Characterization of Volatile Organic Compounds and Essential Oil Profile of Pittosporum tobira (Thunb.) W.T. Aiton Cultivated in Tunisia.

The chemical compositions of the essential oils of Pittosporum tobira organs and of the volatile organic compounds emitted were identified. The EOs are extracted by hydrodistillation and the VOCs by head space. The main EOs compounds are α-neoclovene, ß-caryophyllene and limonene in roots. Viridiflorol in young stems, flowers and young leaves (34.90, 31.60, and 24.60%, respectively), α-cadinol in young stems and leaves, and flowers (13.80, 10.40, and 9.10%, respectively) and (E)-nerolidol in flowers (13.30%). The major detected VOCs are n-undecane, n-nonane, α-cubebene, and α-gurjunene and ß-gurjunene. Principal Component Analysis carried out on the 26 main volatile compounds (relative content exceeding 6%) identified both by HS and in the EOs allowed their classification into two groups; compounds specific to roots and those specific to aerial parts. We can notice that the two methods used to extract P. tobira volatile compounds and identify them are complementary. This study defines and differentiates, for the first time, the specific aroma profile of P. tobira from Tunisia. In addition to its ornamental value, all the organs of this species, could be valued as a source of volatile compounds useful in perfume, cosmetics and as food flavoring products.

Volatiles, phenolic compounds, antioxidant and antibacterial properties of kohlrabi leaves.

This work presents the volatile compounds and phenolic profile investigation of the leaves of Brassica oleracea L. growing in Tunisia, together with antioxidant and antibacterial properties. Volatile constituents were determined by HS-SPME coupled to GC/MS, and the results showed that α-pinene (31.6%) and limonene (16.9%) were the main volatiles. The phenolic profile was determined by HPLC analysis, the methanol extract revealed the presence of four hydroxycinnamic acids (chlorogenic, ferulic, p-coumaric and sinapic acids), two hydroxybenzoic acids (syringic and gallic acids), and four flavonoids (catechol, catechin hydrate, epigallocatechin and epicatechin 3-O-gallate). The methanol extract showed the best significantly antiradical activity by DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS ((2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) antioxidant assays, with EC50 of 0.32 and 0.45 mg/mL, respectively. For antibacterial activity, the methanol extract inhibits all the tested strains. It can be concluded that kohlrabi leaves are rich in bioactive compounds and are a potential source of natural antioxidants and antibacterials.

Ruscus hypophyllum L. extracts: chemical composition, antioxidant, anticoagulant, and antimicrobial activity against a wide range of sensitive and multi-resistant bacteria.

The aim of this study is to evaluate the polyphenolic and flavonoid contents in the leaves extracts of Ruscus hypophyllum. Antioxidant activity was estimated by α,α-diphenyl-ß-picrylhydrazyl (DPPH) and 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS) assays. The anticoagulant activity of Ruscus extracts was evaluated in vitro, using the prothrombin time (PT) and a PTT-activated partial thromboplastin time tests. The antibacterial activity was tested against large number of important medically and resistant bacteria by the broth dilution method. In this study, ethyl acetate and chloroform extracts displayed the highest total phenols contents (74.76 mg EAG/g and 73.89 mg EAG/g, respectively) and flavonoid content 40 and 32.43 mg EC/g, respectively. The GC-MS analysis of ethyl acetate extract confirmed the presence of oxygenated sesquiterpenes and hydrocarbon diterpenes with percentages of 16.41% and 10.72%, respectively, but chloroform extract was rich with, oxygenated monoterpenes, and oxygenated diterpenes, with percentages of 6.19 and 3.27%, respectively. Among tested extracts, ethyl acetate exhibited the best antioxidant and anticoagulant activities. Furthermore, ethyl acetate and chloroform extracts showed important antibacterial activity against resistant bacteria methicillin-resistant Staphylococcus aureus (SARM), Acinetobacter imipenem-resistant (IMP/R), P. aeruginosa imipenem-resistant (IMP/R) and extended-spectrum beta-lactamase producing E. cloacae (BLSE) with minimal inhibitory concentration (MIC) values varying between 0.125 and 0.5 mg/mL.

