p-Coumaric acid kills bacteria through dual damage mechanisms

p-Coumaric acid is present in many fruits, vegetables, and Graminaceous plants. In this study, the antibacterial activity and mechanism of action of p-coumaric acid against bacteria was assessed. The results showed that p-coumaric acid effectively inhibited the growth of all test bacterial pathogens, and the MIC values were ranging from 10 to 80 mu g/ml p-Coumaric acid significantly increased the outer and plasma membrane permeability, resulting in the loss of the barrier function. The leakage of cytoplasmic contents was also demonstrated by the electron micrographs. It was also found p-Coumaric acid could bind to the phosphate anion in DNA double helix, and intercalate the groove in DNA double helix, which might affect the replication, transcription and expression. The results demonstrate that p-coumaric acid has dual mechanisms of bactericidal activity: disrupting bacterial cell membranes and binding to bacterial genomic DNA to inhibit cellular functions, ultimately leading to cell death. (C) 2011 Elsevier Ltd. All rights reserved.