Chemical polymorphism of essential oils from populations of Laurus nobilis grown on Tunisia, Algeria and France.

The compositions of the essential oils isolated from the aerial parts of tree Mediterranean populations of Laurus nobilis L. collected during the flowering phase on Tunisia, Algeria and France, were studied by GC and GC-MS. The analysis has allowed identifying 54 components. The main components were 1,8-cineole, α-terpinyl acetate (10-18.6%), methyl eugenol (10-22.1%), sabinene (1.2-8%), eugenol (1.2-11.7%) α-pinene (tr-4.5%) and β-pinene (0.4-4.2%). The monoterpene fraction was dominant in all the oils analysed and consisted mainly of oxygenated monoterpenes. The oils from the tree populations studied showed a clear chemical polymorphism. The principal component and the hierarchical cluster analyses separated the Laurus nobilis leaf essential oils into three groups

Chemical composition, antioxidant and anti-acetylcholinesterase activities of Tunisian Crithmum maritimum L. essential oils

Acetylcholinesterase properties of the aerial parts and roots essential oils from Crithmum maritimum L., Apiaceae, gathered in the area of Monastir (Tunisia). The essential oils have been analysed by GC and GC-MS. Remarkable differences were found between the constituent percentages of the different studied organs. The most important compounds from the aerial parts were: γ-terpinene (39.3%), methylcarvacrol (21.6%) and p-cymene (11.8%). In the roots oil, the main components were terpinolene (36.9%), dillapiole (26.8%) and γ-terpinene (21.9%). The antioxidant activity of the two oils was evaluated by employing 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging tests. The results showed that the antioxidant capacity assessed by different in vitro tests were moderate, the ABTS assay after 20 min (IC50 = 0.051 mg/mL) of aerial parts and (IC50 = 0.643 mg/mL) of the roots, appeared to be more potent than that for the DPPH assay (IC50 = 0.92 mg/mL) of aerial parts and (IC50 = 0.048 mg/mL) of roots. In addition, the examined oils showed the highest AchE inhibitory 1 mg/mL activity (31.16% and 26.35%, for the aerial parts and roots, respectively

Fractional hydrodistillation and biological evaluation of essential oils from Crithmum maritimum L.

In some previous studies, it has been demonstrated that the final composition of the essential oils can be influenced by the distillation time and some biological activities increased according to the proportion of some types of compounds such as monoterpene alcohols and phenolic derivatives contained in the tested essential oil fractions (1). The aim of the present study was particularly the identification of the bioactive principles of the essential oils from the aerial parts and the roots of Crithmum maritimuL. (2) during their fractional extraction by hydrodistillation. The antioxidant, antibacterial and cytotoxic activities of the essential oils and their collected fractions were also studied. Our results showed that the main constituent of the oils was dillapiole, detected at increasing percentages (67.7-100%) in all the collected fractions during the extraction process. The antioxidant features of all the isolated fractions (F1-F9) of the two oils were also evaluated using DPPH, ABTS, reducing power and paraoxonase assays. The results showed that the IC50 (DPPH) of F9 (aerial parts and roots) were 0.042 ± 0.001 mg/mL and 0.038 ± 0.001 mg/mL, respectively. Moreover, the oil roots exhibited strong growth suppression particularly against Staphylococcus aureus and Enterococcus faecalis. The fraction F9, the aerial parts and the roots essential oils were also tested for their cytotoxic activity and interesting results were noted

Chemical composition and allelopathic potential of essential oils from Tipuana tipu (Benth.) Kuntze cultivated in Tunisia

The present work describes the chemical composition and evaluates the allelopathic effect of the hydrodistilled essential oil from roots, stems, leaves, flowers and samaras of Tipuana tipu (Benth.) Kuntze gathered in the area of Mogran (Tunisia). The chemical composition of the different parts of the species, determined by GC-FID and GC-MS, is reported for the first time. Remarkable differences were found between the constituent percentages in different studied organs. The most important compounds detected in roots were β-caryophyllene (24.1%), germacrene D (20%) and isopropylmyristate (11.7%). Whereas, in stems oil the main compounds found were 4-terpineol (14.6%) and elemicin (12.6%). Hexahydrofarnesyl acetone was the major oxygenated sesquiterpene constituent of leaves and samaras (10.2% and 19.9%, respectively). Essential from Tipuana tipu flowers was mainly rich in α-longipinene (8.3%), 1.7-dimethylnaphthalene (15.6%) and (E)-β-inone (33.8%). Allelopathic effects of the essential oils tested at different concentrations were evaluated on the seed germination and the early growth of Lactuca sativa seedlings. The highest inhibition of 100% was detected for the roots oil at the concentration of 1 mg/mL