Valorisation of the green waste parts from turnip, radish and wild cardoon: Nutritional value, phenolic profile and bioactivity evaluation.

The recovery of bio-wastes to obtain high added value compounds is of great interest for the pharmaceutical, medicinal and food industries. Therefore, the aerial parts of turnip (Brassica rapa L.), radish (Raphanus sativus L.) and leaf blade of wild cardoon (Cynara cardunculus L. var. sylvestris (Lamk) Fiori) were characterized regarding their nutritional composition, as also their content in soluble sugars, organic acids, fatty acids, and tocopherols. Furthermore, their hydroethanolic extracts and infusion preparations, were profiled regarding individual phenolic compounds by HPLC-DAD/ESI-MS and their antioxidant, antibacterial and hepatotoxic activities were evaluated. Regarding the nutritional content, wild cardoon revealed the best results, however it was radish and turnip that showed higher values for organic acids and phenolic compounds. The hydroethanolic extract and infusion preparation of wild cardoon stood out for its antioxidant and antibacterial activity. Overall, the hydroethanolic extracts seemed more effective (regarding antioxidant and antibacterial activity) than the infusions. Total phenolic acids proved to be strongly correlated with the antioxidant and antibacterial (against Morganella morganii) activities. This study showed that the discarded parts of these plants can be used as an important natural source of valuable nutrient content and new and safe bioactive compounds, beneficial for human health. Moreover, the extraction of those compounds from underused parts of turnip, radish and cardoon could be used to preserve foods, avoiding artificial additives and thus, contributing to the development of new natural ingredients.

Profiles of the Essential Oils and Headspace Analysis of Volatiles from Mandragora autumnalis Growing Wild in Tunisia.

Mandragora autumnalis Bertol. (Solanaceae family), synonym of M. officinalis Mill., occurs in North Africa and grows natively in Northern and Central Tunisia, in humid to sub-arid climates. The ripe fruits of mandrake are odiferous with a particular, indescribable, specific odor, shared, to a lesser extent, by the leaves and roots. We carried out an investigation of the essential oils (EOs) and of the aromatic volatiles emitted by fresh leaves, roots and ripe fruits of M. autumnalis growing wild in Central Tunisia. The EOs were obtained from freshly collected plant material by hydrodistillation, while the volatile emissions from the powdered M. autumnalis tissues were sampled by headspace solid phase microextraction (HS-SPME); both types of samples were analyzed by gas chromatography-mass spectrometry (GC/MS). Fifty-one compounds representing 96.2-98.6 % of the total oil compositions were identified in the three tissues and belonged to different chemical classes specifically in 16 esters, 12 alcohols, 12 hydrocarbons, 6 ketones, 3 aldehydes and 3 acids. The main constituents were pentadecanoic acid (34.2 %) and hexadecanol (26.3 %). A total of 78 volatile compounds emanating from M. autumnalis tissues, representing 94.1-96.4 % of the total volatile compositions, were identified: 22 esters, 11 alcohols, 9 aldehydes, 14 ketones, 7 nitrogen, 10 hydrocarbons, 2 lactones, 1 sulfur and 2 ethers. Ethyl hexanoate (12.3 %) and 1,3-butanediol (12.3 %) were at the highest relative percentages. This study characterizes and distinguishes M. autumnalis from Tunisia and attributes the compounds responsible for the intoxicating and particular odor of fruits. Chemosystematic of Mandragora autumnalis based on the identification of essential oils and headspace volatiles of each of its organ can be used to characterize this species according to its geographic distribution.

Phenolic Profile and Bioactive Properties of Carissa macrocarpa (Eckl.) A.DC.: An In Vitro Comparative Study between Leaves, Stems, and Flowers.

