Antibacterial Activity of Selected Hydroxycinnamic Acids

The objective of this study was to determine the antibacterial effectiveness of selected hydroxycinnamic acids (caffeic, ferulic, pcoumaric) against Escherichia coli and Staphylococcus aureus at pH 5.0, 6.0 and 7.0 and Bacillus cereus at pH 6.0, 6.5 and 7.0. p‐Coumaric acid was generally the most effective inhibitor tested causing <99.9% inhibition of E. coli at 1000 μg/ml (pH 5.0, 48 hr), S. aureus at 500 μg/ml (pH 5.0, 48 hr), and B. cereus at 500 μg/ml (pH 7.0, 9 hr). Inhibition increased as pH decreased with E. coli and S. aureus but not B. cereus. Bacillus cereus appeared to be the most susceptible strain with 1000 μg/ml of the compounds tested causing <99% inhibition at all three pH's.