The encapsulation of essential oil components into liposomes was demonstrated to improve their solubility and chemical stability. The aim of the present study is to investigate the effect of chemical structure, henry constant (H " ) value and aqueous solubility of essential oil components on their liposomal encapsulation. Based on ethanol injection method, the essential oil components (estragole, eucalyptol, isoeugenol, pulegone, terpineol, and thymol) were encapsulated in lipoid S100-liposomes. Static headspace gas chromatography method showed that H # of estragole, isoeugenol and eucalyptol was approximately 10 times greater than that of pulegone, terpineol and thymol. Besides, dynamic light scattering and diffraction technique revealed that all liposomal vesicles were of micrometric in size and the presence of phenols, isoeugenol and thymol, promoted enlargement of vesicles. Incorporation in liposomes was better (encapsulation efficiency > 90 %) for the essential oil components exhibiting low aqueous solubility, estragole, isoeugenol, and pulegone. Besides, efficient entrapment in liposomes (loading rate > 18 %) was obtained for isoeugenol, terpineol and thymol. This suggests that the presence of hydroxyl group in the structure and exhibiting lower H " ameliorated the entrapment of essential oil components into liposomes. Furthermore, release rate from liposomes varied among the investigated essential oil components and it was controlled by loading rate of essential oil components into liposomes, size of liposomal batches, location of essential oil components within lipid bilayer, and cholesterol incorporation rate of liposomes. Finally, liposomal encapsulation of isoeugenol, pulegone, terpineol, and thymol was suitable to protect them as a considerable concentration was retained in liposomes after 10 months with respect to initial concentration.
