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Callitris glaucophylla Joy Thomps. & L.A.S. Johnson is a coniferous forest species of the Cupressaceae family native to Australia. This species is rich in essential oils (EOs) but few studies about variability and biological activity of these EOs are available in the literature. The purpose of this study was to evaluate the variability of production of C. glaucophylla EOs in relation to the different plant parts (needles, cones and stems) and to investigate their antioxidant, anti-enzymatic and herbicidal properties. EOs were obtained by hydro distillation and analyzed by GC and GC-MS. The antioxidant potential of EOs was assessed by ABTS, FRAP and DPPH assays, their phytotoxic activities were evaluated against germination and shoots and radical growth of Sinapis arvensis, Trifolium campestre, Lepidium sativum and Lolium rigidum. The EOs were evaluated for their possible anti-enzymatic effects with spectrophotometric assay. EOs resulted rich in monoterpenes hydrocarbons (61.04–77.82 %) and oxygenated monoterpenes (19.52–25.26 %). The main compounds were α-pinene as major compound in all plant parts (36.99–59.84 %), 1,8-cineole (19.88 % in stems) and limonene (18.94 % in needles). Herbicidal assays showed that all EOs have remarkable and significant phytotoxicity towards germination, roots, and aerial parts growth of the tested plants, depending on the EO, the doses and tested species. The EOs showed significant free radical scavenging potential and resulted more active against cholinesterases than α-glucosidase and α-amylase. The data obtained constitute an important contribution in selecting and valorizing appropriate forestry tree biomass as sources of antioxidant and phytotoxic molecules for sustainable application in food preservation and weeds control. The activities against the tested enzymes confirmed a possible use of these EOs as natural pesticides.

In continuation of the search of eco-friendly and safe alternatives for chemical pesticide for weeds management, essential oils (EOs) of forestry tree may be a good candidate. Here, the EOs of Eucalyptus maculata were extracted by hydrodistillation and the study of their chemical composition was carried out by GC and GC/MS analysis. The allelopathic effects of E. maculata EOs was tested against two common weeds in Tunisia: Sinapis arvensis (dicot) and Phalaris canariensis (monocot) and Triticum durum as cereal monocot cultivated crop. The application of EOs has been carried out in two stages of growth: pre-emergence and post emergence. Analysis of the EOs resulted in the identification of 46 components representing 97.7% of the total oil. 1.8-Cineole was detected as the principal compound accounted for 42% of the oil totality and oxygenated monoterpenes (61.5%) was the major subclass that characterize E. maculata growing in Tunisia. On pre-emergence stage, Eucalyptus EOs significantly reduced germination and seedling growth of all tested species in a dose dependent manner and the phytotoxic effect of the EOs was differently effective depending on doses and tested species. On post-emergence stage, volatile oil induces a phytotoxic effect against all tested plants, a decrease in relative water content, an increase of relative electrolyte leakage percentage and levels of proline and malondialdehyde contents which explain their significant phytotoxic potential. Thus, E. maculata EOs inhibits germination and seedling growth of tested herbs in pre-emergence stage and post emergence stage, therefore E. maculata EOs shows potential towards weed management.

This study determined chemical profiles, antibacterial and antibiofilm activities of the essential oils (EOs) obtained by A. visnaga aerial parts and F. vulgare fruits. Butanoic acid, 2-methyl-, 3-methylbutyl ester (38.8%), linalyl propionate (34.7%) and limonene (8.5%) resulted as main constituents of A. visnaga EO. In F. vulgare EO trans-anethole (76.9%) and fenchone (14.1%) resulted as main components. The two EOs were active against five bacterial strains (Acinetobacter baumannii, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, and Staphylococcus aureus) at different degrees. The MIC values ranged from 5 ± 2 to 10 ± 2 μL/mL except for S. aureus (MIC >20 μL/mL). EOs exhibited inhibitory effect on the formation of biofilm up to 53.56 and 48.04% against E. coli and A. baumannii, respectively and activity against bacterial metabolism against A. baumannii and E. coli, with biofilm-inhibition ranging from 61.73 to 73.55%. The binding affinity of the identified components was estimated by docking them into the binding site of S. aureus gyrase (PDB code 2XCT) and S. aureus tyrosyl-tRNA synthetase (PDB code 1JIJ). trans-Anethole and butanoic acid, 2-methyl-, 3-methylbutyl ester showed relatively moderate binding interactions with the amino acid residues of S. aureus tyrosyl-tRNA synthetase. In addition, almost all predicted compounds possess good pharmacokinetic properties with no toxicity, being inactive for cytotoxicity, carcinogenicity, hepatotoxicity, mutagenicity and immunotoxicity parameters. The results encourage the use of these EOs as natural antibacterial agents in food and pharmaceutical industries., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)