Chemical Composition and Allelopathic Potential of Essential Oils from Citharexylum spinosum L. grown in Tunisia

Citharexylum spinosum L. (Verbenaceae) also known as C. quadrangulare Jacq. or C. fruticosum L. is an exotic tree introduced many years ago in Tunisia, specially used as a street and park ornamental tree. Essential oils were obtained by hydrodistillation of the different parts (roots, stems, leaves, flowers and fruits; drupes) collected from trees grown in the area of Monastir (Tunisia). In total, 84 compounds, representing 90.1-98.4% of the whole oil composition, were identified by GC-FID and GC/MS analyses. The root essential oil was distinguished by its high content in monoterpene hydrocarbons (α-phellandrene; 30.8%) whereas that obtained from stems was dominated by sesquiterpene hydrocarbons (cuparene; 16.4%). The leaf oil was rich in an apocarotenoid derivative (hexahydrofarnesyl acetone; 26%) and an aliphatic hydrocarbon (n-nonadecane; 14.5%). Flowers oil was rich in esters (2-phenylethyl benzoate; 33.5%). Finally, drupes oil was rich in oxygenated sesquiterpenes (β-eudesmol; 33.1%). Flowers oil showed a significant phytotoxic effect against lettuce seeds germination, it induces a total inhibition when tested at 1 mg/ml. The highest inhibition of 100% was detected for flower oil tested at 1 mg/ml. Our in vitro studies suggest a possible and new alternative use of C. spinosum essential oils in herbicidal formulations, further experiments involving field conditions are necessary to confirm its herbicidal potential. This article is protected by copyright. All rights reserved

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 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 from Tipuana tipu (Benth.) Kuntze Cultivated in Tunisia

In Tunisia, Tipuana tipu (Benth.) Kuntze is an exotic tree, which was introduced many years ago and planted as ornamental street, garden, and park tree. The present work reported, for the first time, the chemical composition and evaluates the allelopathic effect of the hydrodistilled essential oils of the different parts of this tree, viz., roots, stems, leaves, flowers, and pods gathered in the area of Sousse, a coastal region, in the East of Tunisia. In total, 86 compounds representing 89.9 - 94.9% of the whole oil composition, were identified in these oils by GC-FID and GC/MS analyses. The root essential oil was clearly distinguished for its high content in sesquiterpene hydrocarbons (β-caryophyllene, 1 (44); 24.1% and germacrene D, 2 (53); 20.0%), while those obtained from pods, leaves, stems, and flowers were dominated by non-terpene hydrocarbons. The most important ones were n-tetradecane (41, 16.3%, pod oil), 1,7-dimethylnaphthalene (43, 15.6%, leaf oil), and n-octadecane (77, 13.1%, stem oil). The leaf oil was rich in the apocarotene (E)-β-ionone (4 (54); 33.8%), and the oil obtained from flowers was characterized by hexahydrofarnesylacetone (5 (81); 19.9%) and methyl hexadecanoate (83, 10.2%). Principal component and hierarchical cluster analyses separated the five essential oils into three groups and two subgroups, each characterized by the major oil constituents. Contact tests showed that the germination of lettuce seeds was totally inhibited by the root essential oil tested at 1 mg/ml. The inhibitory effect on the shoot and root elongation varied from -1.6% to -32.4%, and from -2.5% to -64.4%, respectively

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

Volatile compounds and anatomical features of Opuntia sp. cladodes

The cactus pear is belongs to the Cactaceae family Opuntia. The cladodes are known as nopalitos, are frequently consumed and used in folk medicine due to their beneficial effects and phytochemical composition. Cactus in Tunisia is mostly localized in areas characterized by low quality soils and water scarcity. In this study we evaluate the amount of volatile compounds on the powder obtained from Opuntia microdasys Lehm. and macrorhiza Engelm. cladodes were investigated by HS-SPME-GC-MS and anatomical structure of cladodes was identify by light microscopy. The most important compound found in the cladodes of O. microdasys is limonene (11.20 %), while O.macrorhiza was mainly rich in camphor (49.10 %). The highest contents of phytochemicals compounds were found in the cladode of Opuntia microdasys. Light microscopy revealed the presence of a high number of calcium oxalate crystals in fresh cladodes

Ailanthus altissima (Miller) Swingle seed oil: chromatographic characterization by GC-FID and HS-SPME-GC-MS, physicochemical parameters, and pharmacological bioactivities

This study aimed to identify the physicochemical and the chemical properties of Ailanthus altissima (Miller) Swingle seed oil and to evaluate its in vitro antioxidant and antibacterial activities and in vivo analgesic and anti-inflammatory activities. The fatty acids' composition was determined using GC-FID. The oil was screened for antioxidant activity by DPPH test. The analgesic and anti-inflammatory activities were determined using the acetic acid writhing test in mice and the carrageenan-induced paw edema assay in rats, respectively. Volatile compounds were characterized by HS-SPME-GC-MS. A. altissima produces seeds which yielded 17.32% of oil. The seed oil was characterized by a saponification number of 192.6 mg KOH∙g of oil, a peroxide value of 11.4 meq O2∙kg of oil, a K232 of 4.04, a K270 of 1.24, and a phosphorus content of 126.2 ppm. The main fatty acids identified were palmitic (3.06%), stearic (1.56%), oleic (38.35%), and linoleic acids ones (55.76%). The main aroma compounds sampled in the headspace were carbonyl derivatives. The oil presents an important antioxidant activity (IC50 = 24.57 μg/mL) and a modest antimicrobial activity. The seed oil at 1 g/kg showed high analgesic (91.31%) and anti-inflammatory effects (85.17%). The presence of high levels of unsaturated fatty acids and the noteworthy antioxidant capacity of the seed oil can hypothesize its use as an analgesic and anti-inflammatory agent

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