The present work aimed to characterize leaves, stems, and flowers of Carissa macrocarpa (Eckl.) A.DC., by performing an analysis of the phenolic compounds by HPLC-DAD/ESI-MS, correlating them with bioactive properties, such as antioxidant, anti-inflammatory, cytotoxic, and antimicrobial activities. Thirty polyphenols were identified in the hydroethanolic extract, including phenolic acids, flavan-3-ols, and flavonol glycosides derivatives (which presented the highest number of identified compounds). However, flavan-3-ols showed the highest concentration in stems (mainly owing to the presence of dimers, trimmers, and tetramers of type B (epi)catechin). Leaves were distinguished by their high antioxidant and anti-inflammatory activities, as well as their bactericidal effect against E. coli, while stems presented a higher cytotoxic activity and bactericidal effect against Gram-positive bacteria. Moreover, a high correlation between the studied bioactivities and the presence of phenolic compounds was also verified. The obtained results bring added value to the studied plant species.

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.

Caryophyllene Sesquiterpenes from Pulicaria vulgaris Gaertn.: Isolation, Structure Determination, Bioactivity and Structure-Activity Relationship.

A new caryophyllene, named pulicaryenne A (1), along with four other known caryophyllene derivatives (2, 3, 4 and 5) were isolated from the ethyl acetate extract of aerial parts of Pulicaria vulgaris Gaertn. (Asteraceae). All compounds were isolated for the first time from this species. Compound 2 was identified as a new epimer of a known caryophyllene derivative isolated previously from P. dysenterica. Their structures were established by spectroscopic means including NMR analysis (1D- and 2D-NMR) and ESI-TOF-MS. All compounds were evaluated for their anticholinesterase, antityrosinase and cytotoxic activities against two human cell lines (A549 and HeLa). Results showed that compound 5 exhibited the highest cytotoxic effect against A549 and anticholinesterase activity with IC50 values of 8.50±0.75 and 6.45±0.09 µg/mL, respectively. Furthermore, compound 5 showed also an interesting antityrosinase activity with percent inhibition value of 79.0±2.5 % at 50 µg/mL. The bioactivity and drug likeness scores of the isolated compounds 1-5 were calculated using Molinspiration software and discussed. These results may suggest that the five caryophyllene derivatives endowed with good biological properties, which could be used as bioactive alternatives in pharmaceutical preparations.

Valorization of the Green Waste from Two Varieties of Fennel and Carrot Cultivated in Tunisia by Identification of the Phytochemical Profile and Evaluation of the Antimicrobial Activities of Their Essentials Oils.

The purpose of this study was to identify the chemical composition and the antibacterial activity of the essential oils (EOs) extracted from the green tops of Daucus carota L. subsp. sativus (Hoffm.) Arcang. plants producing yellow roots (DcsYR) and those producing orange roots (DcsOR) and from two varieties of Foeniculum vulgare subsp. vulgare cultivated in Tunisia. Analyses revealed that the EOs from the two D. carota varieties were rich in constituents belonging to sesquiterpenes. Phenylpropanoids and non-terpene derivatives were the most abundant classes of compounds in the EOs from the two varieties of F. vulgare, of which compositions were predominated by (E)-anethole and p-acetonylanisole. All the tested EOs were significantly more effective against Gram-negative bacteria, and that obtained from var. azoricum was more active against the yeast Candida albicans than the reference drug. The EOs obtained from these by-products showed indeed interesting potential to be promoted as natural antimicrobials in food preservation systems, as well as the possibility to be used in flavor industries.

Amantagula Fruit (Carissa macrocarpa (Eckl.) A.DC.): Nutritional and Phytochemical Characterization.

Fruits are one of the most promising food matrices and they have been explored in the discovery of new natural and safer bioactive compounds. Carissa macrocarpa (Eckl.) A. DC. fruits are widely consumed in African countries for the preparation of traditional foodstuff, but also for their beneficially health effects. Thus, as the authors' best knowledge there are no studies on the chemical and bioactive characterization of these fruits. Therefore, fruits of C. macrocarpa from Tunisia were chemically characterized regarding their nutritional value and bioactive compounds. Furthermore, the hydroethanolic extract of these fruits was evaluated regarding its bioactive properties. The fruit powder sample showed high amounts of sugars and polyunsaturated fatty acids (PUFA). The organic acids and tocopherols' profiles revealed the presence of five organic acids and two tocopherol isoforms, being quinic acid and α-tocopherol the most abundant. The hydroethanolic extract of the fruits presented high antioxidant, cytotoxic, anti-inflammatory, and antibacterial properties, showing activity against all the bacterial strains studied, also inhibiting the cell growth of all the tested tumor cell lines, with the exception of HepG2, and did not reveal toxicity for the non-tumor cells PLP2. Therefore, the fruits of C. macrocarpa could be included in a daily basis diet as a source of high nutritional quality compounds with high bioactive potential.

