analyzed the capitula essential oil composition of seven Centaurea species, six of which belong to Centaurea calocephala complex, and the related species Centaurea melanocephala Pančić (subgenus Acrocentron, tribus Cardueae, subtribus Centaureinae) which inhabit Balkans Peninsula. The volatile organic compounds were extracted by simultaneous distillation extraction, using Likens-Nickerson type apparatus and the oils were analyzed by GC-FID and GC-MS. In total, 146 compounds were identified (95.5–99.4% of the total oil composition). The essential oils were dominated by sesquiterpenes (39.1–81.7%). The most abundant components were β-caryophyllene (3.1–28.3%), caryophyllene oxide (4.7–31.2%), germacrene D (2.9–22.2%), followed by n-hexacosane, [2Z,6E]-farnesol, eudesma-4(15),7-dien-1-β-ol, α-cadinole, germacrene B, trans-verbenol, and hexanal that were present in some samples in relatively high abundances. The geographic region and the color of capitula were analyzed in correlation with essential oil composition. Also, all investigated species are characterized by the different amount of most dominant components, which leads to the hypothesis that they “choose” different strategies: different combination and amounts of attractants for pollinators. Ecological correlations and taxonomical implications are further discussed.     

The essential oil of Origanum vulgare L. ssp. vulgare growing wild in vilnius district (Lithuania)

The plants of wild Origanum vulgare L. ssp. vulgare were collected in 10 localities of Vilnius district (Lithuania) in 1995-1999. The main constituents of the essential oils from 8 localities were beta-ocimene (14.9-21.6%), germacrene D (10.0-16.2), beta-caryophyllene (10.8- 15.7%) and sabinene (6.6- 4.2%). The essential oils from two localities contained only three above compounds as major components: germacrene D, beta-ocimene and sabinene or beta-caryophyllene, beta-ocimene and germacrene D. Three chemotypes of essential oils were identified. The main chemotype was beta-ocimene germacrene D-beta-caryophyllene. The terpenic hydrocarbons made up 52.8-80.6% of the essential oils. The 42 identified components made up 85.6-98.0% of the essential oil.     

Variability in essential oil composition of Piper dilatatum L.C. Rich

Twelve samples of air-dried aerial parts of Piper dilatatum L. C. Rich yielded essential oils and their volatile constituents were analyzed by GC and GC–MS. Sesquiterpenes, both hydrocarbons and oxygenated, were the most highly represented classes, the former ranging from 31.5% to 87.7% and the latter varying from 1.8% to 49.4%. Using hierarchical cluster analysis, the oils were divided into seven groups, whose main constituents were: (E)-caryophyllene, α-cadinol and germacrene D (group A); spathulenol, bicyclogermacrene and (Z)-β-ocimene, (group B); spathulenol, germacrene D and (E)-nerolidol, (group C); germacrene D, limonene, α-phellandrene and bicyclogermacrene (group D); β-elemene, germacrene D and β-pinene (group E); curzerene, p-cymene and α-eudesmol (group F); and (Z)-α-bisabolene, curzerene and germacrene D (group G). We have seen that Piper oils from the Amazon present as major constituents terpenoids and phenylpropanoids, always with the predominance of one over another. The essential oils of P. dilatatum presented in this paper, containing only mono- and sesquiterpenes as its major components, is further chemotaxonomic evidence of this dichotomy in the Piper genus.     

Chemical Profile and Cytotoxicity Evaluation of Aerial Parts of Marrubium vulgare L. From Different Locations in Turkey

Marrubium vulgare L. (Lamiaceae) is used for respiratory and gastrointestinal system disorders in folk medicine. According to European Pharmacopoeia criteria, standardization of the plant is defined by its marrubiin content. In present study, phenolics, marrubiin and essential oil compositions of M. vulgare from different locations in Turkey were analyzed quantitatively by UPLC, GC and GC/MS. Besides, their cytotoxic potentials were evaluated. In the samples, forsythoside B (77–400 mg/100 g dw), arenarioside (forsythoside F) (0–241 mg/100 g dw), verbascoside (acteoside) (171–416 mg/100 g dw) and apigenin-7-O-glucoside (0–17 mg/100 g dw) were determined in different ranges. Marrubiin contents (0.58–1.46 %) of some samples were two times higher than European Pharmacopoeia standards (0.7 %). β-Caryophyllene (7.24–20.34 %), (Z)-β-farnesene (1.58–34.85 %), germacrene D (9.8–13.37 %), bicyclogermacrene (1.71–8.63 %) and β-bisabolene (0–16.68 %) were detected as major compounds in essential oils. The sample from the west of Aegean Region showed cytotoxicity against human neuroblastoma (SH-SY5Y) cell lines (IC₅₀: 59.80 μg/mL) although it has no effect on non-cancerous NIH-3T3cell lines. This is the first report on phenolic profiles of M. vulgare populations from Turkey. Their potential as marrubiin source for pharmaceutical industry should be considered.     

