Sami Zouari

Variation of chemical composition of essential oils in wild populations of Thymus algeriensis Boiss. et Reut., a North African endemic Species

BackgroundThymus algeriensis is an endemic aromatic plant to Tunisia largely used in folk medicine and as a culinary herb. The bulks aromatic plants come from wild populations whose essential oils compositions as well as their biological properties are severely affected by the geographical location and the phase of the plant development. Therefore, the aim of the present work is to provide more information on the variation of essential oil composition of T. algeriensis collected during the vegetative and the flowering phases and from eight different geographical regions. Besides, influence of population location and phenological stage on yield and metal chelating activity of essential oils is also assessed.MethodsThe essential oil composition of Thymus algeriensis was determined mainly by GC/FID and GC/MS. The chemical differentiation among populations performed on all compounds was assessed by linear discriminate analysis and cluster analysis based on Euclidean distance.ResultsA total of 71 compounds, representing 88.99 to 99.76% of the total oil, were identified. A significant effect of the population location on the chemical composition variability of T. algeriensis oil was observed. Only 18 out of 71 compounds showed a statistically significant variation among population locations and phenological stages. Chemical differentiation among populations was high. Minor compounds play an important role to distinguish between chemical groups. Five chemotypes according to the major compounds have been distinguished. Chemotypes distribution is linked to the population location and not to bioclimate, indicating that local selective environmental factors acted on the chemotype diversity.ConclusionsThe major compounds at the species level were α-pinene (7.41-13.94%), 1,8-cineole (7.55-22.07%), cis-sabinene hydrate (0.10-12.95%), camphor (6.8-19.93%), 4-terpineol (1.55-11.86%), terpenyl acetate (0-14.92%) and viridiflorol (0-11.49%). Based on major compounds, the populations were represented by (α-pinene/1,8-cineole/cis-sabinene hydrate/camphor/viridiflorol), (1,8-cineole/camphor/terpenyl acetate), (α-pinene/1,8-cineole/camphor), (1,8-cineole/camphor/4-terpineol) and (α-pinene/1,8-cineole/cis-sabinene hydrate/camphor/4-terpineol) chemotypes. Variation of phenological stage did not have a statistically significant effect on the yield and metal chelating activity of the essential oil. These results can be used to investigate the geographical location and the harvesting time of this plant for relevant industries.

Chemical Composition and Cytotoxic and Antioxidant Activities of Satureja montana L. Essential Oil and Its Antibacterial Potential against Salmonella Spp. Strains

The present study describes chemical composition as well as cytotoxic, antioxidant, and antimicrobial activities of winter savory Satureja montana L. essential oil (EO). The plant was collected from south France mountain, and its EO was extracted by hydrodistillation (HD) and analysed by gas chromatography/mass spectrometry (GC/MS). Thirty-two compounds were identified accounting for 99.85% of the total oil, where oxygenated monoterpenes constituted the main chemical class (59.11%). The oil was dominated by carvacrol (53.35%), -terpinene (13.54%), and the monoterpenic hydrocarbons p-cymene (13.03%). Moreover, S. montana L. EO exhibited high antibacterial activities with strong effectiveness against several pathogenic food isolated Salmonella spp. including S. enteritidis with a diameter of inhibition zones growth ranging from 21 to 51 mm and MIC and MBC values ranging from 0.39–1.56 mg/mL to 0.39–3.12 mg/mL, respectively. Furthermore, the S. montana L. EO was investigated for its cytotoxic and antioxidant activities. The results revealed a significant cytotoxic effect of S. montana L. EO against A549 cell line and an important antioxidant activity. These findings suggest that S. montana L. EO may be considered as an interesting source of components used as potent agents in food preservation and for therapeutic or nutraceutical industries.

Comparative Study of Chemical Composition of the Essential Oils from Three Calligonum Species Growing-Wild in Tunisian Desert

Abstract The essential oils of three wild species of Calligonum (C. azel, C. arich and C. comosum) growing in the Tunisian desert were obtained by hydrodistillation and were analyzed by GC-FID and GC-MS in order to discern the differences and similarities between the chemical composition of the essential oils of these species. A total of 110 compounds, which accounted for 94.0 – 99.7 % of the total composition of the essential oils, have been identified. The main constituents were viridiflorol (9.6 %) in C. azel, hexadecanoic acid (20.1 %) in C. arich and 9-octadecenoic acid (19.8 %) in C. comosum. Based on their chemical composition, two chemotaxonomic groups may be established: C. azel on one hand, C. arich and C. comosum on the other hand.

