Baya Mhamdi

Antioxidant activities of the essential oils and methanol extracts from myrtle (Myrtus communis var. italica L.) leaf, stem and flower.

This study was designed to examine the chemical composition and antioxidant activity of the essential oils and methanol extracts of Myrtus communis var. italica L. leaf, stem and flower. Myrtle leaf and flower were the valuable organs for the essential oil production representing a yield of 0.61% and 0.30% (w/w), respectively. The essential oil composition of myrtle leaf and flower was characterized by high proportions of alpha-pinene, the main compound of monoterpene hydrocarbon class, with 58.05% for leaf and 17.53% for flower. Stem was rich in oxygenated monoterpenes, largely due to 1,8-cineole with 32.84%. The total phenol contents varied between different myrtle parts; leaf extract had higher total phenol content (33.67 mg GAE/g) than flower (15.70 mg GAE/g) and stem (11.11 mg GAE/g) extracts. Significant differences were also found in total tannin contents among different myrtle parts, representing 26.55 mg GAE/g in leaf, 11.95 mg GAE/g in flower, 3.33 mg GAE/g in stem. The highest contents of total flavonoids and condensed tannins were observed in stem (5.17 and 1.99 mg CE/g, respectively) and leaf (3 and 1.22 mg CE/g, respectively) extracts. The HPLC analysis indicated that the main phenolic class was hydrolysable tannins (gallotannins) in leaf (79.39%, 8.90 mg/g) and flower (60.00%, 3.50mg/g) while the stem was characterized by the predominance of flavonoid class (61.38%, 1.86 mg/g) due to the high presence of catechin (36.91%, 1.12 mg/g). Antioxidant activities of the essential oil and the methanolic extract from different myrtle parts were evaluated by using DPPH radical scavenging, beta-carotene-linoleic acid bleaching, reducing power and metal chelating activity assays. In all tests, methanolic extracts of different myrtle parts showed better antioxidant activity than essential oils.

Antioxidant and antimicrobial activities of the edible medicinal halophyte Tamarix gallica L. and related polyphenolic constituents

Tamarix gallica is a halophytic species having hepatotonic and stimulant properties, as it was traditionally used in the treatment of various liver disorders. Leaf and flower infusion have anti-inflammatory and anti-diarrheic properties. In this work, we have investigated antioxidant and antimicrobial activities of leaf and flower extracts and their phenolic composition. Results showed that flowers exhibit a higher antioxidant activity as compared to the leaves, IC(50) values of the flower extracts are being 1.3 (beta-carotene bleaching) to 19 times (lipid peroxidation inhibition) lower than those for leaves. Accordingly, flower extracts exhibited the highest total phenolic content (135.35 mgGAE/gDW) and RP-HPLC analysis showed that syringic acid, isoquercitin as well as catechin were the major phenolics. Furthermore, Tamarix extracts showed appreciable antibacterial properties against human pathogen strains. The mean inhibition zone was from 0 to 6.5mm when the concentration increased from 2 to 100mg/l. The strongest activity was recorded against Micrococcus luteus and the lowest activity was observed against Escherichia coli. Moreover, organ extracts show a weakly to moderate activity against the tested Candida. These findings suggest that Tamarix may be considered as an interesting source of antioxidants for therapeutic or nutraceutical industries and for food manufactures.

Chemical composition, antioxidant and antimicrobial activities of the edible medicinal Ononis natrix growing wild in Tunisia

Results showed that leaf methanolic extract of Ononis natrix has important total phenol (51 mg GAE/g DW) and flavonoid (14.76 CE/g DW) contents. The chemical composition of O. natrix leaf revealed the presence of quercitine (24.5%), amentoflavone (14.1%), flavones (11.3%) and kaempferol (10.5%). The leaf extract showed a high total antioxidant activity with 60.94 mg of GAE/g DW, displayed a high 2,2-diphenyl-1-picrylhydrazyl scavenging ability with low IC50 value (29 μg/mL) and a great reducing power (EC50 = 100 μg/mL). O. natrix leaf extract exhibited a significant broad spectrum activity against all tested microorganisms with bacterial inhibition zone sizes ranging from 8.5 to 17 mm in diameter.

Changes in Essential Oil Composition of Tunisian Myrtus communis var. italica L. During Its Vegetative Cycle

Abstract Myrtus communis var. italica leaves, fruits and stems were gathered from North Tunisia in order to investigate their essential oils during a one-year vegetative cycle by GC-FID and GC/MS. The yield and composition of myrtle oils were found to depend on the organ type and on the harvest period. The oil yield varied from 0.14–0.61% for the leaves, 0.003–0.11% for the fruits, and 0.001–0.06% for the stems. Forty-eight compounds were identified in leaf oils; α-pinene (28.3–58.0%), 1,8-cineole (12.7–30.7%), linalool (2.4–21.5%) and limonene (0.1–13.3%) were the main components. In the fruit oils, 46 compounds were identified with 1,8-cineole (7.3–44.9%), geranyl acetate (1.8–20.5%), linalool (0.7–18.9%) and α-pinene (1.2–12.6%) being the main compounds. Only 40 components were identified in stem oils, which were rich in 1,8-cineole (21.0–52.4%), linalool (3.1–18.4%) and α-pinene (1.5–16.1%).

Antimicrobial Activities Effects of the Essential Oil of Spice Food Myrtus communis Leaves vr. Italica

Abstract: The essential oil from the leaves of Myrtus communis var. italica (Myrtaceae family) was extracted (yield 0.63 %) using hydro-distillation method and analyzed for its chemical composition by capillary GC-MS. The oil showed the presence of eighteen compounds representing 94.48 % area of total chromatogram. The oil was dominated by monoterpenoids derivatives; hydrocarbons α-pinene (35.60 %) and oxygenated 1,8-cineole (29.60 %) as major constituents. The oil exhibited pronounced antimicrobial activity determined using disc diffusion method. The inhibitory activity of the oil was observed against all tested microorganisms Gram positive and Gram negative bacteria such as Pseudomonas aeruginosa, Salmonella typhimurium, Escherichia coli and Aeromonas hydrophila with strongest inhibition zones (between 18 to 20 mm). Our findings indicate that the essential oil isolated from M. communis leaves could be used as an antimicrobial agent in food, pharmaceutical and pesticide industries.

Changes in Essential Oil Composition During Pistacia vera Leaves Development in Sfax Region (Tunisia)

Abstract Essential oil extraction from leaves of Pistacia vera was performed in order to asses its composition and follow its variability according to the leaf development. Volatile compounds were obtained by hydrodistillation followed by liquid-liquid extraction. Terpinen-4-ol (2.9–12.3 %) and α-terpineol (0.0–14.0 %) were the most abundant compounds except on 30 th June where α-terpinolene (17.0 %) and α-pinene (14.9 %) were the main compounds. The main chemical classes were oxygenated monoterpenes and monoterpene hydrocarbons. The preponderance of terpinen-4-ol in most cases instead of α-pinene as cited in other works may characterize Tunisian samples. Furthermore, many volatile compounds identified in the EO of P. vera leaves are well-known for their biological activities, e.g. α-terpineol, borneol, limonene, α-pinene, farnesol. From a fundamental point of view, EO composition determination opens many perspectives either for bioactive molecules isolation or for the chemical ecology comprehension of these secondary metabolites.