Natural products such as terpenoidal compounds have been extremely tested against pathogenic bacteria. Researches are frequently carried out to find out new natural, semisynthetic and synthetic antibacterial agents due to problems of resistance. Thymoquinone derivative was obtained in our previous study and the current research is a continuation. The antibacterial activity of a monoterpenoid; thymoquinone derivative, 5-isopropyl-2-methyloxepine-1-one (1) has been evaluated for the first time by following the Agar cup bioassay method employed. The bacterial strains used in this study were Escherichia coli and Bacillus subtilis. Compound 1 showed moderate activity against Gram-positive organism; B. subtilis and good activity against Gram-negative species; E. coli with zones of inhibition (ZOI) 10.0 ± 0.2 mm and 11.0 ± 0.2 mm against E. coli and B. subtilis, respectively, and in comparison with antibiotic, imipenem. The zones of inhibition were calculated as the mean of the triplicate. The antibacterial activity of thymoquinone derivative 1 could be explained by the presence of unsaturated lactone.
Keywords: Bacillus subtilis; Escherichia coli; Monoterpenoid; Pathogenic bacteria.
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