Antimicrobial action of p-hydroxyphenyl acrylate

p-Hydroxyphenyl acrylate (HPA) was synthesized and its antimicrobial activity was measured against 6 gram-positive bacteria (two strains of Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Bacillus cereus, Bacillus subtilis) and 6 gram-negative bacteria (Pseudomonas aeruginosa, Proteus vulgaris, Klebsiella pneumoniae, Escherichia coli, Escherichia coli O157:H7, Enterobacter aerogenes). At a concentration higher than the minimum inhibitory concentration, HPA provoked cell lysis, caused leakage of the intracellular constituents, and suppressed the respiratory activity almost completely. HPA increased the proton flux into the cells, indicating that the bacterial membrane potential was progressively collapsed. HPA reduced the amounts of fatty acids, which were the main ingredients of the cell membrane. The weight of the cytoplasmic membrane in the cells decreased in the presence of HPA. Hence, the antimicrobial activity of HPA was ascribed to its interaction with the negatively-charged constituents of the cytoplasmic membrane.