Jazia Sriti

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.

Chemical Composition and Antioxidant Activities of Tunisian and Canadian Coriander (Coriandrum sativum L.) Fruit

Abstract This study was designed to examine the essential oil composition, phenolic contents and antioxidant activity of the essential oils and methanol extracts from two coriander fruit samples, the first from Tunisia (Tn) and the second from Canada (Can). The highest essential oil yield was observed for Can with 0.44% (w/w) and 0.37% (w/w) for Tn. Forty-five compounds were identified in the essential oils and the main compound of both samples was linalool. The total phenol contents varied between two coriander fruit samples; Can sample presented high polyphenol contents (15.16 mg GAE/g) compared with Tn one (12.10 mg GAE/g). Significant differences were also found in total tannin contents among representing 0.7 mg GAE/g in Can and 0.34 mg GAE/g in Tn. The highest contents of total flavonoids were observed in Can sample with 13.2 mg CE/g Antioxidants of essential oils and methanolic extracts of these fruit samples were evaluated by using DPPH radical scavenging, β-carotene-linoleic acid bleaching and reducing power activity assays. In all tests, methanolic extracts of coriander fruits showed better antioxidant activity than essential oils. DPPH scavenging ability of methanolic extracts of two fruits was higher than that of synthetic antioxidant BHT (IC50 = 25 μg/mL). Both extracts and essential oils had lower β-carotene bleaching activity than BHA and BHT and had lower reducing power than ascorbic acid (EC50 = 40 μg/mL)

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%).

Fumigant and repellent potentials of Ricinus communis and Mentha pulegium essential oils against Tribolium castaneum and Lasioderma serricorne

ABSTRACT This work was aimed to investigate the chemical composition of pennyroyal (Mentha pulegium L.) aerial parts and castor (Ricinus communis L.) stems essential oils from Tunisia. Fumigant and repellent toxicities were assessed toward two major stored product beetles: Lasioderma serricorne and Tribolium castaneum. Pennyroyal essential oil was characterized by a clear predominance of the oxygenated monoterpenes fraction (97.10%) instead of phenol fraction (61.47%) in the castor essential oil. The major common compounds of Mentha pulegium were pulegone and isomenthone, whereas 2,4-bis (dimethylbenzyl)-6-t-butylphenol was the main volatile compound of castor essential oil. Pennyroyal essential oil showed a strong antiradical capacity (IC50 = 14 µg/mL) which is higher than synthetic standard. The effectiveness of pennyroyal essential oil against the coleopteran insects showed potential fumigant impact particularly against Lasioderma serricorne with LC50 = 8.46 µL/L air. Moreover, significant pest repellent activity was demonstrated with Ricinus communis and Mentha pulegium where the repellency effects reached 80 and 60% after 1 and 24h of exposure against Tribolium castaneum at doses of 0.31 µL/cm2 and 0.078 µL/cm2 respectively. Hence, these findings underlined the potential insecticidal effect of castor and pennyroyal essential oils and highlighted their use as valuable food and insecticide products instead of synthetic pesticides.

Biochemical Characterization of Coriander Cakes Obtained by Extrusion

This study was designed to examine the effect of operating conditions such as nozzle diameter on fatty acid, sterol, and tocol composition of coriander cakes. Eight fatty acids were identified, with petroselinic acid accounting for 75–77% of the total fatty acids, followed by linoleic, oleic, and palmitic acids, accounting for 12-13%, 5%, and 3%, respectively, of the total fatty acids. β-Sitosterol was the major sterol in all oils with 33–35% of total sterols. The next major sterols in all oils were stigmasterol (24% of total sterols) and Δ7-stigmasterol (15% of total sterols). Coriander cake contained higher amounts of total tocotrienol where γ-tocotrienol was the main compound.

Coupled extruder-headspace, a new method for analysis of the essential oil components of Coriandrum sativum fruits.

A new method involving concurrent single screw extruder combined with continuous headspace dynamic for the extraction and identification of the essential oil of Coriandrum sativum L. fruit was developed. The effect of six different nozzle diameters (5, 6, 7, 8, 9 and 10 mm) on the content and chemical composition of the essential oil of coriander fruit was studied. The oils from fruit samples were obtained by OMEGA 20 extruder. The result showed that the highest yield (0.53%) was obtained by the diameter of the nozzle was 8mm. Twenty-nine components were determined in essential oils, which were mostly hydrocarbons and alcohol monoterpenes. The main components linalool, α-pinene, γ-terpinene, p-cymene and limonene showed significant variations with drying trials.

Comparative Analysis of Fatty Acid, Sterol and Tocol Composition of Tunisian and Canadian Coriander (Coriandrum sativum L.) Fruit

Abstract Oils extracted from Tunisian (Tn) and Canadian (Can) coriander0 fruits were analysed for fatty acid, sterol and tocol composition. Oil yields were 21.87 and 15.84 %for Tn and Can respectively. Petroselinic acid (C 18:1n-12) was the major fatty acid in two coriander fruit samples, with a higher proportion being found in Tn (75.66 % of total fatty acid (TFA)) than in Can (73.23 % TFA). No difference was observed in phytosterol profiles between the both samples. A total of 7 sterols were identified, (3-sitosterol which constituted the major compound. Significant differences were found in total tocol contents among representing 27.78 mg/100 g oil in Tn and 21.14 mg/ 100 g oil in Can.

Phenological stage effect on phenolic composition and repellent potential of Mentha pulegium against Tribolium castaneum and Lasioderma serricorne

Objective: To elucidate for the first time the phenological stage effect on polyphenol, flavonoid and proanthocyanidin contents of pennyroyal (Mentha pulegium) as well as their antioxidant capacities and insecticidal potentials against Tribolium castaneum and Lasioderma serricorne. Methods: Crude methanol extracts from pennyroyal (Mentha pulegium) aerial parts were evaluated for their antiradical, reducing power activities and repellent potentials against selected coleopteran insects during different phenological stages. Results: Phenolic contents of pennyroyal aerial parts and their antioxidant effects were significantly dependent on maturity stage of the plant. The maximum of phenol production was reached during the full flowering stage. Apigenin was the major phenol in Mentha pulegium with an amount of 6.01 mg/g of dry vegetable matter during this period. Nevertheless, at fructification stage, the highest antioxidant activity was not related to high phenolic content. The repulsive effect of pennyroyal extract showed that Lasioderma serricorne was more susceptible to pennyroyal extract than Tribolium castaneum with corresponding median repellent dose values of 0.124 and 0.006 mg/mL respectively. Moreover, great differences in insect repulsion depending on extract concentrations, exposure time and developmental stage was observed. For the lowest concentration (0.125 mg/mL), the repellent effect against Tribolium reached its maximum (90%) during the fructification stage (after 24 h of exposure) while this repellent effect was 80% during the vegetative stage. Conclusions: Due to the strong insecticidal potential of pennyroyal extracts, this study highlights the therapeutic properties of this plant and encourages its use as a safer, environmental-friendly and efficient insecticide in food industry.