This study focused on Atlas pistachio (Pistacia atlantica subsp. atlantica), an endangered species from the Moroccan Middle Atlas, analyzing its leaves to assess their antioxidant and antimicrobial activity. Essential oils (EOPA) were extracted by distillation using a Clevenger apparatus, and their phytochemical compounds were identified by gas chromatography–mass spectrometry (GC/MS). Antioxidant activity tests were carried out using the DPPH and FRAP methods. In addition, antimicrobial activity was tested against Candida albicans to determine its antifungal effect, and against two Gram-positive strains (Staphylococcus aureus and Bacillus subtilis) and three Gram-negative strains (Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae) to determine the antibacterial effect. The results show that the essential oils contained between 23 and 49 compounds, depending on the extraction area, with (-)-germacrene D as the main compound. Antioxidant activity varied by study area, with IC₅₀ ranging from 0.414 mg/mL (Amghas) to 1.520 mg/mL (Ait Naamane), and EC₅₀ from 2.132 mg/mL to 5.4 mg/mL. In terms of antimicrobial activity, Afourgah essential oils showed the best results, with significant inhibition diameters against bacteria and low MIC. In particular, Amghas essential oils inhibited Staphylococcus aureus well, while Ait Naamane essential oils were less effective. This variability in phytochemical composition, as well as antioxidant and antimicrobial activities, may be attributed to climatic differences specific to the distribution zones of the Atlas pistachio tree. This study contributes to a better understanding of the botanical and chemical characterization of the Pistacia genus, and highlights its potential as a source of bioactive agents.

The genus Pistacia, with its species having notable ecological, economic, and medicinal implications, demonstrates remarkable environmental adaptability. The central objective of the study is to analyze interspecific variations between Pistacia atlantica subsp. atlantica and Pistacia terebinthus across three distinct bioclimatic zones in the Middle Atlas region of Morocco. The methodology includes collecting dendrometric measurements and conducting macromorphological examinations on these two taxa, with a detailed analysis of 27 qualitative and quantitative variables. A micro-morphological analysis of leaves, using scanning electron microscopy (SEM), is employed to explore specific features such as size and stomatal density, as well as qualitative aspects like epidermal cell shape and trichomes. Dendrometric measurements have revealed that the canopy surface and the number of trunks per tree can serve as distinctive features between the two species. Regarding the sex ratio of Pistacia atlantica subsp. atlantica, 59% of the examined trees are males, primarily associated with the jujube tree in arid zones and the dwarf palm in humid areas. In contrast, female Pistacia terebinthus exhibit a similar percentage, predominantly associated with oak groves and cade juniper in their distribution areas. Principal component analysis of biometric measurements emphasized a significant disparity between the two species, representing 60.25% of the total variance. The use of SEM unveiled new features facilitating the identification of the two species. By leveraging the macromorphological and micromorphological variability of pistachio trees, we can qualify those best suited to diverse bioclimates. In this regard, we suggest incorporating them into reforestation and rehabilitation programs aimed at restoring our declining ecosystems.

Pistacia terebinthus L., a tree native to the Middle Atlas of Morocco, is traditionally used in folk medicine. This study investigated the phytochemical profile, antioxidant, and antimicrobial properties of leaf essential oils (EOs) from three bioclimatic zones. EOs were extracted by hydrodistillation, analyzed by GC–MS, and tested for antioxidant activity using FRAP and DPPH assays. Molecular docking was performed to assess the interaction of major compounds with antioxidant targets, while antimicrobial activity was evaluated against bacterial and fungal strains by disk diffusion and microdilution. The chemical composition varied markedly among regions, with 61–98 compounds identified. Monoterpenes, particularly α-pinene, were abundant in arid samples, whereas terpinen-4-ol (21.96%) appeared exclusively in subhumid oils. Other relevant constituents included τ-muurolol (8.84%) and D-limonene (7.85%). Antioxidant activity also differed by origin, with IC50 values ranging from 1.40 to 4.17 mg/mL and EC50 from 2.86 to 9.47 mg/mL. Subhumid oils exhibited the highest antimicrobial activity, while arid samples were most effective against Staphylococcus aureus. Docking analysis revealed interactions of key compounds with NADPH oxidase (Ala11, Asp282, Ala300), suggesting a potential mechanism for their antioxidant action. Overall, results highlight that bioclimatic conditions strongly influence the chemical composition and bioactivity of P. terebinthus essential oils, supporting their potential for therapeutic and pharmaceutical applications.