Essential oil polymorphism of Thymus praecox subsp. arcticus on the British Isles

The essential oils of 732 individual plants of Thymus praecox Opiz subsp. arcticus (E. Durand) Jalas (syn. T. drucei Ronn.) collected in Scotland, Ireland, and in the south of England have been analysed by gas chromatography (GC) and mass spectrometry (GC–MS) in order to elucidate the chemical character of this subspecies on the British Isles. In total, 69 components were identified, most of them monoterpenoids and sesquiterpenoids with hedycaryol, linalyl acetate, linalool, the germacradienols, trans-nerolidol, T-cadinol, and β-caryophyllene being the most important compounds. The analysis of the quantitative essential oil data by means of neural networks revealed that T. praecox subsp. arcticus growing in Britain is highly polymorphous. There were 17 chemotypes with the hedycaryol chemotype as the most frequent (24% of the plants), followed by the linalool/linalyl acetate chemotype (22% of the plants) and germacra-1(10),4-dien-6-ol chemotype (18% of the plants). It seems that each part of the British Isles has its special chemotype pattern with 13 chemotypes in Scotland, 11 in Ireland, and 17 in the south of England. An overview of the North Atlantic region of Europe revealed that the polymorphism of T. praecox subsp. arcticus in the essential oil is more distinctive in the southern than in the northern regions, with only 2, 5, and 1 chemotypes in Greenland, Iceland, and Norway, respectively.     

Chemical analysis and biological activities of the essential oil of Teucrium leucocladum Boiss. (Lamiaceae)

The chemical composition of the water-distilled essential oil and n-hexane–ether extract of Teucrium leucocladum Boiss. were determined by GLC and GLC–MS. Altogether 72 compounds were identified. The sesquiterpene alcohols, patchouli alcohol (31.24% and 29.66%) and α-cadinol (9.29% and 21.54%) were the main components in the oil and the extract, respectively. α-Cadinol was isolated and characterized using MS, ¹H- and ¹³C-NMR spectral analyses. Furthermore, the oil and the extract were tested for their bacterostatic and antifungal activities; they showed broad and potent activity against Pseudomonas aeruginosa, Bacillus subtilis and Candida albicans. A marked larvicidal activity of the essential oil, n-hexane–ether extract and crude ethanolic extract was also observed against Culex pipiens, Musca domestica and Ceratitis capitata larvae.     

Chemical composition and antimicrobial activity of the essential oil of Teucrium ramosissimum (Lamiaceae)

The phytochemical composition of the essential oil of Teucrium ramosissimum (aerial parts), harvested in a mountainous region of Tunisia, was analyzed. A total of 68 compounds, accounting for 99.44% of the essential oil, were identified by GC and GC/MS. The major compounds were beta-eudesmol (61; 44.52%), caryophyllene oxide (56; 9.35%), alpha-thujene (1; 5.51%), sabinene (4; 4.71%), and T-cadinol (59; 3.9%). The essential oil, which is being used in Tunisian folk medicine against infectious diseases, was tested for its antimicrobial properties against five different bacteria, and found to have weak to moderate activity, with minimal-inhibitory-concentration (MIC) and minimal-bactericidal-concentration (MBC) values in the range 0.24-0.36 and 1.3-2.9 mg/ml, resp.     

Chemical polymorphism of the essential oils from populations of Thymus caespititius grown on the island S. Jorge (Azores)

The compositions of the essential oils obtained from ten populations of Thymus caespititius grown on S. Jorge (Azores) were studied by GC and GC-MS. All the oils analysed were dominated by their monoterpene fraction (69-9%). The sesquiterpene fraction was rather small (4-17%) and consisted mainly of oxygen-containing compounds (3-13%). Enantiomeric ratio of sabinene and alpha-terpineol was investigated in the oils from some populations. (+)-Sabinene was detected with high enatiomeric purity (96 99%). Although ( +)-alpha terpineol was the predominant enantiomer, its purity varied considerably (66-97%). Cluster analysis of all identified components grouped the oils into four main clusters that corresponded with their major components: alpha-terpineol (43-68%), carvacrol (32-52%), thymol (44-58%) and sabinene (41%). The essential oil from Th. caespititius showed a clear chemical polymorphism, that was particularly evident among four populations growing along a 200 m distance at Pico Verde.     

