title: Combination effects of baicalein with antibiotics against oral pathogens.
abstract: BACKGROUND
  Baicalein is one of the major flavonoids in Scutellaria baicalensis Georgi, which has long been used in Asia as herbal medicine. Several biological effects of baicalein, such as antiviral, anti-inflammatiom, anti-hepatotoxicity, and anti-tumour properties, have been reported.
  
  
  OBJECTIVE
  In this study, the antibacterial activities of baicalein were investigated in combination with ampicillin and/or gentamicin against oral bacteria.
  
  
  RESULTS
  Baicalein was determined with MIC and MBC values ranging from 80 to 320 and 160 to 640 μg/mL against oral bacteria. The range of MIC₅₀ and MIC₉₀ were 20-160 μg/mL and 80-320 μg/mL, respectively. The combination effects of baicalein with antibiotics were synergistic (FIC index <0.375-0.5 and FBCI <0.5) against oral bacteria. Furthermore, a time-kill study showed that the growth of the tested bacteria was completely attenuated after 1-6 h of treatment with the MIC₅₀ of baicalein, regardless of whether it was administered alone or with ampicillin or gentamicin.
  
  
  CONCLUSIONS
  These results suggest that baicalein combined with other antibiotics may be microbiologically beneficial and not antagonistic.
authors.affiliation: Department of Dental Technology, Daegu Health College, Daegu, South Korea.
authors.forename: Eun-Jin
authors.initials: EJ
authors.lastname: Jang
authors.affiliation: Department of Oral Microbiology and Institute of Oral Bioscience, Chonbuk National University, Jeonju, South Korea.
authors.forename: Su-Mi
authors.initials: SM
authors.lastname: Cha
authors.affiliation: Department of Dental Hygiene, Daegu Health College, Daegu, South Korea.
authors.forename: Sung-Mi
authors.initials: SM
authors.lastname: Choi
authors.affiliation: Department of Natural Product Research, Institute of Jinan red ginseng, Jinan, South Korea. Electronic address: joungdan@chonbuk.ac.kr.
authors.forename: Jeong-Dan
authors.initials: JD
authors.lastname: Cha
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D044950:Flavanones / Q000494:pharmacology*; D047309:Flavones / Q000494:pharmacology; D005839:Gentamicins / Q000494:pharmacology; D006801:Humans; D008826:Microbial Sensitivity Tests; D009055:Mouth / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D044950:Flavanones; D047309:Flavones; D005839:Gentamicins; C006680:baicalein; D000667:Ampicillin; C023717:acacetin
keywords: Baicalein; Fractional bactericidal concentration (FBC) index; Fractional inhibitory concentration (FIC) index; Minimum bactericidal concentrations (MBCs); Minimum inhibitory concentrations (MICs); Synergistic effect