Baicalein suppresses the SOS response system of Staphylococcus aureus induced by ciprofloxacin

Cell Physiol Biochem. 2011;28(5):1045-50. doi: 10.1159/000335791. Epub 2011 Dec 15.


Numerous antibiotics can induce an SOS repair system in bacteria that leads to antibiotic-resistant mutation of the bacterium. Therefore, searching for drugs that can prevent the SOS response and thus improve the long-term viability of some antibiotics is important. In this study, we aimed to detect the suppressive effects of baicalein on the SOS system and rifampin-resistant mutation in Staphylococcus aureus. We determined the reactive oxygen species (ROS) formation and intracellular ATP level in S. aureus with baicalein treatment to investigate the mechanisms involved in its effects on the SOS system. The results showed that baicalein was a potent inhibitor of the expression of the SOS genes RecA, LexA and SACOL1400. The rifampin-resistant mutation rate of S. aureus induced by ciprofloxacin was significantly reduced after treatment with baicalein. Treatment with baicalein led to a significant decrease in intracellular reactive oxygen species (ROS) formation and ATP level. Our findings indicate that baicalein may be an SOS-response inhibitor in S. aureus through inhibiting ROS formation and ATP production and may be used to prevent excessive mutation induced by antibiotics.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Anti-Infective Agents / pharmacology
  • Antioxidants / pharmacology*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Ciprofloxacin / pharmacology*
  • Drug Resistance, Bacterial / drug effects
  • Flavanones / pharmacology*
  • Microbial Sensitivity Tests
  • Reactive Oxygen Species / metabolism
  • Rec A Recombinases / genetics
  • Rec A Recombinases / metabolism
  • SOS Response, Genetics / drug effects*
  • Serine Endopeptidases / genetics
  • Serine Endopeptidases / metabolism
  • Staphylococcus aureus / drug effects*
  • Staphylococcus aureus / metabolism


  • Anti-Infective Agents
  • Antioxidants
  • Bacterial Proteins
  • Flavanones
  • LexA protein, Bacteria
  • Reactive Oxygen Species
  • baicalein
  • Ciprofloxacin
  • Adenosine Triphosphate
  • Rec A Recombinases
  • Serine Endopeptidases