The genus Thymus (Lamiaceae) in Sicily

An update on the taxonomy and geographic distribution of the genus Thymus in Sicily is given. This study is based on literature, herbarium and field investigations. In total, five taxa belonging to Thymus sect. Serpyllum (Th.richardii subsp. nitidus, Th.longicaulis and Th.praecox subsp. parvulus) and Th. sect. Hyphodromi (Th.spinulosus and Th.paronychioides) occur in Sicily. For each one, information about taxonomy, habitat, phenology, chromosome number and distribution are provided. Furthermore, the name Thymus pedicillatus Lojac. is here typified. Finally, an analytical key for the identification of the studied taxa is proposed.     

The essential oil secretory structures of Prostanthera ovalifolia (Lamiaceae)

The structure of the essential oil secretory tissues of Prostanthera ovalifolia R.Br was investigated using bright- and dark-field optical microscopy, and scanning and transmission electron microscopy. The leaves of P. ovalifolia have glandular trichomes of the peltate type common to many Lamiaceae species. The trichomes consist of a basal cell embedded in the epidermis, a stalk cell with heavily cutinized walls and a 16-celled secretory head, but they differ from those of many previously reported Lamiaceae species in their morphological form defined by the elevated cuticle. The sub-cuticular space contains a mixture of lipid and aqueous phases. Secretory cells have dense cytoplasm with many leucoplasts present. Volatile terpenoids are eliminated from the cytoplasm into the sub-cuticular space, the site of essential oil accumulation, via granulocrine secretion.     

Development, oil storage and dehiscence of peltate trichomes in Thymus vulgaris (Lamiaceae)

The development, oil storage and dehiscence mechanism of the peltate oil–producing trichome in Thymus vulgaris L. was studied by conventional, fluorescence and electron scanning microscopy. A single epidermal initial forms the glandular trichome whose primordium becomes distinguishable from non–glandular trichomes at its 3–celled stage. The further divisions determine the formation of three functional compartments, (a) a basal reservoir cell, (b) an "endodermal" cell, and (c) a group of secretory head cells. At first, the gland head shows a bowl–like shape with a folded cuticular covering that raises successively assuming a dome–like form. During the differentiation of the gland cells, histochemical tests reveal the occurrence of a precise sequence of metabolic events: synthesis of RNA, proteins, glycoproteins, polysaccharides and, finally osmiophilic substances. At maturity, the cuticular sheath is formed by a non–cellulosic polysaccharide framework on which the cuticle is deposed. Proceeding towards the senescence, the polysaccharide framework disappears and a large crescent shaped pore forms, whereby essential oils are released. Collected results are discussed in order to interpret gland function and essential oil production.     

Typification of the name Thymus serpyllum L. (Lamiaceae)

Lectotypification of the name Thymus serpyllum L. (Lamiaceae) is presented. The name is typified by a specimen from the Burser herbarium (UPS), the only one which corresponds well with the present concept of T serpyllum and undoubtedly represents original material.     

Glandular trichomes and essential oil constituents ofCalamintha menthifolia (Lamiaceae)

Plant material ofCalamintha menthifolia was collected from two populations grown in the Vikos-Aoos area (NW. Greece). The structure and ontogeny of the glandular trichomes and the chemical composition of the secreted essential oil were studied. The leaves ofC. menthifolia have numerous glandular trichomes of three morphological distinct types: 1) glandular scales with a unicellular foot and stalk, and a 12-celled head, 2) glandular hairs with a unicellular foot and stalk, and a unicellular pear-shaped head and 3) glandular hairs with a unicellular foot, a bicellular stalk and a unicellular elongated head. Qualitative and quantitative GC-MS analyses of the essential oils revealed piperitone oxide as the main constituent in both populations. In the light of these results the relationships beweenC. menthifolia and other members of theSatureja group as well as its taxonomy are discussed.     

Pharmacological activity of the essential oil of Satureja viminea (Lamiaceae)