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

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

Comparison of the internal transcribed spacer region (ITS) of the ribosomal RNA genes in wild and cultivated two and six-rowed barleys (Hordeum vulgare L.)

The ITS region of the ribosomal RNA genes from two and six-rowed cultivated barley (Hordeum vulgare subsp. distichon and H. v. subsp. hexastichon, respectively), and its two and six-rowed wild relatives (H. v. subsp. spontaneum and H. v. subsp. agriocrithon, respectively) was isolated and sequenced. The entire ITS region is 598 bp in the two-rowed taxa (H. v. subsp. distichon and H. v. subsp. spontaneum) and 599 bp in the six-rowed ones (agriochriton and hexastichon). The ITS1 is 217 bp in the six-rowed barleys (H. v. subsp. agriochriton and H. v. subsp. hexastichon) and 218 bp in the two-rowed barleys (H. v. subsp. distichon and H. v. subsp. spontaneum). The 5.8S region is 163 bp in all studied H. vulgare taxa. The ITS2 region is 217 bp in the two-rowed barleys (H. v. subsp. distichon and H. v. subsp. spontaneum) and 219 bp in the six rowed ones (H. v. subsp. hexastichon and H. v. subsp. agriochriton). The ITS sequence data of the studied taxa and that of three other wild Hordeum species (H. murinum, H. marinum and H. chilense) were aligned and a phylogeny tree was reconstructed using the Lasergene Program. H. v. subsp. spontaneum was appeared as the ancestor of all other H. vulgare taxa.     

Differential Accumulation of Volatile Organic Compounds by Leaves and Roots of Two Guianese Philodendron Species,P. fragrantissimum Kunth and P. melinonii Brongn.

Leaf and root essential oils of two closely related but ecologically distant Philodendron species were extracted in natural conditions in French Guiana and analysed by GC/MS to i) describe the blends of volatile organic compounds (VOCs) produced by those species and ii) analyse species and environment‐based variations in extracts composition. A total of 135 VOCs were detected with a majority of aliphatic sesquiterpenes. P. fragrantissimum produced mainly β‐bisabolene (on average 29.12% of the extract) as well as α‐ and β‐selinene (14.52% and 17.50%, respectively) while in P. melinonii, four aliphatic sesquiterpenes could alternatively be the main component: (E)‐β‐farnesene (up to 91.42% of the extract), germacrene‐D (73.74%), β‐caryophyllene (51.63%) and trans‐α‐bergamotene (41.26%). A significant effect of species and organs on extracts composition was observed while the environment (sun exposure) only affected the relative proportions of monoterpenes and sesquiterpenes in roots of P. melinonii. These results are discussed in the light of the potential role of leaf and root terpenes in Philodendron species.     

Chemotaxonomy of Serbian Teucrium species inferred from essential oil chemical composition: the case of Teucrium scordium L. ssp. scordioides

The volatile constituents of Teucrium scordium L. ssp. scordioides, T. polium, and T. montanum, obtained by hydrodistillation, were investigated by GC-FID and GC/MS analyses. A total of 296 constituents were identified, representing 89.8-98.4% of the oil compositions. The oils of T. polium and T. montanum consisted mainly of sesquiterpenes (64.3 and 72.7%, resp.), with germacrene D (4; 31.0%) and δ-cadinene (10; 8.1%) as the main constituents, respectively. In contrast, the monoterpene menthofuran (1; 11.9%) predominated in the oil of T. scordium ssp. scordioides, and this clearly distinguished this species from the other Teucrium taxa investigated up to date. The chemistry of the volatiles of eight Teucrium taxa from Serbia and Montenegro were compared using multivariate statistical analysis, and this provided chemotaxonomically important conclusions.     

