Chemical composition and antimicrobial activity of essential oil of Inula crithmoides L. growing in Egypt

The study aimed to determine the chemical composition and antimicrobial properties of the essential oil of Inula crithmoides L. growing in Egypt. The essential oil was obtained from the flowers of Inula crithmoides L. with a yield of 0.18% v/w through hydro distillation. Gas chromatography-mass spectroscopy analysis was used to identify the chemical composition of the essential oil. The antimicrobial activity of the essential oil was tested against selected species of Gram-positive, Gram-negative bacteria, and Candida species using the disc diffusion method, and MICs were determined using the broth micro-dilution method. Twenty-two compounds were identified in the essential oil of Inula crithmoides, with the major components being thymol acetate (32.4%), p-cymene (15.3%), and thymol (14.3%). The essential oil exhibited significant antimicrobial activities against Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa, with an MIC of 25 µg/mL for E. coli and 50 µg/mL for other sensitive bacteria. The oil exhibited significant antifungal activity against all the tested Candida species with MIC 50 µg/mL. This study is the first to explore the chemical composition and antimicrobial activity of the essential oil of Inula crithmoides growing in Egypt, demonstrating its potential as a natural antiseptic agent.