Chlorinated emodin as a natural antibacterial agent against drug-resistant bacteria through dual influence on bacterial cell membranes and DNA.

The rise in infections caused by drug-resistant pathogens and a lack of effective medicines requires the discovery of new antibacterial agents. Naturally chlorinated emodin 1,3,8-trihydroxy-4-chloro-6-methyl-anthraquinone (CE) from fungi and lichens was found to markedly inhibit the growth of Gram-positive bacteria, especially common drug-resistant bacterial strains, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE). CE was confirmed to cause significant potassium leakage, cell membrane depolarization and damage to the selective permeability of cell membranes in bacterial cells, resulting in bacterial cell death. In addition, CE was shown to have a strong electrostatic interaction with bacterial DNA and induce DNA condensation. Thus, CE is a promising natural antibacterial pharmacophore against Gram-positive bacteria, especially common drug-resistant MRSA and VRE isolates, with a dual antibacterial mechanism that damages bacterial cell membranes and DNA.