Variation in the quantity and quality of the essential oil (EO) of wild population of Origanum vulgare at different phenological stages, including vegetative, late vegetative, and flowering set, is reported. The oils of air-dried samples were obtained by hydrodistillation. The yield of oils (w/w%) at different stages were in the order of late vegetative (2.0%), early vegetative (1.7%), and flowering (0.6%) set. The oils were analyzed by gas chromatography (GC) and GC-mass spectrometry (GC-MS). In total, 36, 33, and 16 components were identified and quantified in vegetative, late vegetative, and flowering set, representing 94.47%, 95.91%, and 99.62% of the oil, respectively. Carvacrol was the major compound in all samples. The ranges of major constituents were as follows: carvacrol (61.08-83.37%), p-cymene (3.02-9.87%), and γ-terpinene (4.13-6.34%). Antibacterial activity of the oils was tested against three Gram-positive and two Gram-negative bacteria by the disc diffusion method and determining their diameter of inhibition and the minimum inhibitory concentration (MIC) values. The inhibition zones and MIC values for bacterial strains, which were sensitive to the EO of O. vulgare subsp. glandulosum, were in the range of 9-36 mm and 125-600 μg/mL, respectively. The oils of various phenological stages showed high activity against all tested bacteria, of which Bacillus subtilis was the most sensitive and resistant strain, respectively. Thus, they represent an inexpensive source of natural antibacterial substances that exhibited potential for use in pathogenic systems.

Context: Natural products are reported to have a wide spectrum of pharmacological properties such as antimicrobial, anti-inflammatory and anti-cholinesterase. The genus Hypericum (Hypericaceae) is a source of a variety of molecules with different biological activities, notably hypericin and various phenolics.Objectives: The goals of the present work were the determination of total phenolic and flavonoid content, hypericin and hyperforin concentration as well as the evaluation of biological of Hypericum humifusum L. (Hhu) and Hypericum perfoliatum L. (Hper).Materials and methods: The various extracts of aerial parts were powdered, and then extracted with methanol. Antibacterial activity was performed according to minimum inhibitory concentration (MIC) and minimum bactericidal (MBC) methods against four Gram-positive bacteria, four Gram-negative bacteria and yeast.Results: The results revealed that H. humifusum, bear the highest total phenolic and flavonoid content (48–113 mg GAE/g and 8–41 mg RE/g, respectively) as well as hypericin (60–90 mg/g) and hyperforin (8–30 mg/g) concentration. Both species showed significant antioxidant activity as revealed by DPPH, FRAP, ABTS, and metal chelating assays. H. humifusum exhibited a strong acetylcholinesterase (3.86–4.57 mg GALAEs/g), α-glucosidase (0.73–2.55 mmol ACEs/g) and α-amylase (3–8 mmol ACEs/g) inhibitory activity. The extract of H. humifusum exhibited strong antibacterial activity mainly against Staphylococcus epidermidis, Staphylococus aureus, and Enterococcus faecium (MIC values ranging from 200 to 250 μg/mL). The highest antifungal activity was showed for H. perfoliatum extract (MIC value = 250 μg/mL).Conclusion: The data suggest that H. humifusum could be used as valuable new natural agents with functional properties for pharmacology industries.

The variation of the essential-oil composition among 14 Tunisian natural populations of Thymus algeriensis Boiss. et Reut. (=Thymus hirtus Willd. ssp. algeriensis Boiss. et Reut.) was assessed by GC (RI) and GC/MS. The populations were collected from different geographical regions belonging to the sub-humid, upper semi-arid, mean semi-arid, lower semi-arid, and upper-arid bioclimates. A total of 47 constituents, representing 81.0 to 96.5% of the total oil, were identified. The main volatiles at the species level were 1,8-cineole (17.7%), alpha-pinene (15.5%), and camphor (8.2%). A high variation among populations for the majority of the compounds was shown. Camphor (0.2-14.0%), linalool (0.2-22.4%), borneol (<0.01-24.3%), caryophyllene oxide (<0.01-18.8%), thymol (<0.01-54.9%), gamma-terpinene (0.4-6.5%), alpha-copaene (0.4-7.6%), linalyl acetate (<0.01-6.4%), and methyl eugenol (<0.01-6.9%) were the main constituents differentiating the populations. The chemical differentiation among populations, assessed by principal component analysis (PCA) and a UPGMA (unweighted pair-group method with averaging) cluster analysis performed on all populations and compounds, was high. Six chemotypes according to the main compounds have been distinguished, i.e., caryophyllene oxide/1,8-cineole/alpha-pinene, 1,8-cineole/alpha-pinene, 1,8-cineole/alpha-pinene/camphor, borneol/1,8-cineole/alpha-pinene, linalool, and thymol chemotypes. The spatial chemotype distribution was linked to the geographic distance among populations rather than to bioclimates, indicating that local selective environmental factors act on the chemotype diversity. The high chemical variation among populations according to their geographical and bioclimatic distribution imposes that conservation strategies of populations should be made appropriately, taking into account these factors. The in situ and ex situ conservation strategies should concern all populations representing the different chemotypes.

