Essential oils of Origanum vulgare L. subsp glandulosum (Desf.) letswaart from Tunisia: chemical composition and antioxidant activity

BACKGROUND: Characterisation of the essential oils from O. glandulosum collected in three locations of Tunisia, chemical composition and the evaluation of their antioxidant activities were carried out. RESULTS: The essential oils from Origanum vulgare L. subsp. glandulosum (Desf.) letswaart collected from three localities of north Tunisia - Krib, Bargou and Nefza - were obtained in yields of 2.5, 3.0 and 4.6% (v/w), respectively. The essential oils were analysed by GC and GC/MS and assayed for their total phenolics content, by the Folin-Ciocalteu method, and antioxidant effectiveness, using the 2,2-diphenyl-1-picrylhydrazil (DPPH) radical scavenging assay. The main components of these essential oils, from Nefza, Bargou and Krib, were p-cymene (36%, 40% and 46%), thymol (32%, 39% and 18%), gamma-terpinene (24%, 12% and 16%) and carvacrol (2%, 2% and 15%), respectively). The ability to scavenge the DPPH radicals, expressed by IC50, ranged from 59 to 80 mg L-1. The total phenolic content, expressed in gallic acid equivalent (GAE) g kg(-1) dry weight, varied from 9.37 to 17.70 g kg(-1) dw. CONCLUSIONS: A correlation was identified between the total phenolic content of the essential oils and DPPH radical scavenger capacity. The occurrence of a p-cymene chemotype of O. glandulosum in the northern region of Tunisia is demonstrated

Effect of water and salt stresses on germination of some acacia species in Tunisia

This work has focused on the study of germination characteristics of seeds of Acacia tortilis (Forsk.) Hayne subsp. raddiana (Savi) Brenan, a species native of Tunisia, and of two introduced species : Acacia salicina Lindl. and Acacia ampliceps Maslin, reforested in arid zones of Tunisia. Germination was followed under conditions of water and salt stresses. Pre-treatments designed to remove integumentary inhibitions were applied to seeds. The germination behaviour of acacias in osmotic stress conditions showed a treatment effect, concentration of PEG 6000, highly significant on germination rate and mean time of germination. We found that these species did not tolerate drought and we observed a complete inhibition of germination at -0.8 MPa. The study of the effect of salt stress on germination showed a better tolerance of Acacia tortilis (Forsk.) Hayne subsp. raddiana (Savi) Brenan to salinity than the other two species as it germinated at high salt concentrations. Indeed, at 18 g/l the germination rate reached 32 %. We didn’t find any relationship between seed germinative properties and ecology of the adult plantNotre travail a porté sur l'étude des caractéristiques germinatives des semences d'Acacia tortilis (Forsk.) Hayne subsp. raddiana (Savi) Brenan, espèce autochtone de la Tunisie et deux espèces introduites Acacia salicina Lindl. et Acacia ampliceps Maslin qui sont utilisées en reboisement dans les zones arides de la Tunisie. La germination a été suivie en conditions de stress hydrique et salin. Des prétraitements destinés à lever les inhibitions tégumentaires ont été appliqués aux semences. Le comportement germinatif des acacias en conditions de stress osmotique a mis en évidence un effet traitement hautement significatif concernant le taux de germination et le temps moyen de germination. Nous avons révélé que ces espèces ne tolèrent pas la sécheresse et nous avons observé une inhibition totale de germination à -0.8 MPa. L'étude de la contrainte saline sur la germination a révélé une meilleure tolérance à la salinité de l'Acacia tortilis (Forsk.) Hayne subsp. raddiana (Savi) Brenan par rapport au deux autres espèces puisqu'il a germé à des concentrations élevées de sel. En effet, à 18 g/l le taux de germination atteint 32 %. Enfin nos travaux n'ont pas mis en évidence de relation entre les propriétés germinatives des semences et l'écologie de la plante au stade adulte

Eucalyptus oleosa Essential Oils: Chemical Composition and Antimicrobial and Antioxidant Activities of the Oils from Different Plant Parts (Stems, Leaves, Flowers and Fruits)

Essential oils obtained by hydrodistillation from the different parts (stems, adult leaves, immature flowers and fruits) of Eucalyptus oleosa were screened for their antioxidant and antimicrobial properties and their chemical composition. According to GC-FID and GC-MS, the principal compound of the stem, immature flowers and the fruit oils was 1,8-cineole, representing 31.5%, 47.0% and 29.1%, respectively. Spathulenol (16.1%) and γ-eudesmol (15.0%) were the two principal compounds of adult leaves oil. In the DPPH (1,1-diphenyl-2-picrylhydrazyl) assay, the oils of the four parts showed moderate antioxidant activity. In the ABTS (2,2’-azinobis-3-ethylbenzothiazoline-6-sulphonate) assay, the most active part was the adult leaves, with a IC50 value 13.0 ± 0.6 mg/L, followed by stems (IC50 = 43.5 ± 1.4 mg/L). The essential oils showed a better antibacterial activity against Gram-positive and Gram-negative bacteria, and a significant antifungal activity also was observed against yeast-like fungi. A strong correlations between oxygenated monoterpenes and antimicrobial activity (especially 1,8-cineole) were noted (R2 = 0.99, 0.97 and 0.79 for B. subtilis, P. aeruginosa and C. albicans, respectively)