The aqueous extract and the essential oil of Satureja viminea (Lamiaceae) were tested. General physiologic effects were assessed through the Hippocratic screening test. Non fasted female Sprague Dawley rats were utilized and 250, 500, 750 and 1000 mg/kg doses were used. Two animals were used for each dosage level and for the vehicle alone. Exploratory behavior and curiosity were measured using a hole board apparatus and placing non-trained mice on the board and recording the number of holes explored in a 5 minute period. The Boissier chimney test was used to evaluate motor coordination. Muscle strength was assessed through a grasping test where mice were hung by their fore-limbs 40 cm above the base on a horizontal metal stainless bar. In all these tests, 3 groups of 6 albino mice, were treated with 1000 mg/kg of each the essential oil of S. viminea, the vehicle and diazepan (1 mg/kg) as a positive control. Analgesic activity was explored in Sprague-Dawley rats. The tail flick method described by D'Amour and Smith (1941) modified by CYTED was implemented on three groups (6 rats each) of animals treated with, each the essential oil of S. viminea (1000 mg/kg), the vehicle and indomethacine. The test was carried out just before and 30, 60 and 120 min after oral treatment. Peristaltic activity was measured in albino mice, three groups of 6 animals each, treated orally with each the essential oil of S. viminea (1000 mg/kg), the aqueous extract (1000 mg/kg), and the vehicle. The marker used was activated carbon. Animals were sacrificed 30 min after the marker was given and the percent of total small intestine traversed by it was calculated. Also a lethal dose 50 (LD 50) was determined with the Spearman-Karber method. A dose-related spontaneous motor activity reduction was observed. Exploratory behavior and curiosity were diminished. The grasping strength of mice was reduced. A very clear and significant analgesic effect was observed with the oral administration of the essential oil of S. viminea (1000 mg/kg). This effect is compared to that of indomethacine. Intestinal transit and gastric emptying were inhibited by the essential oil. The LD50 of the essential oil of S. viminea is 556.8 mg/kg.     

Bees visiting flowers of Thymus longicaulis (Lamiaceae)

The aim of this study was to investigate the bee fauna foraging on Thymus longicaulis flowers. Samplings were conducted walking along a transect during the T. longicaulis blooming period (April–June). A total of 547 bee specimens, belonging to 40 different species, were recorded during the survey. Apis mellifera and Bombus terrestris were the most abundant visitors that foraged on thyme. Pollen grains collected on the bodies of the bees suggest that these pollinators may play an important role in the pollination of this plant.     

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.     

Fertilization and embryogeny in Agapanthus praecox ssp. orientalis (Leighton) Leighton

Fertilization and embryogeny in Agapanthus praecox ssp. orientalis are described for the first time, and embryogenic characters of Agapanthus are discussed. The main results are: (1) The pollen tube enters the embryo sac and discharges two sperm 44?C48?h after pollination. (2) The sperm fuse with the egg cell and polar nuclei, forming zygote and primary endosperm nucleus, approximately 50?h after pollination. The zygote then enters a short period of dormancy. (3) Seven days after pollination, the zygote starts division. The first division of the zygote is transversal. (4) The embryo undergoes globular stage, rod-shaped stage, and finally forms a monocotyledonous embryo. (5) The suspensor cells are ephemeral and degenerate at the globular embryo stage. (6) Endosperm cells contain massive starch grains as nutrition for embryo development. (7) Embryogeny conforms to the Onagrad type, and endosperm formation is of the nuclear type; the whole process of embryogeny and endosperm development needs approximately 60?days in A. praecox ssp. orientalis. (8) Dicotyledonous together with monocotyledonous forms of embryo morphogenesis in Agapanthus supports the concept of homology of monocots and dicot cotyledons.     

Chemical polymorphism of the essential oils from populations of Thymus caespititius grown on the islands Pico,Faial and Graciosa (Azores)

The compositions of the essential oils isolated from the aerial parts of 11 populations of Thymus caespititius collected during the flowering phase on Pico, Faial and Graciosa (Azores) were studied by GC and GC-MS. The monoterpene fraction was dominant in all the oils analysed (55-90%) and consisted mainly of oxygen-containing compounds (44-79%). Sesquiterpenes represented an important fraction of the oils from the populations grown on Graciosa (13-28%). In contrast, this fraction was rather small in the oils from the populations grown on Pico and Faial (6-11%). Despite this, oxygen-containing compounds (4-18%) were always dominant. Cluster analysis of all identified oil components grouped the oils into three main clusters that corresponded with their main components. The oils from the 11 populations studied showed a clear chemical polymorphism that, in some cases, was more evident among populations growing on the same island than among those from different islands.     