Random amplified polymorphic DNA markers were used to assess the genetic diversity within and among seven Tunisian diploid and polyploid populations of Teucrium polium L. from five bioclimatic areas. Out of the 141 bands generated from eight selected primers, 124 were polymorphic. The genetic diversity within a population (Shannon's index) was high and varied according both the ploidal levels and bioclimatic zones. The genetic differentiation among populations assessed by G (ST) and Phi(ST) statistics was high, suggesting a low level of gene flow among them. The major proportion of the variation was attributable to individual differences within populations. The UPGMA analysis based on Nei and Li's coefficient showed that individuals from each population clustered together. In a dendrogram using the Phi(ST) distance matrix, population grouping is concordant with bioclimates and cytotypes. Conservation strategies should take into account the level of the genetic diversity of the populations according to their bioclimate and ploidal levels.

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Abstract• Seven RAPD markers were used to assess the genetic diversity and structure of ten Tunisian natural Ceratonia siliqua L. populations from different geographic and bioclimatic zones.• The species maintain a high diversity within population as estimated by the percentage of polymorphic loci and Shannon's index (P% = 76.31, H pop = 0.569). The range of variation between populations was large. Populations from the upper semi-arid bioclimates, with more continuous distribution area showed the highest level of variation.• A high genetic differentiation among populations (Φ ST = 0.250 and G ST = 0.347), as a result of population isolation was revealed. Nevertheless, the genetic structure is in accordance with bioclimate indicating that ecological factors also should influence differentiation. Populations from the sub-humid, upper semi-arid and mean semi-arid zones clustered together and were distinct from those of the lower semi-arid ones.• Conservation strategy should be made according to the level of polymorphism within population and bioclimate.Mots-clés : diversité génétique / RAPD / Ceratonia siliqua / populations naturelles / bioclimat / conservation Résumé -Structure génétique des populations naturelles du caroubier (Ceratonia siliqua L.) en Tunisie estimée par les marqueurs RAPD.• Sept marqueurs RAPD ont été utilisés pour analyser la diversité et la structure génétique de dix populations tunisiennes de caroubier (Ceratonia siliqua L.) prospectées dans différentes zones géo-graphiques et bioclimatiques.• L'espèce maintient une diversité génétique intra population importante (P% = 76.31 ; H pop = 0.569) et les niveaux de variation diffèrent selon les populations. Celles du subhumide et du semi-aride supérieur, à aire de distribution plus continue, ont montré la variation la plus importante.• Une forte différenciation (Φ ST = 0.250 et G ST = 0.347) entre les populations, due à leur fragmentation récente, est observée. Toutefois, cette différenciation concorde avec le bioclimat des sites témoi-gnant l'influence des facteurs écologiques dans cette différenciation. Les populations du subhumide, du semi-aride supérieur et du semi-aride moyen constituent un groupe distinct de celui représenté par les populations du semi-aride inférieur.• La conservation des populations doit tenir compte de leur niveau de diversité génétique intra population et du bioclimat.

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 (H SP = 0.423) was relatively low. A high differentiation (G ST = 0.421) among populations coupled with a low level of gene flow (N m = 0.472) were observed. The analysis of molecular variance (AMOVA) revealed also significant differentiation among populations (Φ ST = 0.371), even at a low scale space. The majority of variation occurred within populations (63.31%). The Mantel test performed on genetic (Φ ST ) 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 Φ ST 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. Mots-clés :RAPD / Crataegus azarolus / diversité génétique / populations naturelles / conservation Résumé -Analyse de la diversité génétique de populations tunisiennes de Crataegus azarolus L. var. aronia L. par des marqueurs RAPD.• 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 (H SP = 0, 423). Une différenciation importante entre les populations (G ST = 0, 421) et un faible flux de gènes entre elles (N m = 0, 472) ont été observés. L'analyse de la variance moléculaire (AMOVA) a révélé, elle aussi, une différenciation significative entre les populations considérées ensemble (Φ ST = 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 (Φ ST ) et géographiques entre les paires des populations, n'a pas révélé une isolation par distance.• Le dendrogramme, établi à partir des distances génétiqu...