Antibacterial effect of chlorogenic acid against Escherichia coli and Lactiplantibacillus plantarum: experimental and molecular dynamic study.

Chlorogenic acid (CGA) is a common plant polyphenol with potential antibacterial activity, the mechanisms of which remain poorly understood. The aim of this study was to compare the effects of CGA on Escherichia coli and Lactiplantibacillus plantarum using experimental and computational approaches. Antibacterial activity was assessed by inhibition zones, changes in optical density, the release of nucleic acids and proteins, and scanning electron microscopy. CGA was found to inhibit the growth of E. coli (IC50 = 1.89 mg/mL; IC80 = 2.58 mg/mL) and L. plantarum (IC50 = 3.80 mg/mL; IC80 = 5.21 mg/mL). However, only E. coli exhibited increased membrane permeability and morphological alterations, whereas no comparable membrane damage was observed in L. plantarum. Molecular dynamics simulations showed that CGA destabilizes the lipid bilayer by increasing the area per lipid, enhancing fluctuations, and promoting the formation of hydrophobic defects. The PMF profile indicates thermodynamically favorable localization of CGA within the hydrophobic region of the membrane. DFT calculations confirmed the amphiphilic nature of the molecule. These results indicate that the antibacterial activity of CGA is associated with disruption of membrane structure, whereas the resistance of L. plantarum may be attributable to specific features of the cellular response and biotransformation of the compound.