Congruence of Phytochemical and Morphological Profiles along an Altitudinal Gradient in Origanum vulgare ssp. vulgare from Venetian Region (NE Italy)

Plants of Origanum vulgare L. ssp. vulgare from the Veneto region (NE Italy) were selected to study the variability of the essential‐oil composition from leaves and inflorescences throughout an elevation gradient. We investigated also the morphology of non‐glandular and glandular trichomes, their distribution on the vegetative and reproductive organs, as well as the histochemistry of the secreted products, with special focus on the terpenoidic fraction. Since glandular trichomes are prerequisite for the essential‐oil synthesis, the second objective was to establish whether its production is related to glandular hair number, and density. Essential‐oil contents decline with increasing altitude, and the micromorphological observations revealed a decrease in trichome density along the same direction. Moreover, GC/MS analysis together with principal component analysis (PCA) showed that the three investigated populations were significantly different in chemical composition. Therefore, an important interpopulation variability for low‐, mid‐, and high‐altitude sites was established, suggesting the likely occurrence of different biotypes associated with altitudinal levels. Hence, the involvement of abiotic factors such as temperature and drought in the chemical polymorphism of O. vulgare associated with elevation is briefly discussed.     

Essential oil from leaves of Cryptocarya mandioccana Meisner (Lauraceae): Composition and intraspecific chemical variability

The composition of the essential oil from leaves of Cryptocarya mandioccana has been determined by chromatographic fractionation and GC–FID, GC–MS and ¹³C NMR analyses, yielding the identification of 64 compounds with predominance of isomeric sesquiterpenes with molecular weights of 204. The main components of the oil obtained by hydrodistillation were β-caryophyllene, spathulenol, caryophyllene oxide, δ-cadinene, germacrene D, benzaldehyde and bicyclogermacrene. However, the oil obtained by steam distillation contained higher levels of sesquiterpene hydrocarbons, with predominance of β-caryophyllene (C), germacrene D (G) and bicyclogermacrene (B), and was considered to be more representative of the composition of the oil in its natural state. The intraspecific chemical variability of the essential oil obtained by steam distillation was evaluated within populations of trees growing at three separate locations in the state of São Paulo, Brazil. Three distinct chemical groups could be characterised due to differences in the relative percentages of the three main sesquiterpenes from essential oil: CGB [relative contents of C (14–34%), G (5–28%), B (8–15%)], BCG [B (17–34%), C (9–24%), G (12–25%)] and GCB [G (22–42%), C (4–17%), B (7–15%)]. Individuals from groups CGB and BCG were found to be more frequent at south locations while group GCB is predominant in north location.     

Cytogenetic diversity of SSR motifs within and between Hordeum species carrying the H genome: H. vulgare L. and H. bulbosum L.

Non-denaturing FISH (ND-FISH) was used to compare the distribution of four simple sequence repeats (SSRs)—(AG) _n , (AAG) _n , (ACT) _n and (ATC) _n —in somatic root tip metaphase spreads of 12 barley (H. vulgare ssp. vulgare) cultivars, seven lines of their wild progenitor H. vulgare ssp. spontaneum, and four lines of their close relative H. bulbosum, to determine whether the range of molecular diversity shown by these highly polymorphic sequences is reflected at the chromosome level. In both, the cultivated and wild barleys, clusters of AG and ATC repeats were invariant. In contrast, clusters of AAG and ACT showed polymorphism. Karyotypes were prepared after the identification of their seven pairs of homologous chromosomes. Variation between these homologues was only observed in one wild accession that showed the segregation of a reciprocal translocation involving chromosomes 5H and 7H. The two subspecies of H. vulgare analysed were no different in terms of their SSRs. Only AAG repeats were found clustered strongly on the chromosomes of all lines of H. bulbosum examined. Wide variation was seen between homologous chromosomes within and across these lines. These results are the first to provide insight into the cytogenetic diversity of SSRs in barley and its closest relatives. Differences in the abundance and distribution of each SSR analysed, between H. vulgare and H. bulbosum, suggest that these species do not share the same H genome, and support the idea that these species are not very closely related. Southern blotting experiments revealed the complex organization of these SSRs, supporting the findings made with ND-FISH.     

The ethnobotany and pharmacognosy of Olea europaea subsp. africana (Oleaceae)

The ethnobotanical uses of wild olive, O. europaea subsp. africana (sometimes referred to as subsp. cuspidata) in southern Africa and in other parts of Africa are reviewed. Chromatographic analyses of secoiridoids (oleuropein and other oleuropeosides) in 25 wild olive leaf samples from 10 localities in South Africa showed substantial amounts of oleuropein (up to 110 mg/g dry weight) and not trace amounts as reported in the literature. Oleuropein is the main active compound in olive leaf, with demonstrated anti-oxidant, anti-microbial, hypolipidemic and hypotensive activities. A comparison with nine cultivated olive leaf samples (subsp. europaea) from six cultivars and two localities showed that commercial olive leaf can be distinguished by the presence of verbascoside, which is absent in wild olive. Extraction methods and solvent systems (TLC and HPLC) were compared, using pure oleuropein (isolated from wild olive leaf and identified by NMR) as an authentic reference sample. The unique peltate scales on the leaves are useful to identify olive leaf raw material (but are the same in both subspecies). The main conclusion is that wild olive leaf is chemically closely similar to cultivated olive leaf and therefore suitable as an alternative source of raw material for olive leaf extract.     

