Chemical composition and antibacterial activity of essential oils from selected species of the genus Cucumis in Ethiopia

ABSTRACT. Chemical composition of the essential oils obtained by hydrodistillation from various parts of Cucumis ficifolius, Cucumis dipsaceus and Cucumis prophetarum were determined by gas chromatography-mass spectrometry (GC/MS) analysis. Compounds 3,7,11,15-tetramethyl-1-hexadecanol, neophytadiene, and isophytol from leaves, phytol and octacosane from the stems, hentriacontane from the fruits, and octacosane, abietadiene from roots were identified the major constituents of Cucumis ficifolius. Hydrocarbons including Octacosane, tricosane, tetracosane, hentriacontane and hexacosane were the principal components of various parts of Cucumis. dispaceus. While leaves, stems and roots of Cucumis prophetarum contain mainly hentriacontane, neophytadiene and octacosane, respectively. The oils were evaluated for their antibacterial activity using disc diffusion method against four bacterial pathogens including E. coli, P. aeruginosa, S. aureus and S. pyogenes. All tested essential oils were sensitive against the bacterial strains. The essential oil from the leaves of Cucumis dispaceus exhibited the highest inhibition zone against E. coli (11.87±2.42 mm) while the other displayed modest activity compared with the positive control, ceftriaxone. Therefore, the antibacterial activities displayed by the essential oils along with the literature reported for their constituents suggest the use of these plants as an antibacterial agent. Furthermore, the results presented herein also support the traditional use of these plants against bacteria.   KEY WORDS: Cucumis ficifolius, Cucumis dipsaceus, Cucumis prophetarum, Antibacteria   Bull. Chem. Soc. Ethiop. 2023, 37(3), 703-715.                                                           DOI: https://dx.doi.org/10.4314/bcse.v37i3.13