Allozyme diversity in the tetraploid endemic Thymus loscosii (Lamiaceae)

BACKGROUND AND AIMS: Thymus loscosii (Lamiaceae) is a tetraploid perennial species endemic to the Ebro river basin (north-eastern Spain), which is included in the National Catalogue of Endangered Species. It is a tetraploid species (2n = 54), presumably an autotetraploid originated by the duplication of a 2n = 28 genome and the subsequent loss of two chromosomes. Allozyme electrophoresis was conducted to survey the levels and distribution of genetic diversity and to test the previous autopolyploid hypothesis for its origin. In addition, both in situ and ex situ conservation measures are proposed. METHODS: Eight populations were sampled for analysis by standard methods of starch gel electrophoresis, and six putative enzymatic loci were resolved (five consistently and one only partially). KEY RESULTS: Banding patterns exhibited no evidence of fixed heterozygosity and showed both balanced and unbalanced heterozygotes. In addition, most individuals showed a pattern consistent with the presence of three or four alleles at a single locus. High levels of genetic variability were found at population level (P = 85 %, A = 3.0, He = 0.422), in addition to a trend of an excess of heterozygotes. CONCLUSIONS: Allozyme data support the hypothesis that T. loscosii is an autotetraploid, and the high number of alleles at some loci may be due to repeated polyploidization events. The high values of genetic variation found in this species agree with those expected for tetraploids. The excess of heterozygotes may be due to some barriers to inbreeding (e.g. occurrence of gynodioecy) and/or selection for heterozygosity.     

Chemical composition,angiotensin I-converting enzyme (ACE) inhibitory,antioxidant and antimicrobial activities of the essential oil from south Tunisian Ajuga pseudoiva Rob. Lamiaceae

The essential oil of Ajuga pseudoiva, collected from Tunisia, was analyzed using gas chromatography–mass spectroscopy. Thirty-two compounds accounting for 95.76% of the total oil were identified. Sesquiterpenes were found to be the most abundant components of A. pseudoiva oil. And they were mainly represented by viridiflorol (30.17%), germacrene B (9.26%) (α, β and γ)-eudesmol (8.11%) and aromadendrene (7.45%). The essential oil of A. pseudoiva showed radical scavengers activity (IC₅₀ = 0.72 mg/mL) and displayed lipid peroxidation inhibitory activity (IC₅₀ = 0.6 mg/mL). A. pseudoiva essential oil was also found to exhibit a dose-dependent ACE inhibitory activity with an IC₅₀ value of 65.5 μg/mL. Moreover, the antimicrobial activity of the essential oil was tested against 17 species of microorganisms, and the results obtained showed significant antibacterial activity against the Gram-positive and Gram-negative bacteria, with inhibition zones and minimal inhibitory concentration values of 14–32 mm and 84–137 μg/mL and 6–21 mm and 105–336 μg/mL, respectively. Higher activity was also found against several fungal strains.     

Volatile oil variability in Thymus serpylloides ssp. gadorensis growing wild in Southeastern Spain

Volatile oils from single plants of Thymus serpylloides ssp. gadorensis were collected from Southeastern Spain and studied to check for chemical variability using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Many of the samples showed a phenolic chemotype, while another important group had significant levels of linalool. Geraniol, myrcene, caryophyllene oxide, terpinen-4-ol and 1,8-cineole were commonly present. Principal Component Analysis (PCA) and Cluster Analysis (CA) of this chemical variability separated two groups of plants characterized by either phenols or linalool, and an isolated third type with geraniol. A few samples were found to have both phenolic and non-phenolic compounds in high quantities, thus showing a mixed chemotype. Multidimensional scaling analysis (MDS) of the percentage concentration for each component of the essential oil showed that thymol, linalool, 1,8-cineole, borneol and geraniol have clear divergent vectors.     

Diversity of essential oil glands of clary sage (Salvia sclarea L., Lamiaceae)

The Lamiaceae is rich in aromatic plant species. Most of these species produce and store essential oils in specialised epidermal oil glands, which are responsible for their specific flavour. Two types of glands producing essential oil and possessing different morphological structure can be found in Salvia sclarea : peltate and capitate glands. The content of single oil glands from different positions on the plant (corolla, calyx and leaf) were sampled using an SPME fibre and analysed by gas chromatography in order to study variability of the essential oil composition. It was found that the composition of terpenoids is quite variable within an individual plant. Capitate oil glands mainly produce three essential oil compounds: the monoterpenes linalool and linalyl acetate, and the diterpene sclareol. Peltate oil glands, however, accumulate noticeable concentrations of sesquiterpenes and an unknown compound (m/z = 354). Furthermore, the oil composition varies within each gland type according to the plant organ. Linalool and linalyl acetate are characteristic substances of flowers, whereas the sesquiterpenes occur in higher proportions in leaves. Even within one gland type on a single leaf, the chemical variability is exceedingly high.