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.