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.

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.

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.

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.

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.

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.

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 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 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.

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 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 ß-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.).

Antioxidant, 5-lipoxygenase inhibitory and cytotoxic activities of compounds isolated from the Ferula lutea flowers.

A phytochemical investigation of the Ferula lutea (Poir.) Maire flowers has led to the isolation of a new compound, (E)-5-ethylidenefuran-2(5H)-one-5-O-ß-d-glucopyranoside (1), designated ferunide, 4-hydroxy-3-methylbut-2-enoic acid (2), reported for the first time as a natural product, together with nine known compounds, verbenone-5-O-ß-d-glucopyranoside (3), 5-O-caffeoylquinic acid (4), methyl caffeate (5), methyl 3,5-O-dicaffeoylquinate (6), 3,5-O-dicaffeoylquinic acid (7), isorhamnetin-3-O-α-l-rhamnopyranosyl(1→6)-ß-d-glucopyranoside, narcissin (8), (-)-marmesin (9), isoimperatorin (10) and 2,3,6-trimethylbenzaldehyde (11). Compounds 3-10 were identified for the first time in Ferula genus. Their structures were elucidated by spectroscopic methods, including 1D and 2D NMR experiments, mass spectroscopy and X-ray diffraction analysis (compound 2), as well as by comparison with literature data. The antioxidant, anti-inflammatory and cytotoxic activities of isolated compounds were evaluated. Results showed that compound 7 exhibited the highest antioxidant activity with IC50 values of 18 ± 0.5 µmol/L and 19.7 ± 0.7 µmol/L by DPPH radical and ABTS radical cation, respectively. The compound 6 exhibited the highest anti-inflammatory activity with an IC50 value of 5.3 ± 0.1 µmol/L against 5-lipoxygenase. In addition, compound 5 was found to be the most cytotoxic, with IC50 values of 22.5 ± 2.4 µmol/L, 17.8 ± 1.1 µmol/L and 25 ± 1.1 µmol/L against the HCT-116, IGROV-1 and OVCAR-3 cell lines, respectively.

New bioactive dihydrofuranocoumarins from the roots of the Tunisian Ferula lutea (Poir.) Maire.

A phytochemical investigation of the roots of Ferula lutea (Poir.) Maire led to the isolation of new dihydrofuranocoumarins as two inseparable isomers, (-)-5-hydroxyprantschimgin 1 and (-)-5-hydroxydeltoin 2, together with eight known compounds, (-)-prantschimgin 3, (-)-deltoin 4, psoralen 5, xanthotoxin 6, umbelliferone 7, caffeic acid 8, ß-sitosterol 9 and stigmasterol 10. Their structures were elucidated on the basis of extensive spectroscopic methods, including 1D and 2D NMR experiments and mass spectroscopy analysis, as well as by comparison with literature data. The anti-acetylcholinesterase and cytotoxic effects of the isolates and antioxidant activities of the mixture (1+2) were also evaluated in this work. Results showed that the mixture (1+2) has the most cytotoxic activity with IC50 values 0.29±0.05 and 1.61±0.57µM against the cell lines HT-29 and HCT 116, respectively. The greatest acetylcholinesterase inhibitory activity (IC50=0.76±0.03) was exhibited by the xanthotoxin 6. In addition, the mixture (1+2) was investigated for its antioxidant activity and showed IC50 values 18.56, 13.06, 7.59, and 4.81µM towards DPPH free radical scavenging, ABTS radical monocation, singlet oxygen and hydrogen peroxide, respectively.

Development of real-time PCR method for the detection and the quantification of a new endogenous reference gene in sugar beet "Beta vulgaris L.": GMO application.

KEY MESSAGE : Here, we describe a new developed quantitative real-time PCR method for the detection and quantification of a new specific endogenous reference gene used in GMO analysis. The key requirement of this study was the identification of a new reference gene used for the differentiation of the four genomic sections of the sugar beet (Beta vulgaris L.) (Beta, Corrollinae, Nanae and Procumbentes) suitable for quantification of genetically modified sugar beet. A specific qualitative polymerase chain reaction (PCR) assay was designed to detect the sugar beet amplifying a region of the adenylate transporter (ant) gene only from the species of the genomic section I of the genus Beta (cultivated and wild relatives) and showing negative PCR results for 7 species of the 3 other sections, 8 related species and 20 non-sugar beet plants. The sensitivity of the assay was 15 haploid genome copies (HGC). A quantitative real-time polymerase chain reaction (QRT-PCR) assay was also performed, having high linearity (R (2) > 0.994) over sugar beet standard concentrations ranging from 20,000 to 10 HGC of the sugar beet DNA per PCR. The QRT-PCR assay described in this study was specific and more sensitive for sugar beet quantification compared to the validated test previously reported in the European Reference Laboratory. This assay is suitable for GMO quantification in routine analysis from a wide variety of matrices.

Chemical composition and antimicrobial and allelopathic activity of Tunisian Conyza sumatrensis (Retz.) E.WALKER essential oils.

