Characterization of Volatile Organic Compounds and Essential Oil Profile of Pittosporum tobira (Thunb.) W.T. Aiton Cultivated in Tunisia.

The chemical compositions of the essential oils (EOs) of roots, young and old leaves and stems, and flowers of Pittosporum tobira (Thunb.) W.T. Aiton cultivated in Tunisia and of the volatile organic compounds (VOCs) emitted by the powder of each organ were identified. The EOs are extracted from fresh material by hydrodistillation, whereas the VOCs are obtained by head space solid-phase microextraction (HS-SPME) from the powdered dry tissues. Fifty-eight VOCs are identified, while, 105 components are detected for the EOs. The main EOs compounds are α-neoclovene, ß-caryophyllene and limonene in roots (22.56, 12.52, and 8.59 %, respectively), viridiflorol in young stems, flowers and young leaves (34.90, 31.60, and 24.60 %, respectively), α-cadinol in young stems and leaves, and flowers (13.80, 10.40, and 9.10 %, respectively), (E)-nerolidol in flowers (13.30 %), and germacrene D in old stems (9.06 %). The major detected VOCs are n-undecane, mainly in young and old leaves (71.40 and 40.90 %, respectively), n-nonane in young leaves and flowers (31.80 and 27.10 %, respectively), α-cubebene in old stems and flowers (22.60 and 15.50 %, respectively), and α-gurjunene and ß-gurjunene in roots (14.20 and 12.20 %, respectively). Principal Component Analysis (PCA) carried out on the 26 main volatile compounds (relative content exceeding 6 %) identified both by HS and in the EOs allowed their classification into two groups; compounds specific to roots and those specific to aerial parts. The later are subdivided in to two subgroups; old leaves and stems compounds subgroup, and young leaves and stems, and flowers one. We can notice that the two methods used to extract P. tobira volatile compounds and identify them are complementary. This study defines and differentiates, for the first time, the specific aroma profile of P. tobira from Tunisia. In addition to its ornamental value, all the organs of this species, could be valued as a source of volatile compounds useful in perfume, cosmetics and as food flavoring products.

Chemical Composition and Insecticidal Activity against Tribolium Castaneum of Thapsia garganica L. Seed Essential Oil.

Due to the several side effects of synthetic pesticides, including environmental pollution, threats to human health, and the development of pest resistance to insecticides, the use of alternative healthy, available and efficient agents in pest management strategies is necessary. Recently, the use of essential oil obtained from aromatic plants has shown significant potential for insect pest management. For this reason, the essential oil isolated from seeds of Thapsia garganica L. was investigated for the first time for its chemical profile, and its toxicity and repellency effects against Tribolium castaneum adults. Qualitative and quantitative analyses of the chemical composition by gas chromatography coupled to mass spectrometry (GC/MS) revealed the presence of 18 organic volatiles representing 96.8 % of the total constituents. The main compounds were 1,4-dimethylazulene (51.3 %) followed by methyl palmitate (8.2 %), methyl linoleate (6.2 %) and costol (5.1 %). Concerning the repellent effect, results revealed that SEO (Seed Essential Oil) was very repellent towards T. castaneum adults, with 100 % repellency after 2 h of exposure. Furthermore, the essential oil exhibited remarkable contact toxicity against T. castaneum (93.3 % of mortality) at the concentration of 10 % (v/v). The median lethal dose (LD50 ) of the topical application of the seed essential oil was 4.4 %. These encouraging outcomes suggested that the essential oil from T. garganica seeds could be considered a potent natural alternative to residual persistent and toxic insecticides.

Chemical Composition and Cytotoxic Activity of the Fractionated Trunk Bark Essential Oil from Tetraclinis articulata (Vahl) Mast. Growing in Tunisia.

