title: Assessment of the antibacterial activity of galangin against 4-quinolone resistant strains of Staphylococcus aureus.
abstract: The flavonol galangin is present in numerous plants and is a major constituent of Helichrysum aureonitens, a perennial herb used by South African indigenes to treat infection. In the present study, the antibacterial activity of galangin was assessed against 17 strains of 4-quinolone resistant S. aureus using an agar dilution assay. It was determined that the flavonol had a minimum inhibitory concentration (MIC) of approximately 50 microg/ml against 16 of these strains, including those which exhibited 250- and 500-fold increases in norfloxacin resistance. The remaining one strain, which possessed an amino acid alteration in the GrlB subunit of topoisomerase IV, had increased susceptibility to galangin. Control strains of 4-quinolone sensitive S. aureus were also found to have MICs of 50 microg/ml. The topoisomerase IV enzyme may therefore be implicated in the antibacterial mechanism of action of galangin. Clearly however, there is no cross-resistance between galangin and the 4-quinolones, and the flavonol therefore warrants further investigation as an antibacterial agent.
authors.affiliation: School of Pharmacy, The Robert Gordon University, Schoolhill, Aberdeen, Scotland, UK.
authors.forename: T P T
authors.initials: TP
authors.lastname: Cushnie
authors.forename: A J
authors.initials: AJ
authors.lastname: Lamb
mesh_terms: D042462:4-Quinolones / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D026942:DNA Topoisomerases / Q000235:genetics; D024881:Drug Resistance, Bacterial; D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology*; D024841:Fluoroquinolones / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000379:methods; D009154:Mutation / Q000187:drug effects / Q000235:genetics; D009643:Norfloxacin / Q000737:chemistry; D010936:Plant Extracts / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics
chemical_list: D042462:4-Quinolones; D000900:Anti-Bacterial Agents; D005419:Flavonoids; D024841:Fluoroquinolones; D010936:Plant Extracts; C037032:galangin; D026942:DNA Topoisomerases; D009643:Norfloxacin; C061363:sparfloxacin