Activity of the Caged Xanthone Morellic Acid against Vancomycin-Resistant Enterococcus Infection by Targeting the Bacterial Membrane

J Nat Prod. 2024 Oct 25;87(10):2366-2375. doi: 10.1021/acs.jnatprod.4c00425. Epub 2024 Oct 10.

Abstract

Vancomycin-resistant Enterococcus (VRE) is an important nosocomial opportunistic pathogen that is associated with multidrug resistance. Here, we demonstrate that morellic acid inhibits VRE by restoring its sensitivity to vancomycin and ampicillin with low drug resistance and efficient biofilm clearance effects. Morellic acid binds to inner membrane phospholipids, such as phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and cardiolipin (CL) of VRE, such that the fluidity and proton-motive force (PMF) interfere with the damaged inner membrane, causing intracellular reactive oxygen species (ROS) accumulation and bacterial death. Transcriptional analyses supported this effect on inner membrane-related pathways such as fatty acid biosynthesis and glycerophospholipid metabolism. Moreover, morellic acid significantly eliminated residual bacteria in the spleen, liver, kidneys, and abdominal effusion in mice. Our findings indicate the potential applications of morellic acid as an antibacterial agent or adjuvant for treating VRE infections.

MeSH terms

  • Animals
  • Anti-Bacterial Agents* / chemistry
  • Anti-Bacterial Agents* / pharmacology
  • Biofilms / drug effects
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Gram-Positive Bacterial Infections / drug therapy
  • Mice
  • Microbial Sensitivity Tests
  • Molecular Structure
  • Reactive Oxygen Species / metabolism
  • Vancomycin* / pharmacology
  • Vancomycin-Resistant Enterococci* / drug effects
  • Xanthones* / chemistry
  • Xanthones* / pharmacology

Substances

  • Anti-Bacterial Agents
  • Vancomycin
  • Xanthones
  • Reactive Oxygen Species