Effet antibactérien et insecticide de huit huiles essentielles de plantes et d’épices et de leur mixture

Abstract

Bacterial resistance to antibiotics has become an increasingly serious public health concern, leading researchers to investigate natural alternatives with antimicrobial properties, particularly essential oils extracted from aromatic and medicinal plants. In this context, the present study was carried out to evaluate the antibacterial and insecticidal activities of several essential oils extracted from aromatic plants and spices. The study focused on the essential oils of Thymus vulgaris, Ammi visnaga, Mentha pulegium, Lavandula angustifolia, Citrus sinensis, Zingiber officinale, Cinnamomum verum, and Syzygium aromaticum, as well as a plant mixture. The essential oils were extracted by hydrodistillation and steam distillation using a Clevenger-type apparatus. The results showed variations in extraction yields depending on the plant species and extraction method. Lavandula angustifolia showed the highest yield (3.58%), whereas Zingiber officinale presented the lowest yield (0.12%). The plant mixture gave a yield of 2.84%. Phytochemical screening revealed the presence of several secondary metabolites, including flavonoids, tannins, coumarins, and saponins, with variations according to the studied plant species. The antibacterial activity evaluated by the aromatogram method demonstrated significant inhibitory effects of the essential oils against the tested bacterial strains: Staphylococcus aureus, Pseudomonas aeruginosa, Moraxella catarrhalis, and Streptococcus β-hemolyticus. Some essential oils, particularly Thymus vulgaris, Mentha pulegium, and Cinnamomum verum, exhibited large inhibition zones indicating strong antibacterial activity, whereas some bacterial strains showed relative resistance to certain oils. The determination of minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) also highlighted the strong effectiveness of some essential oils, especially Thymus vulgaris and Cinnamomum verum, which showed the lowest MIC and MBC values against most of the tested bacterial strains, indicating an important bactericidal effect. In addition, the insecticidal activity of the essential oils was evaluated against Dactylopius opuntiae, where some oils showed remarkable effectiveness after 24 hours of treatment. These findings suggest that the studied essential oils represent promising natural sources that could be used as antibacterial and biological insecticidal agents, with potential applications as natural alternatives to conventional chemical products.