Phytochemical composition and antioxidant activity of Tunisian Laurus nobilis.

We study the composition of Tunisian laurel leaves essential oil (EO), the fatty acid composition of laurel seed fixed oil and the total phenolics, flavonoids and tannins of laurel leaves methanolic extract. We also evaluated its free radical scavenging activity by the DPPH test. The predominant chemical class in Tunisian Laurus nobilis leaves EO was represented by oxygenated monoterpenes accounting for 64.29% of whole EO with the major compound was 1,8-cineole (46.8%). The predominant fatty acid was oleic acid (C18: 1) with an amount of 42.0%. Total polyphenols were present in the methanolic extract of Laurusnobilis leaves at an amount of 174.1 mg GAE.g-1dry matter. Total flavonoids and total tannins accounted respectively for 149.2mg CE.g-1 dry matter and 24.9mg CEg-1 dry matter. Furthermore, concerning free radical scavenging activity, Laurus nobilis leaves methanolic extract presented a significant IC50 (3mg/mL).

Essential Oils' Chemical Characterization and Investigation of Some Biological Activities: A Critical Review.

This review covers literature data summarizing, on one hand, the chemistry of essential oils and, on the other hand, their most important activities. Essential oils, which are complex mixtures of volatile compounds particularly abundant in aromatic plants, are mainly composed of terpenes biogenerated by the mevalonate pathway. These volatile molecules include monoterpenes (hydrocarbon and oxygenated monoterpens), and also sesquiterpenes (hydrocarbon and oxygenated sesquiterpens). Furthermore, they contain phenolic compounds, which are derived via the shikimate pathway. Thanks to their chemical composition, essential oils possess numerous biological activities (antioxidant, anti-inflammatory, antimicrobial, etc…) of great interest in food and cosmetic industries, as well as in the human health field.

Aqueous Extracts from Tunisian Diplotaxis: Phenol Content, Antioxidant and Anti-Acetylcholinesterase Activities, and Impact of Exposure to Simulated Gastrointestinal Fluids.

Antioxidants have been considered essential for preventing cell damage by scavenging deleterious free radicals. The consumption of antioxidant-rich plants is associated with a reduced risk of some chronic diseases. This study evaluates the antioxidant and acetylcholinesterase inhibition activities of aqueous extracts obtained from different parts of Diplotaxis simplex and Diplotaxis harra from Tunisia. The study also aimed to investigate the action of simulated gastrointestinal juice on antioxidant activities of both extracts. The total phenolic, flavone and flavonol, and flavanone and dihydroflavonol contents were determined by Folin-Ciocalteau, aluminum chloride and 2,4-dinitrophenylhydrazine colorimetric methods, respectively. The metal ion chelating activity, acetylcholinesterase inhibition capacity, and free radical scavenging potential of the extracts towards ABTS (2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid), DPPH (2,2-diphenyl-1-picrylhydrazyl), hydroxyl, superoxide and nitric oxide were also evaluated. The action of simulated gastro-intestinal fluids on the flavone and flavonol content and total antioxidant activity of the flower extracts was surveyed. Extracts from the seeds and flowers of D. simplex and D. harra displayed the highest amounts of phenols (2691.7 and 2694.5 mg Caffeic Acid Equivalent (CAE)/100 mg; 3433.4 and 2647.2 mg CAE/100 mg, respectively) and flavonols/flavones (2144.4 and 2061.1 mg Rutin Equivalent (RE)/100 g; 1922.6 and 1461.1 mg RE/100 g, respectively). The flower and seed extracts exhibited the highest rates of antioxidant and acetylcholinesterase inhibition activities. A decrease in the flavonoid content and antioxidant activity was observed after extract exposure to simulated saliva. Antioxidant and acetylcholinesterase inhibition activities were noted to depend on plant species and plant parts. In vitro gastrointestinal digestion is useful in assessing the bio-accessibility of compounds with biological activities from food. The simulated gastrointestinal fluids influenced the flavonoid concentration and antioxidant activity.