Variabilité géographique du pin d'Alep en Tunisie : perspectives d'amélioration de la productivité et de la qualité physique du bois

Doctorat en sciences agronomiques et ingénierie biologique -- UCL, 199

Results of comparative trials between stone Pine (Pinus pinea L.)

Stone pine (Pinus pinea L.) is widely used for reforestation in northern Tunisia to produce both fruit and timber. A genetic improvement programme for this species has begun, the first stage of which is a geographic exploration of its genetic variability. Experimental plots have been established in several countries bordering the Mediterranean Sea. This article reports the results of 10 years of monitoring the two plots in northern Tunisia, at Jbel Essmaa and Oued El Bir. The survival and vigour data recorded for seedlings of various provenances are presented and analysed. Survival and growth of the provenances differ significantly between the two sites whereas differences are not significant within each site taken individually.Le Pin pignon (Pinus pinea L.) est largement utilisé dans les reboisements du Nord de la Tunisie pour ses productions ligneuse et fructifère. Un programme d’amélioration génétique de cette espèce a été mis en oeuvre avec une première étape d’exploration géographique de sa variabilité génétique. Des dispositifs expérimentaux impliquant plusieurs pays du pourtour méditerranéen ont été installés dans différents pays. Nous présentons, ici, le bilan des deux dispositifs de Jbel Essmaa et Oued El Bir situés dans le Nord de la Tunisie après 10 années de suivi. Les résultats enregistrés au niveau de la survie et de la vigueur des plants de différentes provenances et entre les sites sont présentés et analysés. Il en ressort qu’il existe une différence significative entre les deux sites, mais les différences entre la survie et la croissance des provenances ne sont pas significatives à l’intérieur de chaque site

Étude des secteurs écologiques, du milieu physique et des caractéristiques de production de la steppe arborée à Acacia tortilis dans le parc national de Bouhedma (Tunisie méridionale)

Ecology, physical and production characteristics of the steppe with Acacia tortilis in the Bouhedma national park (Tunisia southernmost). The present study was conducted in the Bouhedma national park and its surroundings, located in the arid area of Tunisia and considered a Biosphere reserve by UNESCO in 1977 ; it is a protected area with special ecological characteristics and an important dynamics of space occupation. The park contains the only wooded steppe with Acacia tortilis (Forsk.) Hayne subsp raddiana (Savi.) Brenan var. raddiana Brenan in Tunisia. With the aim of safeguarding and management of the park, a better knowledge of the distribution patterns and dynamics of the vegetation of this zone makes it possible to consider programmes of restoration and sustainable management of the natural environment. Based on the interpretation of remote sensing data and use of SIG, the study was devoted to the elaboration of charts relating to the ecological systems present in 2005, and to the distribution of the steppe with Acacia tortilis according to physical factors such as slope, altitude, type and depth of the soil. Also, the production of seeds was studied to explain the effect of physical factors on the regeneration of the species. The analysis of soil occupation dynamics translates into a good distribution (7056 ha) of steppe with Acacia tortilis. The study shows that Acacia tortilis is located on 6242 ha at an altitude of 20 m to 150 m and on 814 ha at an altitude from 150 to 250 m. This species grows on 5815 ha with a weak slope (0 to 3 %), on 928 ha with a slope of 3 to 5 % and only on 313 ha with a slope > 5 %. The results show that the Acacia tortilis is regenerated on the not very advanced soil of hydrous contribution with a surface of 3832 ha, on rendzina with 1280 ha, the isohumic soil with a surface of 986 ha. Acacia tortilis colonizes the far from deep soil with a surface of 2796 ha, the fairly deep soil with a surface of 2175, the very deep soil with a surface of 1970 ha, the not very deep soil with a surface of 75 ha and the deep soil with a surface of 40 ha.La présente étude a été effectuée dans le parc national de Bouhedma situé dans les zones arides tunisiennes et considéré comme une réserve de la biosphère de l’Unesco dès 1977. Le parc abrite l’unique steppe arborée à Acacia tortilis (Forsk.) Hayne subsp raddiana (Savi.) Brenan var. raddiana Brenan en Tunisie. L’étude a été consacrée, grâce à l’interprétation des données de la télédétection et l’utilisation des SIG, à l’élaboration des cartes relatives aux systèmes écologiques présents en 2005 et aux facteurs physiques du milieu (pente, altitude, type du sol, profondeur du sol). L’analyse du système écologique montre que la dynamique de l’occupation des sols se traduit par une bonne répartition de steppe arborée à Acacia tortilis avec une superficie de 7056 ha. L’étude montre qu’Acacia tortilis se localise sur 6242 ha à une altitude de 20 m à 150 m et sur 814 ha à une altitude de 150 à 250 m. Cette espèce pousse sur 5815 ha avec une faible pente (0 à 3 %), sur 928 ha avec une pente de 3 à 5 % mais seulement sur 313 ha avec une pente > 5 %. Les résultats montrent qu’Acacia tortilis se régénère fortement sur les sols peu évolués d’apport hydrique et sur les sols très peu profonds à profonds.Jaouadi Wahbi, Mechergui Kaouther, Gader Ghazi, Khouja Mohamed Larbi. Étude des secteurs écologiques, du milieu physique et des caractéristiques de production de la steppe arborée à Acacia tortilis dans le parc national de Bouhedma (Tunisie méridionale). In: Revue d'Écologie (La Terre et La Vie), tome 68, n°2, 2013. pp. 143-156

