galangin and sparfloxacin

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.

Topics: 4-Quinolones; Anti-Bacterial Agents; DNA Topoisomerases; Drug Resistance, Bacterial; Flavonoids; Fluoroquinolones; Microbial Sensitivity Tests; Mutation; Norfloxacin; Plant Extracts; Staphylococcus aureus