effect of a series of essential oil molecules on dppc membrane fluidity: a biophysical study

Monoterpenes (mts) were known to cause biological membranes perturbation. here, the interaction of four (eucalyptol, pulegone, terpineol, and thymol) with dipalmitoylphosphatidylcholine (dppc) liposomes was studied by raman spectroscopy, differential scanning calorimetry and fluorescence anisotropy. liposomes were prepared by the thin-film hydration method, and mts were added to dppc at various molar percentages (from 0 to 25%). all the studied mt abolished the pre-transition of dppc membrane and modified the intensity of the raman peak at 715 cm−1, proving their interaction with the choline head group of phospholipids. mts decreased also the main transition temperature suggesting their interaction with the alkyl chains of dppc membrane. besides, a splitting of the main transition peak was obtained with thymol. the results of fluorescence anisotropy showed that the studied molecules fluidized the liposomal membrane at 25, 41, and 50 °c. a mixture of isomers of terpineol fluidized the membrane more than α-terpineol. the presence of a hydroxyl group in the mt structure seems to improve the membrane fluidizing effect of mts.