Evaluation of Antimicrobial Activity of Essential Oil and Plant Extracts of Inula graveolens (L.) Desf.

This research assessed the antimicrobial properties of essential oil and various extracts (ethanol and methanol) obtained from the aerial parts of Inula graveolens (L.) Desf. (Asteraceae). The antibacterial efficacy was evaluated against Bacillus cereus (ATCC 10876), Escherichia coli (ATCC 25922), Enterococcus faecalis, and Staphylococcus aureus (ATCC 25923), while antifungal activity was tested on Candida albicans (ATCC 10231), Saccharomyces cerevisiae (ATCC 9763), Aspergillus spp., and Trichoderma spp. Results showed that the antimicrobial effectiveness of the essential oil and extracts varied with the microorganism strain, generally demonstrating greater activity against fungal species than bacterial strains. The essential oil displayed a notably strong inhibitory effect on C. albicans, with an inhibition zone diameter of 17.77 mm (MIC: 1/64 μg/mL), categorized as “effective”, and showed “effective” activity against E. coli with a zone diameter of 17.50 mm (MIC: 1/16 μg/mL). The ethanol extract exhibited “effective” to “extremely effective” activity against Trichoderma spp. (23.93 mm), Aspergillus spp. (19.10 mm), C. albicans (15.60 mm), S. cerevisiae (16.40 mm), and S. aureus (16.38 mm). The methanol extract demonstrated “effective” antifungal activity solely against Aspergillus spp. (18.27 mm). These results indicate that I. graveolens has potential as a natural antimicrobial agent, especially for use in the food industry.