Remarkable synergies between baicalein and tetracycline, and baicalein and β-lactams against methicillin-resistant Staphylococcus aureus

Mai Fujita, Sumiko Shiota, Teruo Kuroda, Tsutomu Hatano, Takashi Yoshida, Tohru Mizushima, Tomofusa Tsuchiya

Research output: Contribution to journalArticle

80 Citations (Scopus)

Abstract

During the screening of compounds that potentiate the effect of antimicrobial agents against methicillin-resistant Staphylococcus aureus (MRSA), we found that an extract of thyme (Thymus vulgaris L) leaves greatly reduced the minimum inhibitory concentration (MIC) of tetracycline against MRSA. We isolated the effective compound and identified it as baicalein (5, 6, 7-trihydroxyflavone). One of the clinically isolated MRSA strains possessed tetK, a gene encoding active efflux pump for tetracycline. We examined the effect of baicalein on the efflux of tetracycline, using Escherichia coli KAM32/pTZ1252 carrying the tetK. The E. coli KAM32/pTZ1252 showed 8 to 16 times higher MIC than E. coli KAM32. We observed strong inhibition of transport of tetracycline by baicalein with membrane vesicles prepared from E. coli KAM32/pTZ1252. Baicalein also showed synergy with tetracycline in a MRSA strain that doesn't possess tetK, or with β-lactams. Thus, mechanisms of the synergies seem to be versatile.

Original languageEnglish
Pages (from-to)391-396
Number of pages6
JournalMicrobiology and Immunology
Volume49
Issue number4
DOIs
Publication statusPublished - 2005 Jan 1

Keywords

  • Baicalein
  • Inhibition of TetK
  • MRSA
  • Tetracycline

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Virology

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