Chemical composition and allelopathic potential of essential oils obtained from Acacia cyanophylla Lindl. cultivated in Tunisia

Acacia cyanophylla Lindl. (Fabaceae), synonym Acacia saligna (Labill.) H. L.Wendl., native to West Australia and naturalized in North Africa and South Europe, was introduced in Tunisia for rangeland rehabilitation, particularly in the semiarid zones. In addition, this evergreen tree represents a potential forage resource, particularly during periods of drought. A. cyanophylla is abundant in Tunisia and some other Mediterranean countries. The chemical composition of the essential oils obtained by hydrodistillation from different plant parts, viz., roots, stems, phyllodes, flowers, and pods (fully mature fruits without seeds), was characterized for the first time here. According to GC-FID and GC/MS analyses, the principal compound in the phyllode and flower oils was dodecanoic acid (4), representing 22.8 and 66.5% of the total oil, respectively. Phenylethyl salicylate (8; 34.9%), heptyl valerate (3; 17.3%), and nonadecane (36%) were the main compounds in the root, stem, and pod oils, respectively. The phyllode and flower oils were very similar, containing almost the same compounds. Nevertheless, the phyllode oil differed from the flower oil for its higher contents of hexahydrofarnesyl acetone (6), linalool (1), pentadecanal, α-terpineol, and benzyl benzoate (5) and its lower content of 4. Principal component and hierarchical cluster analyses separated the five essential oils into four groups, each characterized by its main constituents. Furthermore, the allelopathic activity of each oil was evaluated using lettuce (Lactuca sativa L.) as a plant model. The phyllode, flower, and pod oils exhibited a strong allelopathic activity against lettuce

Chemical composition and antibacterial activity of essential oils from the Tunisian Allium nigrum L.

The chemical composition of the essential oils of different Allium nigrum L. organs and the antibacterial activity were evaluated. The study is particularly interesting because hitherto there are no reports on the antibacterial screening of this species with specific chemical composition. Therefore, essential oils from different organs (flowers, stems, leaves and bulbs) obtained separately by hydrodistillation were analyzed using gas chromatography–mass spectrometry (GC–MS). The antibacterial activity was evaluated using the disc and microdilution assays. In total, 39 compounds, representing 90.896.9 % of the total oil composition, were identified. The major component was hexadecanoic acid (synonym: palmitic acid) in all the A. nigrum organs oils (39.177.2 %). We also noted the presence of some sesquiterpenes, mainly germacrene D (12.8 %) in leaves oil) and some aliphatic compounds such as n-octadecane (30.5 %) in bulbs oil. Isopentyl isovalerate, 14-oxy-α-muurolene and germacrene D were identified for the first time in the genus Allium L. All the essential oils exhibited antimicrobial activity, especially against Enterococcus faecalis and Staphylococcus aureus. The oil obtained from the leaves exhibited an interesting antibacterial activity, with a Minimum Inhibitory Concentration (MIC) of 62.50 μg/mL against these two latter strains. The findings showed that the studied oils have antibacterial activity, and thus great potential for their application in food preservation and natural health product

Chemical composition and phytotoxic effects of essential oils obtained from Ailanthus altissima (Mill.) Swingle cultivated in Tunisia

