title: The influence of environmentally friendly pesticide - Eucalyptol - alone and in combination with terpinen-4-ol - on model bacterial membranes.
abstract: Eucalyptus oil is known from antimicrobial properties and due to natural origin and low toxicity it can be applied as a green pesticide. This plant extract is a mixture of compounds among which Eucalyptol prevails strongly over the number of minor components including terpinen-4-ol. However, antimicrobial effect of total extract is stronger than the effect of its major component. The mechanism of action of essential oils involves their incorporation into membrane of pathogenic cell. To investigate the effect of eucalyptus oil components on bacterial membrane in this work the influence of Eucalyptol on model lipid systems of various compositions was studied and then compared with the effect induced by the mixture of Eucalyptol and terpinen-4-ol. The analysis of the lipid monolayer properties modified by the presence of the essential oils evidenced that Eucalyptol reduces the lipids packing and decreases membrane rigidity, however, its influence is determined both by the concentration of this terpene and by the composition of lipid film. As indicated the results of calculation of the surface excess values Eucalyptol molecules tend to adsorb at the interface, however, at higher concentration in the subphase, the molecules undergo desorption at membrane-related surface pressure. By mixing of Eucalyptol and terpinen-4-ol stronger monolayer fluidization and destabilization can be achieved as well as stronger adsorption, even at higher surface pressures, occurs. However, these effects are also determined by the composition of model system. The collected data suggest that these compounds may act by penetrating bacterial membrane. Moreover, it can be proposed that although Eucalyptol is a major component of the Eucalyptus oil the antimicrobial effect of total extract is generated also by a minor component. This may explain stronger antimicrobial effect of Eucalyptus oil as compared to sole Eucalyptol confirmed in biological studies.
authors.affiliation: Department of Environmental Chemistry, Faculty of Chemistry, Jagiellonian University, Gronostajowa 3, 30-387, Kraków, Poland. Electronic address: hac@chemia.uj.edu.pl.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Hąc-Wydro
authors.affiliation: Department of Environmental Chemistry, Faculty of Chemistry, Jagiellonian University, Gronostajowa 3, 30-387, Kraków, Poland.
authors.forename: Karolina
authors.initials: K
authors.lastname: Szydło
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry*; D003511:Cyclohexanols / Q000737:chemistry*; D000077591:Eucalyptol; D008567:Membranes, Artificial; D008954:Models, Biological; D039821:Monoterpenes / Q000737:chemistry*; D009822:Oils, Volatile / Q000737:chemistry*; D013729:Terpenes / Q000737:chemistry*
chemical_list: D000890:Anti-Infective Agents; D003511:Cyclohexanols; D008567:Membranes, Artificial; D039821:Monoterpenes; D009822:Oils, Volatile; D013729:Terpenes; C034019:terpinenol-4; D000077591:Eucalyptol
keywords: Bacterial membrane; Essential oils; Eucalyptol; Green pesticides; Lipid monolayers