Antibacterial Activity And Mechanism Of Luteolin On Staphylococcus Aureus

Luteolin, a naturally occurring flavonoid, is present mainly in the herbal medicine, vegetable and fruit. It is widely concerned about by domestic and foreign scholars because of its low side effects, less drug-fast, low cost, wide availability characters. The studies about antibacterial activities and mechanism of luteolin are very important to the development and application in the field of medicine and food preservation. In this paper, the antibacterial activity and drug resistance of luteolin extracted from natural herbal on Staphylococcus aureus was carried out, and its mechanisms were systematically investigated. The results are followed:1. It is found that luteolin has antibacterial activity on Staphylococcus aureus obviously by utilizing oxford cup and 2, 3, 5-triphenyl tetrazolium chloride (TTC), and the minimum inhibitory concentrations (MIC) of luteolin is 0.09 mg/mL.2. The drug resistant screening experiments showed that drug resistance is not easy to be produced by luteolin and the mutation of luteolin-resistant strains is different from quinolone.3. The membrane integrity was indicated by determineing conductivity and content of macromolecules in liquid culture medium. The result showed that luteolin could impact on the membrane permeability of Staphylococcus aureus, but don't destroy the membrane integrity directly.4. With luteolin for 16h, the total content of proteins decreased 64.54%, the quantities of DNA and RNA were reduced 48.44% and 39.35% respectively. It indicated that luteolin inhibited the nucleic acid and protein synthesis.5. Luteolin on DNA topoisomerase activity was indicated by pBR322DNA decatenation experiment, and the result was that luteolin inhibited topoisomeraseⅠ(TOPOⅠ) and topoisomeraseⅡ(TOPOⅡ) significantly on Staphylococcus aureus. The determination about the mechanism of TOPOⅠindicated that luteolin had the ability of stabilizing the cleavable complex formation between DNA and TOPOⅠ, and acts as a TOPOⅠpoison.6. The mode of action of luteolin and DNA was evaluated by utilizing UV spectroscopy and agarose gel electrophoresis. The results showed that the absorption spectrum of luteolin shifted redshift and planarity after interaction with DNA, and luteolin would unwind DNA. As a result that luteolin has DNA intercalative capability.