Antibiofilm formation and anti-adhesive property of three mediterranean essential oils against a foodborne pathogen Salmonella strain

Plant extracts, and their essential oils (EOs) are rich in a wide variety of secondary metabolites with antimicrobial properties. Our aim was to determine the bioactive compound in three mediterranean essential oils belonging to Lamiaceae family, Satureja montana L., Thymus vulgaris L. and Rosmarinus officinalis L., and to assess their antimicrobial, antibiofilm and anti-adhesive potentials against a foodborne pathogen Salmonella strain. The antibacterial activity of EOs and its biofilm inhibition potencies were investigated on 2 reference strains Salmonella typhimurium and 12 Salmonella spp. isolated from food. Biofilm inhibition were assessed using the 2, 3-bis [2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT) reduction assay. The analytical data indicated that various monoterpene hydrocarbons and phenolic monoterpenes constitute the major components of the oils, but their concentrations varied greatly among the oils examined. Our results showed that S. montana L. and T. vulgaris L. essential oils possess remarkable anti biofilm, anti-adhesive and bactericidal properties, compared to R. officinalis EO. There is an indication that Rosmary EO might inhibit biofilm formation at higher concentrations. Therefore, the witer savory and thyme EOs represent a source of natural compounds that exhibit potentials for use in food systems to prevent the growth of foodborne bacteria and extend the shelf life of the processed food.

Chemical Variability of Artemisia herba-alba Asso Growing Wild in Semi-arid and Arid Land (Tunisia)

Abstract Twenty-six oil samples were isolated by hydrodistillation from aerial parts of Artemisia herba-alba Asso growing wild in Tunisia (semi-arid land) and their chemical composition was determined by GC(RI), GC/MS and 13C-NMR. Various compositions were observed, dominated either by a single component (α-thujone, camphor, chrysanthenone or trans-sabinyl acetate) or characterized by the occurrence, at appreciable contents, of two or more of these compounds. These results confrmed the tremendous chemical variability of A. herba-alba.

Chemical Composition of Essential Oils of Calligonum comosum Cultivated at the South-Eastern of Tunisia: A Comparative Study between Flowering and Fructification Stages

Abstract The essential oils of Calligonum comosum subcultured at the South-Eastern of Tunisia (Bir Lahmar and Ghordab locations) and collected at the flowering and the fructification stages, were obtained by hydrodistillation and were analyzed by GC-FID and GC-MS in order to discern the differences and similarities between the investigated essential oils of this species. Sixty seven compounds representing 88.6495.60 % of the total essential oil were identified. The comparison of the essential oil components between the two locations of the subcultured C. comosum shows that there are 3 major common components identified at the two stages which were lauric acid, myristic acid and palmitic acid. Essential oil chemotype of C. comosum cultivated at Bir Lahmar location seems original since linoleic acid, palmitic and lauric acid were the most abundant compounds. While another new chemotype was evidenced from Ghordab location characterized by the dominance of linalool at the fructification stage and pentacosane at the flowering stage.

Chemical composition and chelating activity of Ruta chalepensis L. (Rutaceae) essential oil as influenced by phenological stages and plant organs

Chemical composition and chelating activity of Ruta chalepensis L. essential oils collected from the south-east of Tunisia at the vegetative and the flowering stages were investigated. Essential oils were extracted by hydrodistillation from different organs (leaves, flowers and stems) and analyzed by gas chromatography–flame ionization detector (GC–FID) and GC–mass spectrometry (GC–MS) techniques. The highest essential oil yields were obtained at the flowering stage with a maximum in the flowers (1.8-1.9%). Twenty-five compounds were identified in different essential oils, where ketones and esters constituted the main chemical classes. 2-Nonanone (17.2–25.9%), 2-undecanone (19–37.2%) and octyl acetate (9.1–30.8%) were found to be the major compounds in all essential oils. The majority of essential oil compounds showed homogeneity with respect to the phenological stage and plant organs. At the flowering stage, stems and flowers essential oils showed the highest metal chelating activity, whose ic50 values ranged between 160 and 180 μg/mL.