B-Chromosomen bei der GattungLeucanthemum (Asteraceae) in der Tschechoslowakei

The taxonomic arrangement and the karyological analysis of 166 populations ofLeucanthemum demonstrates the existence of 5 taxa for Czechoslovakia; they are grouped provisionally intoL. rotundifolium (W. K.) DC. (2n = 18) and the polyploid complexL. vulgare Lam. with “subsp.vulgare” (2n = 18), “subsp.alpicola” (2n = 18), “subsp.ircutianum” (2n = ± 36) and “subsp.pannonicum” (2n = ± 54). B-chromosomes have not been traced in diploids but have turned up in great numbers in tetraploid (21%) and hexaploid populations (20%). Their presence is not apparent from external characters. Diploids and polyploids evidently are selfsterile.     

Essential Oil Composition of Centaurea atropurpurea and Centaurea orientalis Inflorescences from the Central Balkans – Ecological Significance and Taxonomic Implications

The essential oil composition of Centaurea atropurpurea and Centaurea orientalis flowering heads (capitula) from Central Balkans have been determined by GC‐FID and GC/MS analyses. In total, 121 compounds were identified, representing on average 97.7% of the oil composition. In all samples, sesquiterpenes were most abundant group, representing 53.9 – 74.0% of the total oil. Sesquiterpene hydrocarbons dominated in all studied populations of C. orientalis and C. atropurpurea, except C. atropurpurea f. flava in which essential oil was characterized with high level of oxygenated sesquiterpenes. The dominant components differed between species, and also between typical C. atropurpurea and C. atropurpurea f. flava. The most abundant compounds of essential oil of C. orientalis were germacrene D and α‐cadinol. In C. atropuruprea, germacrene D and β‐caryophyllene were the most abundant, while caryophyllene oxide and β‐caryophyllene were dominant in C. atropurpurea f. flava oil. Taxonomical and ecological implications are further discussed.     

Piperonyl butoxide synergizes the larvicidal activity of Origanum vulgare essential oil and its major constituents against the larvae of Aedes albopictus and Culex pipiens quinquefasciatus

Mosquitoes bite human beings and transmit many diseases, such as malaria, dengue fever, and Zika virus. Vector control of mosquitoes is an effective strategy for reducing the spread of disease. However, extensive use of insecticides (e.g. pyrethroids and organophosphorus) has caused resistance in mosquitoes, which weakens the effectiveness of mosquito control. Phytochemicals have been considered an alternative approach to mosquito control. Essential oil (EO) was obtained from the leaves and flowers of Origanum vulgare, and its synergistic activity with piperonyl butoxide (PBO) was tested against Aedes albopictus and Culex pipiens quinquefasciatus larvae. Thirty-seven compounds were identified, among which carvacrol and thymol were two major constituents (30.73 % and 18.81 %, respectively). O. vulgare EO had a significant toxic effect against fourth-stage larvae of Cx. p. quinquefasciatus and Ae. albopictus, with LC₅₀ values of 17.51 and 75.90 mg/L. Carvacrol and thymol also each appeared to be more effective against Cx. p. quinquefasciatus (LC₅₀ = 19.30 and 11.56 mg/L, respectively) than Ae. albopictus (LC₅₀ = 26.62 and 26.66 mg/L, respectively). PBO interacted synergistically with O. vulgare EO, carvacrol and thymol with 2.60–6.26 times as much of the active compound needed without PBO as against Cx. p. quinquefasciatus and Ae. albopictus larvae. Overall, our results contribute to the development of new natural mosquito insecticides.     

Arsenic accumulation in Ocimum spp. and its effect on growth and oil constituents

A comparative evaluation of As accumulation and subsequent effects upon exposure to arsenite [As(III)] was performed in three species of Ocimum. Plants accumulated high amount of As (μg g^?1 dry weight; dw) (662 in O. tenuiflorum, 764 in O. basilicum and 831 in O. gratissimum at 100 μM As(III) after 10 days) with the order of accumulation being roots > stem > leaves. A significant reduction in plant height and biomass was observed. However, essential oil yield and major oil constituents, such as eugenol, methyl chevicol, and linalool, increased at lower As(III) concentrations [mostly up to 25 μM As(III)] in all three species. Positively, no detectable amount of As was found in oil of any species. The study proposes that Ocimum may be used as a phytoremediator and at the same time as a source of essential oils under proper regulation.