Chemical Composition and Activity of Essential Oils of Carissa macrocarpa (Eckl.) A.DC. Cultivated in Tunisia and Its Anatomical Features.

This is the first study investigating the chemical composition of essential oils (EOs) isolated from different tissues of Carissa macrocarpa (Eckl.) A.DC., their antimicrobial activity and the anatomical characters of the aerial organs and the fruits. The main EO components were pentadecanal and tetradecan-1-ol (31.9 and 16.5% in fresh leaf EO, respectively), (E)-nerolidol and caryophyllene oxide (27.3 and 15.0% in fruit EO, respectively), linalool and hexahydrofarnesyl acetone (30.9 and 24.9% in stem EO, respectively), benzyl benzoate (24.3% in flower EO). The fruit EO was more active against Candida albicans (MIC = 0.46 mg/mL) compared to the reference antibiotic (17.66 mg/mL). Furthermore, at this concentration it inhibited all the Gram-positive bacteria. Concerning the anatomical features, it is noteworthy to mention the presence of a large cluster of calcium oxalate crystals inside some parenchymatous cells. Large ducts corresponding to non articulated laticifers were identified in the cortex of leaf, stem and fruit pericarp. The laticifers categories and their distribution are taxonomically important to discriminate this species from others acclimated in different countries. Considering the obtained results, EOs of C. macrocarpa can be a good source of antimicrobial compounds, contributing to solve the problem of microbial resistance to antibiotics.

Incorporation of tocopherol-rich extracts from mushroom mycelia into yogurt.

Consumers are well-informed about food additives and it is likely that they prefer natural additives over their synthetic analogues. Antioxidants represent a major class of food preservatives, among which tocopherols stand out as one of the most important examples. Interestingly, these compounds are present in relevant amounts in the mycelia of in vitro cultured mushrooms. Accordingly, the mycelia from Ganoderma lucidum, Pleurotus ostreatus and Pleurotus eryngii were used as alternative sources of tocopherols. These extracts were incorporated into different yogurt formulations, which were further compared among each other and with yogurts containing commercial α-tocopherol (E307), regarding their nutritional parameters, fatty acid profile and antioxidant activity. The proposed approach was validated as an effective functionalization strategy, particularly in the case of the G. lucidum mycelium, which showed the highest antioxidant potential, most likely as a result of its tocopherol profile. Furthermore, yogurts prepared with each mycelium extract allowed maintaining the nutritional properties observed in the "blank" yogurt formulation.

Phytochemical study of the trunk bark of Citharexylum spinosum L. growing in Tunisia: Isolation and structure elucidation of iridoid glycosides.

A phytochemical investigation of the trunk bark ethyl acetate extract of Citharexylum spinosum L. has led to the isolation of four previously undescribed iridoid glycosides, tunispinosides A-D, and five known phenylethanoid glycosides, verbascoside, leucosceptoside A, martynoside, isoverbascoside and plantainoside C, together with 4-hydroxy-2,6-dimethoxyphenyl 6'-O-vanilloyl-ß-D-glucopyranoside, two 8,3'-neolignan glycosides, plucheosides D1-D2, coniferyl aldehyde, vanillic acid, syringic acid, ferulic acid and tyrosol. All compounds were isolated for the first time from C. spinosum. Their isolation was carried out using silica gel column and high performance liquid chromatography (HPLC). Structures were established by spectroscopic means including 1D and 2D NMR experiments, and spectrometric ESI-HRMS analysis.

Chemical Composition and Biological Studies of the Essential Oil from Aerial Parts of Beta vulgaris subsp. maritima (L.) Arcang. Growing in Tunisia.

