Hnia Chograni

Chemical composition and antioxidant activities of essential oils and methanol extracts of three wild Lavandula L. species

A comparative study of essential oil composition, polyphenol content and antioxidant activities of Lavandula coronopifolia, Lavandula multifida and Lavandula stoechas subsp. stoechas were reported. Qualitative and quantitative variations in the composition of oils according to species were shown. Lavandula coronopifolias oil was characterised by high proportions of trans-β-ocimene (26.9%), carvacrol (18.5%), β-bisabolene (13.1%) and myrcene (7.5%). The main components of L. multifida oil are carvacrol (65.1%) and β-bisabolene (24.7%). Lavandula stoechas oil is rich in fenchone (34.3%) and comphor (27.4%). The total phenolic and flavonoid contents also significantly varied among species. Lavandula coronopifolia exhibits the highest phenolic and flavonoid contents (31.3 mg GAE g−1 and 16.3 mg RE g−1, respectively), followed by L. multifida (30.8 mg GAE g−1 and 12.3 mg RE g−1). Methanolic extracts and essential oils displayed significant antioxidant activities. The level of antioxidant capacity varied according to extracts and species.

Essential Oil Variation among Natural Populations of Lavandula multifida L. (Lamiaceae)

Volatiles from twelve wild Tunisian populations of Lavandula multifida L. growing in different bioclimatic zones were assessed by GC (RI) and GC/MS. Thirty‐six constituents, representing 83.48% of the total oil were identified. The major components at the species level were carvacrol (31.81%), β‐bisabolene (14.89%), and acrylic acid dodecyl ester (11.43%). These volatiles, together with α‐pinene, were also the main compounds discriminating the populations. According to these dominant compounds, one chemotype was revealed, a carvacrol/β‐bisabolene/acrylic acid dodecyl ester chemotype. However, a significant variation among the populations was observed for the majority of the constituents.

Comparative Chemical Composition and Antibacterial Activities of Myrtus communis L. Essential Oils Isolated from Tunisian and Algerian Population

The chemical composition of Essential oils isolated by hydrodistillation from leaves of Tunisian and Algerian Myrtus communis L. population was analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). Twenty three compounds were identified, representing 93.73% of total oil, which was found to be rich in monoterpenes hydrocarbons (53.38%) particularly α-Pinene (35.30%) and α-limonene (14.76%). The physico-chemical properties were determined. The percentage of all components varied within and among population. The highest percentages of α-Pinene (45.4%) and 1.8-Cineole (35.7%) were observed in the Algerian population. The percentage of α-limonene was significantly higher in the Tunisian population (18.16%). The study of antibacterial activity revealed that 10 μl of Myrtus communis L. essential oil significantly inhibited the growth of five tested bacteria especially Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Salmonella sp., and Listeria sp.

Genetic diversity in Tunisian Crataegus azarolus L. var. aronia L. populations assessed using RAPD markers

Abstract• The genetic diversity of nine wild Tunisian Crataegus azarolus var. aronia L. populations from different bioclimates was assessed using RAPD markers.• Eight selected primers generated a total of 105 bands, 81 of which were polymorphic. Shannon’s index (H′) ranged from 0.222 to 0.278 according to a population with an average of 0.245. The genetic variation within the species (HSP = 0.423) was relatively low. A high differentiation (GST = 0.421) among populations coupled with a low level of gene flow (Nm = 0.472) were observed. The analysis of molecular variance (AMOVA) revealed also significant differentiation among populations (ΦST = 0.371), even at a low scale space. The majority of variation occurred within populations (63.31%). The Mantel test performed on genetic (ΦST) and geographic distance matrices among population pairs did not reveal an isolation by distance.• Interpretation of Neighbour-joining tree based on Nei’s and Li’s genetic distance among individuals showed distinct population groupings. The UPGMA dendrogram based on ΦST values revealed two population sub-clusters, each including populations from different bioclimates and/or geographic regions.• The low level of genetic diversity and the high genetic structure of populations resulted from genetic drift caused both by habitat fragmentation and the low size of populations.• The high differentiation among populations and the similar low level of diversity within populations suggest that in situ conservation should interest all populations. The ex situ conservation should be based on the collection of seeds rather within than among populations because of the maximum of variation was revealed within populations.Résumé• La diversité génétique de neuf populations naturelles de Crataegus azarolus var. aronia L. en Tunisie, appartenant à différents étages bioclimatiques, a été analysée par des marqueurs RAPD.• Huit amorces retenues ont généré 105 bandes dont 81 sont polymorphes. L’indice de Shannon (H′) varie de 0,222 à 0,278 selon les populations avec une moyenne de 0,245. La variabilité génétique au sein de l’espèce est relativement faible (HSP = 0,423). Une différenciation importante entre les populations (GST = 0,421) et un faible flux de gènes entre elles (Nm = 0,472) ont été observés. L’analyse de la variance moléculaire (AMOVA) a révélé, elle aussi, une différenciation significative entre les populations considérées ensemble (ΦST = 0,371) ou regroupées selon leur localisation bioclimatique. La majeure proportion de la variabilité réside à l’intérieur des populations (63,31 %). Le test de Mantel, effectué sur les matrices des distances génétiques (ΦST) et géographiques entre les paires des populations, n’a pas révélé une isolation par distance.• Le dendrogramme, établi à partir des distances génétiques de Nei et Li, a montré des regroupements des individus dans leurs populations respectives. Le dendrogramme UPGMA, construit à partir des valeurs de ΦST entre les paires des populations, révèle deux groupes de populations. L’agrégation des populations au sein des groupes ne s’opère pas toujours selon leur proximité géographique et/ou leur localisation bioclimatique.• La faible diversité génétique intrapopulation et le niveau élevé de différenciation des populations résulteraient de la dérive génétique due à la fragmentation des habitats et à la taille réduite des populations.• Toutes les populations devraient bénéficier d’une priorité pour leur conservation in situ, vu le niveau élevé de leur différenciation et leur faible diversité génétique. La conservation ex situ devrait s’appuyer sur le prélèvement d’un maximum de semences plutôt au sein qu’entre les populations étant donné que la majeure proportion de la variabilité réside à l’intérieur des populations.

Chemical profiles and antioxidant activities of the essential oils of two medicinal plant species grown in Tunisia

A comparison of leaves essential oil composition and antioxidant activity of the two medicinal plant species Juniperus oxycedrus and Juniperus phoenicea grown in Tunisia is reported in this study. The highest yield of essential oil was recorded for J. phoenicea (0.34%, w/w) whereas J. oxycedrus exhibited the lowest yield (0.18%). Qualitative and quantitative variations in the composition of oils according to species were shown. Tunisian sample of those species are especially rich of β-phellandrene. Based on both tests DPPH (2,2-di-phenyl-1-picrilhydrazyl) and FRAP (ferric reducing antioxidant power), the two species presented high levels of antioxidant capacities. The DPPH test shows the highest antioxidant activity (ic 50=20.1±0.1 μg/mL) for the species J. oxycedrus while J. phoenicea presented the lowest antioxidant activity (ic 50=25.4±0.3 μg/mL). The highest level of ferric reducing ability of volatile oils is recorded for J. oxycedrus (15.90±0.87 μmol Fe2+/g), whereas J. phoenicea exhibits the lowest level (10.99±0.52 μmol Fe2+/g).