Effect of γ-irradiation on Chemical Composition and antibacterial activity of Celery Seeds Essential Oil

The rise of multidrug-resistant bacteria has exacerbated antibiotic resistance. New plant-derived antibacterial agents offer pharmaceutical industry new economic opportunities. This study evaluate the antibacterial activity of the celery (Apium graveolens) seeds extracts (Celery Seeds Essential Oil (CSEO), Celery Seeds Post-Distillation Extract (CSPDE), Celery Seeds Water Extract (CSWE), Celery Seeds Ethanolic Extract (CSEE), and Celery Seeds Hexane Extract (CSHE)) against five MDR clinical isolates (Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Pseudomonas aeruginosa and Staphylococcus aureus) by the minimum inhibitory concentration (MIC), the minimum bactericidal concentration (MBC), and MIC/MBC ratios. the effect of gamma irradiation (5 and 10 kGy) on the chemical composition, and the antibacterial activity of CSEO (the most active extract) were investigated against the most resistant isolate, Enterobacter cloacae. All celery seeds extracts showed antibacterial activity to various degrees. The GC-MS analysis of the non-irradiated CSEO revealed that the main chemical constituents were ꞵ-selinene (35.52 %), D-limonene (22.04 %), ꞵ-cyclocitral (18.61 %), Kessane (8.16 %), ꞵ-pinene (2.97 %), and α-guaiene (2.33 %), while irradiation of CSEO (5 and 10 kGy) showed a fluctuation in the proportions of most of these components along with the emergence and disappearance of specific minor components. CSEO irradiated at 5 kGy had significantly decreased the antibacterial activity against Enterobacter cloacae, with the MIC increasing to from 0.061 mL/mL to 0.245 mL/mL, while irradiation at 10 kGy couldn't affect the antibacterial activity of CSEO against Enterobacter cloacae. Our findings indicate that non-irradiated or irradiated (10 kGy) CSEO could potentially substitute traditional antibiotics as natural antibacterials. Also, suggest that irradiation improves essential oil chemical composition, minimizing physical, chemical, and microbiological contamination and boosting therapeutic efficacy.