Phytochemical and biological studies of Atriplex inflata f. Muell.: isolation of secondary bioactive metabolites Aymen Ben Nejma a , Mansour Znati a , Asma Nguir a , Adam Daich b , Mohamed Othman b , Ata Martin Lawson b and Hichem Ben Jannet a a Laboratory of Heterocyclic Chemistry, Natural Products and Reactivity (LR11ES39), Team: Medicinal Chemistry and Natural Products, Faculty of Science of Monastir, University of Monastir, Monastir, Tunisia and b Normandie Univ, France, UNILEHAVRE, URCOM, EA 3221, FR 3038 CNRS, F- 76600, Le Havre, France Keywords antibacterial; anticholinesterase; antioxidant; Atriplex inflata; secondary metabolites Correspondence Hichem Ben Jannet, Laboratory of Heterocyclic Chemistry, Natural Products and Reactivity (LR11ES39), Team: Medicinal Chemistry and Natural Products, Faculty of Science of Monastir, University of Monastir, Avenue of Environment, 5019 Monastir, Tunisia. E-mail: hich.benjannet@yahoo.fr Received September 18, 2016 Accepted March 26, 2017 doi: 10.1111/jphp.12735 Abstract Objectives This work describes the phytochemical and biological investigation of the Tunisian Atriplex inflata F. Muell (Chenopodiaceae). Methods Their chemical structures were elucidated on the basis of extensive spectroscopic methods, including 1D NMR and 2D NMR, ESI-HRMS and com- parison with available literature data. The isolates were evaluated for their antiox- idant activity by the DPPH • , ABTS +• , Fe 3+ and catalase assays and also for their antibacterial and anticholinesterase activity. Key findings The chemical study of Atriplex inflata F. Muell led to the isolation of two fatty acids (9E)-methyl-8,11,12-trihydroxyoctadec-9-enoate 1 and (9E)- 8,11,12-trihydroxyoctadecenoic acid 2 together with (Z)-litchiol B 3 and 20-hydroxyecdysone 4. Three of which are reported here for the first time in Atriplex genus. Based on the biosynthesis of hydroxylated arachidonic acid and derivatives, a plausible biogenesis pathway of the two fatty acids (1 and 2) was proposed. (Z)-litchiol B (3) was found to be the most active against Staphylococ- cus aureus. According to the literature, this is the first time that compounds 1, 2 and 3 were tested for their eventual biological activity. Conclusions In the results of the present work, we have proposed the biogenesis pathway of unsaturated fatty acid and described the structure–activity relationship. Introduction Plants are usually exposed to a wide range of environmental stresses such as drought, high salinity and temperature fluctuations due to their sessile nature. Response to abiotic stress is very complex as various stages of plant growth and development can be affected by a particular stress and often by several stresses simultaneously. [1] Among plants that growing in these conditions, halophytes can be classified in this category. Indeed, this class of plants possesses a series of ecological and physiological charac- teristics enabling growth and reproduction in saline environment. [2] Molecular responses to abiotic stresses including stress perception, gene expression and metabolic changes can help plants in their adaption to environmental stresses. [3] It is well known that plants respond to survive under abi- otic stress phenomenon via a series of physiology, cellular and molecular processes. [4] In this context and under stress conditions, peroxidation of lipids and fatty acids was observed as resulting from lipoxygenase (LOX) action. [5] LOX genes are really present in plants and are often acti- vated under specific conditions of stress. [6] Generally, plant LOXs act by adding molecular oxygen in an enantiospecific way at the 9th or 13th position of 18 : 2 and 18 : 3 polyun- saturated fatty acid (PUFA). [7] Recent evidence was pro- vided, indicating that plant LOXs are also able to peroxidize esterified PUFAs. The peroxidated fatty acids can be transformed in other compounds by the action of some enzymes such as epoxide hydrolases (EHs), microso- mal EH (mEH), cholesterol EH (ChEH), hepoxilin hydro- lase and leukotriene A 4 (LTA 4 ) hydrolase. [8] © 2017 Royal Pharmaceutical Society, Journal of Pharmacy and Pharmacology, ** (2017), pp. **–** 1 Research Paper