The chemical composition, antioxidant, cytotoxic, anticholinesterase and anti-tyrosinase activities of the hydrodistilled essential oil of the aerial parts of Beta vulgaris subsp. maritime (L.) Arcang. from Tunisia have been evaluated. The chemical composition of the oil (yield 0.037% [w/w]), determined by GC-FID and GC/MS is reported for the first time. Twenty five components, accounting for 98.1% of the total oil have been identified. The oil was characterized by a high proportion of oxygenated sesquiterpenes (39.2%), followed by sesquiterpene hydrocarbons (30.3%) and one apocarotenoids (26.3%). The main compounds were γ-irone (26.3%), α-cadinol (12.1%), T-cadinol (10.6%), bicyclogermacrene (10.4%) and δ-cadinene (6.0%). The isolated oil was tested for its antioxidant activity using the DPPH· , ABTS+· , catalase, and paraoxonase assays and also for its cytotoxic, anticholinesterase, and anti-tyrosinase activities. The essential oil exhibited high antioxidant activity (IC50  = 0.055 ± 0.006 mg/ml) and important result oncatalase (524.447 ± 2.58 Units/mg protein). Furthermore, it exerted a significant cytotoxic effect against A549 cell line, with IC50  = 42.44 ± 1.40 µg/ml. The results indicate that the essential oil of B. vulgaris subsp. maritima (L.) Arcang. aerial parts may be used in future as an alternative to synthetic antioxidant agents, with potential application in the food and pharmaceutical industries.

Chemical composition, antibacterial and antifungal activities of flowerhead and root essential oils of Santolina chamaecyparissus L., growing wild in Tunisia.

The antimicrobial properties of essential oil from various Santolina species have not been investigated enough in the previous studies dealing with the biological activities of medicinal plants. In Tunisia, Santolina chamaecyparissus L. (Asteraceae) is the only Santolina species recorded and is used as vermifuge and emmenagogue. The chemical composition, antibacterial and antifungal properties of essential oils from the flowerheads and roots of spontaneous S. chamaecyparissus growing in Tunisia and the chemical composition which leads to the Tunisian chemotype are investigated here for the first time. Essential oils isolated by hydro distillation from flowerheads and roots of S. chamaecyparissus were analyzed by GC and GC/MS. Two methods served for antimicrobial assays of the essential oils: diffusion in a solid medium and micro-well dilution assay. Antifungal tests were carried out by the agar incorporation method. Sixty-seven constituents were identified from the essential oil of the flowerhead. The major constituents were: 1,8-cineole and ß-eudesmol. Two non identified compounds were present at the highest concentration in root oil. Flowerhead oil was characterized by high contents in monoterpenes and sesquiterpenes oxygenated compounds. The flowerhead essential oil demonstrated potent of antibacterial properties against Pseudomonas aeruginosa ATCC and Enterococcus faecalis ATCC, with MIC of 0.625 µg/ml. These findings demonstrate that the flowerhead essential oils of S. chamaecyparissus have excellent antibacterial properties and for this reason they could contribute to decrease the problem of microbial resistance to antibiotics.

In vitro Toxicity and Genotoxic Activity of Aqueous Leaf Extracts From Four Varieties of Olea europea (L).

AIM: Despite its therapeutic value almost nothing is known about potential adverse health effects of Olea europea L. We therefore investigated the in vitro toxicity and genotoxicity of leaf extracts of this plant. MATERIAL AND METHODS: Extracts from olive tree leaves were obtained from four different regions in Tunisia. We investigated the in vitro toxicity, genotoxicity and antigenotoxicity of their aqueous extracts using the neutral red (NR) uptake, Vitotox and alkaline comet assays. RESULTS: None of the extracts were found to be toxic and none of them were genotoxic, although some doubt exists for the extract obtained at Meski (North of Tunisia). On the basis of the Vitotox test only, none of the extracts appeared to have antigenotoxic (or cogenotoxic) properties. DISCUSSION: The negative genotoxicity underline the safe use of the leaves, for example, as hypoglycemic and antidiabetic preparations. Lack of antigenotoxicity may indicate that the previously reported anticancer effects do not result from protection against genotoxicity. HIGHLIGHTS: We investigated the in vitro toxicity and genotoxicity of aqueous extracts of olivesThe neutral Red Uptake test, Vitotox and alkaline comet assay were usedLeaf extracts from 4 different origins were investigatedNone of them showed in vitro toxicity or genotoxicityThe extracts also didn't have antigenotoxic properties Abbreviation list: BaP: benzo(α)pyrene, EMS: ethyl methane sulfonate, LMP: low melting point, NI50: 50% inhibition of NRU, NR: neutral red, NRU: neutral red uptake, OD: optical density, PBS: phosphate buffer saline, SDS: sodium dodecyl sulphate, S/N: signal to noise ratio, 4NQO: 4-nitroquinoline oxide.