A New Essential Oil Chemotype of Allium Roseum Analyzed by an Apolar Column

This study deals with the chemical characterization of a medicinal and an aromatic plant of the Tunisian flora: Allium roseum var. odoratissimum, and aimed to identify new bioactive natural compounds in its flower essential oil. These compounds were extracted by hydrodistillation and were analyzed by GC and GC/MS, using an apolar column. The most important compounds characterized were organo-sulphurous (46%), including methyl 2-propenyl trisulfide, di-2-propenyl trisulfide, di-1-propenyl disulfide, di-2-propenyl disulfide, dimethyl trisulfide, methyl 2-propenyl disulfide, and di-1-propenyl trisulfide, found as 10.75, 9.07, 5.81, 4.98, 3.90, 3.30, and 2.53%, respectively. Moreover, heneicosane and pentacosane were identified for the first time at relatively high rates (8.18 and 4.49%, respectively) in the Allium roseum essential oil. This essential oil composition exhibited newly identified sulphurous compounds at relatively high rates (46.53%) when compared with what was found while using polar column.

Essential oil variation in wild populations of Artemisia saharae (Asteraceae) from Tunisia: chemical composition, antibacterial and antioxidant properties

BackgroundArtemisia saharae Pomel is a new taxon of Artemisia herba-alba Asso (Asteraceae) which is endemic to Tunisia and Algeria. This shrub, commonly known as white wormwood or desert wormwood, is largely used in folk medicine and as a culinary herb. The bulks aromatic plants come from wild populations whose essential oils compositions as well as their biological properties are severely affected by several factors such as geographic conditions. Therefore, the aim of the present work is to provide more information about the influence of altitude variation on the essential oil composition, antimicrobial and antioxidant properties of Artemisia saharae growing wild in the same geographical area.ResultsEssential oils were extracted by hydrodistillation of leaves and flowers of the plant collected from seven different altitudes of the Baten Zamour region (southwest of Tunisia). The highest essential oil yields (2.70-2.80%) were obtained for populations of high altitudes.Seventy-five compounds, representing 92.78 to 96.95% of the total essential oils, were separated and identified. Essential oils were characterized by very high percentage of oxygenated monoterpenes (52.1–72.6%) which constituted the predominant class. From the analyzed populations, the major compounds (>7%) were α-thujone, β-thujone, chrysanthenone, camphor, chrysanthenyl acetate, and sabinyl acetate. Sabinyl acetate which was detected in some populations at relatively high percentages (7.7–10.8%) seems to be characteristic to Southern Tunisian A. saharae. The studied essential oil showed a chemical diversity depending on the population altitude as revealed by linear discriminant and cluster analyses.ConclusionsThree population groups associated with altitudinal levels were distinguished. It is worthy to note that the most discriminating compounds of chemical groups were the minor ones. Despite the high variation of essential oil compositions, the high altitude population did not affect severely the antibacterial activity against the most tested strains. Altitude seems to be an important factor influencing the yield and the chemical profile of Artemisia saharae essential oils. Knowledge of the chemical composition of essential oils in relation to environmental factors is a very important quality criterion for their marketing and contributes to their valorization as functional ingredient in food technology.

Variation in Volatiles of Astragalus gombiformis Pomel

The essential oils obtained by hydrodistillation (Clevenger apparatus) from aerial parts of Astragalus gombiformis were analysed by gas chromatography coupled with mass spectrometry (GC/MS). This study showed that the A. gombiformis essential oils are complex mixtures of important natural compounds, which varied qualitatively and quantitatively between cultivated and wild plants and between phenological stages of development. All analysed oils are characterized by the constant presence of phytol, 6,10,14-trimethyl-2-pentadecanone, 4-terpineol, and γ-terpinene. This study is the fi rst report on the chemical composition of essential oils from A. gombiformis and indicates that these oils should be more studied.