The aim of the present research was to determine the chemical composition and the cytotoxic effects of Tetraclinis articulata trunk bark essential oil (HEE) obtained by steam distillation and five fractions obtained by normal phase silica chromatographic separation. Chemical analysis allowed the identification of 54 known compounds. Relatively high amounts of oxygenated sesquiterpenes (44.4-70.2%) were detected, mainly consisting of caryophyllene oxide (13.1-26.6%), carotol (9.2-21.2%),14-hydroxy-9-epi-(E)-caryophyllene (3.2-15.5%) and humulene epoxide II (2.6-7.2%). The cytotoxic activity against human mammary carcinoma cell lines (MDA-MB-231) and colorectal carcinoma cell lines (SW620) of the essential oil and its fractions were assessed. All the samples displayed moderate to weak activity compared to 5-fluorouracil. The colorectal carcinoma cell line was relatively more sensitive to the essential oil and its fractions compared to the breast cancer cell line, showing IC50 values from 25.7 to 96.5 µg/mL. In addition, the essential oil and its fraction E.2 revealed a cytotoxic activity against colorectal carcinoma cell line, with IC50 values lower than 30 µg/mL. This is the first report on the chemical composition and cytotoxic activity of the trunk bark essential oil of T. articulata.

Chemical Composition and Insecticidal Activity of Crithmum Maritimum L. Essential Oil against Stored-Product Beetle Tribolium Castaneum.

Several plant essential oils have been used against diverse insect pests since, unlike conventional pesticides, they pose almost no risk to humans and the environment. For this reason, the essential oil (EO) isolated from the fresh leaves of Crithmum maritimum L. and its fractions (F1 -F5 ) obtained by chromatographic simplification were investigated for their chemical profile, as well as for their toxicity and repellency effects against Tribolium castaneum (Herbst) adults. The analysis by GC/MS allowed the identification of 92.8-99.1 % of the compositions of the total oil (EO) and of its fractions (F1 -F5 ). The EO and its fractions F3 -F5 were characterized by the presence of a high amount of phenylpropanoids (94.4, 94.8, 93.6, and 88.7 %, respectively): in all the samples, dill apiole was the most abundant component (EO: 94.1 %, F3 : 94.6 %, F4 : 93.4 %, and F5 : 83.3 %). In addition, the repellency assay results showed that the volatile fraction F5 and the complete EO exhibited a higher repellency towards T. castaneum (97 % and 93 %, respectively) after 2 h of exposure at the dose of 0.04 µL/cm2 . The median lethal dose of the topical application of the EO was 9 %. Furthermore, the fraction F1 possessed interesting contact toxicity against T. castaneum (80 % of mortality) at the concentration of 10 %. These results suggested that the essential oil of C. maritimum leaves might be used as an alternative to synthetic insecticides in order to prevent insects from damaging the stored products.

Caryophyllene Sesquiterpenes from Pulicaria vulgaris Gaertn.: Isolation, Structure Determination, Bioactivity and Structure-Activity Relationship.

A new caryophyllene, named pulicaryenne A (1), along with four other known caryophyllene derivatives (2, 3, 4 and 5) were isolated from the ethyl acetate extract of aerial parts of Pulicaria vulgaris Gaertn. (Asteraceae). All compounds were isolated for the first time from this species. Compound 2 was identified as a new epimer of a known caryophyllene derivative isolated previously from P. dysenterica. Their structures were established by spectroscopic means including NMR analysis (1D- and 2D-NMR) and ESI-TOF-MS. All compounds were evaluated for their anticholinesterase, antityrosinase and cytotoxic activities against two human cell lines (A549 and HeLa). Results showed that compound 5 exhibited the highest cytotoxic effect against A549 and anticholinesterase activity with IC50 values of 8.50±0.75 and 6.45±0.09 µg/mL, respectively. Furthermore, compound 5 showed also an interesting antityrosinase activity with percent inhibition value of 79.0±2.5 % at 50 µg/mL. The bioactivity and drug likeness scores of the isolated compounds 1-5 were calculated using Molinspiration software and discussed. These results may suggest that the five caryophyllene derivatives endowed with good biological properties, which could be used as bioactive alternatives in pharmaceutical preparations.

Isocostic Acid, a Promising Bioactive Agent from the Essential Oil of Inula viscosa (L.): Insights from Drug Likeness Properties, Molecular Docking and SAR Analysis.

