The influence of eucalyptol/terpinen-4-ol mixtures on monolayers imitating plant pathogen Botrytis cinerea membranes

Terpenes - the essential oil components - due to confirmed antimicrobial effect can be applied e.g. as ecological pesticides instead of synthetic and environmentally hazardous compounds. A practical use of these systems must be proceeded by the analysis of the properties and activity of a given mixture. In this paper the monolayers at the air/water solution interface were applied to verify the influence of eucalyptol/terpinen-4-ol mixtures on plant pathogen Botrytis cinerea model membrane. The experiments included the measurements of the surface pressure - area isotherms for model membranes on water and terpene solutions as well as terpenes penetration into lipid monolayers. In the studies done for particular terpenes stronger ability of terpinen-4-ol over eucalyptol to incorporate into membrane, alter the membrane lateral elasticity and decrease its stability was found. Based on the results for the mixtures composed of terpenes in various concentrations it was found that not only the concentration of the system but also its composition, namely the proportion of both terpenes, determines the influence on lipid system. Moreover, terpinen-4-ol, but not eucalyptol, even in low concentrations, was of strong influence on membrane activity of total mixture. Additionally, it was suggested that terpinen-4-ol acts as penetration enhancer for eucalyptol into the model membrane system.