Ailanthus altissima Mill. Swingle (Simaroubaceae), also known as tree of heaven, is used in the Chinese traditional medicine as a bitter aromatic drug for the treatment of colds and gastric diseases. In Tunisia, Ailanthus altissima is an exotic tree, which was introduced many years ago and used particularly as a street ornamental tree. Here, the essential oils of different plant parts of this tree, viz., roots, stems, leaves, flowers, and samaras (ripe fruits), were obtained by hydrodistillation. In total, 69 compounds, representing 91.0–97.2% of the whole oil composition, were identified in these oils by GC-FID and GC/MS analyses. The root essential oil was clearly distinguishable for its high content in aldehydes (hexadecanal (1); 22.6%), while those obtained from flowers and leaves were dominated by oxygenated sesquiterpenes (74.8 and 42.1%, resp.), with caryophyllene oxide (4) as the major component (42.5 and 22.7%, resp.). The samara oil was rich in the apocarotenoid derivative hexahydrofarnesyl acetone (6; 58.0%), and the oil obtained from stems was characterized by sesquiterpene hydrocarbons (54.1%), mainly β-caryophyllene (18.9%). Principal component and hierarchical cluster analyses separated the five essential oils into four groups, each characterized by the major oil constituents. Contact tests showed that the germination of lettuce seeds was totally inhibited by all the essential oils except of the samara oil at a dose of 1 mg/ml. The flower oil also showed a significant phytotoxic effect against lettuce germination at 0.04 and 0.4 mg/ml (−55.0±3.5 and −85.0±0.7%, resp.). Moreover, the root and shoot elongation was even more affected by the oils than germination. The inhibitory effect of the shoot and root elongation varied from −9.8 to −100% and from −38.6 to −100%, respectively. Total inhibition of the elongation (−100%) at 1 mg/ml was detected for all the oils, with the exception of the samara oil (−74.7 and −75.1% for roots and shoots, resp.)

Phytochemicals, antioxidant and antifungal activities of Allium roseum var. grandiflorum subvar. typicum Regel

The chemical composition of essential oil hydrodistillized from Allium roseum var. grandiflorum subvar. typicum Regel. leaves was analyzed by GC and GC/MS. Nine extracts obtained from flowers, stems and leaves and bulbs and bulblets of A. roseum var. grandiflorum were tested for their total phenol, total flavonoid and total flavonol content. All these extracts and the essential oils from fresh stems, leaves and flowers were screened for their possible antioxidant and antifungal properties. The results showed that the hexadecanoic acid was detected as the major component of the leaf essential oil (75.9%). The ethyl acetate extract of stems and leaves had the highest antioxidant activity with a 50% inhibition concentration (IC50) of 0.35 ± 0.01 mg/mL of DPPH• and 0.71 ± 0.01 mg/mL of ABTS•+. All the extracts appeared to be able to inhibit most of the tested fungi. The essential oil of the leaves had an antifungal growth effect on Fusarium solani f. sp. cucurbitae and Botrytis cinerea (39.13 and 52.50%, respectively). This could be attributed to the presence of hexadecanoic acid, known for its strong antifungal activity. In conclusion, in addition to the health benefits of A. roseum, it can be used as an alternative pesticide in the control of plant disease and in the protection of agriculture product

Variability of chemical composition and biological activities of Allium triquetrum L. essential oils

The present work describes the chemical composition and evaluates the antimicrobial properties of the essential oils from the Tunisian Allium triquetrum L. It is particularly interesting study because there are no reports on of this species in any sector and with specific chemical composition. The chemical composition of four essential oil samples (flowers, stems, leaves and bulbs) of A. triquetrum, obtained separately by hydrodistillation were analyzed by combination of GC-FID and GCMS. Altogether, 45 compounds were identified representing 90.5-95.3% of the total oil content. The chemical composition of bulbs oil was characterized by a high proportion of sulfurous compounds (81.9%) among which dipropyl trisulfide (11.7%) and di-2-propenyl trisulfide (10.0%) were the predominant compounds. The oxygenated sesquiterpenes represent the major fraction (79.2%) in stem oil giving T-cadinol (26.8%), α-eudesmol (11.4%) and β-eudesmol (16.8%) as the main components; they were present also in leaf oil. We also noted the presence of some alkane compounds such n-nonadecane (13.3%) in flower oil. Some compounds identified in this plant have not been reported about other species of Allium such elemol, β-copaen-4-α-ol, globulol, viridiflorol, guaiol, eremoligenol, α-eudesmol, β-eudesmol and pimaradiene. Furthermore, the isolated oils were evaluated for antibacterial and antifungal activities. All the oils exhibited significant in vitro antibacterial activity, especially against Enterococcus faecalis and Staphylococcus aureus. The oil obtained from the stem, leaf and bulbs exhibited an interesting antibacterial activity, with a Minimum Inhibitory Concentration (MIC) of 31.25µg/mL against S. aureus. It was found also that stem and bulbs oil showed the highest growth inhibition of almost fungi especially against Fusarium solani (75.33and 71.33%, resp.) even greater than the positive control: benomyl (69.33%). The results indicate that the essential oil of A. triquetrum contains chemical compounds with good potential for application in natural health products and in the protection of agriculture products