Full Length Research Paper

The proposed mechanism of bactericidal action of eugenol, α-terpineol and g-terpinene against Listeria monocytogenes, Streptococcus pyogenes, Proteus vulgaris and Escherichia coli

S. O. Oyedemi*, A. I. Okoh, L. V. Mabinya, G. Pirochenva and A. J. Afolayan

School of Biological Sciences, University of Fort Hare, Alice 5700, South Africa.

*Corresponding author. E-mail: silvanusdemi@yahoo.com.

Accepted 19 November, 2008

The mechanism of antimicrobial activity of essential oils components; α- terpineol, g-terpinene and eugenol was studied to evaluate their effect on the bacterial membrane against four strains of bacteria: Listeria monocytogenes, Streptococcus pyogenes, Proteus vulgaris and Escherichia coli.  The study was done to observe changes in membrane composition by assaying for the leakage of protein and lipid using Bradford and van Handel’s method respectively. The oils components were capable of inducing cell lysis by the leakage of protein and lipid contents. Eugenol at 2 × MIC was highly effective toward protein content leakage after 120 min of exposure. Alpha terpineol and g-terpinene showed similar effect at 2 × MIC under the same condition. Gamma terpinene displayed the highest activity toward lipid content leakage at 2 x MIC while α-terpineol and eugenol showed similar effect after 120 min of exposure. The result revealed that both cell wall and membrane of the treated gram negative and gram positive bacteria were significantly damaged.

Key word: Mechanism of action, essential oil components, lipid content, protein content.