Conyza sumatrensis (Retz.) E.WALKER (Asteraceae) is a spontaneous annual herb, fairly widespread throughout Tunisia, which has rarely been studied or valued in any sector. Essential oils were obtained by hydrodistillation of different parts (flower heads, leaves, stems, and roots) of C. sumatrensis plants, which were collected in autumn (November 2007) at the flowering stage in the area of Monastir, Tunisia. In total, 98 compounds, representing 88.1-99.3% of the oil composition, were identified by GC-FID and GC/MS analyses. The root essential oil was distinguished by its high content in acetylenes (matricaria ester, 4; 74.3%), while those from flower heads and leaves were dominated by oxygenated sesquiterpenes (61.1 and 50.3%, resp.). The oils of C. sumatrensis from Tunisia belonged to a matricaria ester/caryophyllene oxide chemotype. All the oils were evaluated for antibacterial, antifungal, and allelopathic activities. The results indicate that the leaf oil exhibited significant in vitro antibacterial activity against Enterococcus faecalis, Staphylococcus aureus, and Proteus mirabilis and that the C. sumatrensis oils isolated from the aerial parts presented high mycelia-growth inhibition of Candida albicans and the filamentous fungi tested. Moreover, the essential oils of the different plant parts inhibited the shoot and root growth of Raphanus sativus (radish) seedlings. Indeed, the inhibition of the hypocotyl growth varied from 28.6 to 90.1% and that of the radicle from 42.3 to 96.2%.

Chemical composition of 8 eucalyptus species' essential oils and the evaluation of their antibacterial, antifungal and antiviral activities.

BACKGROUND: In 1957, Tunisia introduced 117 species of Eucalyptus; they have been used as fire wood, for the production of mine wood and to fight erosion. Actually, Eucalyptus essential oil is traditionally used to treat respiratory tract disorders such as pharyngitis, bronchitis, and sinusitis. A few investigations were reported on the biological activities of Eucalyptus oils worldwide. In Tunisia, our previous works conducted in 2010 and 2011 had been the first reports to study the antibacterial activities against reference strains. At that time it was not possible to evaluate their antimicrobial activities against clinical bacterial strains and other pathogens such as virus and fungi. METHODS: The essential oils of eight Eucalyptus species harvested from the Jbel Abderrahman, Korbous (North East Tunisia) and Souinet arboreta (North of Tunisia) were evaluated for their antimicrobial activities by disc diffusion and microbroth dilution methods against seven bacterial isolates: Haemophilus influenzae, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus agalactiae, Streptococcus pneumoniae and Streptococcus pyogenes. In addition, the bactericidal, fungicidal and the antiviral activities of the tested oils were carried out. RESULTS: Twenty five components were identified by GC/FID and GC/MS. These components were used to correlate with the biological activities of the tested oils. The chemical principal component analysis identified three groups, each of them constituted a chemotype. According to the values of zone diameter and percentage of the inhibition (zdi, % I, respectively), four groups and subgroups of bacterial strains and three groups of fungal strains were characterized by their sensitivity levels to Eucalyptus oils. The cytotoxic effect and the antiviral activity varied significantly within Eucalyptus species oils. CONCLUSIONS: E. odorata showed the strongest activity against S. aureus, H. influenzae, S. agalactiae, S. pyogenes, S. pneumoniae and against all the tested fungal strains. In addition, E. odorata oil showed the most cytotoxic effect. However, the best antiviral activity appeared with E. bicostata. Virus pretreatment with E. bicostata essential oil showed better antiviral activity (IC(50) = 0.7 mg/ml, SI = 22.8) than cell-pretreatment (IC(50) = 4.8 mg/ml, SI = 3.33). The essential oil of E. astringens showed antiviral activity only when incubated with virus prior to cell infection. This activity was dose-dependent and the antiviral activity diminished with the decreasing essential oil concentration.

Correlation between chemical composition and antibacterial activity of essential oils from fifteen Eucalyptus species growing in the Korbous and Jbel Abderrahman arboreta (North East Tunisia).

The essential oils of fifteen Eucalyptus species harvested from the Jbel Abderrahman and Korbous arboreta (North East Tunisia) were screened for their antibacterial activities by the agar disc diffusion method. Eighteen major components as identified by GC/FID and GC/MS were selected for a study of the chemical and biological activity variability. The main one was 1,8-cineole, followed by spathulenol, trans-pinocarveol, α-pinene, p-cymene, globulol, cryptone, ß-phellandrene, viridiflorol, borneol, limonene and isospathulenol. The chemical principal component analysis identified five species groups and subgroups, where each group constituted a chemotype, however that of the values of zone diameter of the inhibition (zdi) identified six groups of Eucalyptus oils, characterized by their antibacterial inhibition ability. The strongest activity was shown by E. platypus oil against Enterococcus faecalis and by E. lamannii oil against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. A correlation between the levels of some major components and the antibacterial activities was observed.

In vitro growth and organogenesis of Prosopis farcta plantlets (Fabaceae, Mimosoideae) in culture medium supplemented with various concentrations of Ca++ and Na+.

The objective of this study was to vary the mineral composition of the culture medium of Prosopis farcta seedlings per addition of Na+ and Ca++ ions with the aim to identify the culture media which support the growth and/or the expression of the in vitro plant organogenesis. The Na+ and Ca++ ions were added in the culture medium in various concentrations by taking the Gamborg medium, in which macroelements were diluted 10 times, as the basic one. After two months of culture, parameters relating to the vegetative development of plant seedlings and to the various expressions of organogenesis were measured. Weak concentrations in sodium and calcium ions as well as a weak concentration in Ca++ (0.1 mM) with 50 mM in Na+ support the best vegetative development of the plantlets. The most important percentage of plant seedlings presenting a bud initiation was obtained on a medium containing 0.1 mM of Na+ and 50 mM of Ca++. Our study defined several media likely to support in vitro development of Prosopis farcta plantlets allowing the selection of salt tolerant plants or cellular lines. Some other media were chosen for improving micropropagation of the species without adding growth substances.