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

Citharexylum spinosum L. (Verbenaceae) also known as Citharexylum quadrangulare Jacq. or Citharexylum fruticosum L. is an exotic tree introduced many years ago in Tunisia, specially used as a street and park ornamental tree. Essential oils (EOs) 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 EO 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 (hexahydrofarnesylacetone; 26%) and an aliphatic hydrocarbon (nonadecane; 14.5%). Flowers oil was rich in esters (2-phenylethyl benzoate; 33.5%). Finally, drupes oil was rich in oxygenated sesquiterpenes (ß-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. Root and shoot elongation seemed to be more affected than germination. The inhibition of the shoot length varied from 3.6% to 100% and that of the root from 16.1% to 100%. 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 EOs in herbicidal formulations, further experiments involving field conditions are necessary to confirm its herbicidal potential.

Chemical Composition and Antimicrobial Activity of the Essential Oil from Aerial Parts and Roots of Eryngium barrelieri Boiss. and Eryngium glomeratum Lam. from Tunisia.

The study of chemical composition and biological activity of unexplored essential oils may open new perspectives on their potential use in facing major health concerns such as drug-resistant infections. The present study investigates the chemical composition and antimicrobial effects of previously unstudied essential oils obtained from genus Eryngium: Eryngium glomeratum Lam. and Eryngium barrelieri Boiss. The chemical compositions of the essential oils from aerial parts and roots of both species were studied using GC and GC/MS analytical technics. The analysis led to the identification of 102 compounds totalizing 85 - 94% of all detected compounds. Essential oils were characterized by the predominance of oxygenated sesquiterpenes. The oils obtained from aerial parts were tested against 36 microbial strains by agar dilution method and showed minimum inhibitory concentrations (MIC) in the range of 2 - 625 µg/ml. A strong antibacterial activity against multiresistant Pseudomonas aeruginosa was observed especially from E. glomeratum essential oil with MIC value up to 2 µg/ml. These findings give significant information about the pharmacological activity of these essential oils, which suggest their potential use to develop new remedies, or as sources of active compounds.

Chemical Composition, Cytotoxic and Antibacterial Activities of the Essential Oil from the Tunisian Ononis angustissima L. (Fabaceae).

The chemical composition, cytotoxic and antibacterial activities of the hydrodistilled essential oil of the aerial parts of Ononis angustissima from south Tunisia has been evaluated. The oil yield was 0.04% (w/w). The chemical composition, determined by GC and GC-MS is reported for the first time. Forty-five components, accounting for 93.7% of the total oil have been identified. The oil was characterized by a high proportion of oxygenated sesquiterpenes (33.2%), followed by sesquiterpene hydrocarbons (6.3%) and apocarotenoids (10.3%). The main components of the oil were α-eudesmol (22.4%), 2-tridecanone (9.3%) and acetophenone (7.4%). The essential oil was tested for its possible cytotoxic activity towards the human cervical cell line HeLa using the MTT assay and the antibacterial activity against Pseudomonas aeruginosa, Escherichia coli, Enterococcus faecalis, Staphylococcus aureus and the clinical strain Acinetobacter sp. This oil exerted a cytotoxic activity with an IC50 of 0.53 ± 0.02 mg/mL and a significant antibacterial effect against P. aeruginosa and E. faecalis.

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 (ß-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)-ß-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.