ANTIMICROBIAL CONSTITUENTS OF THE ESSENTIAL OIL OF ECHINOPHORA TENUIFOLIA L. SUBSP. SIBTHORPIANA (GUSS.) TUTIN

The hydrodistilled essential oil of Echinophora tenuifolia L. subsp. sibthorpiana commonly known as “çörtük,” “tarhana grass,” or “pickle grass” was evaluated for its antimicrobial activity against 17 microorganisms (16 bacteria and Candida albicans) by using microdilution and bioautography methods. Methyl eugenol (38.8%), δ-3-carene (31.2%) and p-cymene (9.0%) were determined by GC-FID and GC/MS systems as main constituents of the essential oil. The oil showed strong inhibitory effects, particularly against the plant pathogens Xanthomonas campestris and X. campestris pv. phaseoli with minimum inhibitory concentrations (MIC) of 62.5 and 31.25 µg/mL, respectively. Candida albicans was inhibited by the oil at 500 µg/mL. According to the results of TLC-bioautography assay, methyl eugenol and δ-3-carene were identified as the compounds responsible for antimicrobial activity. These bioactive compounds were further tested with the essential oil at the same time against certain pathogens for the determination of possible synergistic effects.