Evaluation of Combined Antibacterial Effects of Eugenol, Cinnamaldehyde, Thymol, and Carvacrol against E. coli with an Improved Method

• Published in: Journal of food science Vol. 74; no. 7; pp. M379 - M383
• Main Authors: Pei, Rui-song, Zhou, Feng, Ji, Bao-ping, Xu, Jing
• Format: Journal Article
• Language: English
• Published: Malden, USA Blackwell Publishing Inc 01.09.2009; Wiley; Wiley Subscription Services, Inc
• Subjects: Acrolein - analogs & derivatives; Acrolein - pharmacology; Anti-Bacterial Agents - pharmacology; antibacterial activity; antibacterial properties; Aroma and flavouring agent industries; bacterial contamination; Biological and medical sciences; carvacrol; Chemical compounds; chemical concentration; cinnamaldehyde; Colony Count, Microbial; Dose-Response Relationship, Drug; Drug Synergism; E coli; Effects; Escherichia coli; Escherichia coli - drug effects; essential oils; essential oils component; eugenol; Eugenol - pharmacology; evaluation method; Food industries; Food microbiology; food pathogens; Food Preservatives - pharmacology; Food science; fractional inhibitory concentration; Fundamental and applied biological sciences. Psychology; microbial growth; Microbial Sensitivity Tests - methods; minimal inhibitory concentration; Monoterpenes - pharmacology; odors; phytochemicals; sensory properties; Studies; synergism; thymol; antibacterial activity; Evaluation; evaluation method; Chemical composition; Essential oil; Method; Antibacterial agent; essential oils component; Eugenol; Synergism; E. coli
• ISSN: 0022-1147; 1750-3841
• DOI: 10.1111/j.1750-3841.2009.01287.x

In this study, the antibacterial activities of eugenol, cinnamaldehyde, thymol, carvacrol, and their combinations against E. coli were investigated separately. First, broth macro-dilution assay was adopted to determine the minimal inhibitory concentration (MIC) of the 4 components. Second, the combination testing was performed using chequerboard method. Finally, the combined effects were evaluated with an improved method, which was based on the indices of fractional inhibitory concentration (FIC) and Effect of the Combination (EC) jointly. The results indicated that MICs of the 4 components were 1600, 400, 400, and 400 mg/L, respectively; treatments with cinnamaldehyde/eugenol, thymol/eugenol, carvacrol/eugenol, and thymol/carvacrol revealed synergistic effects according to the 2 indices. By means of combination, MICs of eugenol, cinnamaldehyde, thymol, and carvacrol decreased to 400, 100, 100, and 100 mg/L, respectively. Consequently, the negative impacts of unpleasant smell of these 4 components could be minimized, making it possible to add them to foods as preservatives. In addition, this improved evaluation method provided a more accurate and comprehensive way to evaluate combined effects.