Dihydroxy Flavone - Induced Cytoplasmic Membrane Damage in Staphylococcus aureus

S Meghashri, Shubha Gopal


Leucasin is one of the active antimicrobial principle of Leucas aspera. The effect of this compound and other antibacterial agents with known mechanisms of action upon the cytoplasmic membrane integrity of Staphylococcus aureus was investigated by comparing scanning electron microscopy (SEM) and potassium loss profiles from bacterial cell suspensions. The minimum inhibitory concentrations (MICs) of leucasin, novobiocin - the bacteriostatic antibiotic and penicillin G – the bactericidal antibiotic against S. aureus (ATCC 12600) were determined as 35 μg/ml, 55 ng/ml and 40 ng/ml respectively. The morphology of S. aureus was impaired, when treated with leucasin showing mucilaginous mass, which could lead to the impairment in cell division, as observed under SEM. When S. aureus were suspended in potassium free media containing 35 μg/ml leucasin, a 100 fold decrease in viability was observed after 12 h. Potassium loss assay revealed that S. aureus treated with 35 μg/ml leucasin lost 17% more potassium than untreated control populations whereas, cells treated with 40 ng/ml of penicillin G exhibited 9% increase in potassium loss and 55 ng/ml of novobiocin had no effect on potassium loss. This data may be attributed to either direct damage to the cytoplasmic membrane or indirect damage affected through autolysis/weakening of the cell wall and consequent osmotic lysis.


Leucasin; Mechanism of action; Staphylococcus aureus; Cytoplasmic membrane damage; Potassium loss.

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Havsteen, B.H. The biochemistry and medical significance of the flavonoids. Pharmacol Ther. 2002; 96: 67-202.

Grange, J.M., and Davey, R.W. Antibacterial properties of propolis (bee glue). J R Soc Med. 1990; 83: 159-160.

Meghashri, S., Vijay Kumar, H., and Gopal, S. Antioxidant properties of a novel flavonoid from leaves of Leucas aspera. Food Chem. 2010; 122: 105-110.

Sadhu, S.K., Okuyama, E., Fujimoto, H., and Ishibashi, M. Separation of Leucas aspera, a medicinal plant of Bangladesh, guided by prostaglandin inhibitory and antioxidant activities. Chem Pharm Bull. 2003; 51: 595-598.

Kamaraj, C., Bagavan, A., Rahuman, A.A., Zahir, A.A., Elango, G., and Pandiyan, G. Larvicidal potential of medicinal plant extracts against Anopheles subpictus, Grassi and Culex tritaeniorhynchus Giles (Diptera: Culicidae). Parasitol Res. 2009; 104: 1163-1171.

Kothari, S., Mishra, V., Bharat, S., and Tonpay, S.D. Antimicrobial activity and phytochemical screening of serial extracts from leaves of Aegle marmelos (Linn.). Acta Pol Pharm. 2011; 68: 687-692.

Ikigai, H., Nakae, T., Hara, Y., and Shimamura, T. Bactericidal catechins damage the lipid bilayer. Biochem Biophys Acta. 1993; 1147: 132-136.

Tsuchiya, H., and Iinuma, M. Reduction of membrane fluidity by antibacterial sophoraflavanone G isolated from Sophora exigua. Phytomedicine. 2000; 7: 161-165.

Mirzoeva, O.K., Grishanin, R.N., and Calder, P.C. Antimicrobial action of propolis and some of its components: the effects on growth membrane potential and motility of bacteria. Microbiol Res. 1997; 152: 239-246.

Lambert, R.J., Skandamis, P.N., Coote, P.J., and Nychas, G.J. A study of the minimum inhibitory concentration and mode of action of oregano essential oil, thymol and carvacrol. J Appl Microbiol. 2001; 91: 453-462.

Cushnie, T.P.T., Hamilton, V.E.S., and Lamb, A.J. Assessment of the antibacterial activity of selected flavonoids and consideration of discrepancies between previous reports. Microbiol Res. 2003; 158: 281-289.

Zameer, F., Shubha, G., Krohne, G., and Kreft, J. Development of biofilms model for Listeria monocytogenes. World J Microbiol Biotechnol. 2010; 26: 1143-1147.

Cushnie, T.P.T., and Lamb, A.J. Antimicrobial activity of flavonoids. Int J Anti Agents. 2005; 26: 343–356.

Lewis, K. Programmed death in bacteria. Microbiol Mol Biol Rev. 2000; 64: 503-514.

Epstein, W. The roles and regulation of potassium in bacteria. Prog Nucleic Acid Res Mol Biol. 2003; 75: 293-320.

Block, J.H., Beale, J.M., and Wilson, G. Textbook of organic medicinal and pharmaceutical chemistry. Lippincott Williams and Wilkins, London. 2004.

Plaper, A., Golob, M., Hafner, I., Oblak, M., Solmajer, T., and Jerala, R. Characterization of quercetin binding site on DNA gyrase. Biochem Biophys Res Commun. 2003; 306: 530-536.

Walsh, C. Molecular mechanisms that confer antibacterial drug resistance. Nature. 2000; 406: 775-781.

Heidrich, C., Templin, M.F., Ursinus, A., Merdanovic, M., Berger, J., Schwartz, H., de Pedro, M.A., and Holtje, J.V. Involvement of N-acetylmuramyl-L-alanine amidases in cell separation and antibiotic induced autolysis of E. coli. Mol Microbiol. 2001; 41: 167-178.


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