Purpose: Essential oils (EOs) are volatile liquids miscible in lipid and organic solvents, produced by higher plants and constituted by secondary metabolites. Thanks to their physico-chemical and biological properties, EOs are widely used in several industrial applications, especially pharmaceuticals, cosmetics, foodstuffs and biopesticides [1]. Although many EOs possess interesting perspectives for health, there are several drawbacks that have limited their use. Particularly, EOs have low water solubility and stability, together with high volatility and associated side effects [2]. These drawbacks could be overcome by selecting an appropriate formulation strategy to vehiculate EOs. Currently, the nanoencapsulation technology appears to be the most suitable approach. The EOs loaded nanocarriers can increase the oil chemical stability in the presence of air, light, moisture and high temperatures providing at the same time an easier and safer handling. Moreover, nanocarriers can improve the water solubility and control the oil delivery kinetic, assuring higher bioavailability and reducing the toxic side effects [3]. Methods: Crithmum maritimum L. (sea fennel) flowering aerial parts, Trachyspermum ammi (ajwain) and Pimpinella anisum (anise) dry fruits were subjected to hydrodistillation in a Clevenger-type apparatus for 3 h. Once obtained, EOs were characterized by gas chromatography-mass spectrometry (GC-MS) analysis. All the microemulsions were prepared by adding drop-by-drop deionised water to the oil phase under stirring, until the final concentration was obtained. The oil phase was prepared using the following methods: polysorbate 80 and alcohols (ethanol and glycerine) were added to the EOs or EOs-ethyloleate mixture. Microemulsions were characterized through polarizing optical microscopy and dynamic light scattering (DLS). Results: After having tested the oil phases at different concentrations, we determined the maximum amount of EOs that could be incorporated in order to obtain stable microemulsions: i.e. 1.5% for C. maritimum and T. ammi, and 1.15% for P. anisum in presence of 0.35% of ethyloleate used as diluted agent to avoid the precipitation and/or crystallization of EO. Moreover, keeping constant the concentration of the oil phase at 1.5%, we prepared binary mixtures at 1:1 (P. anisum plus C. maritimum) and 2:1 (P. anisum plus C. maritimum) ratios. In these last two cases the solubilizing action of ethyloleate was replaces by that of EOs. The effect of storage time on the droplets size distribution and microemulsion stability have been tested for 5 months. Conclusions:
Microencapsulation of commercial essential oils to enhance their physico-chemical properties and stability
L. Pavoni;M. Cespi;G. Bonacucina;F. Maggi
2018-01-01
Abstract
Purpose: Essential oils (EOs) are volatile liquids miscible in lipid and organic solvents, produced by higher plants and constituted by secondary metabolites. Thanks to their physico-chemical and biological properties, EOs are widely used in several industrial applications, especially pharmaceuticals, cosmetics, foodstuffs and biopesticides [1]. Although many EOs possess interesting perspectives for health, there are several drawbacks that have limited their use. Particularly, EOs have low water solubility and stability, together with high volatility and associated side effects [2]. These drawbacks could be overcome by selecting an appropriate formulation strategy to vehiculate EOs. Currently, the nanoencapsulation technology appears to be the most suitable approach. The EOs loaded nanocarriers can increase the oil chemical stability in the presence of air, light, moisture and high temperatures providing at the same time an easier and safer handling. Moreover, nanocarriers can improve the water solubility and control the oil delivery kinetic, assuring higher bioavailability and reducing the toxic side effects [3]. Methods: Crithmum maritimum L. (sea fennel) flowering aerial parts, Trachyspermum ammi (ajwain) and Pimpinella anisum (anise) dry fruits were subjected to hydrodistillation in a Clevenger-type apparatus for 3 h. Once obtained, EOs were characterized by gas chromatography-mass spectrometry (GC-MS) analysis. All the microemulsions were prepared by adding drop-by-drop deionised water to the oil phase under stirring, until the final concentration was obtained. The oil phase was prepared using the following methods: polysorbate 80 and alcohols (ethanol and glycerine) were added to the EOs or EOs-ethyloleate mixture. Microemulsions were characterized through polarizing optical microscopy and dynamic light scattering (DLS). Results: After having tested the oil phases at different concentrations, we determined the maximum amount of EOs that could be incorporated in order to obtain stable microemulsions: i.e. 1.5% for C. maritimum and T. ammi, and 1.15% for P. anisum in presence of 0.35% of ethyloleate used as diluted agent to avoid the precipitation and/or crystallization of EO. Moreover, keeping constant the concentration of the oil phase at 1.5%, we prepared binary mixtures at 1:1 (P. anisum plus C. maritimum) and 2:1 (P. anisum plus C. maritimum) ratios. In these last two cases the solubilizing action of ethyloleate was replaces by that of EOs. The effect of storage time on the droplets size distribution and microemulsion stability have been tested for 5 months. Conclusions:I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