Effect of harvest year on production, chemical composition and antioxidant activities of essential oil of oregano (Origanum vulgare subsp glandulosum (Desf.) Ietswaart) growing in North Africa

Dried flowers and leaves of Origanum glandulosum (Desf.) Ietswaart collected at different harvesting years were submitted to hydrodistillation. The isolated essential oils were analyzed by GC and GC/MS to study the harvest year effect on oregano chemical composition. Total phenolic contents and antioxidant effectiveness were performed. Nefza essential oils were obtained in yields of 4.6%, 5.8% and 4.3% from plants collected in 2007, 2008 and 2009, respectively. The values of essential oil content of Krib population were close (2-2.7%). There are qualitative and quantitative differences in the chemical composition of essential oils of Krib and Nefza populations from one harvest year to another. p-cymene, -terpinene, thymol and carvacrol are the main compounds of all oils, regardless of the year of harvest. The year that has the highest value in rainfall and which declines in cooler conditions during the flowering period, has been the most important value in essential oil yield. Wide variations were noted in total phenolic content, expressed in gallic acid equivalent which varied in Nefza population, between 8.52–17.67 g GAE/kg dw. The anti-radical activity expressed by IC50 of oregano essential oils was varied from one year to another, from 59.2 mg/L in 2007, to 226.19 mg/L in 2008 for Nefza population. Those of Krib varied from 79.8 to 151.85 mg/L. The controlled culture of oregano is better that using the wild populations if we would like have stable constituents destined to the industries or pharmacological uses. So, we can adjust the controlled parameters of our culture according to our purpose.info:eu-repo/semantics/publishedVersio

Morphological evaluation of cork oak (Quercus suber): Mediterranean provenance variability in Tunisia

Twenty-six provenances (2 340 plants) of cork oak (Quercus suber spp.) originating from Portugal, Spain, Italy, Morocco, Algeria, and Tunisia were tested for genetic variation among and within provenances by growth traits. Seven morphometrical characters were measured in 90 plants from each provenance. Analysis of variance showed highly significant differences for all characters. The phenotypic coefficient of differentiation reached 0.24 for the form and 0.22 for height, thus revealing a strong structuring between the provenances. Comparative study of growth among the provenances revealed more vigorous growth and better survival rate for those from Morocco, Spain, and Portugal, which may constitute better materials for afforestation. Furthermore, this variability appeared to be geographically structured and would be mainly genetically controlled, as cork oak provenances were cultivated under the same environmental conditions. Our results should be helpful for guide forest managers in afforestation.Évaluation morphologique chez le chêne liège (Quercus suber) : variabilité des provenances méditerranéennes en Tunisie. La variabilité génétique inter et intra-provenances a été étudiée pour des caractères de croissance chez Quercus suber spp. 26 provenances (2 340 individus) de chêne liège originaires d'Espagne, du Portugal, d'Italie, du Maroc, d'Algérie et de la Tunisie ont été implantées et testées. Sept caractères morphométriques, jugés discriminants, ont été mesurés chez 90 individus par provenance. L'analyse statistique des résultats a montré des différences hautement significatives entre ces provenances. Le plus haut coefficient de différentiation Qst est trouvé pour les caractères forme (0,24 %) et hauteur (0,22 %). L'étude comparative a en outre révélé une croissance plus vigoureuse associée à une moindre mortalité chez les provenances originaires du Portugal, d'Espagne et du Maroc, leur conférant ainsi un intérêt potentiel pour le reboisement. La variabilité observée chez le chêne liège apparaît structurée selon l'origine géographique et serait essentiellement de nature génétique, puisque toutes les provenances ont été cultivées dans les mêmes conditions pédoclimatiques