Baicalin synergy with beta-lactam antibiotics against methicillin-resistant Staphylococcus aureus and other beta-lactam-resistant strains of S. aureus

J Pharm Pharmacol. 2000 Mar;52(3):361-6. doi: 10.1211/0022357001773922.


Bacterial resistance to antibiotics is a serious global problem and includes strains of beta-lactam-resistant Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). Novel antimicrobials and/or new approaches to combat the problem are urgently needed. The Chinese herb Xi-nan Huangqin (Scutellaria amoena C.H. Wright) has been used in traditional Chinese medicine to treat a wide range of infectious diseases. In this study we have examined the antibacterial action of baicalin, a flavone isolated from the herb. When combined with 16 microg mL(-1) baicalin, minimum inhibitory concentrations (MICs) of benzylpenicillin against MRSA and penicillin-resistant S. aureus were reduced from 125 and 250 microg mL(-1) to 4 and 16 microg mL(-1), respectively. This activity of baicalin was dose-dependent. Viable counts showed that the killing of MRSA and beta-lactam-resistant S. aureus cells by 10 to 50 microg mL(-1) ampicillin, amoxycillin, benzylpenicillin, methicillin and cefotaxime was potentiated by 25 microg mL(-1) baicalin. From the study it was concluded that baicalin has the potential to restore the effectiveness of beta-lactam antibiotics against MRSA and other strains of beta-lactam-resistant S. aureus. In view of its limited toxicity baicalin offers potential for the development of a valuable adjunct to beta-lactam treatments against otherwise resistant strains of microorganisms.

MeSH terms

  • Ampicillin / pharmacology
  • Anti-Bacterial Agents / pharmacology*
  • Cefotaxime / pharmacology
  • Dose-Response Relationship, Drug
  • Drug Resistance, Microbial*
  • Drug Synergism
  • Drug Therapy, Combination / pharmacology
  • Drugs, Chinese Herbal / chemistry
  • Drugs, Chinese Herbal / pharmacology*
  • Flavonoids / pharmacology*
  • Methicillin / pharmacology
  • Microbial Sensitivity Tests
  • Penicillin G / pharmacology
  • Staphylococcus aureus / drug effects*
  • beta-Lactam Resistance


  • Anti-Bacterial Agents
  • Drugs, Chinese Herbal
  • Flavonoids
  • baicalin
  • Ampicillin
  • Cefotaxime
  • Penicillin G
  • Methicillin