The chemical composition of the essential oil (LEO) and its volatile fractions (V1 -V10 ) collected during the hydrodistillation process every 15 min from the fresh leaves of I. viscosa (L.), growing in Tunisia, were analyzed by GC-FID and GC/MS. Eighty-two compounds, representing 90.9-99.4 % of the total samples, were identified. The crude essential oil (LEO) and its fractions (V1 -V10 ) were characterized by the presence of a high amount of oxygenated sesquiterpenes (82.7-95.8 %). Isocostic acid (1) was found to be the most abundant component (37.4-83.9 %) and was isolated from the same essential oil over silica gel column chromatography and identified by spectroscopic methods (1 H, 13 C, DEPT 135 NMR and EI-MS) and by comparison with literature data. Furthermore, the fresh leaves essential oil (LEO), its volatile fractions (V1 -V10 ) as well as compound 1 were screened for their antibacterial, antityrosinase, anticholinesterase and anti-5-lipoxygenase activities. It was found that the isolated compound 1 exhibited an interesting antibacterial activity against Staphylococcus aureus ATCC 25923 (MIC=32 µg/mL) and Enterococcus faecalis ATCC 29212 (MIC=32 µg/mL) and the highest antityrosinase activity (IC50 =13.82±0.87 µg/mL). Compound 1 was also found to be able to strongly inhibit 5-lipoxygenase with an IC50 value of 59.21±0.85 µg/mL. The bioactivity and drug likeness scores of compound 1 were calculated using Molinspiration software and interpreted, and the structure-activity relationship (SAR) was discussed with the help of molecular docking analysis.

Chemical Composition and Biological Studies of the Essential Oil from Aerial Parts of Beta vulgaris subsp. maritima (L.) Arcang. Growing in Tunisia.

The chemical composition, antioxidant, cytotoxic, anticholinesterase and anti-tyrosinase activities of the hydrodistilled essential oil of the aerial parts of Beta vulgaris subsp. maritime (L.) Arcang. from Tunisia have been evaluated. The chemical composition of the oil (yield 0.037% [w/w]), determined by GC-FID and GC/MS is reported for the first time. Twenty five components, accounting for 98.1% of the total oil have been identified. The oil was characterized by a high proportion of oxygenated sesquiterpenes (39.2%), followed by sesquiterpene hydrocarbons (30.3%) and one apocarotenoids (26.3%). The main compounds were γ-irone (26.3%), α-cadinol (12.1%), T-cadinol (10.6%), bicyclogermacrene (10.4%) and δ-cadinene (6.0%). The isolated oil was tested for its antioxidant activity using the DPPH· , ABTS+· , catalase, and paraoxonase assays and also for its cytotoxic, anticholinesterase, and anti-tyrosinase activities. The essential oil exhibited high antioxidant activity (IC50  = 0.055 ± 0.006 mg/ml) and important result oncatalase (524.447 ± 2.58 Units/mg protein). Furthermore, it exerted a significant cytotoxic effect against A549 cell line, with IC50  = 42.44 ± 1.40 µg/ml. The results indicate that the essential oil of B. vulgaris subsp. maritima (L.) Arcang. aerial parts may be used in future as an alternative to synthetic antioxidant agents, with potential application in the food and pharmaceutical industries.

Two new unusual monoterpene acid glycosides from Acacia cyclops with potential cytotoxic activity.

A phytochemical investigation of the Tunisian plant Acacia cyclops pods led to the isolation of two new monoterpenoid glycosides, which have been designated Cyclopside 1 and Cyclopside 2. Their structures were elucidated on the basis of extensive spectroscopic procedures including IR, MS and 2D-NMR. The cytotoxic effect of the isolates was also evaluated in vitro against the human breast cancer (MCF-7) and ovarian cancer (OVAR) cell lines. Results showed that the highest cytotoxic activity (90.88%) was against MCF-7 cell line and was exhibited by the Cyclopside 1 at the concentration of 50 µg/mL.